Merge pull request #2259 from stevecheckoway/improve-test-output

Color test output and shorten chapter paths

.gitattributes

@@ -2,7 +2,7 @@
 
 * text=auto eol=lf
 *.rs rust
-*.woff -text
-*.ttf -text
-*.otf -text
-*.png -text
+*.woff binary
+*.ttf binary
+*.otf binary
+*.png binary

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -0,0 +1,45 @@
+name: Bug Report
+description: Create a report to help us improve
+labels: ["C-bug"]
+body:
+  - type: markdown
+    attributes:
+      value: Thanks for filing a 🐛 bug report 😄!
+  - type: textarea
+    id: problem
+    attributes:
+      label: Problem
+      description: >
+        Please provide a clear and concise description of what the bug is,
+        including what currently happens and what you expected to happen.
+    validations:
+      required: true
+  - type: textarea
+    id: steps
+    attributes:
+      label: Steps
+      description: Please list the steps to reproduce the bug.
+      placeholder: |
+        1.
+        2.
+        3.
+  - type: textarea
+    id: possible-solutions
+    attributes:
+      label: Possible Solution(s)
+      description: >
+        Not obligatory, but suggest a fix/reason for the bug,
+        or ideas how to implement the addition or change.
+  - type: textarea
+    id: notes
+    attributes:
+      label: Notes
+      description: Provide any additional notes that might be helpful.
+  - type: textarea
+    id: version
+    attributes:
+      label: Version
+      description: >
+        Please paste the output of running `mdbook --version` or which version
+        of the library you are using.
+      render: text

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -0,0 +1,28 @@
+name: Enhancement
+description: Suggest an idea for enhancing mdBook
+labels: ["C-enhancement"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for filing a 🙋 feature request 😄!
+  - type: textarea
+    id: problem
+    attributes:
+      label: Problem
+      description: >
+        Please provide a clear description of your use case and the problem
+        this feature request is trying to solve.
+    validations:
+      required: true
+  - type: textarea
+    id: solution
+    attributes:
+      label: Proposed Solution
+      description: >
+        Please provide a clear and concise description of what you want to happen.
+  - type: textarea
+    id: notes
+    attributes:
+      label: Notes
+      description: Provide any additional context or information that might be helpful.

.github/ISSUE_TEMPLATE/question.yml

@@ -0,0 +1,24 @@
+name: Question
+description: Have a question on how to use mdBook?
+labels: ["C-question"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Got a question on how to do something with mdBook?
+  - type: textarea
+    id: question
+    attributes:
+      label: Question
+      description: >
+        Enter your question here. Please try to provide as much detail as possible.
+    validations:
+      required: true
+  - type: textarea
+    id: version
+    attributes:
+      label: Version
+      description: >
+        Please paste the output of running `mdbook --version` or which version
+        of the library you are using.
+      render: text

.github/workflows/deploy.yml

@@ -0,0 +1,73 @@
+name: Deploy
+on:
+  release:
+    types: [created]
+
+defaults:
+  run:
+    shell: bash
+
+permissions:
+  contents: write
+
+jobs:
+  release:
+    name: Deploy Release
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        target:
+          - aarch64-unknown-linux-musl
+          - x86_64-unknown-linux-gnu
+          - x86_64-unknown-linux-musl
+          - x86_64-apple-darwin
+          - x86_64-pc-windows-msvc
+        include:
+          - target: aarch64-unknown-linux-musl
+            os: ubuntu-20.04
+          - target: x86_64-unknown-linux-gnu
+            os: ubuntu-20.04
+          - target: x86_64-unknown-linux-musl
+            os: ubuntu-20.04
+          - target: x86_64-apple-darwin
+            os: macos-latest
+          - target: x86_64-pc-windows-msvc
+            os: windows-latest
+    steps:
+    - uses: actions/checkout@master
+    - name: Install Rust
+      run: ci/install-rust.sh stable ${{ matrix.target }}
+    - name: Build asset
+      run: ci/make-release-asset.sh ${{ matrix.os }} ${{ matrix.target }}
+    - name: Update release with new asset
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      run: gh release upload $MDBOOK_TAG $MDBOOK_ASSET
+  pages:
+    name: GitHub Pages
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@master
+    - name: Install Rust (rustup)
+      run: rustup update stable --no-self-update && rustup default stable
+    - name: Build book
+      run: cargo run -- build guide
+    - name: Deploy to GitHub
+      env:
+        GITHUB_DEPLOY_KEY: ${{ secrets.GITHUB_DEPLOY_KEY }}
+      run: |
+        touch guide/book/.nojekyll
+        curl -LsSf https://raw.githubusercontent.com/rust-lang/simpleinfra/master/setup-deploy-keys/src/deploy.rs | rustc - -o /tmp/deploy
+        cd guide/book
+        /tmp/deploy
+  publish:
+    name: Publish to crates.io
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@master
+      - name: Install Rust (rustup)
+        run: rustup update stable --no-self-update && rustup default stable
+      - name: Publish
+        env:
+          CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}
+        run: cargo publish --no-verify

.github/workflows/main.yml

@@ -0,0 +1,66 @@
+name: CI
+on:
+  pull_request:
+  merge_group:
+
+jobs:
+  test:
+    name: Test
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        build: [stable, beta, nightly, macos, windows, msrv]
+        include:
+          - build: stable
+            os: ubuntu-latest
+            rust: stable
+          - build: beta
+            os: ubuntu-latest
+            rust: beta
+          - build: nightly
+            os: ubuntu-latest
+            rust: nightly
+          - build: macos
+            os: macos-latest
+            rust: stable
+          - build: windows
+            os: windows-latest
+            rust: stable
+          - build: msrv
+            os: ubuntu-20.04
+            # sync MSRV with docs: guide/src/guide/installation.md and Cargo.toml
+            rust: 1.71.0
+    steps:
+    - uses: actions/checkout@v3
+    - name: Install Rust
+      run: bash ci/install-rust.sh ${{ matrix.rust }}
+    - name: Build and run tests
+      run: cargo test --locked
+    - name: Test no default
+      run: cargo test --no-default-features
+
+  rustfmt:
+    name: Rustfmt
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - name: Install Rust
+      run: rustup update stable && rustup default stable && rustup component add rustfmt
+    - run: cargo fmt --check
+
+  # The success job is here to consolidate the total success/failure state of
+  # all other jobs. This job is then included in the GitHub branch protection
+  # rule which prevents merges unless all other jobs are passing. This makes
+  # it easier to manage the list of jobs via this yml file and to prevent
+  # accidentally adding new jobs without also updating the branch protections.
+  success:
+    name: Success gate
+    if: always()
+    needs:
+      - test
+      - rustfmt
+    runs-on: ubuntu-latest
+    steps:
+      - run: jq --exit-status 'all(.result == "success")' <<< '${{ toJson(needs) }}'
+      - name: Done
+        run: exit 0

.gitignore

@@ -4,8 +4,15 @@ target
 .DS_Store
 
 book-test
-book-example/book
+guide/book
 
 .vscode
 tests/dummy_book/book/
+test_book/book/
 
+# Ignore Jetbrains specific files.
+.idea/
+
+# Ignore Vim temporary and swap files.
+*.sw?
+*~

.travis.yml

@@ -1,48 +0,0 @@
-language: rust
-
-rust:
-  - stable
-  - beta
-  - nightly
-
-os:
-  - linux
-  - osx
-
-cache: 
-  timeout: 360
-  cargo: true
-
-before_cache:
-  - chmod -R a+r $HOME/.cargo
-
-env:
-  global:
-    - CRATE_NAME=mdbook
-
-script:
-  - cargo test --all
-  - cargo test --all --no-default-features
-
-before_deploy:
-  - sh ci/before_deploy.sh
-
-deploy:
-  provider: releases
-  api_key:
-    - secure: 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
-  file_glob: true
-  file: "$CRATE_NAME-$TRAVIS_TAG-$TARGET.*"
-  on:
-    condition: "$TRAVIS_RUST_VERSION = stable"
-    tags: true
-  skip_cleanup: true
-
-branches:
-  only:
-    - master
-    - /^v\d+\.\d+\.\d+.*$/
-
-notifications:
-  email:
-    on_success: never

CODE_OF_CONDUCT.md

@@ -0,0 +1,3 @@
+# The Rust Code of Conduct
+
+The Code of Conduct for this repository [can be found online](https://www.rust-lang.org/conduct.html).

CONTRIBUTING.md

@@ -5,33 +5,41 @@ Welcome stranger!
 If you have come here to learn how to contribute to mdBook, we have some tips for you!
 
 First of all, don't hesitate to ask questions!
-Use the [issue tracker](https://github.com/rust-lang-nursery/mdBook/issues), no question is too simple.
-If we don't respond in a couple of days, ping us @Michael-F-Bryan, @budziq, @steveklabnik, @frewsxcv it might just be that we forgot. :wink:
+Use the [issue tracker](https://github.com/rust-lang/mdBook/issues), no question is too simple.
+
+### Issue assignment
+
+**:warning: Important :warning:**
+
+Before working on pull request, please ping us on the corresponding issue.
+The current PR backlog is beyond what we can process at this time.
+Only issues that have an [`E-Help-wanted`](https://github.com/rust-lang/mdBook/labels/E-Help-wanted) or [`Feature accepted`](https://github.com/rust-lang/mdBook/labels/Feature%20accepted) label will likely receive reviews.
+If there isn't already an open issue for what you want to work on, please open one first to see if it is something we would be available to review.
 
 ### Issues to work on
 
-Any issue is up for the grabbing, but if you are starting out, you might be interested in the
-[E-Easy issues](https://github.com/rust-lang-nursery/mdBook/issues?q=is%3Aopen+is%3Aissue+label%3AE-Easy).
+If you are starting out, you might be interested in the
+[E-Easy issues](https://github.com/rust-lang/mdBook/issues?q=is%3Aopen+is%3Aissue+label%3AE-Easy).
 Those are issues that are considered more straightforward for beginners to Rust or the codebase itself.
-These issues can be a good launching pad for more involved issues. Easy tasks for a first time contribution
-include documentation improvements, new tests, examples, updating dependencies, etc.
+These issues can be a good launching pad for more involved issues.
+Easy tasks for a first time contribution include documentation improvements, new tests, examples, updating dependencies, etc.
 
 If you come from a web development background, you might be interested in issues related to web technologies tagged
-[A-JavaScript](https://github.com/rust-lang-nursery/mdBook/issues?q=is%3Aopen+is%3Aissue+label%3AA-JavaScript),
-[A-Style](https://github.com/rust-lang-nursery/mdBook/issues?q=is%3Aopen+is%3Aissue+label%3AA-Style),
-[A-HTML](https://github.com/rust-lang-nursery/mdBook/issues?q=is%3Aopen+is%3Aissue+label%3AA-HTML) or
-[A-Mobile](https://github.com/rust-lang-nursery/mdBook/issues?q=is%3Aopen+is%3Aissue+label%3AA-Mobile).
+[A-JavaScript](https://github.com/rust-lang/mdBook/issues?q=is%3Aopen+is%3Aissue+label%3AA-JavaScript),
+[A-Style](https://github.com/rust-lang/mdBook/issues?q=is%3Aopen+is%3Aissue+label%3AA-Style),
+[A-HTML](https://github.com/rust-lang/mdBook/issues?q=is%3Aopen+is%3Aissue+label%3AA-HTML) or
+[A-Mobile](https://github.com/rust-lang/mdBook/issues?q=is%3Aopen+is%3Aissue+label%3AA-Mobile).
 
-When you decide you want to work on a specific issue, ping us on that issue so that we can assign it to you.
+When you decide you want to work on a specific issue, and it isn't already assigned to someone else, assign the issue to yourself by leaving a comment with the text `@rustbot claim`.
 Again, do not hesitate to ask questions. We will gladly mentor anyone that want to tackle an issue.
 
 Issues on the issue tracker are categorized with the following labels:
 
 - **A**-prefixed labels state which area of the project an issue relates to.
 - **E**-prefixed labels show an estimate of the experience necessary to fix the issue.
-- **M**-prefixed labels are meta-issues used for questions, discussions, or tracking issues
+- **M**-prefixed labels are meta-issues regarding the management of the mdBook project itself
 - **S**-prefixed labels show the status of the issue
-- **T**-prefixed labels show the type of issue
+- **C**-prefixed labels show the category of issue
 
 ### Building mdBook
 
@@ -41,20 +49,127 @@ mdBook builds on stable Rust, if you want to build mdBook from source, here are
 0. Clone this repository with git.
 
    ```
-   git clone https://github.com/rust-lang-nursery/mdBook.git
+   git clone https://github.com/rust-lang/mdBook.git
    ```
 0. Navigate into the newly created `mdBook` directory
 0. Run `cargo build`
 
-The resulting binary can be found in `mdBook/target/debug/` under the name `mdBook` or `mdBook.exe`.
+The resulting binary can be found in `mdBook/target/debug/` under the name `mdbook` or `mdbook.exe`.
+
+### Code Quality
+
+We love code quality and Rust has some excellent tools to assist you with contributions.
+
+#### Formatting Code with rustfmt
+
+Before you make your Pull Request to the project, please run it through the `rustfmt` utility.
+This will ensure we have good quality source code that is better for us all to maintain.
+
+[rustfmt](https://github.com/rust-lang/rustfmt) has a lot more information on the project.
+The quick guide is
+
+1. Install it (`rustfmt` is usually installed by default via [rustup](https://rustup.rs/)):
+    ```
+    rustup component add rustfmt
+    ```
+1. You can now run `rustfmt` on a single file simply by...
+    ```
+    rustfmt src/path/to/your/file.rs
+    ```
+   ... or you can format the entire project with
+   ```
+   cargo fmt
+   ```
+   When run through `cargo` it will format all bin and lib files in the current package.
+
+For more information, such as running it from your favourite editor, please see the `rustfmt` project. [rustfmt](https://github.com/rust-lang/rustfmt)
+
+
+#### Finding Issues with Clippy
+
+[Clippy](https://doc.rust-lang.org/clippy/) is a code analyser/linter detecting mistakes, and therefore helps to improve your code.
+Like formatting your code with `rustfmt`, running clippy regularly and before your Pull Request will help us maintain awesome code.
+
+1. To install
+    ```
+    rustup component add clippy
+    ```
+2. Running clippy
+    ```
+    cargo clippy
+    ```
+
+### Change requirements
+
+Please consider the following when making a change:
+
+* Almost all changes that modify the Rust code must be accompanied with a test.
+
+* Almost all features and changes must update the documentation.
+  mdBook has the [mdBook Guide](https://rust-lang.github.io/mdBook/) whose source is at <https://github.com/rust-lang/mdBook/tree/master/guide>.
+
+* Almost all Rust items should be documented with doc comments.
+  See the [Rustdoc Book](https://doc.rust-lang.org/rustdoc/) for more information on writing doc comments.
+
+* Breaking the API can only be done in major SemVer releases.
+  These are done very infrequently, so it is preferred to avoid these when possible.
+  See [SemVer Compatibility](https://doc.rust-lang.org/cargo/reference/semver.html) for more information on what a SemVer breaking change is.
+
+  (Note: At this time, some SemVer breaking changes are inevitable due to the current code structure.
+  An example is adding new fields to the config structures.
+  These are intended to be fixed in the next major release.)
+
+* Similarly, the CLI interface is considered to be stable.
+  Care should be taken to avoid breaking existing workflows.
+
+* Check out the [Rust API Guidelines](https://rust-lang.github.io/api-guidelines/) for guidelines on designing the API.
 
 ### Making a pull-request
 
 When you feel comfortable that your changes could be integrated into mdBook, you can create a pull-request on GitHub.
 One of the core maintainers will then approve the changes or request some changes before it gets merged.
 
-If you want to make your pull-request even better, you might want to run [Clippy](https://github.com/Manishearth/rust-clippy)
-and [rustfmt](https://github.com/rust-lang-nursery/rustfmt) on the code first.
-This is not a requirement though and will never block a pull-request from being merged.
-
 That's it, happy contributions! :tada: :tada: :tada:
+
+## Browser compatibility and testing
+
+Currently we don't have a strict browser compatibility matrix due to our limited resources.
+We generally strive to keep mdBook compatible with a relatively recent browser on all of the most major platforms.
+That is, supporting Chrome, Safari, Firefox, Edge on Windows, macOS, Linux, iOS, and Android.
+If possible, do your best to avoid breaking older browser releases.
+
+Any change to the HTML or styling is encouraged to manually check on as many browsers and platforms that you can.
+Unfortunately at this time we don't have any automated UI or browser testing, so your assistance in testing is appreciated.
+
+## Updating highlight.js
+
+The following are instructions for updating [highlight.js](https://highlightjs.org/).
+
+1. Clone the repository at <https://github.com/highlightjs/highlight.js>
+1. Check out a tagged release (like `10.1.1`).
+1. Run `npm install`
+1. Run `node tools/build.js :common apache armasm coffeescript d handlebars haskell http julia nginx nim nix properties r scala x86asm yaml`
+1. Compare the language list that it spits out to the one in [`syntax-highlighting.md`](https://github.com/camelid/mdBook/blob/master/guide/src/format/theme/syntax-highlighting.md). If any are missing, add them to the list and rebuild (and update these docs). If any are added to the common set, add them to `syntax-highlighting.md`.
+1. Copy `build/highlight.min.js` to mdbook's directory [`highlight.js`](https://github.com/rust-lang/mdBook/blob/master/src/theme/highlight.js).
+1. Be sure to check the highlight.js [CHANGES](https://github.com/highlightjs/highlight.js/blob/main/CHANGES.md) for any breaking changes. Breaking changes that would affect users will need to wait until the next major release.
+1. Build mdbook with the new file and build some books with the new version and compare the output with a variety of languages to see if anything changes. The [test_book](https://github.com/rust-lang/mdBook/tree/master/test_book) contains a chapter with many languages to examine.
+
+## Publishing new releases
+
+Instructions for mdBook maintainers to publish a new release:
+
+1. Create a PR to update the version and update the CHANGELOG:
+    1. Update the version in `Cargo.toml`
+    2. Run `cargo test` to verify that everything is passing, and to update `Cargo.lock`.
+    3. Double-check for any SemVer breaking changes.
+       Try [`cargo-semver-checks`](https://crates.io/crates/cargo-semver-checks), though beware that the current version of mdBook isn't properly adhering to SemVer due to the lack of `#[non_exhaustive]` and other issues. See https://github.com/rust-lang/mdBook/issues/1835.
+    4. Update `CHANGELOG.md` with any changes that users may be interested in.
+    5. Update `continuous-integration.md` to update the version number for the installation instructions.
+    6. Commit the changes, and open a PR.
+2. After the PR has been merged, create a release in GitHub. This can either be done in the GitHub web UI, or on the command-line:
+   ```bash
+   MDBOOK_VERS="`cargo read-manifest | jq -r .version`" ; \
+    gh release create -R rust-lang/mdbook v$MDBOOK_VERS \
+        --title v$MDBOOK_VERS \
+        --notes "See https://github.com/rust-lang/mdBook/blob/master/CHANGELOG.md#mdbook-${MDBOOK_VERS//.} for a complete list of changes."
+   ```

Cargo.toml

@@ -1,66 +1,74 @@
 [package]
 name = "mdbook"
-version = "0.2.2-alpha.0"
+version = "0.4.37"
 authors = [
     "Mathieu David <mathieudavid@mathieudavid.org>",
     "Michael-F-Bryan <michaelfbryan@gmail.com>",
     "Matt Ickstadt <mattico8@gmail.com>"
 ]
-description = "Create books from markdown files"
-documentation = "http://rust-lang-nursery.github.io/mdBook/index.html"
-repository = "https://github.com/rust-lang-nursery/mdBook"
+documentation = "https://rust-lang.github.io/mdBook/index.html"
+edition = "2021"
+exclude = ["/guide/*"]
 keywords = ["book", "gitbook", "rustbook", "markdown"]
 license = "MPL-2.0"
 readme = "README.md"
-exclude = ["book-example/*"]
+repository = "https://github.com/rust-lang/mdBook"
+description = "Creates a book from markdown files"
+rust-version = "1.71"
 
 [dependencies]
-clap = "2.24"
-chrono = "0.4"
-handlebars = "1.0"
-serde = "1.0"
-serde_derive = "1.0"
-error-chain = "0.12"
-serde_json = "1.0"
-pulldown-cmark = "0.1.2"
-lazy_static = "1.0"
-log = "0.4"
-env_logger = "0.5"
-toml = "0.4"
-memchr = "2.0"
-open = "1.1"
-regex = "1.0.0"
-tempfile = "3.0"
-itertools = "0.7"
-shlex = "0.1"
-toml-query = "0.7"
+anyhow = "1.0.71"
+chrono = { version = "0.4.24", default-features = false, features = ["clock"] }
+clap = { version = "4.3.12", features = ["cargo", "wrap_help"] }
+clap_complete = "4.3.2"
+once_cell = "1.17.1"
+env_logger = "0.11.1"
+handlebars = "5.0"
+log = "0.4.17"
+memchr = "2.5.0"
+opener = "0.6.1"
+pulldown-cmark = { version = "0.10.0", default-features = false, features = ["html"] }
+regex = "1.8.1"
+serde = { version = "1.0.163", features = ["derive"] }
+serde_json = "1.0.96"
+shlex = "1.3.0"
+tempfile = "3.4.0"
+toml = "0.5.11" # Do not update, see https://github.com/rust-lang/mdBook/issues/2037
+topological-sort = "0.2.2"
 
 # Watch feature
-notify = { version = "4.0", optional = true }
+notify = { version = "6.1.1", optional = true }
+notify-debouncer-mini = { version = "0.4.1", optional = true }
+ignore = { version = "0.4.20", optional = true }
+pathdiff = { version = "0.2.1", optional = true }
 
 # Serve feature
-iron = { version = "0.6", optional = true }
-staticfile = { version = "0.5", optional = true }
-ws = { version = "0.7", optional = true}
+futures-util = { version = "0.3.28", optional = true }
+tokio = { version = "1.28.1", features = ["macros", "rt-multi-thread"], optional = true }
+warp = { version = "0.3.6", default-features = false, features = ["websocket"], optional = true }
 
 # Search feature
-elasticlunr-rs = { version = "2.3", optional = true, default-features = false }
-ammonia = { version = "1.1", optional = true }
+elasticlunr-rs = { version = "3.0.2", optional = true }
+ammonia = { version = "3.3.0", optional = true }
 
 [dev-dependencies]
-select = "0.4"
-pretty_assertions = "0.5"
-walkdir = "2.0"
-pulldown-cmark-to-cmark = "1.1.0"
+assert_cmd = "2.0.11"
+predicates = "3.0.3"
+select = "0.6.0"
+semver = "1.0.17"
+pretty_assertions = "1.3.0"
+walkdir = "2.3.3"
 
 [features]
-default = ["output", "watch", "serve", "search"]
-debug = []
-output = []
-watch = ["notify"]
-serve = ["iron", "staticfile", "ws"]
-search = ["elasticlunr-rs", "ammonia"]
+default = ["watch", "serve", "search"]
+watch = ["dep:notify", "dep:notify-debouncer-mini", "dep:ignore", "dep:pathdiff"]
+serve = ["dep:futures-util", "dep:tokio", "dep:warp"]
+search = ["dep:elasticlunr-rs", "dep:ammonia"]
 
 [[bin]]
 doc = false
 name = "mdbook"
+
+[[example]]
+name = "nop-preprocessor"
+test = true

README.md

@@ -1,191 +1,20 @@
 # mdBook
 
-<table>
-    <tr>
-        <td><strong>Linux / OS X</strong></td>
-        <td>
-            <a href="https://travis-ci.org/rust-lang-nursery/mdBook"><img src="https://travis-ci.org/rust-lang-nursery/mdBook.svg?branch=master"></a>
-        </td>
-    </tr>
-    <tr>
-        <td><strong>Windows</strong></td>
-        <td>
-            <a href="https://ci.appveyor.com/project/rust-lang-libs/mdbook"><img src="https://ci.appveyor.com/api/projects/status/ysyke2rvo85sni55?svg=true"></a>
-        </td>
-    </tr>
-    <tr>
-        <td colspan="2">
-            <a href="https://crates.io/crates/mdbook"><img src="https://img.shields.io/crates/v/mdbook.svg"></a>
-            <a href="LICENSE"><img src="https://img.shields.io/github/license/rust-lang-nursery/mdBook.svg"></a>
-        </td>
-    </tr>
-</table>
+[![Build Status](https://github.com/rust-lang/mdBook/workflows/CI/badge.svg?event=push)](https://github.com/rust-lang/mdBook/actions?workflow=CI)
+[![crates.io](https://img.shields.io/crates/v/mdbook.svg)](https://crates.io/crates/mdbook)
+[![LICENSE](https://img.shields.io/github/license/rust-lang/mdBook.svg)](LICENSE)
 
 mdBook is a utility to create modern online books from Markdown files.
 
+Check out the **[User Guide]** for a list of features and installation and usage information.
+The User Guide also serves as a demonstration to showcase what a book looks like.
 
-## What does it look like?
-
-The [User Guide] for mdBook has been written in Markdown and is using mdBook to
-generate the online book-like website you can read. The documentation uses the
-latest version on GitHub and showcases the available features.
-
-## Installation
-
-There are multiple ways to install mdBook.
-
-1. **Binaries**
-
-   Binaries are available for download [here][releases]. Make sure to put the
-   path to the binary into your `PATH`.
-
-2. **From Crates.io**
-
-   This requires at least [Rust] 1.20 and Cargo to be installed. Once you have installed
-   Rust, type the following in the terminal:
-
-   ```
-   cargo install mdbook
-   ```
-
-   This will download and compile mdBook for you, the only thing left to do is
-   to add the Cargo bin directory to your `PATH`.
-
-   **Note for automatic deployment**
-
-   If you are using a script to do automatic deployments using Travis or
-   another CI server, we recommend that you specify a semver version range for
-   mdBook when you install it through your script!
-
-   This will constrain the server to install the latests **non-breaking**
-   version of mdBook and will prevent your books from failing to build because
-   we released a new version. For example:
-
-   ```
-   cargo install mdbook --vers "^0.1.0"
-   ```
-
-3. **From Git**  
-
-   The version published to crates.io will ever so slightly be behind the
-   version hosted here on GitHub. If you need the latest version you can build
-   the git version of mdBook yourself. Cargo makes this ***super easy***!
-
-   ```
-   cargo install --git https://github.com/rust-lang-nursery/mdBook.git mdbook
-   ```
-
-   Again, make sure to add the Cargo bin directory to your `PATH`.
-
-4. **For Contributions**  
-
-   If you want to contribute to mdBook you will have to clone the repository on
-   your local machine:
-
-   ```
-   git clone https://github.com/rust-lang-nursery/mdBook.git
-   ```
-
-   `cd` into `mdBook/` and run
-
-   ```
-   cargo build
-   ```
-
-   The resulting binary can be found in `mdBook/target/debug/` under the name
-   `mdBook` or `mdBook.exe`.
-
-
-## Usage
-
-mdBook will primarily be used as a command line tool, even though it exposes
-all its functionality as a Rust crate for integration in other projects.
-
-Here are the main commands you will want to run. For a more exhaustive
-explanation, check out the [User Guide].
-
-- `mdbook init`
-
-    The init command will create a directory with the minimal boilerplate to
-    start with.
-
-    ```
-    book-test/
-    ├── book
-    └── src
-        ├── chapter_1.md
-        └── SUMMARY.md
-    ```
-
-    `book` and `src` are both directories. `src` contains the markdown files
-    that will be used to render the output to the `book` directory.
-
-    Please, take a look at the [CLI docs] for more information and some neat tricks.
-
-- `mdbook build`
-
-    This is the command you will run to render your book, it reads the
-    `SUMMARY.md` file to understand the structure of your book, takes the
-    markdown files in the source directory as input and outputs static html
-    pages that you can upload to a server.
-
-- `mdbook watch`
-
-    When you run this command, mdbook will watch your markdown files to rebuild
-    the book on every change. This avoids having to come back to the terminal
-    to type `mdbook build` over and over again.
-
-- `mdbook serve`
-
-    Does the same thing as `mdbook watch` but additionally serves the book at
-    `http://localhost:3000` (port is changeable) and reloads the browser when a
-    change occurs.
-
-- `mdbook clean`
-
-    Delete directory in which generated book is located.
-
-
-### As a library
-
-Aside from the command line interface, this crate can also be used as a
-library. This means that you could integrate it in an existing project, like a
-web-app for example. Since the command line interface is just a wrapper around
-the library functionality, when you use this crate as a library you have full
-access to all the functionality of the command line interface with an easy to
-use API and more!
-
-See the [User Guide] and the [API docs] for more information.
-
-## Contributions
-
-Contributions are highly appreciated and encouraged! Don't hesitate to
-participate to discussions in the issues, propose new features and ask for
-help.
-
-If you are just starting out with Rust, there are a series of issus that are
-tagged [E-Easy] and **we will gladly mentor you** so that you can successfully
-go through the process of fixing a bug or adding a new feature! Let us know if
-you need any help.
-
-For more info about contributing, check out our [contribution guide] who helps
-you go through the build and contribution process!
-
-There is also a [rendered version][master-docs] of the latest API docs
-available, for those hacking on `master`.
-
+If you are interested in contributing to the development of mdBook, check out the [Contribution Guide].
 
 ## License
 
 All the code in this repository is released under the ***Mozilla Public License v2.0***, for more information take a look at the [LICENSE] file.
 
-
-[User Guide]: https://rust-lang-nursery.github.io/mdBook/
-[API docs]: https://docs.rs/mdbook/*/mdbook/
-[E-Easy]: https://github.com/rust-lang-nursery/mdBook/issues?q=is%3Aopen+is%3Aissue+label%3AE-Easy
-[contribution guide]: https://github.com/rust-lang-nursery/mdBook/blob/master/CONTRIBUTING.md
-[LICENSE]: https://github.com/rust-lang-nursery/mdBook/blob/master/LICENSE
-[releases]: https://github.com/rust-lang-nursery/mdBook/releases
-[Rust]: https://www.rust-lang.org/
-[CLI docs]: http://rust-lang-nursery.github.io/mdBook/cli/init.html
-[master-docs]: http://rust-lang-nursery.github.io/mdBook/mdbook/
+[User Guide]: https://rust-lang.github.io/mdBook/
+[contribution guide]: https://github.com/rust-lang/mdBook/blob/master/CONTRIBUTING.md
+[LICENSE]: https://github.com/rust-lang/mdBook/blob/master/LICENSE

appveyor.yml

@@ -1,64 +0,0 @@
-environment:
-  global:
-    PROJECT_NAME: mdBook
-  matrix:
-    # Stable channel
-    - TARGET: i686-pc-windows-msvc
-      RUST_CHANNEL: stable
-    - TARGET: x86_64-pc-windows-msvc
-      RUST_CHANNEL: stable
-    # Beta channel
-    - TARGET: i686-pc-windows-msvc
-      RUST_CHANNEL: beta
-    - TARGET: x86_64-pc-windows-msvc
-      RUST_CHANNEL: beta
-    # Nightly channel
-    - TARGET: i686-pc-windows-msvc
-      RUST_CHANNEL: nightly
-    - TARGET: x86_64-pc-windows-msvc
-      RUST_CHANNEL: nightly
-
-# Install Rust and Cargo
-install:
-  - ps: >-
-      If ($Env:TARGET -eq 'x86_64-pc-windows-gnu') {
-        $Env:PATH += ';C:\msys64\mingw64\bin'
-      } ElseIf ($Env:TARGET -eq 'i686-pc-windows-gnu') {
-        $Env:PATH += ';C:\msys64\mingw32\bin'
-      }
-  - curl -sSf -o rustup-init.exe https://win.rustup.rs/
-  - rustup-init.exe -y --default-host %TARGET% --default-toolchain %RUST_CHANNEL%
-  - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
-  - rustc -Vv
-  - cargo -V
-
-build: false
-
-# Equivalent to Travis' `script` phase
-test_script:
-  - cargo test --all
-  - cargo test --all --no-default-features
-
-before_deploy:
-  # Generate artifacts for release
-  - cargo rustc --bin mdbook --release -- -C lto
-  - mkdir staging
-  - copy target\release\mdbook.exe staging
-  - cd staging
-  - 7z a ../%PROJECT_NAME%-%APPVEYOR_REPO_TAG_NAME%-%TARGET%.zip *
-  - appveyor PushArtifact ../%PROJECT_NAME%-%APPVEYOR_REPO_TAG_NAME%-%TARGET%.zip
-
-deploy:
-  description: 'Windows release'
-  artifact: /.*\.zip/
-  auth_token:
-    secure: QQhjKVyz7mpjlyGhlXytbFQQfKFQWTahHkD+B0NzIUoEVqO7ZLWjnoWasvLqW4nE
-  provider: GitHub
-  on:
-    RUST_CHANNEL: stable
-    appveyor_repo_tag: true
-
-branches:
-  only:
-    - master
-    - /^v\d+\.\d+\.\d+.*$/

book-example/book.toml

@@ -1,19 +0,0 @@
-[book]
-title = "mdBook Documentation"
-description = "Create book from markdown files. Like Gitbook but implemented in Rust"
-authors = ["Mathieu David", "Michael-F-Bryan"]
-
-[output.html]
-mathjax-support = true
-
-[output.html.playpen]
-editable = true
-
-[output.html.search]
-limit-results = 20
-use-boolean-and = true
-boost-title = 2
-boost-hierarchy = 2
-boost-paragraph = 1
-expand = true
-heading-split-level = 2

book-example/src/README.md

@@ -1,25 +0,0 @@
-# mdBook
-
-**mdBook** is a command line tool and Rust crate to create books using Markdown
-files. It's very similar to Gitbook but written in
-[Rust](http://www.rust-lang.org).
-
-What you are reading serves as an example of the output of mdBook and at the
-same time as a high-level documentation.
-
-mdBook is free and open source, you can find the source code on
-[GitHub](https://github.com/rust-lang-nursery/mdBook). Issues and feature
-requests can be posted on the [GitHub issue
-tracker](https://github.com/rust-lang-nursery/mdBook/issues).
-
-## API docs
-
-Alongside this book you can also read the [API
-docs](https://docs.rs/mdbook/*/mdbook/) generated by Rustdoc if you would like
-to use mdBook as a crate or write a new renderer and need a more low-level
-overview.
-
-## License
-
-mdBook, all the source code, is released under the [Mozilla Public License
-v2.0](https://www.mozilla.org/MPL/2.0/).

book-example/src/cli/README.md

@@ -1,55 +0,0 @@
-# Command Line Tool
-
-mdBook can be used either as a command line tool or a [Rust
-crate](https://crates.io/crates/mdbook). Let's focus on the command line tool
-capabilities first.
-
-## Install From Binaries
-
-Precompiled binaries are provided for major platforms on a best-effort basis.
-Visit [the releases page](https://github.com/rust-lang-nursery/mdBook/releases)
-to download the appropriate version for your platform.
-
-## Install From Source
-
-mdBook can also be installed from source
-
-### Pre-requisite
-
-mdBook is written in **[Rust](https://www.rust-lang.org/)** and therefore needs
-to be compiled with **Cargo**. If you haven't already installed Rust, please go
-ahead and [install it](https://www.rust-lang.org/downloads.html) now.
-
-### Install Crates.io version
-
-Installing mdBook is relatively easy if you already have Rust and Cargo
-installed. You just have to type this snippet in your terminal:
-
-```bash
-cargo install mdbook
-```
-
-This will fetch the source code for the latest release from
-[Crates.io](https://crates.io/) and compile it. You will have to add Cargo's
-`bin` directory to your `PATH`.
-
-Run `mdbook help` in your terminal to verify if it works. Congratulations, you
-have installed mdBook!
-
-
-### Install Git version
-
-The **[git version](https://github.com/rust-lang-nursery/mdBook)** contains all
-the latest bug-fixes and features, that will be released in the next version on
-**Crates.io**, if you can't wait until the next release. You can build the git
-version yourself. Open your terminal and navigate to the directory of you
-choice. We need to clone the git repository and then build it with Cargo.
-
-```bash
-git clone --depth=1 https://github.com/rust-lang-nursery/mdBook.git
-cd mdBook
-cargo build --release
-```
-
-The executable `mdbook` will be in the `./target/release` folder, this should be
-added to the path.

book-example/src/cli/serve.md

@@ -1,49 +0,0 @@
-# The serve command
-
-The serve command is used to preview a book by serving it over HTTP at
-`localhost:3000` by default. Additionally it watches the book's directory for
-changes, rebuilding the book and refreshing clients for each change. A websocket
-connection is used to trigger the client-side refresh.
-
-#### Specify a directory
-
-The `serve` command can take a directory as an argument to use as the book's
-root instead of the current working directory.
-
-```bash
-mdbook serve path/to/book
-```
-
-#### Server options
-
-`serve` has four options: the HTTP port, the WebSocket port, the HTTP hostname
-to listen on, and the hostname for the browser to connect to for WebSockets.
-
-For example: suppose you have an nginx server for SSL termination which has a
-public address of 192.168.1.100 on port 80 and proxied that to 127.0.0.1 on port
-8000\. To run use the nginx proxy do:
-
-```bash
-mdbook serve path/to/book -p 8000 -n 127.0.0.1 --websocket-hostname 192.168.1.100
-```
-
-If you were to want live reloading for this you would need to proxy the
-websocket calls through nginx as well from `192.168.1.100:<WS_PORT>` to
-`127.0.0.1:<WS_PORT>`. The `-w` flag allows for the websocket port to be
-configured.
-
-#### --open
-
-When you use the `--open` (`-o`) flag, mdbook will open the book in your your
-default web browser after starting the server.
-
-#### --dest-dir
-
-The `--dest-dir` (`-d`) option allows you to change the output directory for the
-book. If not specified it will default to the value of the `build.build-dir` key
-in `book.toml`, or to `./book` relative to the book's root directory.
-
------
-
-***Note:*** *The `serve` command is for testing, and is not intended to be a
-complete HTTP server for a website.*

book-example/src/cli/watch.md

@@ -1,26 +0,0 @@
-# The watch command
-
-The `watch` command is useful when you want your book to be rendered on every
-file change. You could repeatedly issue `mdbook build` every time a file is
-changed. But using `mdbook watch` once will watch your files and will trigger a
-build automatically whenever you modify a file.
-
-#### Specify a directory
-
-The `watch` command can take a directory as an argument to use as the book's
-root instead of the current working directory.
-
-```bash
-mdbook watch path/to/book
-```
-
-#### --open
-
-When you use the `--open` (`-o`) option, mdbook will open the rendered book in
-your default web browser.
-
-#### --dest-dir
-
-The `--dest-dir` (`-d`) option allows you to change the output directory for the
-book. If not specified it will default to the value of the `build.build-dir` key
-in `book.toml`, or to `./book` relative to the book's root directory.

book-example/src/continuous-integration.md

@@ -1,56 +0,0 @@
-# Running `mdbook` in Continuous Integration
-
-While the following examples use Travis CI, their principles should
-straightforwardly transfer to other continuous integration providers as well.
-
-## Ensuring Your Book Builds and Tests Pass
-
-Here is a sample Travis CI `.travis.yml` configuration that ensures `mdbook
-build` and `mdbook test` run successfully. The key to fast CI turnaround times
-is caching `mdbook` installs, so that you aren't compiling `mdbook` on every CI
-run.
-
-```yaml
-language: rust
-sudo: false
-
-cache:
-  - cargo
-
-rust:
-  - stable
-
-before_script:
-  - (test -x $HOME/.cargo/bin/cargo-install-update || cargo install cargo-update)
-  - (test -x $HOME/.cargo/bin/mdbook || cargo install --vers "^0.1" mdbook)
-  - cargo install-update -a
-
-script:
-  - cd path/to/mybook && mdbook build && mdbook test
-```
-
-## Deploying Your Book to GitHub Pages
-
-Following these instructions will result in your book being published to GitHub
-pages after a successful CI run on your repository's `master` branch.
-
-First, create a new GitHub "Personal Access Token" with the "public_repo"
-permissions (or "repo" for private repositories). Go to your repository's Travis
-CI settings page and add an environment variable named `GITHUB_TOKEN` that is
-marked secure and *not* shown in the logs.
-
-Then, append this snippet to your `.travis.yml` and update the path to the
-`book` directory:
-
-```yaml
-deploy:
-  provider: pages
-  skip-cleanup: true
-  github-token: $GITHUB_TOKEN
-  local-dir: path/to/mybook/book
-  keep-history: false
-  on:
-    branch: master
-```
-
-That's it!

book-example/src/for_developers/preprocessors.md

@@ -1,97 +0,0 @@
-# Preprocessors
-
-A *preprocessor* is simply a bit of code which gets run immediately after the
-book is loaded and before it gets rendered, allowing you to update and mutate
-the book. Possible use cases are:
-
-- Creating custom helpers like `\{{#include /path/to/file.md}}`
-- Updating links so `[some chapter](some_chapter.md)` is automatically changed
-  to `[some chapter](some_chapter.html)` for the HTML renderer
-- Substituting in latex-style expressions (`$$ \frac{1}{3} $$`) with their
-  mathjax equivalents
-
-
-## Implementing a Preprocessor
-
-A preprocessor is represented by the `Preprocessor` trait.
-
-```rust
-pub trait Preprocessor {
-    fn name(&self) -> &str;
-    fn run(&self, ctx: &PreprocessorContext, book: &mut Book) -> Result<()>;
-}
-```
-
-Where the `PreprocessorContext` is defined as
-
-```rust
-pub struct PreprocessorContext {
-    pub root: PathBuf,
-    pub config: Config,
-}
-```
-
-## A complete Example
-
-The magic happens within the `run(...)` method of the
-[`Preprocessor`][preprocessor-docs] trait implementation.
-
-As direct access to the chapters is not possible, you will probably end up
-iterating them using `for_each_mut(...)`:
-
-```rust
-book.for_each_mut(|item: &mut BookItem| {
-    if let BookItem::Chapter(ref mut chapter) = *item {
-      eprintln!("{}: processing chapter '{}'", self.name(), chapter.name);
-      res = Some(
-          match Deemphasize::remove_emphasis(&mut num_removed_items, chapter) {
-              Ok(md) => {
-                  chapter.content = md;
-                  Ok(())
-              }
-              Err(err) => Err(err),
-          },
-      );
-  }
-});
-```
-
-The `chapter.content` is just a markdown formatted string, and you will have to
-process it in some way. Even though it's entirely possible to implement some
-sort of manual find & replace operation, if that feels too unsafe you can use
-[`pulldown-cmark`][pc] to parse the string into events and work on them instead.
-
-Finally you can use [`pulldown-cmark-to-cmark`][pctc] to transform these events
-back to a string.
-
-The following code block shows how to remove all emphasis from markdown, and do
-so safely.
-
-```rust
-fn remove_emphasis(num_removed_items: &mut i32, chapter: &mut Chapter) -> Result<String> {
-    let mut buf = String::with_capacity(chapter.content.len());
-    let events = Parser::new(&chapter.content).filter(|e| {
-        let should_keep = match *e {
-            Event::Start(Tag::Emphasis)
-            | Event::Start(Tag::Strong)
-            | Event::End(Tag::Emphasis)
-            | Event::End(Tag::Strong) => false,
-            _ => true,
-        };
-        if !should_keep {
-            *num_removed_items += 1;
-        }
-        should_keep
-    });
-    cmark(events, &mut buf, None)
-        .map(|_| buf)
-        .map_err(|err| Error::from(format!("Markdown serialization failed: {}", err)))
-}
-```
-
-For everything else, have a look [at the complete example][example].
-
-[preprocessor-docs]: https://docs.rs/mdbook/0.1.3/mdbook/preprocess/trait.Preprocessor.html
-[pc]: https://crates.io/crates/pulldown-cmark
-[pctc]: https://crates.io/crates/pulldown-cmark-to-cmark
-[example]: https://github.com/rust-lang-nursery/mdBook/blob/master/examples/de-emphasize.rs

book-example/src/format/config.md

@@ -1,217 +0,0 @@
-# Configuration
-
-You can configure the parameters for your book in the ***book.toml*** file.
-
-Here is an example of what a ***book.toml*** file might look like:
-
-```toml
-[book]
-title = "Example book"
-author = "John Doe"
-description = "The example book covers examples."
-
-[build]
-build-dir = "my-example-book"
-create-missing = false
-
-[output.html]
-additional-css = ["custom.css"]
-
-[output.html.search]
-limit-results = 15
-```
-
-## Supported configuration options
-
-It is important to note that **any** relative path specified in the in the
-configuration will always be taken relative from the root of the book where the
-configuration file is located.
-
-
-### General metadata
-
-This is general information about your book.
-
-- **title:** The title of the book
-- **authors:** The author(s) of the book
-- **description:** A description for the book, which is added as meta
-  information in the html `<head>` of each page
-- **src:** By default, the source directory is found in the directory named
-  `src` directly under the root folder. But this is configurable with the `src`
-  key in the configuration file.
-
-**book.toml**
-```toml
-[book]
-title = "Example book"
-authors = ["John Doe", "Jane Doe"]
-description = "The example book covers examples."
-src = "my-src"  # the source files will be found in `root/my-src` instead of `root/src`
-```
-
-### Build options
-
-This controls the build process of your book.
-
-- **build-dir:** The directory to put the rendered book in. By default this is
-  `book/` in the book's root directory.
-- **create-missing:** By default, any missing files specified in `SUMMARY.md`
-  will be created when the book is built (i.e. `create-missing = true`). If this
-  is `false` then the build process will instead exit with an error if any files
-  do not exist.
-- **preprocess:** Specify which preprocessors to be applied. Default is
-  `["links", "index"]`. To disable default preprocessors, pass an empty array
-  `[]` in.
-
-
-The following preprocessors are available and included by default:
-
-- `links`: Expand the `{{# playpen}}` and `{{# include}}` handlebars helpers in
-  a chapter.
-- `index`: Convert all chapter files named `README.md` into `index.md`. That is
-  to say, all `README.md` would be rendered to an index file `index.html` in the
-  rendered book.
-
-
-**book.toml**
-```toml
-[build]
-build-dir = "build"
-create-missing = false
-preprocess = ["links", "index"]
-```
-
-### HTML renderer options
-The HTML renderer has a couple of options as well. All the options for the
-renderer need to be specified under the TOML table `[output.html]`.
-
-The following configuration options are available:
-
-- **theme:** mdBook comes with a default theme and all the resource files needed
-  for it. But if this option is set, mdBook will selectively overwrite the theme
-  files with the ones found in the specified folder.
-- **curly-quotes:** Convert straight quotes to curly quotes, except for those
-  that occur in code blocks and code spans. Defaults to `false`.
-- **google-analytics:** If you use Google Analytics, this option lets you enable
-  it by simply specifying your ID in the configuration file.
-- **additional-css:** If you need to slightly change the appearance of your book
-  without overwriting the whole style, you can specify a set of stylesheets that
-  will be loaded after the default ones where you can surgically change the
-  style.
-- **additional-js:** If you need to add some behaviour to your book without
-  removing the current behaviour, you can specify a set of JavaScript files that
-  will be loaded alongside the default one.
-- **no-section-label:** mdBook by defaults adds section label in table of
-  contents column. For example, "1.", "2.1". Set this option to true to disable
-  those labels. Defaults to `false`.
-- **playpen:** A subtable for configuring various playpen settings.
-- **search:** A subtable for configuring the in-browser search functionality.
-  mdBook must be compiled with the `search` feature enabled (on by default).
-
-Available configuration options for the `[output.html.playpen]` table:
-
-- **editable:** Allow editing the source code. Defaults to `false`.
-- **copy-js:** Copy JavaScript files for the editor to the output directory.
-  Defaults to `true`.
-
-[Ace]: https://ace.c9.io/
-
-Available configuration options for the `[output.html.search]` table:
-
-- **enable:** Enables the search feature. Defaults to `true`.
-- **limit-results:** The maximum number of search results. Defaults to `30`.
-- **teaser-word-count:** The number of words used for a search result teaser.
-  Defaults to `30`.
-- **use-boolean-and:** Define the logical link between multiple search words. If
-  true, all search words must appear in each result. Defaults to `true`.
-- **boost-title:** Boost factor for the search result score if a search word
-  appears in the header. Defaults to `2`.
-- **boost-hierarchy:** Boost factor for the search result score if a search word
-  appears in the hierarchy. The hierarchy contains all titles of the parent
-  documents and all parent headings. Defaults to `1`.
-- **boost-paragraph:** Boost factor for the search result score if a search word
-  appears in the text. Defaults to `1`.
-- **expand:** True if search should match longer results e.g. search `micro`
-  should match `microwave`. Defaults to `true`.
-- **heading-split-level:** Search results will link to a section of the document
-  which contains the result. Documents are split into sections by headings this
-  level or less. Defaults to `3`. (`### This is a level 3 heading`)
-- **copy-js:** Copy JavaScript files for the search implementation to the output
-  directory. Defaults to `true`.
-
-This shows all available options in the **book.toml**:
-```toml
-[book]
-title = "Example book"
-authors = ["John Doe", "Jane Doe"]
-description = "The example book covers examples."
-
-[build]
-build-dir = "book"
-create-missing = true
-preprocess = ["links", "index"]
-
-[output.html]
-theme = "my-theme"
-curly-quotes = true
-google-analytics = "123456"
-additional-css = ["custom.css", "custom2.css"]
-additional-js = ["custom.js"]
-
-[output.html.playpen]
-editor = "./path/to/editor"
-editable = false
-
-[output.html.search]
-enable = true
-searcher = "./path/to/searcher"
-limit-results = 30
-teaser-word-count = 30
-use-boolean-and = true
-boost-title = 2
-boost-hierarchy = 1
-boost-paragraph = 1
-expand = true
-heading-split-level = 3
-copy-js = true
-```
-
-
-## Environment Variables
-
-All configuration values can be overridden from the command line by setting the
-corresponding environment variable. Because many operating systems restrict
-environment variables to be alphanumeric characters or `_`, the configuration
-key needs to be formatted slightly differently to the normal `foo.bar.baz` form.
-
-Variables starting with `MDBOOK_` are used for configuration. The key is created
-by removing the `MDBOOK_` prefix and turning the resulting string into
-`kebab-case`. Double underscores (`__`) separate nested keys, while a single
-underscore (`_`) is replaced with a dash (`-`).
-
-For example:
-
-- `MDBOOK_foo` -> `foo`
-- `MDBOOK_FOO` -> `foo`
-- `MDBOOK_FOO__BAR` -> `foo.bar`
-- `MDBOOK_FOO_BAR` -> `foo-bar`
-- `MDBOOK_FOO_bar__baz` -> `foo-bar.baz`
-
-So by setting the `MDBOOK_BOOK__TITLE` environment variable you can override the
-book's title without needing to touch your `book.toml`.
-
-> **Note:** To facilitate setting more complex config items, the value of an
-> environment variable is first parsed as JSON, falling back to a string if the
-> parse fails.
->
-> This means, if you so desired, you could override all book metadata when
-> building the book with something like
->
-> ```text
-> $ export MDBOOK_BOOK="{'title': 'My Awesome Book', authors: ['Michael-F-Bryan']}"
-> $ mdbook build
-> ```
-
-The latter case may be useful in situations where `mdbook` is invoked from a
-script or CI, where it sometimes isn't possible to update the `book.toml` before
-building.

book-example/src/format/example.rs

@@ -1,6 +0,0 @@
-fn main() {
-    println!("Hello World!");
-#
-#    // You can even hide lines! :D
-#   println!("I am hidden! Expand the code snippet to see me");
-}

book-example/src/format/mdbook.md

@@ -1,74 +0,0 @@
-# mdBook-specific markdown
-
-## Hiding code lines
-
-There is a feature in mdBook that lets you hide code lines by prepending them
-with a `#`.
-
-```bash
-# fn main() {
-    let x = 5;
-    let y = 6;
-
-    println!("{}", x + y);
-# }
-```
-
-Will render as
-
-```rust
-# fn main() {
-    let x = 5;
-    let y = 7;
-
-    println!("{}", x + y);
-# }
-```
-
-## Including files
-
-With the following syntax, you can include files into your book:
-
-```hbs
-\{{#include file.rs}}
-```
-
-The path to the file has to be relative from the current source file.
-
-Usually, this command is used for including code snippets and examples. In this
-case, oftens one would include a specific part of the file e.g. which only
-contains the relevant lines for the example. We support four different modes of
-partial includes:
-
-```hbs
-\{{#include file.rs:2}}
-\{{#include file.rs::10}}
-\{{#include file.rs:2:}}
-\{{#include file.rs:2:10}}
-```
-
-The first command only includes the second line from file `file.rs`. The second
-command includes all lines up to line 10, i.e. the lines from 11 till the end of
-the file are omitted. The third command includes all lines from line 2, i.e. the
-first line is omitted. The last command includes the excerpt of `file.rs`
-consisting of lines 2 to 10.
-
-## Inserting runnable Rust files
-
-With the following syntax, you can insert runnable Rust files into your book:
-
-```hbs
-\{{#playpen file.rs}}
-```
-
-The path to the Rust file has to be relative from the current source file.
-
-When play is clicked, the code snippet will be sent to the [Rust Playpen] to be
-compiled and run. The result is sent back and displayed directly underneath the
-code.
-
-Here is what a rendered code snippet looks like:
-
-{{#playpen example.rs}}
-
-[Rust Playpen]: https://play.rust-lang.org/

book-example/src/format/summary.md

@@ -1,38 +0,0 @@
-# SUMMARY.md
-
-The summary file is used by mdBook to know what chapters to include, in what
-order they should appear, what their hierarchy is and where the source files
-are. Without this file, there is no book.
-
-Even though `SUMMARY.md` is a markdown file, the formatting is very strict to
-allow for easy parsing. Let's see how you should format your `SUMMARY.md` file.
-
-#### Allowed elements
-
-1. ***Title*** It's common practice to begin with a title, generally <code
-   class="language-markdown"># Summary</code>. But it is not mandatory, the
-   parser just ignores it. So you can too if you feel like it.
-
-2. ***Prefix Chapter*** Before the main numbered chapters you can add a couple
-   of elements that will not be numbered. This is useful for forewords,
-   introductions, etc. There are however some constraints. You can not nest
-   prefix chapters, they should all be on the root level. And you can not add
-   prefix chapters once you have added numbered chapters.
-   ```markdown
-   [Title of prefix element](relative/path/to/markdown.md)
-   ```
-
-3. ***Numbered Chapter*** Numbered chapters are the main content of the book,
-   they will be numbered and can be nested, resulting in a nice hierarchy
-   (chapters, sub-chapters, etc.)
-   ```markdown
-   - [Title of the Chapter](relative/path/to/markdown.md)
-   ```
-   You can either use `-` or `*` to indicate a numbered chapter.
-
-4. ***Suffix Chapter*** After the numbered chapters you can add a couple of
-   non-numbered chapters. They are the same as prefix chapters but come after
-   the numbered chapters instead of before.
-
-All other elements are unsupported and will be ignored at best or result in an
-error.

book-example/src/format/theme/README.md

@@ -1,34 +0,0 @@
-# Theme
-
-The default renderer uses a [handlebars](http://handlebarsjs.com/) template to
-render your markdown files and comes with a default theme included in the mdBook
-binary.
-
-The theme is totally customizable, you can selectively replace every file from
-the theme by your own by adding a `theme` directory next to `src` folder in your
-project root. Create a new file with the name of the file you want to override
-and now that file will be used instead of the default file.
-
-Here are the files you can override:
-
-- ***index.hbs*** is the handlebars template.
-- ***book.css*** is the style used in the output. If you want to change the
-  design of your book, this is probably the file you want to modify. Sometimes
-  in conjunction with `index.hbs` when you want to radically change the layout.
-- ***book.js*** is mostly used to add client side functionality, like hiding /
-  un-hiding the sidebar, changing the theme, ...
-- ***highlight.js*** is the JavaScript that is used to highlight code snippets,
-  you should not need to modify this.  
-- ***highlight.css*** is the theme used for the code highlighting
-- ***favicon.png*** the favicon that will be used
-
-Generally, when you want to tweak the theme, you don't need to override all the
-files. If you only need changes in the stylesheet, there is no point in
-overriding all the other files. Because custom files take precedence over
-built-in ones, they will not get updated with new fixes / features.
-
-**Note:** When you override a file, it is possible that you break some
-functionality. Therefore I recommend to use the file from the default theme as
-template and only add / modify what you need. You can copy the default theme
-into your source directory automatically by using `mdbook init --theme` just
-remove the files you don't want to override.

book-example/src/format/theme/syntax-highlighting.md

@@ -1,70 +0,0 @@
-# Syntax Highlighting
-
-For syntax highlighting I use [Highlight.js](https://highlightjs.org) with a
-custom theme.
-
-Automatic language detection has been turned off, so you will probably want to
-specify the programming language you use like this
-
-<pre><code class="language-markdown">```rust
-fn main() {
-    // Some code
-}
-```</code></pre>
-
-## Custom theme
-Like the rest of the theme, the files used for syntax highlighting can be
-overridden with your own.
-
-- ***highlight.js*** normally you shouldn't have to overwrite this file, unless
-  you want to use a more recent version.
-- ***highlight.css*** theme used by highlight.js for syntax highlighting.
-
-If you want to use another theme for `highlight.js` download it from their
-website, or make it yourself, rename it to `highlight.css` and put it in
-`src/theme` (or the equivalent if you changed your source folder)
-
-Now your theme will be used instead of the default theme.
-
-## Hiding code lines
-
-There is a feature in mdBook that lets you hide code lines by prepending them
-with a `#`.
-
-
-```bash
-# fn main() {
-    let x = 5;
-    let y = 6;
-
-    println!("{}", x + y);
-# }
-```
-
-Will render as
-
-```rust
-# fn main() {
-    let x = 5;
-    let y = 7;
-
-    println!("{}", x + y);
-# }
-```
-
-**At the moment, this only works for code examples that are annotated with
-`rust`. Because it would collide with semantics of some programming languages.
-In the future, we want to make this configurable through the `book.toml` so that
-everyone can benefit from it.**
-
-
-## Improve default theme
-
-If you think the default theme doesn't look quite right for a specific language,
-or could be improved. Feel free to [submit a new
-issue](https://github.com/rust-lang-nursery/mdBook/issues) explaining what you
-have in mind and I will take a look at it.
-
-You could also create a pull-request with the proposed improvements.
-
-Overall the theme should be light and sober, without to many flashy colors.

book-example/src/misc/introduction.md

@@ -1,3 +0,0 @@
-# Introduction
-
-A frontmatter chapter.

ci/before_deploy.sh

@@ -1,32 +0,0 @@
-# This script takes care of building your crate and packaging it for release
-
-set -ex
-
-main() {
-    local src=$(pwd) \
-          stage=
-
-    case $TRAVIS_OS_NAME in
-        linux)
-            stage=$(mktemp -d)
-            ;;
-        osx)
-            stage=$(mktemp -d -t tmp)
-            ;;
-    esac
-
-    # This will slow down the build, but is necessary to not run out of disk space
-    cargo clean
-
-    cargo rustc --bin mdbook --target $TARGET --release -- -C lto
-
-    cp target/$TARGET/release/mdbook $stage/
-
-    cd $stage
-    tar czf $src/$CRATE_NAME-$TRAVIS_TAG-$TARGET.tar.gz *
-    cd $src
-
-    rm -rf $stage
-}
-
-main

ci/install-rust.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+# Install/update rust.
+# The first argument should be the toolchain to install.
+
+set -ex
+if [ -z "$1" ]
+then
+    echo "First parameter must be toolchain to install."
+    exit 1
+fi
+TOOLCHAIN="$1"
+
+rustup set profile minimal
+rustup component remove --toolchain=$TOOLCHAIN rust-docs || echo "already removed"
+rustup update --no-self-update $TOOLCHAIN
+if [ -n "$2" ]
+then
+    TARGET="$2"
+    HOST=$(rustc -Vv | grep ^host: | sed -e "s/host: //g")
+    if [ "$HOST" != "$TARGET" ]
+    then
+        rustup component add llvm-tools-preview --toolchain=$TOOLCHAIN
+        rustup component add rust-std-$TARGET --toolchain=$TOOLCHAIN
+    fi
+fi
+
+rustup default $TOOLCHAIN
+rustup -V
+rustc -Vv
+cargo -V

ci/make-release-asset.sh

@@ -0,0 +1,53 @@
+#!/usr/bin/env bash
+# Builds the release and creates an archive and optionally deploys to GitHub.
+set -ex
+
+if [[ -z "$GITHUB_REF" ]]
+then
+  echo "GITHUB_REF must be set"
+  exit 1
+fi
+# Strip mdbook-refs/tags/ from the start of the ref.
+TAG=${GITHUB_REF#*/tags/}
+
+host=$(rustc -Vv | grep ^host: | sed -e "s/host: //g")
+target=$2
+if [ "$host" != "$target" ]
+then
+  export "CARGO_TARGET_$(echo $target | tr a-z- A-Z_)_LINKER"=rust-lld
+fi
+export CARGO_PROFILE_RELEASE_LTO=true
+cargo build --locked --bin mdbook --release --target $target
+cd target/$target/release
+case $1 in
+  ubuntu*)
+    asset="mdbook-$TAG-$target.tar.gz"
+    tar czf ../../$asset mdbook
+    ;;
+  macos*)
+    asset="mdbook-$TAG-$target.tar.gz"
+    # There is a bug with BSD tar on macOS where the first 8MB of the file are
+    # sometimes all NUL bytes. See https://github.com/actions/cache/issues/403
+    # and https://github.com/rust-lang/cargo/issues/8603 for some more
+    # information. An alternative solution here is to install GNU tar, but
+    # flushing the disk cache seems to work, too.
+    sudo /usr/sbin/purge
+    tar czf ../../$asset mdbook
+    ;;
+  windows*)
+    asset="mdbook-$TAG-$target.zip"
+    7z a ../../$asset mdbook.exe
+    ;;
+  *)
+    echo "OS should be first parameter, was: $1"
+    ;;
+esac
+cd ../..
+
+if [[ -z "$GITHUB_ENV" ]]
+then
+  echo "GITHUB_ENV not set, run: gh release upload $TAG target/$asset"
+else
+  echo "MDBOOK_TAG=$TAG" >> $GITHUB_ENV
+  echo "MDBOOK_ASSET=target/$asset" >> $GITHUB_ENV
+fi

examples/de-emphasize.rs

@@ -1,94 +0,0 @@
-//! This program removes all forms of emphasis from the markdown of the book.
-extern crate mdbook;
-extern crate pulldown_cmark;
-extern crate pulldown_cmark_to_cmark;
-
-use mdbook::book::{Book, BookItem, Chapter};
-use mdbook::errors::{Error, Result};
-use mdbook::preprocess::{Preprocessor, PreprocessorContext};
-use mdbook::MDBook;
-use pulldown_cmark::{Event, Parser, Tag};
-use pulldown_cmark_to_cmark::fmt::cmark;
-
-use std::env::{args, args_os};
-use std::ffi::OsString;
-use std::process;
-
-struct Deemphasize;
-
-impl Preprocessor for Deemphasize {
-    fn name(&self) -> &str {
-        "md-links-to-html-links"
-    }
-
-    fn run(&self, _ctx: &PreprocessorContext, book: &mut Book) -> Result<()> {
-        eprintln!("Running '{}' preprocessor", self.name());
-        let mut res: Option<_> = None;
-        let mut num_removed_items = 0;
-        book.for_each_mut(|item: &mut BookItem| {
-            if let Some(Err(_)) = res {
-                return;
-            }
-            if let BookItem::Chapter(ref mut chapter) = *item {
-                eprintln!("{}: processing chapter '{}'", self.name(), chapter.name);
-                res = Some(
-                    match Deemphasize::remove_emphasis(&mut num_removed_items, chapter) {
-                        Ok(md) => {
-                            chapter.content = md;
-                            Ok(())
-                        }
-                        Err(err) => Err(err),
-                    },
-                );
-            }
-        });
-        eprintln!(
-            "{}: removed {} events from markdown stream.",
-            self.name(),
-            num_removed_items
-        );
-        match res {
-            Some(res) => res,
-            None => Ok(()),
-        }
-    }
-}
-
-fn do_it(book: OsString) -> Result<()> {
-    let mut book = MDBook::load(book)?;
-    book.with_preprecessor(Deemphasize);
-    book.build()
-}
-
-fn main() {
-    if args_os().count() != 2 {
-        eprintln!("USAGE: {} <book>", args().next().expect("executable"));
-        return;
-    }
-    if let Err(e) = do_it(args_os().skip(1).next().expect("one argument")) {
-        eprintln!("{}", e);
-        process::exit(1);
-    }
-}
-
-impl Deemphasize {
-    fn remove_emphasis(num_removed_items: &mut i32, chapter: &mut Chapter) -> Result<String> {
-        let mut buf = String::with_capacity(chapter.content.len());
-        let events = Parser::new(&chapter.content).filter(|e| {
-            let should_keep = match *e {
-                Event::Start(Tag::Emphasis)
-                | Event::Start(Tag::Strong)
-                | Event::End(Tag::Emphasis)
-                | Event::End(Tag::Strong) => false,
-                _ => true,
-            };
-            if !should_keep {
-                *num_removed_items += 1;
-            }
-            should_keep
-        });
-        cmark(events, &mut buf, None)
-            .map(|_| buf)
-            .map_err(|err| Error::from(format!("Markdown serialization failed: {}", err)))
-    }
-}

examples/nop-preprocessor.rs

@@ -0,0 +1,160 @@
+use crate::nop_lib::Nop;
+use clap::{Arg, ArgMatches, Command};
+use mdbook::book::Book;
+use mdbook::errors::Error;
+use mdbook::preprocess::{CmdPreprocessor, Preprocessor, PreprocessorContext};
+use semver::{Version, VersionReq};
+use std::io;
+use std::process;
+
+pub fn make_app() -> Command {
+    Command::new("nop-preprocessor")
+        .about("A mdbook preprocessor which does precisely nothing")
+        .subcommand(
+            Command::new("supports")
+                .arg(Arg::new("renderer").required(true))
+                .about("Check whether a renderer is supported by this preprocessor"),
+        )
+}
+
+fn main() {
+    let matches = make_app().get_matches();
+
+    // Users will want to construct their own preprocessor here
+    let preprocessor = Nop::new();
+
+    if let Some(sub_args) = matches.subcommand_matches("supports") {
+        handle_supports(&preprocessor, sub_args);
+    } else if let Err(e) = handle_preprocessing(&preprocessor) {
+        eprintln!("{}", e);
+        process::exit(1);
+    }
+}
+
+fn handle_preprocessing(pre: &dyn Preprocessor) -> Result<(), Error> {
+    let (ctx, book) = CmdPreprocessor::parse_input(io::stdin())?;
+
+    let book_version = Version::parse(&ctx.mdbook_version)?;
+    let version_req = VersionReq::parse(mdbook::MDBOOK_VERSION)?;
+
+    if !version_req.matches(&book_version) {
+        eprintln!(
+            "Warning: The {} plugin was built against version {} of mdbook, \
+             but we're being called from version {}",
+            pre.name(),
+            mdbook::MDBOOK_VERSION,
+            ctx.mdbook_version
+        );
+    }
+
+    let processed_book = pre.run(&ctx, book)?;
+    serde_json::to_writer(io::stdout(), &processed_book)?;
+
+    Ok(())
+}
+
+fn handle_supports(pre: &dyn Preprocessor, sub_args: &ArgMatches) -> ! {
+    let renderer = sub_args
+        .get_one::<String>("renderer")
+        .expect("Required argument");
+    let supported = pre.supports_renderer(renderer);
+
+    // Signal whether the renderer is supported by exiting with 1 or 0.
+    if supported {
+        process::exit(0);
+    } else {
+        process::exit(1);
+    }
+}
+
+/// The actual implementation of the `Nop` preprocessor. This would usually go
+/// in your main `lib.rs` file.
+mod nop_lib {
+    use super::*;
+
+    /// A no-op preprocessor.
+    pub struct Nop;
+
+    impl Nop {
+        pub fn new() -> Nop {
+            Nop
+        }
+    }
+
+    impl Preprocessor for Nop {
+        fn name(&self) -> &str {
+            "nop-preprocessor"
+        }
+
+        fn run(&self, ctx: &PreprocessorContext, book: Book) -> Result<Book, Error> {
+            // In testing we want to tell the preprocessor to blow up by setting a
+            // particular config value
+            if let Some(nop_cfg) = ctx.config.get_preprocessor(self.name()) {
+                if nop_cfg.contains_key("blow-up") {
+                    anyhow::bail!("Boom!!1!");
+                }
+            }
+
+            // we *are* a no-op preprocessor after all
+            Ok(book)
+        }
+
+        fn supports_renderer(&self, renderer: &str) -> bool {
+            renderer != "not-supported"
+        }
+    }
+
+    #[cfg(test)]
+    mod test {
+        use super::*;
+
+        #[test]
+        fn nop_preprocessor_run() {
+            let input_json = r##"[
+                {
+                    "root": "/path/to/book",
+                    "config": {
+                        "book": {
+                            "authors": ["AUTHOR"],
+                            "language": "en",
+                            "multilingual": false,
+                            "src": "src",
+                            "title": "TITLE"
+                        },
+                        "preprocessor": {
+                            "nop": {}
+                        }
+                    },
+                    "renderer": "html",
+                    "mdbook_version": "0.4.21"
+                },
+                {
+                    "sections": [
+                        {
+                            "Chapter": {
+                                "name": "Chapter 1",
+                                "content": "# Chapter 1\n",
+                                "number": [1],
+                                "sub_items": [],
+                                "path": "chapter_1.md",
+                                "source_path": "chapter_1.md",
+                                "parent_names": []
+                            }
+                        }
+                    ],
+                    "__non_exhaustive": null
+                }
+            ]"##;
+            let input_json = input_json.as_bytes();
+
+            let (ctx, book) = mdbook::preprocess::CmdPreprocessor::parse_input(input_json).unwrap();
+            let expected_book = book.clone();
+            let result = Nop::new().run(&ctx, book);
+            assert!(result.is_ok());
+
+            // The nop-preprocessor should not have made any changes to the book content.
+            let actual_book = result.unwrap();
+            assert_eq!(actual_book, expected_book);
+        }
+    }
+}

guide/book.toml

@@ -0,0 +1,33 @@
+[book]
+title = "mdBook Documentation"
+description = "Create book from markdown files. Like Gitbook but implemented in Rust"
+authors = ["Mathieu David", "Michael-F-Bryan"]
+language = "en"
+
+[rust]
+edition = "2018"
+
+[output.html]
+mathjax-support = true
+site-url = "/mdBook/"
+git-repository-url = "https://github.com/rust-lang/mdBook/tree/master/guide"
+edit-url-template = "https://github.com/rust-lang/mdBook/edit/master/guide/{path}"
+
+[output.html.playground]
+editable = true
+line-numbers = true
+
+[output.html.code.hidelines]
+python = "~"
+
+[output.html.search]
+limit-results = 20
+use-boolean-and = true
+boost-title = 2
+boost-hierarchy = 2
+boost-paragraph = 1
+expand = true
+heading-split-level = 2
+
+[output.html.redirect]
+"/format/config.html" = "configuration/index.html"

guide/src/404.md

@@ -0,0 +1,3 @@
+# Document not found (404)
+
+This URL is invalid, sorry. Try the search instead!

guide/src/README.md

@@ -0,0 +1,41 @@
+# Introduction
+
+**mdBook** is a command line tool to create books with Markdown.
+It is ideal for creating product or API documentation, tutorials, course materials or anything that requires a clean,
+easily navigable and customizable presentation.
+
+* Lightweight [Markdown] syntax helps you focus more on your content
+* Integrated [search] support
+* Color [syntax highlighting] for code blocks for many different languages
+* [Theme] files allow customizing the formatting of the output
+* [Preprocessors] can provide extensions for custom syntax and modifying content
+* [Backends] can render the output to multiple formats
+* Written in [Rust] for speed, safety, and simplicity
+* Automated testing of [Rust code samples]
+
+This guide is an example of what mdBook produces.
+mdBook is used by the Rust programming language project, and [The Rust Programming Language][trpl] book is another fine example of mdBook in action.
+
+[Markdown]: format/markdown.md
+[search]: guide/reading.md#search
+[syntax highlighting]: format/theme/syntax-highlighting.md
+[theme]: format/theme/index.html
+[preprocessors]: format/configuration/preprocessors.md
+[backends]: format/configuration/renderers.md
+[Rust]: https://www.rust-lang.org/
+[trpl]: https://doc.rust-lang.org/book/
+[Rust code samples]: cli/test.md
+
+## Contributing
+
+mdBook is free and open source. You can find the source code on
+[GitHub](https://github.com/rust-lang/mdBook) and issues and feature requests can be posted on
+the [GitHub issue tracker](https://github.com/rust-lang/mdBook/issues). mdBook relies on the community to fix bugs and
+add features: if you'd like to contribute, please read
+the [CONTRIBUTING](https://github.com/rust-lang/mdBook/blob/master/CONTRIBUTING.md) guide and consider opening
+a [pull request](https://github.com/rust-lang/mdBook/pulls).
+
+## License
+
+The mdBook source and documentation are released under
+the [Mozilla Public License v2.0](https://www.mozilla.org/MPL/2.0/).

guide/src/SUMMARY.md

@@ -1,6 +1,15 @@
 # Summary
 
-- [mdBook](README.md)
+[Introduction](README.md)
+
+# User Guide
+
+- [Installation](guide/installation.md)
+- [Reading Books](guide/reading.md)
+- [Creating a Book](guide/creating.md)
+
+# Reference Guide
+
 - [Command Line Tool](cli/README.md)
     - [init](cli/init.md)
     - [build](cli/build.md)
@@ -8,19 +17,26 @@
     - [serve](cli/serve.md)
     - [test](cli/test.md)
     - [clean](cli/clean.md)
+    - [completions](cli/completions.md)
 - [Format](format/README.md)
     - [SUMMARY.md](format/summary.md)
-    - [Configuration](format/config.md)
+        - [Draft chapter]()
+    - [Configuration](format/configuration/README.md)
+        - [General](format/configuration/general.md)
+        - [Preprocessors](format/configuration/preprocessors.md)
+        - [Renderers](format/configuration/renderers.md)
+        - [Environment Variables](format/configuration/environment-variables.md)
     - [Theme](format/theme/README.md)
         - [index.hbs](format/theme/index-hbs.md)
         - [Syntax highlighting](format/theme/syntax-highlighting.md)
         - [Editor](format/theme/editor.md)
     - [MathJax Support](format/mathjax.md)
-    - [mdBook specific features](format/mdbook.md)
+    - [mdBook-specific features](format/mdbook.md)
+    - [Markdown](format/markdown.md)
 - [Continuous Integration](continuous-integration.md)
 - [For Developers](for_developers/README.md)
     - [Preprocessors](for_developers/preprocessors.md)
-    - [Alternate Backends](for_developers/backends.md)
+    - [Alternative Backends](for_developers/backends.md)
 
 -----------
 

guide/src/cli/README.md

@@ -0,0 +1,14 @@
+# Command Line Tool
+
+The `mdbook` command-line tool is used to create and build books.
+After you have [installed](../guide/installation.md) `mdbook`, you can run the `mdbook help` command in your terminal to view the available commands.
+
+This following sections provide in-depth information on the different commands available.
+
+* [`mdbook init <directory>`](init.md) — Creates a new book with minimal boilerplate to start with.
+* [`mdbook build`](build.md) — Renders the book.
+* [`mdbook watch`](watch.md) — Rebuilds the book any time a source file changes.
+* [`mdbook serve`](serve.md) — Runs a web server to view the book, and rebuilds on changes.
+* [`mdbook test`](test.md) — Tests Rust code samples.
+* [`mdbook clean`](clean.md) — Deletes the rendered output.
+* [`mdbook completions`](completions.md) — Support for shell auto-completion.

guide/src/cli/build.md

@@ -7,7 +7,8 @@ mdbook build
 ```
 
 It will try to parse your `SUMMARY.md` file to understand the structure of your
-book and fetch the corresponding files.
+book and fetch the corresponding files. Note that this will also create files
+mentioned in `SUMMARY.md` which are not yet present.
 
 The rendered output will maintain the same directory structure as the source for
 convenience. Large books will therefore remain structured when rendered.
@@ -29,10 +30,11 @@ your default web browser after building it.
 #### --dest-dir
 
 The `--dest-dir` (`-d`) option allows you to change the output directory for the
-book. If not specified it will default to the value of the `build.build-dir` key
-in `book.toml`, or to `./book` relative to the book's root directory.
+book. Relative paths are interpreted relative to the book's root directory. If
+not specified it will default to the value of the `build.build-dir` key in
+`book.toml`, or to `./book`.
 
 -------------------
 
-***Note:*** *Make sure to run the build command in the root directory and not in
-the source directory*
+***Note:*** *The build command copies all files (excluding files with `.md` extension) from the source directory
+into the build directory.*

guide/src/cli/clean.md

@@ -19,9 +19,9 @@ mdbook clean path/to/book
 #### --dest-dir
 
 The `--dest-dir` (`-d`) option allows you to override the book's output
-directory, which will be deleted by this command. If not specified it will
-default to the value of the `build.build-dir` key in `book.toml`, or to `./book`
-relative to the book's root directory.
+directory, which will be deleted by this command. Relative paths are interpreted
+relative to the book's root directory. If not specified it will default to the
+value of the `build.build-dir` key in `book.toml`, or to `./book`.
 
 ```bash
 mdbook clean --dest-dir=path/to/book

guide/src/cli/completions.md

@@ -0,0 +1,20 @@
+# The completions command
+
+The completions command is used to generate auto-completions for some common shells.
+This means when you type `mdbook` in your shell, you can then press your shell's auto-complete key (usually the Tab key) and it may display what the valid options are, or finish partial input.
+
+The completions first need to be installed for your shell:
+
+```bash
+# bash
+mdbook completions bash > ~/.local/share/bash-completion/completions/mdbook
+# oh-my-zsh
+mdbook completions zsh > ~/.oh-my-zsh/completions/_mdbook
+autoload -U compinit && compinit
+```
+
+The command prints a completion script for the given shell.
+Run `mdbook completions --help` for a list of supported shells.
+
+Where to place the completions depend on which shell you are using and your operating system.
+Consult your shell's documentation for more information one where to place the script.

guide/src/cli/init.md

@@ -19,15 +19,15 @@ book-test/
     └── SUMMARY.md
 ```
 
-- The `src` directory is were you write your book in markdown. It contains all
+- The `src` directory is where you write your book in markdown. It contains all
   the source files, configuration files, etc.
 
 - The `book` directory is where your book is rendered. All the output is ready
   to be uploaded to a server to be seen by your audience.
 
-- The `SUMMARY.md` file is the most important file, it's the skeleton of your
-  book and is discussed in more detail [in another
-  chapter](../format/summary.md)
+- The `SUMMARY.md` is the skeleton of your
+  book, and is discussed in more detail [in another
+  chapter](../format/summary.md).
 
 #### Tip: Generate chapters from SUMMARY.md
 
@@ -52,3 +52,31 @@ directory called `theme` in your source directory so that you can modify it.
 
 The theme is selectively overwritten, this means that if you don't want to
 overwrite a specific file, just delete it and the default file will be used.
+
+#### --title
+
+Specify a title for the book. If not supplied, an interactive prompt will ask for 
+a title. 
+
+```bash
+mdbook init --title="my amazing book"
+```
+
+#### --ignore
+
+Create a `.gitignore` file configured to ignore the `book` directory created when [building] a book. 
+If not supplied, an interactive prompt will ask whether it should be created.
+
+```bash
+mdbook init --ignore=none
+```
+
+```bash
+mdbook init --ignore=git
+```
+
+[building]: build.md
+
+#### --force
+
+Skip the prompts to create a `.gitignore` and for the title for the book.

guide/src/cli/serve.md

@@ -0,0 +1,56 @@
+# The serve command
+
+The serve command is used to preview a book by serving it via HTTP at
+`localhost:3000` by default: 
+
+```bash
+mdbook serve
+```
+
+The `serve` command  watches the book's `src` directory for
+changes, rebuilding the book and refreshing clients for each change; this includes
+re-creating deleted files still mentioned in `SUMMARY.md`! A websocket
+connection is used to trigger the client-side refresh.
+
+***Note:*** *The `serve` command is for testing a book's HTML output, and is not
+intended to be a complete HTTP server for a website.*
+
+#### Specify a directory
+
+The `serve` command can take a directory as an argument to use as the book's
+root instead of the current working directory.
+
+```bash
+mdbook serve path/to/book
+```
+
+### Server options
+
+The `serve` hostname defaults to `localhost`, and the port defaults to `3000`. Either option can be specified on the command line:
+
+```bash
+mdbook serve path/to/book -p 8000 -n 127.0.0.1 
+```
+
+#### --open
+
+When you use the `--open` (`-o`) flag, mdbook will open the book in your
+default web browser after starting the server.
+
+#### --dest-dir
+
+The `--dest-dir` (`-d`) option allows you to change the output directory for the
+book. Relative paths are interpreted relative to the book's root directory. If
+not specified it will default to the value of the `build.build-dir` key in
+`book.toml`, or to `./book`.
+
+#### Specify exclude patterns
+
+The `serve` command will not automatically trigger a build for files listed in
+the `.gitignore` file in the book root directory. The `.gitignore` file may
+contain file patterns described in the [gitignore
+documentation](https://git-scm.com/docs/gitignore). This can be useful for
+ignoring temporary files created by some editors.
+
+***Note:*** *Only the `.gitignore` from the book root directory is used. Global
+`$HOME/.gitignore` or `.gitignore` files in parent directories are not used.*

guide/src/cli/test.md

@@ -6,8 +6,7 @@ of code examples that could get outdated. Therefore it is very important for
 them to be able to automatically test these code examples.
 
 mdBook supports a `test` command that will run all available tests in a book. At
-the moment, only rustdoc tests are supported, but this may be expanded upon in
-the future.
+the moment, only Rust tests are supported.
 
 #### Disable tests on a code block
 
@@ -43,10 +42,26 @@ mdbook test path/to/book
 The `--library-path` (`-L`) option allows you to add directories to the library
 search path used by `rustdoc` when it builds and tests the examples. Multiple
 directories can be specified with multiple options (`-L foo -L bar`) or with a
-comma-delimited list (`-L foo,bar`).
+comma-delimited list (`-L foo,bar`). The path should point to the Cargo
+[build cache](https://doc.rust-lang.org/cargo/guide/build-cache.html) `deps` directory that
+contains the build output of your project. For example, if your Rust project's book is in a directory
+named `my-book`, the following command would include the crate's dependencies when running `test`:
+
+```shell
+mdbook test my-book -L target/debug/deps/
+```
+
+See the `rustdoc` command-line [documentation](https://doc.rust-lang.org/rustdoc/command-line-arguments.html#-l--library-path-where-to-look-for-dependencies)
+for more information.
 
 #### --dest-dir
 
 The `--dest-dir` (`-d`) option allows you to change the output directory for the
-book. If not specified it will default to the value of the `build.build-dir` key
-in `book.toml`, or to `./book` relative to the book's root directory.
+book. Relative paths are interpreted relative to the book's root directory. If
+not specified it will default to the value of the `build.build-dir` key in
+`book.toml`, or to `./book`.
+
+#### --chapter
+
+The `--chapter` (`-c`) option allows you to test a specific chapter of the
+book using the chapter name or the relative path to the chapter.

guide/src/cli/watch.md

@@ -0,0 +1,40 @@
+# The watch command
+
+The `watch` command is useful when you want your book to be rendered on every
+file change. You could repeatedly issue `mdbook build` every time a file is
+changed. But using `mdbook watch` once will watch your files and will trigger a
+build automatically whenever you modify a file; this includes re-creating
+deleted files still mentioned in `SUMMARY.md`!
+
+#### Specify a directory
+
+The `watch` command can take a directory as an argument to use as the book's
+root instead of the current working directory.
+
+```bash
+mdbook watch path/to/book
+```
+
+#### --open
+
+When you use the `--open` (`-o`) option, mdbook will open the rendered book in
+your default web browser.
+
+#### --dest-dir
+
+The `--dest-dir` (`-d`) option allows you to change the output directory for the
+book. Relative paths are interpreted relative to the book's root directory. If
+not specified it will default to the value of the `build.build-dir` key in
+`book.toml`, or to `./book`.
+
+
+#### Specify exclude patterns
+
+The `watch` command will not automatically trigger a build for files listed in
+the `.gitignore` file in the book root directory. The `.gitignore` file may
+contain file patterns described in the [gitignore
+documentation](https://git-scm.com/docs/gitignore). This can be useful for
+ignoring temporary files created by some editors.
+
+_Note: Only `.gitignore` from book root directory is used. Global
+`$HOME/.gitignore` or `.gitignore` files in parent directories are not used._

guide/src/continuous-integration.md

@@ -0,0 +1,121 @@
+# Running `mdbook` in Continuous Integration
+
+There are a variety of services such as [GitHub Actions] or [GitLab CI/CD] which can be used to test and deploy your book automatically.
+
+The following provides some general guidelines on how to configure your service to run mdBook.
+Specific recipes can be found at the [Automated Deployment] wiki page.
+
+[GitHub Actions]: https://docs.github.com/en/actions
+[GitLab CI/CD]: https://docs.gitlab.com/ee/ci/
+[Automated Deployment]: https://github.com/rust-lang/mdBook/wiki/Automated-Deployment
+
+## Installing mdBook
+
+There are several different strategies for installing mdBook.
+The particular method depends on your needs and preferences.
+
+### Pre-compiled binaries
+
+Perhaps the easiest method is to use the pre-compiled binaries found on the [GitHub Releases page][releases].
+A simple approach would be to use the popular `curl` CLI tool to download the executable:
+
+```sh
+mkdir bin
+curl -sSL https://github.com/rust-lang/mdBook/releases/download/v0.4.37/mdbook-v0.4.37-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=bin
+bin/mdbook build
+```
+
+Some considerations for this approach:
+
+* This is relatively fast, and does not necessarily require dealing with caching.
+* This does not require installing Rust.
+* Specifying a specific URL means you have to manually update your script to get a new version.
+  This may be a benefit if you want to lock to a specific version.
+  However, some users prefer to automatically get a newer version when they are published.
+* You are reliant on the GitHub CDN being available.
+
+[releases]: https://github.com/rust-lang/mdBook/releases
+
+### Building from source
+
+Building from source will require having Rust installed.
+Some services have Rust pre-installed, but if your service does not, you will need to add a step to install it.
+
+After Rust is installed, `cargo install` can be used to build and install mdBook.
+We recommend using a SemVer version specifier so that you get the latest **non-breaking** version of mdBook.
+For example:
+
+```sh
+cargo install mdbook --no-default-features --features search --vers "^0.4" --locked
+```
+
+This includes several recommended options:
+
+* `--no-default-features` — Disables features like the HTTP server used by `mdbook serve` that is likely not needed on CI.
+  This will speed up the build time significantly.
+* `--features search` — Disabling default features means you should then manually enable features that you want, such as the built-in [search] capability.
+* `--vers "^0.4"` — This will install the most recent version of the `0.4` series.
+  However, versions after like `0.5.0` won't be installed, as they may break your build.
+  Cargo will automatically upgrade mdBook if you have an older version already installed.
+* `--locked` — This will use the dependencies that were used when mdBook was released.
+  Without `--locked`, it will use the latest version of all dependencies, which may include some fixes since the last release, but may also (rarely) cause build problems.
+
+You will likely want to investigate caching options, as building mdBook can be somewhat slow.
+
+[search]: guide/reading.md#search
+
+## Running tests
+
+You may want to run tests using [`mdbook test`] every time you push a change or create a pull request.
+This can be used to validate Rust code examples in the book.
+
+This will require having Rust installed.
+Some services have Rust pre-installed, but if your service does not, you will need to add a step to install it.
+
+Other than making sure the appropriate version of Rust is installed, there's not much more than just running `mdbook test` from the book directory.
+
+You may also want to consider running other kinds of tests, like [mdbook-linkcheck] which will check for broken links.
+Or if you have your own style checks, spell checker, or any other tests it might be good to run them in CI.
+
+[`mdbook test`]: cli/test.md
+[mdbook-linkcheck]: https://github.com/Michael-F-Bryan/mdbook-linkcheck#continuous-integration
+
+## Deploying
+
+You may want to automatically deploy your book.
+Some may want to do this every time a change is pushed, and others may want to only deploy when a specific release is tagged.
+
+You'll also need to understand the specifics on how to push a change to your web service.
+For example, [GitHub Pages] just requires committing the output onto a specific git branch.
+Other services may require using something like SSH to connect to a remote server.
+
+The basic outline is that you need to run `mdbook build` to generate the output, and then transfer the files (which are in the `book` directory) to the correct location.
+
+You may then want to consider if you need to invalidate any caches on your web service.
+
+See the [Automated Deployment] wiki page for examples of various different services.
+
+[GitHub Pages]: https://docs.github.com/en/pages
+
+### 404 handling
+
+mdBook automatically generates a 404 page to be used for broken links.
+The default output is a file named `404.html` at the root of the book.
+Some services like [GitHub Pages] will automatically use this page for broken links.
+For other services, you may want to consider configuring the web server to use this page as it will provide the reader navigation to get back to the book.
+
+If your book is not deployed at the root of the domain, then you should set the [`output.html.site-url`] setting so that the 404 page works correctly.
+It needs to know where the book is deployed in order to load the static files (like CSS) correctly.
+For example, this guide is deployed at <https://rust-lang.github.io/mdBook/>, and the `site-url` setting is configured like this:
+
+```toml
+# book.toml
+[output.html]
+site-url = "/mdBook/"
+```
+
+You can customize the look of the 404 page by creating a file named `src/404.md` in your book.
+If you want to use a different filename, you can set [`output.html.input-404`] to a different filename.
+
+[`output.html.site-url`]: format/configuration/renderers.md#html-renderer-options
+[`output.html.input-404`]: format/configuration/renderers.md#html-renderer-options

guide/src/for_developers/README.md

@@ -12,7 +12,7 @@ The *For Developers* chapters are here to show you the more advanced usage of
 The two main ways a developer can hook into the book's build process is via,
 
 - [Preprocessors](preprocessors.md)
-- [Alternate Backends](backends.md)
+- [Alternative Backends](backends.md)
 
 
 ## The Build Process
@@ -24,8 +24,9 @@ The process of rendering a book project goes through several steps.
        exist
     - Load the book chapters into memory
     - Discover which preprocessors/backends should be used
-2. Run the preprocessors
-3. Call each backend in turn
+2. For each backend:
+   1. Run all the preprocessors.
+   2. Call the backend to render the processed result.
 
 
 ## Using `mdbook` as a Library
@@ -41,6 +42,6 @@ The easiest way to find out how to use the `mdbook` crate is by looking at the
 explanation on the configuration system.
 
 
-[`MDBook`]: http://rust-lang-nursery.github.io/mdBook/mdbook/book/struct.MDBook.html
-[API Docs]: http://rust-lang-nursery.github.io/mdBook/mdbook/
-[config]: file:///home/michael/Documents/forks/mdBook/target/doc/mdbook/config/index.html
+[`MDBook`]: https://docs.rs/mdbook/*/mdbook/book/struct.MDBook.html
+[API Docs]: https://docs.rs/mdbook/*/mdbook/
+[config]: https://docs.rs/mdbook/*/mdbook/config/index.html

guide/src/for_developers/backends.md

@@ -1,30 +1,25 @@
-# Alternate Backends
+# Alternative Backends
 
 A "backend" is simply a program which `mdbook` will invoke during the book
 rendering process. This program is passed a JSON representation of the book and
 configuration information via `stdin`. Once the backend receives this
 information it is free to do whatever it wants.
 
-There are already several alternate backends on GitHub which can be used as a
-rough example of how this is accomplished in practice.
-
-- [mdbook-linkcheck] - a simple program for verifying the book doesn't contain
-  any broken links
-- [mdbook-epub] - an EPUB renderer
-- [mdbook-test] - a program to run the book's contents through [rust-skeptic] to
-  verify everything compiles and runs correctly (similar to `rustdoc --test`)
-
-This page will step you through creating your own alternate backend in the form
-of a simple word counting program. Although it will be written in Rust, there's
-no reason why it couldn't be accomplished using something like Python or Ruby.
+See [Configuring Renderers](../format/configuration/renderers.md) for more information about using backends.
 
+The community has developed several backends.
+See the [Third Party Plugins] wiki page for a list of available backends.
 
 ## Setting Up
 
+This page will step you through creating your own alternative backend in the form
+of a simple word counting program. Although it will be written in Rust, there's
+no reason why it couldn't be accomplished using something like Python or Ruby.
+
 First you'll want to create a new binary program and add `mdbook` as a
 dependency.
 
-```
+```shell
 $ cargo new --bin mdbook-wordcount
 $ cd mdbook-wordcount
 $ cargo add mdbook
@@ -92,8 +87,8 @@ fn count_words(ch: &Chapter) -> usize {
 Now we've got the basics running, we want to actually use it. First, install the
 program.
 
-```
-$ cargo install
+```shell
+$ cargo install --path .
 ```
 
 Then `cd` to the particular book you'd like to count the words of and update its
@@ -120,7 +115,7 @@ to make sure to add the HTML backend, even if its table just stays empty.
 Now you just need to build your book like normal, and everything should *Just
 Work*.
 
-```
+```shell
 $ mdbook build
 ...
 2018-01-16 07:31:15 [INFO] (mdbook::renderer): Invoking the "mdbook-wordcount" renderer
@@ -140,7 +135,7 @@ Syntax highlighting: 314
 MathJax Support: 153
 Rust code specific features: 148
 For Developers: 788
-Alternate Backends: 710
+Alternative Backends: 710
 Contributors: 85
 ```
 
@@ -261,6 +256,10 @@ in [`RenderContext`].
 > **Note:** There is no guarantee that the destination directory exists or is
 > empty (`mdbook` may leave the previous contents to let backends do caching),
 > so it's always a good idea to create it with `fs::create_dir_all()`.
+>
+> If the destination directory already exists, don't assume it will be empty.
+> To allow backends to cache the results from previous runs, `mdbook` may leave
+> old content in the directory.
 
 There's always the possibility that an error will occur while processing a book
 (just look at all the `unwrap()`'s we've written already), so `mdbook` will
@@ -288,7 +287,7 @@ like this:
 +             if cfg.deny_odds && num_words % 2 == 1 {
 +               eprintln!("{} has an odd number of words!", ch.name);
 +               process::exit(1);
-              }
++             }
           }
       }
   }
@@ -303,8 +302,8 @@ like this:
 
 Now, if we reinstall the backend and build a book,
 
-```
-$ cargo install --force
+```shell
+$ cargo install --path . --force
 $ mdbook build /path/to/book
 ...
 2018-01-16 21:21:39 [INFO] (mdbook::renderer): Invoking the "wordcount" renderer
@@ -325,11 +324,10 @@ generation or a warning).
 All environment variables are passed through to the backend, allowing you to use
 the usual `RUST_LOG` to control logging verbosity.
 
-
 ## Wrapping Up
 
 Although contrived, hopefully this example was enough to show how you'd create
-an alternate backend for `mdbook`. If you feel it's missing something, don't
+an alternative backend for `mdbook`. If you feel it's missing something, don't
 hesitate to create an issue in the [issue tracker] so we can improve the user
 guide.
 
@@ -338,14 +336,11 @@ as a good example of how it's done in real life, so feel free to skim through
 the source code or ask questions.
 
 
-[mdbook-linkcheck]: https://github.com/Michael-F-Bryan/mdbook-linkcheck
-[mdbook-epub]: https://github.com/Michael-F-Bryan/mdbook-epub
-[mdbook-test]: https://github.com/Michael-F-Bryan/mdbook-test
-[rust-skeptic]: https://github.com/budziq/rust-skeptic
-[`RenderContext`]: http://rust-lang-nursery.github.io/mdBook/mdbook/renderer/struct.RenderContext.html
-[`RenderContext::from_json()`]: http://rust-lang-nursery.github.io/mdBook/mdbook/renderer/struct.RenderContext.html#method.from_json
+[Third Party Plugins]: https://github.com/rust-lang/mdBook/wiki/Third-party-plugins
+[`RenderContext`]: https://docs.rs/mdbook/*/mdbook/renderer/struct.RenderContext.html
+[`RenderContext::from_json()`]: https://docs.rs/mdbook/*/mdbook/renderer/struct.RenderContext.html#method.from_json
 [`semver`]: https://crates.io/crates/semver
-[`Book`]: http://rust-lang-nursery.github.io/mdBook/mdbook/book/struct.Book.html
-[`Book::iter()`]: http://rust-lang-nursery.github.io/mdBook/mdbook/book/struct.Book.html#method.iter
-[`Config`]: http://rust-lang-nursery.github.io/mdBook/mdbook/config/struct.Config.html
-[issue tracker]: https://github.com/rust-lang-nursery/mdBook/issues
+[`Book`]: https://docs.rs/mdbook/*/mdbook/book/struct.Book.html
+[`Book::iter()`]: https://docs.rs/mdbook/*/mdbook/book/struct.Book.html#method.iter
+[`Config`]: https://docs.rs/mdbook/*/mdbook/config/struct.Config.html
+[issue tracker]: https://github.com/rust-lang/mdBook/issues

guide/src/for_developers/preprocessors.md

@@ -0,0 +1,134 @@
+# Preprocessors
+
+A *preprocessor* is simply a bit of code which gets run immediately after the
+book is loaded and before it gets rendered, allowing you to update and mutate
+the book. Possible use cases are:
+
+- Creating custom helpers like `\{{#include /path/to/file.md}}`
+- Substituting in latex-style expressions (`$$ \frac{1}{3} $$`) with their
+  mathjax equivalents
+
+See [Configuring Preprocessors](../format/configuration/preprocessors.md) for more information about using preprocessors.
+
+## Hooking Into MDBook
+
+MDBook uses a fairly simple mechanism for discovering third party plugins.
+A new table is added to `book.toml` (e.g. `[preprocessor.foo]` for the `foo`
+preprocessor) and then `mdbook` will try to invoke the `mdbook-foo` program as
+part of the build process.
+
+Once the preprocessor has been defined and the build process starts, mdBook executes the command defined in the `preprocessor.foo.command` key twice.
+The first time it runs the preprocessor to determine if it supports the given renderer.
+mdBook passes two arguments to the process: the first argument is the string `supports` and the second argument is the renderer name.
+The preprocessor should exit with a status code 0 if it supports the given renderer, or return a non-zero exit code if it does not.
+
+If the preprocessor supports the renderer, then mdbook runs it a second time, passing JSON data into stdin.
+The JSON consists of an array of `[context, book]` where `context` is the serialized object [`PreprocessorContext`] and `book` is a [`Book`] object containing the content of the book.
+
+The preprocessor should return the JSON format of the [`Book`] object to stdout, with any modifications it wishes to perform.
+
+The easiest way to get started is by creating your own implementation of the
+`Preprocessor` trait (e.g. in `lib.rs`) and then creating a shell binary which
+translates inputs to the correct `Preprocessor` method. For convenience, there
+is [an example no-op preprocessor] in the `examples/` directory which can easily
+be adapted for other preprocessors.
+
+<details>
+<summary>Example no-op preprocessor</summary>
+
+```rust
+// nop-preprocessors.rs
+
+{{#include ../../../examples/nop-preprocessor.rs}}
+```
+</details>
+
+## Hints For Implementing A Preprocessor
+
+By pulling in `mdbook` as a library, preprocessors can have access to the
+existing infrastructure for dealing with books.
+
+For example, a custom preprocessor could use the
+[`CmdPreprocessor::parse_input()`] function to deserialize the JSON written to
+`stdin`. Then each chapter of the `Book` can be mutated in-place via
+[`Book::for_each_mut()`], and then written to `stdout` with the `serde_json`
+crate.
+
+Chapters can be accessed either directly (by recursively iterating over
+chapters) or via the `Book::for_each_mut()` convenience method.
+
+The `chapter.content` is just a string which happens to be markdown. While it's
+entirely possible to use regular expressions or do a manual find & replace,
+you'll probably want to process the input into something more computer-friendly.
+The [`pulldown-cmark`][pc] crate implements a production-quality event-based
+Markdown parser, with the [`pulldown-cmark-to-cmark`][pctc] crate allowing you to
+translate events back into markdown text.
+
+The following code block shows how to remove all emphasis from markdown,
+without accidentally breaking the document.
+
+```rust
+fn remove_emphasis(
+    num_removed_items: &mut usize,
+    chapter: &mut Chapter,
+) -> Result<String> {
+    let mut buf = String::with_capacity(chapter.content.len());
+
+    let events = Parser::new(&chapter.content).filter(|e| {
+        let should_keep = match *e {
+            Event::Start(Tag::Emphasis)
+            | Event::Start(Tag::Strong)
+            | Event::End(Tag::Emphasis)
+            | Event::End(Tag::Strong) => false,
+            _ => true,
+        };
+        if !should_keep {
+            *num_removed_items += 1;
+        }
+        should_keep
+    });
+
+    cmark(events, &mut buf, None).map(|_| buf).map_err(|err| {
+        Error::from(format!("Markdown serialization failed: {}", err))
+    })
+}
+```
+
+For everything else, have a look [at the complete example][example].
+
+## Implementing a preprocessor with a different language
+
+The fact that mdBook utilizes stdin and stdout to communicate with the preprocessors makes it easy to implement them in a language other than Rust.
+The following code shows how to implement a simple preprocessor in Python, which will modify the content of the first chapter.
+The example below follows the configuration shown above with `preprocessor.foo.command` actually pointing to a Python script.
+
+```python
+import json
+import sys
+
+
+if __name__ == '__main__':
+    if len(sys.argv) > 1: # we check if we received any argument
+        if sys.argv[1] == "supports": 
+            # then we are good to return an exit status code of 0, since the other argument will just be the renderer's name
+            sys.exit(0)
+
+    # load both the context and the book representations from stdin
+    context, book = json.load(sys.stdin)
+    # and now, we can just modify the content of the first chapter
+    book['sections'][0]['Chapter']['content'] = '# Hello'
+    # we are done with the book's modification, we can just print it to stdout, 
+    print(json.dumps(book))
+```
+
+
+
+[preprocessor-docs]: https://docs.rs/mdbook/latest/mdbook/preprocess/trait.Preprocessor.html
+[pc]: https://crates.io/crates/pulldown-cmark
+[pctc]: https://crates.io/crates/pulldown-cmark-to-cmark
+[example]: https://github.com/rust-lang/mdBook/blob/master/examples/nop-preprocessor.rs
+[an example no-op preprocessor]: https://github.com/rust-lang/mdBook/blob/master/examples/nop-preprocessor.rs
+[`CmdPreprocessor::parse_input()`]: https://docs.rs/mdbook/latest/mdbook/preprocess/trait.Preprocessor.html#method.parse_input
+[`Book::for_each_mut()`]: https://docs.rs/mdbook/latest/mdbook/book/struct.Book.html#method.for_each_mut
+[`PreprocessorContext`]: https://docs.rs/mdbook/latest/mdbook/preprocess/struct.PreprocessorContext.html
+[`Book`]: https://docs.rs/mdbook/latest/mdbook/book/struct.Book.html

guide/src/format/configuration/README.md

@@ -0,0 +1,12 @@
+# Configuration
+
+This section details the configuration options available in the ***book.toml***:
+- **[General]** configuration including the `book`, `rust`, `build` sections
+- **[Preprocessor]** configuration for default and custom book preprocessors
+- **[Renderer]** configuration for the HTML, Markdown and custom renderers
+- **[Environment Variable]** configuration for overriding configuration options in your environment
+
+[General]: general.md
+[Preprocessor]: preprocessors.md
+[Renderer]: renderers.md
+[Environment Variable]: environment-variables.md

guide/src/format/configuration/environment-variables.md

@@ -0,0 +1,38 @@
+# Environment Variables
+
+All configuration values can be overridden from the command line by setting the
+corresponding environment variable. Because many operating systems restrict
+environment variables to be alphanumeric characters or `_`, the configuration
+key needs to be formatted slightly differently to the normal `foo.bar.baz` form.
+
+Variables starting with `MDBOOK_` are used for configuration. The key is created
+by removing the `MDBOOK_` prefix and turning the resulting string into
+`kebab-case`. Double underscores (`__`) separate nested keys, while a single
+underscore (`_`) is replaced with a dash (`-`).
+
+For example:
+
+- `MDBOOK_foo` -> `foo`
+- `MDBOOK_FOO` -> `foo`
+- `MDBOOK_FOO__BAR` -> `foo.bar`
+- `MDBOOK_FOO_BAR` -> `foo-bar`
+- `MDBOOK_FOO_bar__baz` -> `foo-bar.baz`
+
+So by setting the `MDBOOK_BOOK__TITLE` environment variable you can override the
+book's title without needing to touch your `book.toml`.
+
+> **Note:** To facilitate setting more complex config items, the value of an
+> environment variable is first parsed as JSON, falling back to a string if the
+> parse fails.
+>
+> This means, if you so desired, you could override all book metadata when
+> building the book with something like
+>
+> ```shell
+> $ export MDBOOK_BOOK='{"title": "My Awesome Book", "authors": ["Michael-F-Bryan"]}'
+> $ mdbook build
+> ```
+
+The latter case may be useful in situations where `mdbook` is invoked from a
+script or CI, where it sometimes isn't possible to update the `book.toml` before
+building.

guide/src/format/configuration/general.md

@@ -0,0 +1,118 @@
+# General Configuration
+
+You can configure the parameters for your book in the ***book.toml*** file.
+
+Here is an example of what a ***book.toml*** file might look like:
+
+```toml
+[book]
+title = "Example book"
+authors = ["John Doe"]
+description = "The example book covers examples."
+
+[rust]
+edition = "2018"
+
+[build]
+build-dir = "my-example-book"
+create-missing = false
+
+[preprocessor.index]
+
+[preprocessor.links]
+
+[output.html]
+additional-css = ["custom.css"]
+
+[output.html.search]
+limit-results = 15
+```
+
+## Supported configuration options
+
+It is important to note that **any** relative path specified in the
+configuration will always be taken relative from the root of the book where the
+configuration file is located.
+
+### General metadata
+
+This is general information about your book.
+
+- **title:** The title of the book
+- **authors:** The author(s) of the book
+- **description:** A description for the book, which is added as meta
+  information in the html `<head>` of each page
+- **src:** By default, the source directory is found in the directory named
+  `src` directly under the root folder. But this is configurable with the `src`
+  key in the configuration file.
+- **language:** The main language of the book, which is used as a language attribute `<html lang="en">` for example.
+  This is also used to derive the direction of text (RTL, LTR) within the book.
+- **text-direction**: The direction of text in the book: Left-to-right (LTR) or Right-to-left (RTL). Possible values: `ltr`, `rtl`.
+  When not specified, the text direction is derived from the book's `language` attribute.
+
+**book.toml**
+```toml
+[book]
+title = "Example book"
+authors = ["John Doe", "Jane Doe"]
+description = "The example book covers examples."
+src = "my-src"  # the source files will be found in `root/my-src` instead of `root/src`
+language = "en"
+text-direction = "ltr"
+```
+
+### Rust options
+
+Options for the Rust language, relevant to running tests and playground
+integration.
+
+```toml
+[rust]
+edition = "2015"   # the default edition for code blocks
+```
+
+- **edition**: Rust edition to use by default for the code snippets. Default
+  is "2015". Individual code blocks can be controlled with the `edition2015`, 
+  `edition2018` or `edition2021` annotations, such as:
+
+  ~~~text
+  ```rust,edition2015
+  // This only works in 2015.
+  let try = true;
+  ```
+  ~~~
+
+### Build options
+
+This controls the build process of your book.
+
+```toml
+[build]
+build-dir = "book"                # the directory where the output is placed
+create-missing = true             # whether or not to create missing pages
+use-default-preprocessors = true  # use the default preprocessors
+extra-watch-dirs = []             # directories to watch for triggering builds
+```
+
+- **build-dir:** The directory to put the rendered book in. By default this is
+  `book/` in the book's root directory.
+  This can overridden with the `--dest-dir` CLI option.
+- **create-missing:** By default, any missing files specified in `SUMMARY.md`
+  will be created when the book is built (i.e. `create-missing = true`). If this
+  is `false` then the build process will instead exit with an error if any files
+  do not exist.
+- **use-default-preprocessors:** Disable the default preprocessors (of `links` &
+  `index`) by setting this option to `false`.
+
+  If you have the same, and/or other preprocessors declared via their table
+  of configuration, they will run instead.
+
+  - For clarity, with no preprocessor configuration, the default `links` and
+    `index` will run.
+  - Setting `use-default-preprocessors = false` will disable these
+    default preprocessors from running.
+  - Adding `[preprocessor.links]`, for example, will ensure, regardless of
+    `use-default-preprocessors` that `links` it will run.
+- **extra-watch-dirs**: A list of paths to directories that will be watched in
+  the `watch` and `serve` commands. Changes to files under these directories will
+  trigger rebuilds. Useful if your book depends on files outside its `src` directory.

guide/src/format/configuration/preprocessors.md

@@ -0,0 +1,87 @@
+# Configuring Preprocessors
+
+Preprocessors are extensions that can modify the raw Markdown source before it gets sent to the renderer.
+
+The following preprocessors are built-in and included by default:
+
+- `links`: Expands the `{{ #playground }}`, `{{ #include }}`, and `{{ #rustdoc_include }}` handlebars
+  helpers in a chapter to include the contents of a file.
+  See [Including files] for more.
+- `index`: Convert all chapter files named `README.md` into `index.md`. That is
+  to say, all `README.md` would be rendered to an index file `index.html` in the
+  rendered book.
+
+The built-in preprocessors can be disabled with the [`build.use-default-preprocessors`] config option.
+
+The community has developed several preprocessors.
+See the [Third Party Plugins] wiki page for a list of available preprocessors.
+
+For information on how to create a new preprocessor, see the [Preprocessors for Developers] chapter.
+
+[Including files]: ../mdbook.md#including-files
+[`build.use-default-preprocessors`]: general.md#build-options
+[Third Party Plugins]: https://github.com/rust-lang/mdBook/wiki/Third-party-plugins
+[Preprocessors for Developers]: ../../for_developers/preprocessors.md
+
+## Custom Preprocessor Configuration
+
+Preprocessors can be added by including a `preprocessor` table in `book.toml` with the name of the preprocessor.
+For example, if you have a preprocessor called `mdbook-example`, then you can include it with:
+
+```toml
+[preprocessor.example]
+```
+
+With this table, mdBook will execute the `mdbook-example` preprocessor.
+
+This table can include additional key-value pairs that are specific to the preprocessor.
+For example, if our example preprocessor needed some extra configuration options:
+
+```toml
+[preprocessor.example]
+some-extra-feature = true
+```
+
+## Locking a Preprocessor dependency to a renderer
+
+You can explicitly specify that a preprocessor should run for a renderer by
+binding the two together.
+
+```toml
+[preprocessor.example]
+renderers = ["html"]  # example preprocessor only runs with the HTML renderer
+```
+
+## Provide Your Own Command
+
+By default when you add a `[preprocessor.foo]` table to your `book.toml` file,
+`mdbook` will try to invoke the `mdbook-foo` executable. If you want to use a
+different program name or pass in command-line arguments, this behaviour can
+be overridden by adding a `command` field.
+
+```toml
+[preprocessor.random]
+command = "python random.py"
+```
+
+## Require A Certain Order
+
+The order in which preprocessors are run can be controlled with the `before` and `after` fields.
+For example, suppose you want your `linenos` preprocessor to process lines that may have been `{{#include}}`d; then you want it to run after the built-in `links` preprocessor, which you can require using either the `before` or `after` field:
+
+```toml
+[preprocessor.linenos]
+after = [ "links" ]
+```
+
+or
+
+```toml
+[preprocessor.links]
+before = [ "linenos" ]
+```
+
+It would also be possible, though redundant, to specify both of the above in the same config file.
+
+Preprocessors having the same priority specified through `before` and `after` are sorted by name.
+Any infinite loops will be detected and produce an error.

guide/src/format/configuration/renderers.md

@@ -0,0 +1,319 @@
+# Configuring Renderers
+
+Renderers (also called "backends") are responsible for creating the output of the book.
+
+The following backends are built-in:
+
+* [`html`](#html-renderer-options) — This renders the book to HTML.
+  This is enabled by default if no other `[output]` tables are defined in `book.toml`.
+* [`markdown`](#markdown-renderer) — This outputs the book as markdown after running the preprocessors.
+  This is useful for debugging preprocessors.
+
+The community has developed several backends.
+See the [Third Party Plugins] wiki page for a list of available backends.
+
+For information on how to create a new backend, see the [Backends for Developers] chapter.
+
+[Third Party Plugins]: https://github.com/rust-lang/mdBook/wiki/Third-party-plugins
+[Backends for Developers]: ../../for_developers/backends.md
+
+## Output tables
+
+Backends can be added by including a `output` table in `book.toml` with the name of the backend.
+For example, if you have a backend called `mdbook-wordcount`, then you can include it with:
+
+```toml
+[output.wordcount]
+```
+
+With this table, mdBook will execute the `mdbook-wordcount` backend.
+
+This table can include additional key-value pairs that are specific to the backend.
+For example, if our example backend needed some extra configuration options:
+
+```toml
+[output.wordcount]
+ignores = ["Example Chapter"]
+```
+
+If you define any `[output]` tables, then the `html` backend is not enabled by default.
+If you want to keep the `html` backend running, then just include it in the `book.toml` file.
+For example:
+
+```toml
+[book]
+title = "My Awesome Book"
+
+[output.wordcount]
+
+[output.html]
+```
+
+If more than one `output` table is included, this changes the behavior for the layout of the output directory.
+If there is only one backend, then it places its output directly in the `book` directory (see [`build.build-dir`] to override this location).
+If there is more than one backend, then each backend is placed in a separate directory underneath `book`.
+For example, the above would have directories `book/html` and `book/wordcount`.
+
+[`build.build-dir`]: general.md#build-options
+
+### Custom backend commands
+
+By default when you add an `[output.foo]` table to your `book.toml` file,
+`mdbook` will try to invoke the `mdbook-foo` executable.
+If you want to use a different program name or pass in command-line arguments,
+this behaviour can be overridden by adding a `command` field.
+
+```toml
+[output.random]
+command = "python random.py"
+```
+
+### Optional backends
+
+If you enable a backend that isn't installed, the default behavior is to throw an error.
+This behavior can be changed by marking the backend as optional:
+
+```toml
+[output.wordcount]
+optional = true
+```
+
+This demotes the error to a warning.
+
+
+## HTML renderer options
+
+The HTML renderer has a variety of options detailed below.
+They should be specified in the `[output.html]` table of the `book.toml` file.
+
+```toml
+# Example book.toml file with all output options.
+[book]
+title = "Example book"
+authors = ["John Doe", "Jane Doe"]
+description = "The example book covers examples."
+
+[output.html]
+theme = "my-theme"
+default-theme = "light"
+preferred-dark-theme = "navy"
+smart-punctuation = true
+mathjax-support = false
+copy-fonts = true
+additional-css = ["custom.css", "custom2.css"]
+additional-js = ["custom.js"]
+no-section-label = false
+git-repository-url = "https://github.com/rust-lang/mdBook"
+git-repository-icon = "fa-github"
+edit-url-template = "https://github.com/rust-lang/mdBook/edit/master/guide/{path}"
+site-url = "/example-book/"
+cname = "myproject.rs"
+input-404 = "not-found.md"
+```
+
+The following configuration options are available:
+
+- **theme:** mdBook comes with a default theme and all the resource files needed
+  for it. But if this option is set, mdBook will selectively overwrite the theme
+  files with the ones found in the specified folder.
+- **default-theme:** The theme color scheme to select by default in the
+  'Change Theme' dropdown. Defaults to `light`.
+- **preferred-dark-theme:** The default dark theme. This theme will be used if
+  the browser requests the dark version of the site via the
+  ['prefers-color-scheme'](https://developer.mozilla.org/en-US/docs/Web/CSS/@media/prefers-color-scheme)
+  CSS media query. Defaults to `navy`.
+- **smart-punctuation:** Converts quotes to curly quotes, `...` to `…`, `--` to en-dash, and `---` to em-dash.
+  See [Smart Punctuation].
+  Defaults to `false`.
+- **curly-quotes:** Deprecated alias for `smart-punctuation`.
+- **mathjax-support:** Adds support for [MathJax](../mathjax.md). Defaults to
+  `false`.
+- **copy-fonts:** (**Deprecated**) If `true` (the default), mdBook uses its built-in fonts which are copied to the output directory.
+  If `false`, the built-in fonts will not be used.
+  This option is deprecated. If you want to define your own custom fonts,
+  create a `theme/fonts/fonts.css` file and store the fonts in the `theme/fonts/` directory.
+- **google-analytics:** This field has been deprecated and will be removed in a future release.
+  Use the `theme/head.hbs` file to add the appropriate Google Analytics code instead.
+- **additional-css:** If you need to slightly change the appearance of your book
+  without overwriting the whole style, you can specify a set of stylesheets that
+  will be loaded after the default ones where you can surgically change the
+  style.
+- **additional-js:** If you need to add some behaviour to your book without
+  removing the current behaviour, you can specify a set of JavaScript files that
+  will be loaded alongside the default one.
+- **no-section-label:** mdBook by defaults adds numeric section labels in the table of
+  contents column. For example, "1.", "2.1". Set this option to true to disable
+  those labels. Defaults to `false`.
+- **git-repository-url:**  A url to the git repository for the book. If provided
+  an icon link will be output in the menu bar of the book.
+- **git-repository-icon:** The FontAwesome icon class to use for the git
+  repository link. Defaults to `fa-github` which looks like <i class="fa fa-github"></i>.
+  If you are not using GitHub, another option to consider is `fa-code-fork` which looks like <i class="fa fa-code-fork"></i>.
+- **edit-url-template:** Edit url template, when provided shows a
+  "Suggest an edit" button (which looks like <i class="fa fa-edit"></i>) for directly jumping to editing the currently
+  viewed page. For e.g. GitHub projects set this to
+  `https://github.com/<owner>/<repo>/edit/<branch>/{path}` or for
+  Bitbucket projects set it to
+  `https://bitbucket.org/<owner>/<repo>/src/<branch>/{path}?mode=edit`
+  where {path} will be replaced with the full path of the file in the
+  repository.
+- **input-404:** The name of the markdown file used for missing files.
+  The corresponding output file will be the same, with the extension replaced with `html`.
+  Defaults to `404.md`.
+- **site-url:** The url where the book will be hosted. This is required to ensure
+  navigation links and script/css imports in the 404 file work correctly, even when accessing
+  urls in subdirectories. Defaults to `/`. If `site-url` is set,
+  make sure to use document relative links for your assets, meaning they should not start with `/`.
+- **cname:** The DNS subdomain or apex domain at which your book will be hosted.
+  This string will be written to a file named CNAME in the root of your site, as
+  required by GitHub Pages (see [*Managing a custom domain for your GitHub Pages
+  site*][custom domain]).
+
+[custom domain]: https://docs.github.com/en/github/working-with-github-pages/managing-a-custom-domain-for-your-github-pages-site
+
+### `[output.html.print]`
+
+The `[output.html.print]` table provides options for controlling the printable output.
+By default, mdBook will include an icon on the top right of the book (which looks like <i class="fa fa-print"></i>) that will print the book as a single page.
+
+```toml
+[output.html.print]
+enable = true    # include support for printable output
+page-break = true # insert page-break after each chapter
+```
+
+- **enable:** Enable print support. When `false`, all print support will not be
+  rendered. Defaults to `true`.
+- **page-break:** Insert page breaks between chapters. Defaults to `true`.
+
+### `[output.html.fold]`
+
+The `[output.html.fold]` table provides options for controlling folding of the chapter listing in the navigation sidebar.
+
+```toml
+[output.html.fold]
+enable = false    # whether or not to enable section folding
+level = 0         # the depth to start folding
+```
+
+- **enable:** Enable section-folding. When off, all folds are open.
+  Defaults to `false`.
+- **level:** The higher the more folded regions are open. When level is 0, all
+  folds are closed. Defaults to `0`.
+
+### `[output.html.playground]`
+
+The `[output.html.playground]` table provides options for controlling Rust sample code blocks, and their integration with the [Rust Playground].
+
+[Rust Playground]: https://play.rust-lang.org/
+
+```toml
+[output.html.playground]
+editable = false         # allows editing the source code
+copyable = true          # include the copy button for copying code snippets
+copy-js = true           # includes the JavaScript for the code editor
+line-numbers = false     # displays line numbers for editable code
+runnable = true          # displays a run button for rust code
+```
+
+- **editable:** Allow editing the source code. Defaults to `false`.
+- **copyable:** Display the copy button on code snippets. Defaults to `true`.
+- **copy-js:** Copy JavaScript files for the editor to the output directory.
+  Defaults to `true`.
+- **line-numbers:** Display line numbers on editable sections of code. Requires both `editable` and `copy-js` to be `true`. Defaults to `false`.
+- **runnable:** Displays a run button for rust code snippets. Changing this to `false` will disable the run in playground feature globally. Defaults to `true`.
+
+[Ace]: https://ace.c9.io/
+
+### `[output.html.code]`
+
+The `[output.html.code]` table provides options for controlling code blocks.
+
+```toml
+[output.html.code]
+# A prefix string per language (one or more chars).
+# Any line starting with whitespace+prefix is hidden.
+hidelines = { python = "~" }
+```
+
+- **hidelines:** A table that defines how [hidden code lines](../mdbook.md#hiding-code-lines) work for each language.
+  The key is the language and the value is a string that will cause code lines starting with that prefix to be hidden.
+
+### `[output.html.search]`
+
+The `[output.html.search]` table provides options for controlling the built-in text [search].
+mdBook must be compiled with the `search` feature enabled (on by default).
+
+[search]: ../../guide/reading.md#search
+
+```toml
+[output.html.search]
+enable = true            # enables the search feature
+limit-results = 30       # maximum number of search results
+teaser-word-count = 30   # number of words used for a search result teaser
+use-boolean-and = true   # multiple search terms must all match
+boost-title = 2          # ranking boost factor for matches in headers
+boost-hierarchy = 1      # ranking boost factor for matches in page names
+boost-paragraph = 1      # ranking boost factor for matches in text
+expand = true            # partial words will match longer terms
+heading-split-level = 3  # link results to heading levels
+copy-js = true           # include Javascript code for search
+```
+
+- **enable:** Enables the search feature. Defaults to `true`.
+- **limit-results:** The maximum number of search results. Defaults to `30`.
+- **teaser-word-count:** The number of words used for a search result teaser.
+  Defaults to `30`.
+- **use-boolean-and:** Define the logical link between multiple search words. If
+  true, all search words must appear in each result. Defaults to `false`.
+- **boost-title:** Boost factor for the search result score if a search word
+  appears in the header. Defaults to `2`.
+- **boost-hierarchy:** Boost factor for the search result score if a search word
+  appears in the hierarchy. The hierarchy contains all titles of the parent
+  documents and all parent headings. Defaults to `1`.
+- **boost-paragraph:** Boost factor for the search result score if a search word
+  appears in the text. Defaults to `1`.
+- **expand:** True if search should match longer results e.g. search `micro`
+  should match `microwave`. Defaults to `true`.
+- **heading-split-level:** Search results will link to a section of the document
+  which contains the result. Documents are split into sections by headings this
+  level or less. Defaults to `3`. (`### This is a level 3 heading`)
+- **copy-js:** Copy JavaScript files for the search implementation to the output
+  directory. Defaults to `true`.
+
+### `[output.html.redirect]`
+
+The `[output.html.redirect]` table provides a way to add redirects.
+This is useful when you move, rename, or remove a page to ensure that links to the old URL will go to the new location.
+
+```toml
+[output.html.redirect]
+"/appendices/bibliography.html" = "https://rustc-dev-guide.rust-lang.org/appendix/bibliography.html"
+"/other-installation-methods.html" = "../infra/other-installation-methods.html"
+```
+
+The table contains key-value pairs where the key is where the redirect file needs to be created, as an absolute path from the build directory, (e.g. `/appendices/bibliography.html`).
+The value can be any valid URI the browser should navigate to (e.g. `https://rust-lang.org/`, `/overview.html`, or `../bibliography.html`).
+
+This will generate an HTML page which will automatically redirect to the given location.
+Note that the source location does not support `#` anchor redirects.
+
+## Markdown Renderer
+
+The Markdown renderer will run preprocessors and then output the resulting
+Markdown. This is mostly useful for debugging preprocessors, especially in
+conjunction with `mdbook test` to see the Markdown that `mdbook` is passing
+to `rustdoc`.
+
+The Markdown renderer is included with `mdbook` but disabled by default.
+Enable it by adding an empty table to your `book.toml` as follows:
+
+```toml
+[output.markdown]
+```
+
+There are no configuration options for the Markdown renderer at this time;
+only whether it is enabled or disabled.
+
+See [the preprocessors documentation](preprocessors.md) for how to
+specify which preprocessors should run before the Markdown renderer.

guide/src/format/example.rs

@@ -0,0 +1,6 @@
+fn main() {
+    println!("Hello World!");
+#
+#     // You can even hide lines! :D
+#     println!("I am hidden! Expand the code snippet to see me");
+}

guide/src/format/images/rust-logo-blk.svg

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guide/src/format/markdown.md

@@ -0,0 +1,235 @@
+# Markdown
+
+mdBook's [parser](https://github.com/raphlinus/pulldown-cmark) adheres to the [CommonMark](https://commonmark.org/) specification with some extensions described below.
+You can take a quick [tutorial](https://commonmark.org/help/tutorial/),
+or [try out](https://spec.commonmark.org/dingus/) CommonMark in real time. A complete Markdown overview is out of scope for 
+this documentation, but below is a high level overview of some of the basics. For a more in-depth experience, check out the
+[Markdown Guide](https://www.markdownguide.org).
+
+## Text and Paragraphs
+
+Text is rendered relatively predictably: 
+
+```markdown
+Here is a line of text.
+
+This is a new line.
+```
+
+Will look like you might expect:
+
+Here is a line of text.
+
+This is a new line.
+
+## Headings
+
+Headings use the `#` marker and should be on a line by themselves. More `#` mean smaller headings:
+
+```markdown
+### A heading 
+
+Some text.
+
+#### A smaller heading 
+
+More text.
+```
+
+### A heading 
+
+Some text.
+
+#### A smaller heading 
+
+More text.
+
+## Lists
+
+Lists can be unordered or ordered. Ordered lists will order automatically:
+
+```markdown
+* milk
+* eggs
+* butter
+
+1. carrots
+1. celery
+1. radishes
+```
+
+* milk
+* eggs
+* butter
+
+1. carrots
+1. celery
+1. radishes
+
+## Links
+
+Linking to a URL or local file is easy:
+
+```markdown
+Use [mdBook](https://github.com/rust-lang/mdBook). 
+
+Read about [mdBook](mdbook.md).
+
+A bare url: <https://www.rust-lang.org>.
+```
+
+Use [mdBook](https://github.com/rust-lang/mdBook). 
+
+Read about [mdBook](mdbook.md).
+
+A bare url: <https://www.rust-lang.org>.
+
+----
+
+Relative links that end with `.md` will be converted to the `.html` extension.
+It is recommended to use `.md` links when possible.
+This is useful when viewing the Markdown file outside of mdBook, for example on GitHub or GitLab which render Markdown automatically.
+
+Links to `README.md` will be converted to `index.html`.
+This is done since some services like GitHub render README files automatically, but web servers typically expect the root file to be called `index.html`.
+
+You can link to individual headings with `#` fragments.
+For example, `mdbook.md#text-and-paragraphs` would link to the [Text and Paragraphs](#text-and-paragraphs) section above.
+The ID is created by transforming the heading such as converting to lowercase and replacing spaces with dashes.
+You can click on any heading and look at the URL in your browser to see what the fragment looks like.
+
+## Images
+
+Including images is simply a matter of including a link to them, much like in the _Links_ section above. The following markdown
+includes the Rust logo SVG image found in the `images` directory at the same level as this file:
+
+```markdown
+![The Rust Logo](images/rust-logo-blk.svg)
+```
+
+Produces the following HTML when built with mdBook:
+
+```html
+<p><img src="images/rust-logo-blk.svg" alt="The Rust Logo" /></p>
+```
+
+Which, of course displays the image like so:
+
+![The Rust Logo](images/rust-logo-blk.svg)
+
+## Extensions
+
+mdBook has several extensions beyond the standard CommonMark specification.
+
+### Strikethrough
+
+Text may be rendered with a horizontal line through the center by wrapping the
+text with one or two tilde characters on each side:
+
+```text
+An example of ~~strikethrough text~~.
+```
+
+This example will render as:
+
+> An example of ~~strikethrough text~~.
+
+This follows the [GitHub Strikethrough extension][strikethrough].
+
+### Footnotes
+
+A footnote generates a small numbered link in the text which when clicked
+takes the reader to the footnote text at the bottom of the item. The footnote
+label is written similarly to a link reference with a caret at the front. The
+footnote text is written like a link reference definition, with the text
+following the label. Example:
+
+```text
+This is an example of a footnote[^note].
+
+[^note]: This text is the contents of the footnote, which will be rendered
+    towards the bottom.
+```
+
+This example will render as:
+
+> This is an example of a footnote[^note].
+>
+> [^note]: This text is the contents of the footnote, which will be rendered
+>     towards the bottom.
+
+The footnotes are automatically numbered based on the order the footnotes are
+written.
+
+### Tables
+
+Tables can be written using pipes and dashes to draw the rows and columns of
+the table. These will be translated to HTML table matching the shape. Example:
+
+```text
+| Header1 | Header2 |
+|---------|---------|
+| abc     | def     |
+```
+
+This example will render similarly to this:
+
+| Header1 | Header2 |
+|---------|---------|
+| abc     | def     |
+
+See the specification for the [GitHub Tables extension][tables] for more
+details on the exact syntax supported.
+
+### Task lists
+
+Task lists can be used as a checklist of items that have been completed.
+Example:
+
+```md
+- [x] Complete task
+- [ ] Incomplete task
+```
+
+This will render as:
+
+> - [x] Complete task
+> - [ ] Incomplete task
+
+See the specification for the [task list extension] for more details.
+
+### Smart punctuation
+
+Some ASCII punctuation sequences will be automatically turned into fancy Unicode
+characters:
+
+| ASCII sequence | Unicode |
+|----------------|---------|
+| `--`           | –       |
+| `---`          | —       |
+| `...`          | …       |
+| `"`            | “ or ”, depending on context |
+| `'`            | ‘ or ’, depending on context |
+
+So, no need to manually enter those Unicode characters!
+
+This feature is disabled by default.
+To enable it, see the [`output.html.smart-punctuation`] config option.
+
+[strikethrough]: https://github.github.com/gfm/#strikethrough-extension-
+[tables]: https://github.github.com/gfm/#tables-extension-
+[task list extension]: https://github.github.com/gfm/#task-list-items-extension-
+[`output.html.smart-punctuation`]: configuration/renderers.md#html-renderer-options
+
+### Heading attributes
+
+Headings can have a custom HTML ID and classes. This lets you maintain the same ID even if you change the heading's text, it also lets you add multiple classes in the heading.
+
+Example:
+```md
+# Example heading { #first .class1 .class2 }
+```
+
+This makes the level 1 heading with the content `Example heading`, ID `first`, and classes `class1` and `class2`. Note that the attributes should be space-separated.
+
+More information can be found in the [heading attrs spec page](https://github.com/raphlinus/pulldown-cmark/blob/master/pulldown-cmark/specs/heading_attrs.txt).

guide/src/format/mdbook.md

@@ -0,0 +1,364 @@
+# mdBook-specific features
+
+## Hiding code lines
+
+There is a feature in mdBook that lets you hide code lines by prepending them with a specific prefix.
+
+For the Rust language, you can use the `#` character as a prefix which will hide lines [like you would with Rustdoc][rustdoc-hide].
+
+[rustdoc-hide]: https://doc.rust-lang.org/stable/rustdoc/write-documentation/documentation-tests.html#hiding-portions-of-the-example
+
+```bash
+# fn main() {
+    let x = 5;
+    let y = 6;
+
+    println!("{}", x + y);
+# }
+```
+
+Will render as
+
+```rust
+# fn main() {
+    let x = 5;
+    let y = 6;
+
+    println!("{}", x + y);
+# }
+```
+
+When you tap or hover the mouse over the code block, there will be an eyeball icon (<i class="fa fa-eye"></i>) which will toggle the visibility of the hidden lines.
+
+By default, this only works for code examples that are annotated with `rust`.
+However, you can define custom prefixes for other languages by adding a new line-hiding prefix in your `book.toml` with the language name and prefix character(s):
+
+```toml
+[output.html.code.hidelines]
+python = "~"
+```
+
+The prefix will hide any lines that begin with the given prefix. With the python prefix shown above, this:
+
+```bash
+~hidden()
+nothidden():
+~    hidden()
+    ~hidden()
+    nothidden()
+```
+
+will render as
+
+```python
+~hidden()
+nothidden():
+~    hidden()
+    ~hidden()
+    nothidden()
+```
+
+This behavior can be overridden locally with a different prefix. This has the same effect as above:
+
+~~~markdown
+```python,hidelines=!!!
+!!!hidden()
+nothidden():
+!!!    hidden()
+    !!!hidden()
+    nothidden()
+```
+~~~
+
+## Rust Playground
+
+Rust language code blocks will automatically get a play button (<i class="fa fa-play"></i>) which will execute the code and display the output just below the code block.
+This works by sending the code to the [Rust Playground].
+
+```rust
+println!("Hello, World!");
+```
+
+If there is no `main` function, then the code is automatically wrapped inside one.
+
+If you wish to disable the play button for a code block, you can include the `noplayground` option on the code block like this:
+
+~~~markdown
+```rust,noplayground
+let mut name = String::new();
+std::io::stdin().read_line(&mut name).expect("failed to read line");
+println!("Hello {}!", name);
+```
+~~~
+
+Or, if you wish to disable the play button for all code blocks in your book, you can write the config to the `book.toml` like this.
+
+```toml
+[output.html.playground]
+runnable = false
+```
+
+## Rust code block attributes
+
+Additional attributes can be included in Rust code blocks with comma, space, or tab-separated terms just after the language term. For example:
+
+~~~markdown
+```rust,ignore
+# This example won't be tested.
+panic!("oops!");
+```
+~~~
+
+These are particularly important when using [`mdbook test`] to test Rust examples.
+These use the same attributes as [rustdoc attributes], with a few additions:
+
+* `editable` — Enables the [editor].
+* `noplayground` — Removes the play button, but will still be tested.
+* `mdbook-runnable` — Forces the play button to be displayed.
+  This is intended to be combined with the `ignore` attribute for examples that should not be tested, but you want to allow the reader to run.
+* `ignore` — Will not be tested and no play button is shown, but it is still highlighted as Rust syntax.
+* `should_panic` — When executed, it should produce a panic.
+* `no_run` — The code is compiled when tested, but it is not run.
+  The play button is also not shown.
+* `compile_fail` — The code should fail to compile.
+* `edition2015`, `edition2018`, `edition2021` — Forces the use of a specific Rust edition.
+  See [`rust.edition`] to set this globally.
+
+[`mdbook test`]: ../cli/test.md
+[rustdoc attributes]: https://doc.rust-lang.org/rustdoc/documentation-tests.html#attributes
+[editor]: theme/editor.md
+[`rust.edition`]: configuration/general.md#rust-options
+
+## Including files
+
+With the following syntax, you can include files into your book:
+
+```hbs
+\{{#include file.rs}}
+```
+
+The path to the file has to be relative from the current source file.
+
+mdBook will interpret included files as Markdown. Since the include command
+is usually used for inserting code snippets and examples, you will often
+wrap the command with ```` ``` ```` to display the file contents without
+interpreting them.
+
+````hbs
+```
+\{{#include file.rs}}
+```
+````
+
+## Including portions of a file
+Often you only need a specific part of the file, e.g. relevant lines for an
+example. We support four different modes of partial includes:
+
+```hbs
+\{{#include file.rs:2}}
+\{{#include file.rs::10}}
+\{{#include file.rs:2:}}
+\{{#include file.rs:2:10}}
+```
+
+The first command only includes the second line from file `file.rs`. The second
+command includes all lines up to line 10, i.e. the lines from 11 till the end of
+the file are omitted. The third command includes all lines from line 2, i.e. the
+first line is omitted. The last command includes the excerpt of `file.rs`
+consisting of lines 2 to 10.
+
+To avoid breaking your book when modifying included files, you can also
+include a specific section using anchors instead of line numbers.
+An anchor is a pair of matching lines. The line beginning an anchor must
+match the regex `ANCHOR:\s*[\w_-]+` and similarly the ending line must match
+the regex `ANCHOR_END:\s*[\w_-]+`. This allows you to put anchors in
+any kind of commented line.
+
+Consider the following file to include:
+```rs
+/* ANCHOR: all */
+
+// ANCHOR: component
+struct Paddle {
+    hello: f32,
+}
+// ANCHOR_END: component
+
+////////// ANCHOR: system
+impl System for MySystem { ... }
+////////// ANCHOR_END: system
+
+/* ANCHOR_END: all */
+```
+
+Then in the book, all you have to do is:
+````hbs
+Here is a component:
+```rust,no_run,noplayground
+\{{#include file.rs:component}}
+```
+
+Here is a system:
+```rust,no_run,noplayground
+\{{#include file.rs:system}}
+```
+
+This is the full file.
+```rust,no_run,noplayground
+\{{#include file.rs:all}}
+```
+````
+
+Lines containing anchor patterns inside the included anchor are ignored.
+
+## Including a file but initially hiding all except specified lines
+
+The `rustdoc_include` helper is for including code from external Rust files that contain complete
+examples, but only initially showing particular lines specified with line numbers or anchors in the
+same way as with `include`.
+
+The lines not in the line number range or between the anchors will still be included, but they will
+be prefaced with `#`. This way, a reader can expand the snippet to see the complete example, and
+Rustdoc will use the complete example when you run `mdbook test`.
+
+For example, consider a file named `file.rs` that contains this Rust program:
+
+```rust
+fn main() {
+    let x = add_one(2);
+    assert_eq!(x, 3);
+}
+
+fn add_one(num: i32) -> i32 {
+    num + 1
+}
+```
+
+We can include a snippet that initially shows only line 2 by using this syntax:
+
+````hbs
+To call the `add_one` function, we pass it an `i32` and bind the returned value to `x`:
+
+```rust
+\{{#rustdoc_include file.rs:2}}
+```
+````
+
+This would have the same effect as if we had manually inserted the code and hidden all but line 2
+using `#`:
+
+````hbs
+To call the `add_one` function, we pass it an `i32` and bind the returned value to `x`:
+
+```rust
+# fn main() {
+    let x = add_one(2);
+#     assert_eq!(x, 3);
+# }
+#
+# fn add_one(num: i32) -> i32 {
+#     num + 1
+# }
+```
+````
+
+That is, it looks like this (click the "expand" icon to see the rest of the file):
+
+```rust
+# fn main() {
+    let x = add_one(2);
+#     assert_eq!(x, 3);
+# }
+#
+# fn add_one(num: i32) -> i32 {
+#     num + 1
+# }
+```
+
+## Inserting runnable Rust files
+
+With the following syntax, you can insert runnable Rust files into your book:
+
+```hbs
+\{{#playground file.rs}}
+```
+
+The path to the Rust file has to be relative from the current source file.
+
+When play is clicked, the code snippet will be sent to the [Rust Playground] to be
+compiled and run. The result is sent back and displayed directly underneath the
+code.
+
+Here is what a rendered code snippet looks like:
+
+{{#playground example.rs}}
+
+Any additional values passed after the filename will be included as attributes of the code block.
+For example `\{{#playground example.rs editable}}` will create the code block like the following:
+
+~~~markdown
+```rust,editable
+# Contents of example.rs here.
+```
+~~~
+
+And the `editable` attribute will enable the [editor] as described at [Rust code block attributes](#rust-code-block-attributes).
+
+[Rust Playground]: https://play.rust-lang.org/
+
+## Controlling page \<title\>
+
+A chapter can set a \<title\> that is different from its entry in the table of
+contents (sidebar) by including a `\{{#title ...}}` near the top of the page.
+
+```hbs
+\{{#title My Title}}
+```
+
+## HTML classes provided by mdBook
+
+<img class="right" src="images/rust-logo-blk.svg" alt="The Rust logo">
+
+### `class="left"` and `"right"`
+
+These classes are provided by default, for inline HTML to float images.
+
+```html
+<img class="right" src="images/rust-logo-blk.svg" alt="The Rust logo">
+```
+
+### `class="hidden"`
+
+HTML tags with class `hidden` will not be shown.
+
+```html
+<div class="hidden">This will not be seen.</div>
+```
+
+<div class="hidden">This will not be seen.</div>
+
+### `class="warning"`
+
+To make a warning or similar note stand out, wrap it in a warning div.
+
+```html
+<div class="warning">
+
+This is a bad thing that you should pay attention to.
+
+Warning blocks should be used sparingly in documentation, to avoid "warning
+fatigue," where people are trained to ignore them because they usually don't
+matter for what they're doing.
+
+</div>
+```
+
+<div class="warning">
+
+This is a bad thing that you should pay attention to.
+
+Warning blocks should be used sparingly in documentation, to avoid "warning
+fatigue," where people are trained to ignore them because they usually don't
+matter for what they're doing.
+
+</div>

guide/src/format/summary.md

@@ -0,0 +1,100 @@
+# SUMMARY.md
+
+The summary file is used by mdBook to know what chapters to include, in what
+order they should appear, what their hierarchy is and where the source files
+are. Without this file, there is no book.
+
+This markdown file must be named `SUMMARY.md`. Its formatting
+is very strict and must follow the structure outlined below to allow for easy
+parsing. Any element not specified below, be it formatting or textual, is likely
+to be ignored at best, or may cause an error when attempting to build the book.
+
+### Structure
+
+1. ***Title*** - While optional, it's common practice to begin with a title, generally <code
+   class="language-markdown"># Summary</code>. This is ignored by the parser however, and
+   can be omitted.
+   ```markdown
+   # Summary
+   ```
+
+1. ***Prefix Chapter*** - Before the main numbered chapters, prefix chapters can be added
+   that will not be numbered. This is useful for forewords,
+   introductions, etc. There are, however, some constraints. Prefix chapters cannot be
+   nested; they should all be on the root level. And you cannot add
+   prefix chapters once you have added numbered chapters.
+   ```markdown
+   [A Prefix Chapter](relative/path/to/markdown.md)
+
+   - [First Chapter](relative/path/to/markdown2.md)
+   ```
+
+1. ***Part Title*** -
+   Level 1 headers can be used as a title for the following numbered chapters.
+   This can be used to logically separate different sections of the book.
+   The title is rendered as unclickable text.
+   Titles are optional, and the numbered chapters can be broken into as many parts as desired.
+   Part titles must be h1 headers (one `#`), other heading levels are ignored.
+   ```markdown
+   # My Part Title
+
+   - [First Chapter](relative/path/to/markdown.md)
+   ```
+
+1. ***Numbered Chapter*** - Numbered chapters outline the main content of the book
+   and can be nested, resulting in a nice hierarchy
+   (chapters, sub-chapters, etc.).
+   ```markdown
+   # Title of Part
+
+   - [First Chapter](relative/path/to/markdown.md)
+   - [Second Chapter](relative/path/to/markdown2.md)
+      - [Sub Chapter](relative/path/to/markdown3.md)
+
+   # Title of Another Part
+
+   - [Another Chapter](relative/path/to/markdown4.md)
+   ```
+   Numbered chapters can be denoted with either `-` or `*` (do not mix delimiters). 
+   
+1. ***Suffix Chapter*** - Like prefix chapters, suffix chapters are unnumbered, but they come after 
+   numbered chapters.
+   ```markdown
+   - [Last Chapter](relative/path/to/markdown.md)
+
+   [Title of Suffix Chapter](relative/path/to/markdown2.md)
+   ```
+
+1. ***Draft chapters*** - Draft chapters are chapters without a file and thus content.
+   The purpose of a draft chapter is to signal future chapters still to be written.
+   Or when still laying out the structure of the book to avoid creating the files
+   while you are still changing the structure of the book a lot.
+   Draft chapters will be rendered in the HTML renderer as disabled links in the table
+   of contents, as you can see for the next chapter in the table of contents on the left.
+   Draft chapters are written like normal chapters but without writing the path to the file.
+   ```markdown
+   - [Draft Chapter]()
+   ```
+
+1. ***Separators*** - Separators can be added before, in between, and after any other element. They result
+   in an HTML rendered line in the built table of contents.  A separator is
+   a line containing exclusively dashes and at least three of them: `---`.
+   ```markdown
+   # My Part Title
+   
+   [A Prefix Chapter](relative/path/to/markdown.md)
+
+   ---
+
+   - [First Chapter](relative/path/to/markdown2.md)
+   ```
+  
+
+### Example
+
+Below is the markdown source for the `SUMMARY.md` for this guide, with the resulting table
+of contents as rendered to the left.
+
+```markdown
+{{#include ../SUMMARY.md}}
+```

guide/src/format/theme/README.md

@@ -0,0 +1,52 @@
+# Theme
+
+The default renderer uses a [handlebars](https://handlebarsjs.com) template to
+render your markdown files and comes with a default theme included in the mdBook
+binary.
+
+The theme is totally customizable, you can selectively replace every file from
+the theme by your own by adding a `theme` directory next to `src` folder in your
+project root. Create a new file with the name of the file you want to override
+and now that file will be used instead of the default file.
+
+Here are the files you can override:
+
+- **_index.hbs_** is the handlebars template.
+- **_head.hbs_** is appended to the HTML `<head>` section.
+- **_header.hbs_** content is appended on top of every book page.
+- **_css/_** contains the CSS files for styling the book.
+    - **_css/chrome.css_** is for UI elements.
+    - **_css/general.css_** is the base styles.
+    - **_css/print.css_** is the style for printer output.
+    - **_css/variables.css_** contains variables used in other CSS files.
+- **_book.js_** is mostly used to add client side functionality, like hiding /
+  un-hiding the sidebar, changing the theme, ...
+- **_highlight.js_** is the JavaScript that is used to highlight code snippets,
+  you should not need to modify this.
+- **_highlight.css_** is the theme used for the code highlighting.
+- **_favicon.svg_** and **_favicon.png_** the favicon that will be used. The SVG
+  version is used by [newer browsers].
+- **fonts/fonts.css** contains the definition of which fonts to load.
+  Custom fonts can be included in the `fonts` directory.
+
+Generally, when you want to tweak the theme, you don't need to override all the
+files. If you only need changes in the stylesheet, there is no point in
+overriding all the other files. Because custom files take precedence over
+built-in ones, they will not get updated with new fixes / features.
+
+**Note:** When you override a file, it is possible that you break some
+functionality. Therefore I recommend to use the file from the default theme as
+template and only add / modify what you need. You can copy the default theme
+into your source directory automatically by using `mdbook init --theme` and just
+remove the files you don't want to override.
+
+`mdbook init --theme` will not create every file listed above.
+Some files, such as `head.hbs`, do not have built-in equivalents.
+Just create the file if you need it.
+
+If you completely replace all built-in themes, be sure to also set
+[`output.html.preferred-dark-theme`] in the config, which defaults to the
+built-in `navy` theme.
+
+[`output.html.preferred-dark-theme`]: ../configuration/renderers.md#html-renderer-options
+[newer browsers]: https://caniuse.com/#feat=link-icon-svg

guide/src/format/theme/editor.md

@@ -1,25 +1,27 @@
 # Editor
 
-In addition to providing runnable code playpens, mdBook optionally allows them
+In addition to providing runnable code playgrounds, mdBook optionally allows them
 to be editable. In order to enable editable code blocks, the following needs to
 be added to the ***book.toml***:
 
 ```toml
-[output.html.playpen]
+[output.html.playground]
 editable = true
 ```
 
 To make a specific block available for editing, the attribute `editable` needs
 to be added to it:
 
-<pre><code class="language-markdown">```rust,editable
+~~~markdown
+```rust,editable
 fn main() {
     let number = 5;
     print!("{}", number);
 }
-```</code></pre>
+```
+~~~
 
-The above will result in this editable playpen:
+The above will result in this editable playground:
 
 ```rust,editable
 fn main() {
@@ -28,19 +30,19 @@ fn main() {
 }
 ```
 
-Note the new `Undo Changes` button in the editable playpens.
+Note the new `Undo Changes` button in the editable playgrounds.
 
 ## Customizing the Editor
 
 By default, the editor is the [Ace](https://ace.c9.io/) editor, but, if desired,
-the functionality may be overriden by providing a different folder:
+the functionality may be overridden by providing a different folder:
 
 ```toml
-[output.html.playpen]
+[output.html.playground]
 editable = true
 editor = "/path/to/editor"
 ```
 
 Note that for the editor changes to function correctly, the `book.js` inside of
-the `theme` folder will need to be overriden as it has some couplings with the
+the `theme` folder will need to be overridden as it has some couplings with the
 default Ace editor.

guide/src/format/theme/index-hbs.md

@@ -17,10 +17,10 @@ handlebars template you can access this information by using
 
 Here is a list of the properties that are exposed:
 
-- ***language*** Language of the book in the form `en`. To use in <code
-  class="language-html">\<html lang="{{ language }}"></code> for example. At the
-  moment it is hardcoded.
-- ***title*** Title of the book, as specified in `book.toml`
+- ***language*** Language of the book in the form `en`, as specified in `book.toml` (if not specified, defaults to `en`). To use in <code
+  class="language-html">\<html lang="{{ language }}"></code> for example.
+- ***title*** Title used for the current page. This is identical to `{{ chapter_title }} - {{ book_title }}` unless `book_title` is not set in which case it just defaults to the `chapter_title`.
+- ***book_title*** Title of the book, as specified in `book.toml`
 - ***chapter_title*** Title of the current chapter, as listed in `SUMMARY.md`
 
 - ***path*** Relative path to the original markdown file from the source
@@ -45,53 +45,57 @@ at your disposal.
 
 ### 1. toc
 
-    The toc helper is used like this
+The toc helper is used like this
 
-    ```handlebars
-    {{#toc}}{{/toc}}
-    ```
+```handlebars
+{{#toc}}{{/toc}}
+```
 
-    and outputs something that looks like this, depending on the structure of your book
+and outputs something that looks like this, depending on the structure of your
+book
 
-    ```html
-    <ul class="chapter">
+```html
+<ul class="chapter">
     <li><a href="link/to/file.html">Some chapter</a></li>
     <li>
         <ul class="section">
             <li><a href="link/to/other_file.html">Some other Chapter</a></li>
         </ul>
     </li>
-    </ul>
-    ```
+</ul>
+```
 
-    If you would like to make a toc with another structure, you have access to the chapters property containing all the data.
-    The only limitation at the moment is that you would have to do it with JavaScript instead of with a handlebars helper.
+If you would like to make a toc with another structure, you have access to the
+chapters property containing all the data. The only limitation at the moment
+is that you would have to do it with JavaScript instead of with a handlebars
+helper.
 
-    ```html
-    <script>
-    var chapters = {{chapters}};
-    // Processing here
-    </script>
-    ```
+```html
+<script>
+var chapters = {{chapters}};
+// Processing here
+</script>
+```
 
 ### 2. previous / next
 
-    The previous and next helpers expose a `link` and `name` property to the previous and next chapters.
+The previous and next helpers expose a `link` and `title` property to the
+previous and next chapters.
 
-    They are used like this
+They are used like this
 
-    ```handlebars
-    {{#previous}}
+```handlebars
+{{#previous}}
     <a href="{{link}}" class="nav-chapters previous">
-            <i class="fa fa-angle-left"></i>
+        <i class="fa fa-angle-left"></i> {{title}}
     </a>
-    {{/previous}}
-    ```
+{{/previous}}
+```
 
-    The inner html will only be rendered if the previous / next chapter exists.
-    Of course the inner html can be changed to your liking.
+The inner html will only be rendered if the previous / next chapter exists.
+Of course the inner html can be changed to your liking.
 
 ------
 
 *If you would like other properties or helpers exposed, please [create a new
-issue](https://github.com/rust-lang-nursery/mdBook/issues)*
+issue](https://github.com/rust-lang/mdBook/issues)*

guide/src/format/theme/syntax-highlighting.md

@@ -0,0 +1,91 @@
+# Syntax Highlighting
+
+mdBook uses [Highlight.js](https://highlightjs.org) with a custom theme
+for syntax highlighting.
+
+Automatic language detection has been turned off, so you will probably want to
+specify the programming language you use like this:
+
+~~~markdown
+```rust
+fn main() {
+    // Some code
+}
+```
+~~~
+
+## Supported languages
+
+These languages are supported by default, but you can add more by supplying
+your own `highlight.js` file:
+
+- apache
+- armasm
+- bash
+- c
+- coffeescript
+- cpp
+- csharp
+- css
+- d
+- diff
+- go
+- handlebars
+- haskell
+- http
+- ini
+- java
+- javascript
+- json
+- julia
+- kotlin
+- less
+- lua
+- makefile
+- markdown
+- nginx
+- nim
+- nix
+- objectivec
+- perl
+- php
+- plaintext
+- properties
+- python
+- r
+- ruby
+- rust
+- scala
+- scss
+- shell
+- sql
+- swift
+- typescript
+- x86asm
+- xml
+- yaml
+
+## Custom theme
+Like the rest of the theme, the files used for syntax highlighting can be
+overridden with your own.
+
+- ***highlight.js*** normally you shouldn't have to overwrite this file, unless
+  you want to use a more recent version.
+- ***highlight.css*** theme used by highlight.js for syntax highlighting.
+
+If you want to use another theme for `highlight.js` download it from their
+website, or make it yourself, rename it to `highlight.css` and put it in
+the `theme` folder of your book.
+
+Now your theme will be used instead of the default theme.
+
+## Improve default theme
+
+If you think the default theme doesn't look quite right for a specific language,
+or could be improved, feel free to [submit a new
+issue](https://github.com/rust-lang/mdBook/issues) explaining what you
+have in mind and I will take a look at it.
+
+You could also create a pull-request with the proposed improvements.
+
+Overall the theme should be light and sober, without too many flashy colors.

guide/src/guide/README.md

@@ -0,0 +1,7 @@
+# User Guide
+
+This user guide provides an introduction to basic concepts of using mdBook.
+
+- [Installation](installation.md)
+- [Reading Books](reading.md)
+- [Creating a Book](creating.md)

guide/src/guide/creating.md

@@ -0,0 +1,109 @@
+# Creating a Book
+
+Once you have the `mdbook` CLI tool installed, you can use it to create and render a book.
+
+## Initializing a book
+
+The `mdbook init` command will create a new directory containing an empty book for you to get started.
+Give it the name of the directory that you want to create:
+
+```sh
+mdbook init my-first-book
+```
+
+It will ask a few questions before generating the book.
+After answering the questions, you can change the current directory into the new book:
+
+```sh
+cd my-first-book
+```
+
+There are several ways to render a book, but one of the easiest methods is to use the `serve` command, which will build your book and start a local webserver:
+
+```sh
+mdbook serve --open
+```
+
+The `--open` option will open your default web browser to view your new book.
+You can leave the server running even while you edit the content of the book, and `mdbook` will automatically rebuild the output *and* automatically refresh your web browser.
+
+Check out the [CLI Guide](../cli/index.html) for more information about other `mdbook` commands and CLI options.
+
+## Anatomy of a book
+
+A book is built from several files which define the settings and layout of the book.
+
+### `book.toml`
+
+In the root of your book, there is a `book.toml` file which contains settings for describing how to build your book.
+This is written in the [TOML markup language](https://toml.io/).
+The default settings are usually good enough to get you started.
+When you are interested in exploring more features and options that mdBook provides, check out the [Configuration chapter](../format/configuration/index.html) for more details.
+
+A very basic `book.toml` can be as simple as this:
+
+```toml
+[book]
+title = "My First Book"
+```
+
+### `SUMMARY.md`
+
+The next major part of a book is the summary file located at `src/SUMMARY.md`.
+This file contains a list of all the chapters in the book.
+Before a chapter can be viewed, it must be added to this list.
+
+Here's a basic summary file with a few chapters:
+
+```md
+# Summary
+
+[Introduction](README.md)
+
+- [My First Chapter](my-first-chapter.md)
+- [Nested example](nested/README.md)
+    - [Sub-chapter](nested/sub-chapter.md)
+```
+
+Try opening up `src/SUMMARY.md` in your editor and adding a few chapters.
+If any of the chapter files do not exist, `mdbook` will automatically create them for you.
+
+For more details on other formatting options for the summary file, check out the [Summary chapter](../format/summary.md).
+
+### Source files
+
+The content of your book is all contained in the `src` directory.
+Each chapter is a separate Markdown file.
+Typically, each chapter starts with a level 1 heading with the title of the chapter.
+
+```md
+# My First Chapter
+
+Fill out your content here.
+```
+
+The precise layout of the files is up to you.
+The organization of the files will correspond to the HTML files generated, so keep in mind that the file layout is part of the URL of each chapter.
+
+While the `mdbook serve` command is running, you can open any of the chapter files and start editing them.
+Each time you save the file, `mdbook` will rebuild the book and refresh your web browser.
+
+Check out the [Markdown chapter](../format/markdown.md) for more information on formatting the content of your chapters.
+
+All other files in the `src` directory will be included in the output.
+So if you have images or other static files, just include them somewhere in the `src` directory.
+
+## Publishing a book
+
+Once you've written your book, you may want to host it somewhere for others to view.
+The first step is to build the output of the book.
+This can be done with the `mdbook build` command in the same directory where the `book.toml` file is located:
+
+```sh
+mdbook build
+```
+
+This will generate a directory named `book` which contains the HTML content of your book.
+You can then place this directory on any web server to host it.
+
+For more information about publishing and deploying, check out the [Continuous Integration chapter](../continuous-integration.md) for more.

guide/src/guide/installation.md

@@ -0,0 +1,52 @@
+# Installation
+
+There are multiple ways to install the mdBook CLI tool.
+Choose any one of the methods below that best suit your needs.
+If you are installing mdBook for automatic deployment, check out the [continuous integration] chapter for more examples on how to install.
+
+[continuous integration]: ../continuous-integration.md
+
+## Pre-compiled binaries
+
+Executable binaries are available for download on the [GitHub Releases page][releases].
+Download the binary for your platform (Windows, macOS, or Linux) and extract the archive.
+The archive contains an `mdbook` executable which you can run to build your books.
+
+To make it easier to run, put the path to the binary into your `PATH`.
+
+[releases]: https://github.com/rust-lang/mdBook/releases
+
+## Build from source using Rust
+
+To build the `mdbook` executable from source, you will first need to install Rust and Cargo.
+Follow the instructions on the [Rust installation page].
+mdBook currently requires at least Rust version 1.71.
+
+Once you have installed Rust, the following command can be used to build and install mdBook:
+
+```sh
+cargo install mdbook
+```
+
+This will automatically download mdBook from [crates.io], build it, and install it in Cargo's global binary directory (`~/.cargo/bin/` by default).
+
+To uninstall, run the command `cargo uninstall mdbook`.
+
+[Rust installation page]: https://www.rust-lang.org/tools/install
+[crates.io]: https://crates.io/
+
+### Installing the latest master version
+
+The version published to crates.io will ever so slightly be behind the version hosted on GitHub.
+If you need the latest version you can build the git version of mdBook yourself.
+Cargo makes this ***super easy***!
+
+```sh
+cargo install --git https://github.com/rust-lang/mdBook.git mdbook
+```
+
+Again, make sure to add the Cargo bin directory to your `PATH`.
+
+If you are interested in making modifications to mdBook itself, check out the [Contributing Guide] for more information.
+
+[Contributing Guide]: https://github.com/rust-lang/mdBook/blob/master/CONTRIBUTING.md

guide/src/guide/reading.md

@@ -0,0 +1,74 @@
+# Reading Books
+
+This chapter gives an introduction on how to interact with a book produced by mdBook.
+This assumes you are reading an HTML book.
+The options and formatting will be different for other output formats such as PDF.
+
+A book is organized into *chapters*.
+Each chapter is a separate page.
+Chapters can be nested into a hierarchy of sub-chapters.
+Typically, each chapter will be organized into a series of *headings* to subdivide a chapter.
+
+## Navigation
+
+There are several methods for navigating through the chapters of a book.
+
+The **sidebar** on the left provides a list of all chapters.
+Clicking on any of the chapter titles will load that page.
+
+The sidebar may not automatically appear if the window is too narrow, particularly on mobile displays.
+In that situation, the menu icon (three horizontal bars) at the top-left of the page can be pressed to open and close the sidebar.
+
+The **arrow buttons** at the bottom of the page can be used to navigate to the previous or the next chapter.
+
+The **left and right arrow keys** on the keyboard can be used to navigate to the previous or the next chapter.
+
+## Top menu bar
+
+The menu bar at the top of the page provides some icons for interacting with the book.
+The icons displayed will depend on the settings of how the book was generated.
+
+| Icon | Description |
+|------|-------------|
+| <i class="fa fa-bars"></i> | Opens and closes the chapter listing sidebar. |
+| <i class="fa fa-paint-brush"></i> | Opens a picker to choose a different color theme. |
+| <i class="fa fa-search"></i> | Opens a search bar for searching within the book. |
+| <i class="fa fa-print"></i> | Instructs the web browser to print the entire book. |
+| <i class="fa fa-github"></i> | Opens a link to the website that hosts the source code of the book. |
+| <i class="fa fa-edit"></i> | Opens a page to directly edit the source of the page you are currently reading. |
+
+Tapping the menu bar will scroll the page to the top.
+
+## Search
+
+Each book has a built-in search system.
+Pressing the search icon (<i class="fa fa-search"></i>) in the menu bar, or pressing the `S` key on the keyboard will open an input box for entering search terms.
+Typing some terms will show matching chapters and sections in real time.
+
+Clicking any of the results will jump to that section.
+The up and down arrow keys can be used to navigate the results, and enter will open the highlighted section.
+
+After loading a search result, the matching search terms will be highlighted in the text.
+Clicking a highlighted word or pressing the `Esc` key will remove the highlighting.
+
+## Code blocks
+
+mdBook books are often used for programming projects, and thus support highlighting code blocks and samples.
+Code blocks may contain several different icons for interacting with them:
+
+| Icon | Description |
+|------|-------------|
+| <i class="fa fa-copy"></i> | Copies the code block into your local clipboard, to allow pasting into another application. |
+| <i class="fa fa-play"></i> | For Rust code examples, this will execute the sample code and display the compiler output just below the example (see [playground]). |
+| <i class="fa fa-eye"></i> | For Rust code examples, this will toggle visibility of "hidden" lines. Sometimes, larger examples will hide lines which are not particularly relevant to what is being illustrated (see [hiding code lines]). |
+| <i class="fa fa-history"></i> | For [editable code examples][editor], this will undo any changes you have made. |
+
+Here's an example:
+
+```rust
+println!("Hello, World!");
+```
+
+[editor]: ../format/theme/editor.md
+[playground]: ../format/mdbook.md#rust-playground
+[hiding code lines]: ../format/mdbook.md#hiding-code-lines

guide/src/misc/contributors.md

@@ -15,6 +15,10 @@ shout-out to them!
 - [projektir](https://github.com/projektir)
 - [Phaiax](https://github.com/Phaiax)
 - Matt Ickstadt ([mattico](https://github.com/mattico))
-- Weihang Lo ([@weihanglo](https://github.com/weihanglo))
+- Weihang Lo ([weihanglo](https://github.com/weihanglo))
+- Avision Ho ([avisionh](https://github.com/avisionh))
+- Vivek Akupatni ([apatniv](https://github.com/apatniv))
+- Eric Huss ([ehuss](https://github.com/ehuss))
+- Josh Rotenberg ([joshrotenberg](https://github.com/joshrotenberg))
 
 If you feel you're missing from this list, feel free to add yourself in a PR.

src/book/book.rs

@@ -5,8 +5,11 @@ use std::io::{Read, Write};
 use std::path::{Path, PathBuf};
 
 use super::summary::{parse_summary, Link, SectionNumber, Summary, SummaryItem};
-use config::BuildConfig;
-use errors::*;
+use crate::config::BuildConfig;
+use crate::errors::*;
+use crate::utils::bracket_escape;
+use log::debug;
+use serde::{Deserialize, Serialize};
 
 /// Load a book into memory from its `src/` directory.
 pub fn load_book<P: AsRef<Path>>(src_dir: P, cfg: &BuildConfig) -> Result<Book> {
@@ -14,14 +17,15 @@ pub fn load_book<P: AsRef<Path>>(src_dir: P, cfg: &BuildConfig) -> Result<Book>
     let summary_md = src_dir.join("SUMMARY.md");
 
     let mut summary_content = String::new();
-    File::open(summary_md)
-        .chain_err(|| "Couldn't open SUMMARY.md")?
+    File::open(&summary_md)
+        .with_context(|| format!("Couldn't open SUMMARY.md in {:?} directory", src_dir))?
         .read_to_string(&mut summary_content)?;
 
-    let summary = parse_summary(&summary_content).chain_err(|| "Summary parsing failed")?;
+    let summary = parse_summary(&summary_content)
+        .with_context(|| format!("Summary parsing failed for file={:?}", summary_md))?;
 
     if cfg.create_missing {
-        create_missing(&src_dir, &summary).chain_err(|| "Unable to create missing chapters")?;
+        create_missing(src_dir, &summary).with_context(|| "Unable to create missing chapters")?;
     }
 
     load_book_from_disk(&summary, src_dir)
@@ -35,11 +39,10 @@ fn create_missing(src_dir: &Path, summary: &Summary) -> Result<()> {
         .chain(summary.suffix_chapters.iter())
         .collect();
 
-    while !items.is_empty() {
-        let next = items.pop().expect("already checked");
-
+    while let Some(next) = items.pop() {
         if let SummaryItem::Link(ref link) = *next {
-            let filename = src_dir.join(&link.location);
+            if let Some(ref location) = link.location {
+                let filename = src_dir.join(location);
                 if !filename.exists() {
                     if let Some(parent) = filename.parent() {
                         if !parent.exists() {
@@ -48,8 +51,11 @@ fn create_missing(src_dir: &Path, summary: &Summary) -> Result<()> {
                     }
                     debug!("Creating missing file {}", filename.display());
 
-                let mut f = File::create(&filename)?;
-                writeln!(f, "# {}", link.name)?;
+                    let mut f = File::create(&filename).with_context(|| {
+                        format!("Unable to create missing file: {}", filename.display())
+                    })?;
+                    writeln!(f, "# {}", bracket_escape(&link.name))?;
+                }
             }
 
             items.extend(&link.nested_items);
@@ -61,7 +67,7 @@ fn create_missing(src_dir: &Path, summary: &Summary) -> Result<()> {
 
 /// A dumb tree structure representing a book.
 ///
-/// For the moment a book is just a collection of `BookItems` which are
+/// For the moment a book is just a collection of [`BookItems`] which are
 /// accessible by either iterating (immutably) over the book with [`iter()`], or
 /// recursively applying a closure to each section to mutate the chapters, using
 /// [`for_each_mut()`].
@@ -82,7 +88,7 @@ impl Book {
     }
 
     /// Get a depth-first iterator over the items in the book.
-    pub fn iter(&self) -> BookItems {
+    pub fn iter(&self) -> BookItems<'_> {
         BookItems {
             items: self.sections.iter().collect(),
         }
@@ -116,7 +122,7 @@ where
     I: IntoIterator<Item = &'a mut BookItem>,
 {
     for item in items {
-        if let &mut BookItem::Chapter(ref mut ch) = item {
+        if let BookItem::Chapter(ch) = item {
             for_each_mut(func, &mut ch.sub_items);
         }
 
@@ -131,6 +137,8 @@ pub enum BookItem {
     Chapter(Chapter),
     /// A section separator.
     Separator,
+    /// A part title.
+    PartTitle(String),
 }
 
 impl From<Chapter> for BookItem {
@@ -152,8 +160,22 @@ pub struct Chapter {
     /// Nested items.
     pub sub_items: Vec<BookItem>,
     /// The chapter's location, relative to the `SUMMARY.md` file.
-    pub path: PathBuf,
-    /// An ordered list of the names of each chapter above this one, in the hierarchy.
+    ///
+    /// **Note**: After the index preprocessor runs, any README files will be
+    /// modified to be `index.md`. If you need access to the actual filename
+    /// on disk, use [`Chapter::source_path`] instead.
+    ///
+    /// This is `None` for a draft chapter.
+    pub path: Option<PathBuf>,
+    /// The chapter's source file, relative to the `SUMMARY.md` file.
+    ///
+    /// **Note**: Beware that README files will internally be treated as
+    /// `index.md` via the [`Chapter::path`] field. The `source_path` field
+    /// exists if you need access to the true file path.
+    ///
+    /// This is `None` for a draft chapter.
+    pub source_path: Option<PathBuf>,
+    /// An ordered list of the names of each chapter above this one in the hierarchy.
     pub parent_names: Vec<String>,
 }
 
@@ -162,24 +184,44 @@ impl Chapter {
     pub fn new<P: Into<PathBuf>>(
         name: &str,
         content: String,
-        path: P,
+        p: P,
         parent_names: Vec<String>,
     ) -> Chapter {
+        let path: PathBuf = p.into();
         Chapter {
             name: name.to_string(),
-            content: content,
-            path: path.into(),
-            parent_names: parent_names,
+            content,
+            path: Some(path.clone()),
+            source_path: Some(path),
+            parent_names,
             ..Default::default()
         }
     }
+
+    /// Create a new draft chapter that is not attached to a source markdown file (and thus
+    /// has no content).
+    pub fn new_draft(name: &str, parent_names: Vec<String>) -> Self {
+        Chapter {
+            name: name.to_string(),
+            content: String::new(),
+            path: None,
+            source_path: None,
+            parent_names,
+            ..Default::default()
+        }
+    }
+
+    /// Check if the chapter is a draft chapter, meaning it has no path to a source markdown file.
+    pub fn is_draft_chapter(&self) -> bool {
+        self.path.is_none()
+    }
 }
 
 /// Use the provided `Summary` to load a `Book` from disk.
 ///
 /// You need to pass in the book's source directory because all the links in
 /// `SUMMARY.md` give the chapter locations relative to it.
-fn load_book_from_disk<P: AsRef<Path>>(summary: &Summary, src_dir: P) -> Result<Book> {
+pub(crate) fn load_book_from_disk<P: AsRef<Path>>(summary: &Summary, src_dir: P) -> Result<Book> {
     debug!("Loading the book from disk");
     let src_dir = src_dir.as_ref();
 
@@ -202,16 +244,17 @@ fn load_book_from_disk<P: AsRef<Path>>(summary: &Summary, src_dir: P) -> Result<
     })
 }
 
-fn load_summary_item<P: AsRef<Path>>(
+fn load_summary_item<P: AsRef<Path> + Clone>(
     item: &SummaryItem,
     src_dir: P,
     parent_names: Vec<String>,
 ) -> Result<BookItem> {
-    match *item {
+    match item {
         SummaryItem::Separator => Ok(BookItem::Separator),
         SummaryItem::Link(ref link) => {
-            load_chapter(link, src_dir, parent_names).map(|c| BookItem::Chapter(c))
+            load_chapter(link, src_dir, parent_names).map(BookItem::Chapter)
         }
+        SummaryItem::PartTitle(title) => Ok(BookItem::PartTitle(title.clone())),
     }
 }
 
@@ -220,28 +263,40 @@ fn load_chapter<P: AsRef<Path>>(
     src_dir: P,
     parent_names: Vec<String>,
 ) -> Result<Chapter> {
-    debug!("Loading {} ({})", link.name, link.location.display());
     let src_dir = src_dir.as_ref();
 
-    let location = if link.location.is_absolute() {
-        link.location.clone()
+    let mut ch = if let Some(ref link_location) = link.location {
+        debug!("Loading {} ({})", link.name, link_location.display());
+
+        let location = if link_location.is_absolute() {
+            link_location.clone()
         } else {
-        src_dir.join(&link.location)
+            src_dir.join(link_location)
         };
 
         let mut f = File::open(&location)
-        .chain_err(|| format!("Chapter file not found, {}", link.location.display()))?;
+            .with_context(|| format!("Chapter file not found, {}", link_location.display()))?;
 
         let mut content = String::new();
-    f.read_to_string(&mut content)
-        .chain_err(|| format!("Unable to read \"{}\" ({})", link.name, location.display()))?;
+        f.read_to_string(&mut content).with_context(|| {
+            format!("Unable to read \"{}\" ({})", link.name, location.display())
+        })?;
+
+        if content.as_bytes().starts_with(b"\xef\xbb\xbf") {
+            content.replace_range(..3, "");
+        }
 
         let stripped = location
-        .strip_prefix(&src_dir)
+            .strip_prefix(src_dir)
             .expect("Chapters are always inside a book");
 
-    let mut sub_item_parents = parent_names.clone();
-    let mut ch = Chapter::new(&link.name, content, stripped, parent_names);
+        Chapter::new(&link.name, content, stripped, parent_names.clone())
+    } else {
+        Chapter::new_draft(&link.name, parent_names.clone())
+    };
+
+    let mut sub_item_parents = parent_names;
+
     ch.number = link.number.clone();
 
     sub_item_parents.push(link.name.clone());
@@ -262,8 +317,6 @@ fn load_chapter<P: AsRef<Path>>(
 ///
 /// This struct shouldn't be created directly, instead prefer the
 /// [`Book::iter()`] method.
-///
-/// [`Book::iter()`]: struct.Book.html#method.iter
 pub struct BookItems<'a> {
     items: VecDeque<&'a BookItem>,
 }
@@ -274,7 +327,7 @@ impl<'a> Iterator for BookItems<'a> {
     fn next(&mut self) -> Option<Self::Item> {
         let item = self.items.pop_front();
 
-        if let Some(&BookItem::Chapter(ref ch)) = item {
+        if let Some(BookItem::Chapter(ch)) = item {
             // if we wanted a breadth-first iterator we'd `extend()` here
             for sub_item in ch.sub_items.iter().rev() {
                 self.items.push_front(sub_item);
@@ -286,7 +339,7 @@ impl<'a> Iterator for BookItems<'a> {
 }
 
 impl Display for Chapter {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         if let Some(ref section_number) = self.number {
             write!(f, "{} ", section_number)?;
         }
@@ -298,10 +351,9 @@ impl Display for Chapter {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::io::Write;
     use tempfile::{Builder as TempFileBuilder, TempDir};
 
-    const DUMMY_SRC: &'static str = "
+    const DUMMY_SRC: &str = "
 # Dummy Chapter
 
 this is some dummy text.
@@ -317,7 +369,7 @@ And here is some \
         let chapter_path = temp.path().join("chapter_1.md");
         File::create(&chapter_path)
             .unwrap()
-            .write(DUMMY_SRC.as_bytes())
+            .write_all(DUMMY_SRC.as_bytes())
             .unwrap();
 
         let link = Link::new("Chapter 1", chapter_path);
@@ -333,7 +385,7 @@ And here is some \
 
         File::create(&second_path)
             .unwrap()
-            .write_all("Hello World!".as_bytes())
+            .write_all(b"Hello World!")
             .unwrap();
 
         let mut second = Link::new("Nested Chapter 1", &second_path);
@@ -341,7 +393,7 @@ And here is some \
 
         root.nested_items.push(second.clone().into());
         root.nested_items.push(SummaryItem::Separator);
-        root.nested_items.push(second.clone().into());
+        root.nested_items.push(second.into());
 
         (root, temp_dir)
     }
@@ -360,6 +412,29 @@ And here is some \
         assert_eq!(got, should_be);
     }
 
+    #[test]
+    fn load_a_single_chapter_with_utf8_bom_from_disk() {
+        let temp_dir = TempFileBuilder::new().prefix("book").tempdir().unwrap();
+
+        let chapter_path = temp_dir.path().join("chapter_1.md");
+        File::create(&chapter_path)
+            .unwrap()
+            .write_all(("\u{feff}".to_owned() + DUMMY_SRC).as_bytes())
+            .unwrap();
+
+        let link = Link::new("Chapter 1", chapter_path);
+
+        let should_be = Chapter::new(
+            "Chapter 1",
+            DUMMY_SRC.to_string(),
+            "chapter_1.md",
+            Vec::new(),
+        );
+
+        let got = load_chapter(&link, temp_dir.path(), Vec::new()).unwrap();
+        assert_eq!(got, should_be);
+    }
+
     #[test]
     fn cant_load_a_nonexistent_chapter() {
         let link = Link::new("Chapter 1", "/foo/bar/baz.md");
@@ -376,7 +451,8 @@ And here is some \
             name: String::from("Nested Chapter 1"),
             content: String::from("Hello World!"),
             number: Some(SectionNumber(vec![1, 2])),
-            path: PathBuf::from("second.md"),
+            path: Some(PathBuf::from("second.md")),
+            source_path: Some(PathBuf::from("second.md")),
             parent_names: vec![String::from("Chapter 1")],
             sub_items: Vec::new(),
         };
@@ -384,12 +460,13 @@ And here is some \
             name: String::from("Chapter 1"),
             content: String::from(DUMMY_SRC),
             number: None,
-            path: PathBuf::from("chapter_1.md"),
+            path: Some(PathBuf::from("chapter_1.md")),
+            source_path: Some(PathBuf::from("chapter_1.md")),
             parent_names: Vec::new(),
             sub_items: vec![
                 BookItem::Chapter(nested.clone()),
                 BookItem::Separator,
-                BookItem::Chapter(nested.clone()),
+                BookItem::Chapter(nested),
             ],
         });
 
@@ -408,7 +485,8 @@ And here is some \
             sections: vec![BookItem::Chapter(Chapter {
                 name: String::from("Chapter 1"),
                 content: String::from(DUMMY_SRC),
-                path: PathBuf::from("chapter_1.md"),
+                path: Some(PathBuf::from("chapter_1.md")),
+                source_path: Some(PathBuf::from("chapter_1.md")),
                 ..Default::default()
             })],
             ..Default::default()
@@ -448,7 +526,8 @@ And here is some \
                     name: String::from("Chapter 1"),
                     content: String::from(DUMMY_SRC),
                     number: None,
-                    path: PathBuf::from("Chapter_1/index.md"),
+                    path: Some(PathBuf::from("Chapter_1/index.md")),
+                    source_path: Some(PathBuf::from("Chapter_1/index.md")),
                     parent_names: Vec::new(),
                     sub_items: vec![
                         BookItem::Chapter(Chapter::new(
@@ -481,7 +560,8 @@ And here is some \
             .filter_map(|i| match *i {
                 BookItem::Chapter(ref ch) => Some(ch.name.clone()),
                 _ => None,
-            }).collect();
+            })
+            .collect();
         let should_be: Vec<_> = vec![
             String::from("Chapter 1"),
             String::from("Hello World"),
@@ -499,7 +579,8 @@ And here is some \
                     name: String::from("Chapter 1"),
                     content: String::from(DUMMY_SRC),
                     number: None,
-                    path: PathBuf::from("Chapter_1/index.md"),
+                    path: Some(PathBuf::from("Chapter_1/index.md")),
+                    source_path: Some(PathBuf::from("Chapter_1/index.md")),
                     parent_names: Vec::new(),
                     sub_items: vec![
                         BookItem::Chapter(Chapter::new(
@@ -536,9 +617,10 @@ And here is some \
         let summary = Summary {
             numbered_chapters: vec![SummaryItem::Link(Link {
                 name: String::from("Empty"),
-                location: PathBuf::from(""),
+                location: Some(PathBuf::from("")),
                 ..Default::default()
             })],
+
             ..Default::default()
         };
 
@@ -555,7 +637,7 @@ And here is some \
         let summary = Summary {
             numbered_chapters: vec![SummaryItem::Link(Link {
                 name: String::from("nested"),
-                location: dir,
+                location: Some(dir),
                 ..Default::default()
             })],
             ..Default::default()

src/book/init.rs

@@ -1,12 +1,13 @@
 use std::fs::{self, File};
 use std::io::Write;
 use std::path::PathBuf;
-use toml;
 
 use super::MDBook;
-use config::Config;
-use errors::*;
-use theme;
+use crate::config::Config;
+use crate::errors::*;
+use crate::theme;
+use crate::utils::fs::write_file;
+use log::{debug, error, info, trace};
 
 /// A helper for setting up a new book and its directory structure.
 #[derive(Debug, Clone, PartialEq)]
@@ -29,7 +30,7 @@ impl BookBuilder {
         }
     }
 
-    /// Set the `Config` to be used.
+    /// Set the [`Config`] to be used.
     pub fn with_config(&mut self, cfg: Config) -> &mut BookBuilder {
         self.config = cfg;
         self
@@ -65,19 +66,19 @@ impl BookBuilder {
         info!("Creating a new book with stub content");
 
         self.create_directory_structure()
-            .chain_err(|| "Unable to create directory structure")?;
+            .with_context(|| "Unable to create directory structure")?;
 
         self.create_stub_files()
-            .chain_err(|| "Unable to create stub files")?;
+            .with_context(|| "Unable to create stub files")?;
 
         if self.create_gitignore {
             self.build_gitignore()
-                .chain_err(|| "Unable to create .gitignore")?;
+                .with_context(|| "Unable to create .gitignore")?;
         }
 
         if self.copy_theme {
             self.copy_across_theme()
-                .chain_err(|| "Unable to copy across the theme")?;
+                .with_context(|| "Unable to copy across the theme")?;
         }
 
         self.write_book_toml()?;
@@ -98,24 +99,20 @@ impl BookBuilder {
     fn write_book_toml(&self) -> Result<()> {
         debug!("Writing book.toml");
         let book_toml = self.root.join("book.toml");
-        let cfg = toml::to_vec(&self.config).chain_err(|| "Unable to serialize the config")?;
+        let cfg = toml::to_vec(&self.config).with_context(|| "Unable to serialize the config")?;
 
         File::create(book_toml)
-            .chain_err(|| "Couldn't create book.toml")?
+            .with_context(|| "Couldn't create book.toml")?
             .write_all(&cfg)
-            .chain_err(|| "Unable to write config to book.toml")?;
+            .with_context(|| "Unable to write config to book.toml")?;
         Ok(())
     }
 
     fn copy_across_theme(&self) -> Result<()> {
         debug!("Copying theme");
 
-        let themedir = self
-            .config
-            .html_config()
-            .and_then(|html| html.theme)
-            .unwrap_or_else(|| self.config.book.src.join("theme"));
-        let themedir = self.root.join(themedir);
+        let html_config = self.config.html_config().unwrap_or_default();
+        let themedir = html_config.theme_dir(&self.root);
 
         if !themedir.exists() {
             debug!(
@@ -129,7 +126,9 @@ impl BookBuilder {
         index.write_all(theme::INDEX)?;
 
         let cssdir = themedir.join("css");
+        if !cssdir.exists() {
             fs::create_dir(&cssdir)?;
+        }
 
         let mut general_css = File::create(cssdir.join("general.css"))?;
         general_css.write_all(theme::GENERAL_CSS)?;
@@ -137,14 +136,19 @@ impl BookBuilder {
         let mut chrome_css = File::create(cssdir.join("chrome.css"))?;
         chrome_css.write_all(theme::CHROME_CSS)?;
 
+        if html_config.print.enable {
             let mut print_css = File::create(cssdir.join("print.css"))?;
             print_css.write_all(theme::PRINT_CSS)?;
+        }
 
         let mut variables_css = File::create(cssdir.join("variables.css"))?;
         variables_css.write_all(theme::VARIABLES_CSS)?;
 
         let mut favicon = File::create(themedir.join("favicon.png"))?;
-        favicon.write_all(theme::FAVICON)?;
+        favicon.write_all(theme::FAVICON_PNG)?;
+
+        let mut favicon = File::create(themedir.join("favicon.svg"))?;
+        favicon.write_all(theme::FAVICON_SVG)?;
 
         let mut js = File::create(themedir.join("book.js"))?;
         js.write_all(theme::JS)?;
@@ -155,6 +159,19 @@ impl BookBuilder {
         let mut highlight_js = File::create(themedir.join("highlight.js"))?;
         highlight_js.write_all(theme::HIGHLIGHT_JS)?;
 
+        write_file(&themedir.join("fonts"), "fonts.css", theme::fonts::CSS)?;
+        for (file_name, contents) in theme::fonts::LICENSES {
+            write_file(&themedir, file_name, contents)?;
+        }
+        for (file_name, contents) in theme::fonts::OPEN_SANS.iter() {
+            write_file(&themedir, file_name, contents)?;
+        }
+        write_file(
+            &themedir,
+            theme::fonts::SOURCE_CODE_PRO.0,
+            theme::fonts::SOURCE_CODE_PRO.1,
+        )?;
+
         Ok(())
     }
 
@@ -173,15 +190,19 @@ impl BookBuilder {
         let src_dir = self.root.join(&self.config.book.src);
 
         let summary = src_dir.join("SUMMARY.md");
-        let mut f = File::create(&summary).chain_err(|| "Unable to create SUMMARY.md")?;
+        if !summary.exists() {
+            trace!("No summary found creating stub summary and chapter_1.md.");
+            let mut f = File::create(&summary).with_context(|| "Unable to create SUMMARY.md")?;
             writeln!(f, "# Summary")?;
-        writeln!(f, "")?;
+            writeln!(f)?;
             writeln!(f, "- [Chapter 1](./chapter_1.md)")?;
 
             let chapter_1 = src_dir.join("chapter_1.md");
-        let mut f = File::create(&chapter_1).chain_err(|| "Unable to create chapter_1.md")?;
+            let mut f = File::create(chapter_1).with_context(|| "Unable to create chapter_1.md")?;
             writeln!(f, "# Chapter 1")?;
-
+        } else {
+            trace!("Existing summary found, no need to create stub files.");
+        }
         Ok(())
     }
 
@@ -190,10 +211,10 @@ impl BookBuilder {
         fs::create_dir_all(&self.root)?;
 
         let src = self.root.join(&self.config.book.src);
-        fs::create_dir_all(&src)?;
+        fs::create_dir_all(src)?;
 
         let build = self.root.join(&self.config.build.build_dir);
-        fs::create_dir_all(&build)?;
+        fs::create_dir_all(build)?;
 
         Ok(())
     }

src/book/mod.rs

@@ -5,6 +5,7 @@
 //!
 //! [1]: ../index.html
 
+#[allow(clippy::module_inception)]
 mod book;
 mod init;
 mod summary;
@@ -13,18 +14,23 @@ pub use self::book::{load_book, Book, BookItem, BookItems, Chapter};
 pub use self::init::BookBuilder;
 pub use self::summary::{parse_summary, Link, SectionNumber, Summary, SummaryItem};
 
-use std::io::Write;
-use std::path::PathBuf;
+use log::{debug, error, info, log_enabled, trace, warn};
+use std::ffi::OsString;
+use std::io::{IsTerminal, Write};
+use std::path::{Path, PathBuf};
 use std::process::Command;
 use tempfile::Builder as TempFileBuilder;
 use toml::Value;
+use topological_sort::TopologicalSort;
 
-use errors::*;
-use preprocess::{IndexPreprocessor, LinkPreprocessor, Preprocessor, PreprocessorContext};
-use renderer::{CmdRenderer, HtmlHandlebars, RenderContext, Renderer};
-use utils;
+use crate::errors::*;
+use crate::preprocess::{
+    CmdPreprocessor, IndexPreprocessor, LinkPreprocessor, Preprocessor, PreprocessorContext,
+};
+use crate::renderer::{CmdRenderer, HtmlHandlebars, MarkdownRenderer, RenderContext, Renderer};
+use crate::utils;
 
-use config::Config;
+use crate::config::{Config, RustEdition};
 
 /// The object used to manage and build a book.
 pub struct MDBook {
@@ -34,10 +40,10 @@ pub struct MDBook {
     pub config: Config,
     /// A representation of the book's contents in memory.
     pub book: Book,
-    renderers: Vec<Box<Renderer>>,
+    renderers: Vec<Box<dyn Renderer>>,
 
-    /// List of pre-processors to be run on the book
-    preprocessors: Vec<Box<Preprocessor>>,
+    /// List of pre-processors to be run on the book.
+    preprocessors: Vec<Box<dyn Preprocessor>>,
 }
 
 impl MDBook {
@@ -53,7 +59,7 @@ impl MDBook {
             warn!("This format is no longer used, so you should migrate to the");
             warn!("book.toml format.");
             warn!("Check the user guide for migration information:");
-            warn!("\thttps://rust-lang-nursery.github.io/mdBook/format/config.html");
+            warn!("\thttps://rust-lang.github.io/mdBook/format/config.html");
         }
 
         let mut config = if config_location.exists() {
@@ -65,7 +71,27 @@ impl MDBook {
 
         config.update_from_env();
 
-        if log_enabled!(::log::Level::Trace) {
+        if let Some(html_config) = config.html_config() {
+            if html_config.google_analytics.is_some() {
+                warn!(
+                    "The output.html.google-analytics field has been deprecated; \
+                     it will be removed in a future release.\n\
+                     Consider placing the appropriate site tag code into the \
+                     theme/head.hbs file instead.\n\
+                     The tracking code may be found in the Google Analytics Admin page.\n\
+                   "
+                );
+            }
+            if html_config.curly_quotes {
+                warn!(
+                    "The output.html.curly-quotes field has been renamed to \
+                     output.html.smart-punctuation.\n\
+                     Use the new name in book.toml to remove this warning."
+                );
+            }
+        }
+
+        if log_enabled!(log::Level::Trace) {
             for line in format!("Config: {:#?}", config).lines() {
                 trace!("{}", line);
             }
@@ -74,12 +100,35 @@ impl MDBook {
         MDBook::load_with_config(book_root, config)
     }
 
-    /// Load a book from its root directory using a custom config.
+    /// Load a book from its root directory using a custom `Config`.
     pub fn load_with_config<P: Into<PathBuf>>(book_root: P, config: Config) -> Result<MDBook> {
         let root = book_root.into();
 
         let src_dir = root.join(&config.book.src);
-        let book = book::load_book(&src_dir, &config.build)?;
+        let book = book::load_book(src_dir, &config.build)?;
+
+        let renderers = determine_renderers(&config);
+        let preprocessors = determine_preprocessors(&config)?;
+
+        Ok(MDBook {
+            root,
+            config,
+            book,
+            renderers,
+            preprocessors,
+        })
+    }
+
+    /// Load a book from its root directory using a custom `Config` and a custom summary.
+    pub fn load_with_config_and_summary<P: Into<PathBuf>>(
+        book_root: P,
+        config: Config,
+        summary: Summary,
+    ) -> Result<MDBook> {
+        let root = book_root.into();
+
+        let src_dir = root.join(&config.book.src);
+        let book = book::load_book_from_disk(&summary, src_dir)?;
 
         let renderers = determine_renderers(&config);
         let preprocessors = determine_preprocessors(&config)?;
@@ -94,20 +143,18 @@ impl MDBook {
     }
 
     /// Returns a flat depth-first iterator over the elements of the book,
-    /// it returns an [BookItem enum](bookitem.html):
+    /// it returns a [`BookItem`] enum:
     /// `(section: String, bookitem: &BookItem)`
     ///
     /// ```no_run
-    /// # extern crate mdbook;
     /// # use mdbook::MDBook;
     /// # use mdbook::book::BookItem;
-    /// # #[allow(unused_variables)]
-    /// # fn main() {
     /// # let book = MDBook::load("mybook").unwrap();
     /// for item in book.iter() {
     ///     match *item {
     ///         BookItem::Chapter(ref chapter) => {},
     ///         BookItem::Separator => {},
+    ///         BookItem::PartTitle(ref title) => {}
     ///     }
     /// }
     ///
@@ -118,9 +165,8 @@ impl MDBook {
     /// // 2. Chapter 2
     /// //
     /// // etc.
-    /// # }
     /// ```
-    pub fn iter(&self) -> BookItems {
+    pub fn iter(&self) -> BookItems<'_> {
         self.book.iter()
     }
 
@@ -149,104 +195,184 @@ impl MDBook {
     pub fn build(&self) -> Result<()> {
         info!("Book building has started");
 
-        let mut preprocessed_book = self.book.clone();
-        let preprocess_ctx = PreprocessorContext::new(self.root.clone(), self.config.clone());
-
-        for preprocessor in &self.preprocessors {
-            debug!("Running the {} preprocessor.", preprocessor.name());
-            preprocessor.run(&preprocess_ctx, &mut preprocessed_book)?;
-        }
-
         for renderer in &self.renderers {
-            info!("Running the {} backend", renderer.name());
-            self.run_renderer(&preprocessed_book, renderer.as_ref())?;
+            self.execute_build_process(&**renderer)?;
         }
 
         Ok(())
     }
 
-    fn run_renderer(&self, preprocessed_book: &Book, renderer: &Renderer) -> Result<()> {
-        let name = renderer.name();
-        let build_dir = self.build_dir_for(name);
-        if build_dir.exists() {
-            debug!(
-                "Cleaning build dir for the \"{}\" renderer ({})",
-                name,
-                build_dir.display()
+    /// Run preprocessors and return the final book.
+    pub fn preprocess_book(&self, renderer: &dyn Renderer) -> Result<(Book, PreprocessorContext)> {
+        let preprocess_ctx = PreprocessorContext::new(
+            self.root.clone(),
+            self.config.clone(),
+            renderer.name().to_string(),
         );
-
-            utils::fs::remove_dir_content(&build_dir)
-                .chain_err(|| "Unable to clear output directory")?;
+        let mut preprocessed_book = self.book.clone();
+        for preprocessor in &self.preprocessors {
+            if preprocessor_should_run(&**preprocessor, renderer, &self.config) {
+                debug!("Running the {} preprocessor.", preprocessor.name());
+                preprocessed_book = preprocessor.run(&preprocess_ctx, preprocessed_book)?;
+            }
+        }
+        Ok((preprocessed_book, preprocess_ctx))
     }
 
-        let render_context = RenderContext::new(
+    /// Run the entire build process for a particular [`Renderer`].
+    pub fn execute_build_process(&self, renderer: &dyn Renderer) -> Result<()> {
+        let (preprocessed_book, preprocess_ctx) = self.preprocess_book(renderer)?;
+
+        let name = renderer.name();
+        let build_dir = self.build_dir_for(name);
+
+        let mut render_context = RenderContext::new(
             self.root.clone(),
-            preprocessed_book.clone(),
+            preprocessed_book,
             self.config.clone(),
             build_dir,
         );
+        render_context
+            .chapter_titles
+            .extend(preprocess_ctx.chapter_titles.borrow_mut().drain());
 
+        info!("Running the {} backend", renderer.name());
         renderer
             .render(&render_context)
-            .chain_err(|| "Rendering failed")
+            .with_context(|| "Rendering failed")
     }
 
     /// You can change the default renderer to another one by using this method.
-    /// The only requirement is for your renderer to implement the [`Renderer`
-    /// trait](../renderer/trait.Renderer.html)
+    /// The only requirement is that your renderer implement the [`Renderer`]
+    /// trait.
     pub fn with_renderer<R: Renderer + 'static>(&mut self, renderer: R) -> &mut Self {
         self.renderers.push(Box::new(renderer));
         self
     }
 
-    /// Register a [`Preprocessor`](../preprocess/trait.Preprocessor.html) to be used when rendering the book.
-    pub fn with_preprecessor<P: Preprocessor + 'static>(&mut self, preprocessor: P) -> &mut Self {
+    /// Register a [`Preprocessor`] to be used when rendering the book.
+    pub fn with_preprocessor<P: Preprocessor + 'static>(&mut self, preprocessor: P) -> &mut Self {
         self.preprocessors.push(Box::new(preprocessor));
         self
     }
 
     /// Run `rustdoc` tests on the book, linking against the provided libraries.
     pub fn test(&mut self, library_paths: Vec<&str>) -> Result<()> {
-        let library_args: Vec<&str> = (0..library_paths.len())
-            .map(|_| "-L")
-            .zip(library_paths.into_iter())
-            .flat_map(|x| vec![x.0, x.1])
+        // test_chapter with chapter:None will run all tests.
+        self.test_chapter(library_paths, None)
+    }
+
+    /// Run `rustdoc` tests on a specific chapter of the book, linking against the provided libraries.
+    /// If `chapter` is `None`, all tests will be run.
+    pub fn test_chapter(&mut self, library_paths: Vec<&str>, chapter: Option<&str>) -> Result<()> {
+        let cwd = std::env::current_dir()?;
+        let library_args: Vec<OsString> = library_paths
+            .into_iter()
+            .flat_map(|path| {
+                let path = Path::new(path);
+                let path = if path.is_relative() {
+                    cwd.join(path).into_os_string()
+                } else {
+                    path.to_path_buf().into_os_string()
+                };
+                [OsString::from("-L"), path]
+            })
             .collect();
 
         let temp_dir = TempFileBuilder::new().prefix("mdbook-").tempdir()?;
 
-        let preprocess_context = PreprocessorContext::new(self.root.clone(), self.config.clone());
+        let mut chapter_found = false;
 
-        LinkPreprocessor::new().run(&preprocess_context, &mut self.book)?;
-        // Index Preprocessor is disabled so that chapter paths continue to point to the
-        // actual markdown files.
+        struct TestRenderer;
+        impl Renderer for TestRenderer {
+            // FIXME: Is "test" the proper renderer name to use here?
+            fn name(&self) -> &str {
+                "test"
+            }
 
-        for item in self.iter() {
+            fn render(&self, _: &RenderContext) -> Result<()> {
+                Ok(())
+            }
+        }
+
+        // Index Preprocessor is disabled so that chapter paths
+        // continue to point to the actual markdown files.
+        self.preprocessors = determine_preprocessors(&self.config)?
+            .into_iter()
+            .filter(|pre| pre.name() != IndexPreprocessor::NAME)
+            .collect();
+        let (book, _) = self.preprocess_book(&TestRenderer)?;
+
+        let color_output = std::io::stderr().is_terminal();
+        let mut failed = false;
+        for item in book.iter() {
             if let BookItem::Chapter(ref ch) = *item {
-                if !ch.path.as_os_str().is_empty() {
-                    let path = self.source_dir().join(&ch.path);
-                    let content = utils::fs::file_to_string(&path)?;
-                    info!("Testing file: {:?}", path);
+                let chapter_path = match ch.path {
+                    Some(ref path) if !path.as_os_str().is_empty() => path,
+                    _ => continue,
+                };
+
+                if let Some(chapter) = chapter {
+                    if ch.name != chapter && chapter_path.to_str() != Some(chapter) {
+                        if chapter == "?" {
+                            info!("Skipping chapter '{}'...", ch.name);
+                        }
+                        continue;
+                    }
+                }
+                chapter_found = true;
+                info!("Testing chapter '{}': {:?}", ch.name, chapter_path);
 
                 // write preprocessed file to tempdir
-                    let path = temp_dir.path().join(&ch.path);
+                let path = temp_dir.path().join(chapter_path);
                 let mut tmpf = utils::fs::create_file(&path)?;
-                    tmpf.write_all(content.as_bytes())?;
+                tmpf.write_all(ch.content.as_bytes())?;
 
-                    let output = Command::new("rustdoc")
-                        .arg(&path)
+                let mut cmd = Command::new("rustdoc");
+                cmd.current_dir(temp_dir.path())
+                    .arg(&chapter_path)
                     .arg("--test")
-                        .args(&library_args)
-                        .output()?;
+                    .args(&library_args);
+
+                if let Some(edition) = self.config.rust.edition {
+                    match edition {
+                        RustEdition::E2015 => {
+                            cmd.args(["--edition", "2015"]);
+                        }
+                        RustEdition::E2018 => {
+                            cmd.args(["--edition", "2018"]);
+                        }
+                        RustEdition::E2021 => {
+                            cmd.args(["--edition", "2021"]);
+                        }
+                    }
+                }
+
+                if color_output {
+                    cmd.args(&["--color", "always"]);
+                }
+
+                debug!("running {:?}", cmd);
+                let output = cmd.output()?;
 
                 if !output.status.success() {
-                        bail!(ErrorKind::Subprocess(
-                            "Rustdoc returned an error".to_string(),
-                            output
-                        ));
+                    failed = true;
+                    error!(
+                        "rustdoc returned an error:\n\
+                        \n--- stdout\n{}\n--- stderr\n{}",
+                        String::from_utf8_lossy(&output.stdout),
+                        String::from_utf8_lossy(&output.stderr)
+                    );
                 }
             }
         }
+        if failed {
+            bail!("One or more tests failed");
+        }
+        if let Some(chapter) = chapter {
+            if !chapter_found {
+                bail!("Chapter not found: {}", chapter);
+            }
         }
         Ok(())
     }
@@ -255,7 +381,7 @@ impl MDBook {
     /// artefacts.
     ///
     /// If there is only 1 renderer, put it in the directory pointed to by the
-    /// `build.build_dir` key in `Config`. If there is more than one then the
+    /// `build.build_dir` key in [`Config`]. If there is more than one then the
     /// renderer gets its own directory within the main build dir.
     ///
     /// i.e. If there were only one renderer (in this case, the HTML renderer):
@@ -300,19 +426,19 @@ impl MDBook {
 }
 
 /// Look at the `Config` and try to figure out what renderers to use.
-fn determine_renderers(config: &Config) -> Vec<Box<Renderer>> {
-    let mut renderers: Vec<Box<Renderer>> = Vec::new();
+fn determine_renderers(config: &Config) -> Vec<Box<dyn Renderer>> {
+    let mut renderers = Vec::new();
 
-    if let Some(output_table) = config.get("output").and_then(|o| o.as_table()) {
-        for (key, table) in output_table.iter() {
-            // the "html" backend has its own Renderer
+    if let Some(output_table) = config.get("output").and_then(Value::as_table) {
+        renderers.extend(output_table.iter().map(|(key, table)| {
             if key == "html" {
-                renderers.push(Box::new(HtmlHandlebars::new()));
+                Box::new(HtmlHandlebars::new()) as Box<dyn Renderer>
+            } else if key == "markdown" {
+                Box::new(MarkdownRenderer::new()) as Box<dyn Renderer>
             } else {
-                let renderer = interpret_custom_renderer(key, table);
-                renderers.push(renderer);
-            }
+                interpret_custom_renderer(key, table)
             }
+        }));
     }
 
     // if we couldn't find anything, add the HTML renderer as a default
@@ -323,53 +449,185 @@ fn determine_renderers(config: &Config) -> Vec<Box<Renderer>> {
     renderers
 }
 
-fn default_preprocessors() -> Vec<Box<Preprocessor>> {
-    vec![
-        Box::new(LinkPreprocessor::new()),
-        Box::new(IndexPreprocessor::new()),
-    ]
+const DEFAULT_PREPROCESSORS: &[&str] = &["links", "index"];
+
+fn is_default_preprocessor(pre: &dyn Preprocessor) -> bool {
+    let name = pre.name();
+    name == LinkPreprocessor::NAME || name == IndexPreprocessor::NAME
 }
 
 /// Look at the `MDBook` and try to figure out what preprocessors to run.
-fn determine_preprocessors(config: &Config) -> Result<Vec<Box<Preprocessor>>> {
-    let preprocess_list = match config.build.preprocess {
-        Some(ref p) => p,
-        // If no preprocessor field is set, default to the LinkPreprocessor and
-        // IndexPreprocessor. This allows you to disable default preprocessors
-        // by setting "preprocess" to an empty list.
-        None => return Ok(default_preprocessors()),
+fn determine_preprocessors(config: &Config) -> Result<Vec<Box<dyn Preprocessor>>> {
+    // Collect the names of all preprocessors intended to be run, and the order
+    // in which they should be run.
+    let mut preprocessor_names = TopologicalSort::<String>::new();
+
+    if config.build.use_default_preprocessors {
+        for name in DEFAULT_PREPROCESSORS {
+            preprocessor_names.insert(name.to_string());
+        }
+    }
+
+    if let Some(preprocessor_table) = config.get("preprocessor").and_then(Value::as_table) {
+        for (name, table) in preprocessor_table.iter() {
+            preprocessor_names.insert(name.to_string());
+
+            let exists = |name| {
+                (config.build.use_default_preprocessors && DEFAULT_PREPROCESSORS.contains(&name))
+                    || preprocessor_table.contains_key(name)
             };
 
-    let mut preprocessors: Vec<Box<Preprocessor>> = Vec::new();
+            if let Some(before) = table.get("before") {
+                let before = before.as_array().ok_or_else(|| {
+                    Error::msg(format!(
+                        "Expected preprocessor.{}.before to be an array",
+                        name
+                    ))
+                })?;
+                for after in before {
+                    let after = after.as_str().ok_or_else(|| {
+                        Error::msg(format!(
+                            "Expected preprocessor.{}.before to contain strings",
+                            name
+                        ))
+                    })?;
 
-    for key in preprocess_list {
-        match key.as_ref() {
-            "links" => preprocessors.push(Box::new(LinkPreprocessor::new())),
-            "index" => preprocessors.push(Box::new(IndexPreprocessor::new())),
-            _ => bail!("{:?} is not a recognised preprocessor", key),
+                    if !exists(after) {
+                        // Only warn so that preprocessors can be toggled on and off (e.g. for
+                        // troubleshooting) without having to worry about order too much.
+                        warn!(
+                            "preprocessor.{}.after contains \"{}\", which was not found",
+                            name, after
+                        );
+                    } else {
+                        preprocessor_names.add_dependency(name, after);
+                    }
                 }
             }
 
+            if let Some(after) = table.get("after") {
+                let after = after.as_array().ok_or_else(|| {
+                    Error::msg(format!(
+                        "Expected preprocessor.{}.after to be an array",
+                        name
+                    ))
+                })?;
+                for before in after {
+                    let before = before.as_str().ok_or_else(|| {
+                        Error::msg(format!(
+                            "Expected preprocessor.{}.after to contain strings",
+                            name
+                        ))
+                    })?;
+
+                    if !exists(before) {
+                        // See equivalent warning above for rationale
+                        warn!(
+                            "preprocessor.{}.before contains \"{}\", which was not found",
+                            name, before
+                        );
+                    } else {
+                        preprocessor_names.add_dependency(before, name);
+                    }
+                }
+            }
+        }
+    }
+
+    // Now that all links have been established, queue preprocessors in a suitable order
+    let mut preprocessors = Vec::with_capacity(preprocessor_names.len());
+    // `pop_all()` returns an empty vector when no more items are not being depended upon
+    for mut names in std::iter::repeat_with(|| preprocessor_names.pop_all())
+        .take_while(|names| !names.is_empty())
+    {
+        // The `topological_sort` crate does not guarantee a stable order for ties, even across
+        // runs of the same program. Thus, we break ties manually by sorting.
+        // Careful: `str`'s default sorting, which we are implicitly invoking here, uses code point
+        // values ([1]), which may not be an alphabetical sort.
+        // As mentioned in [1], doing so depends on locale, which is not desirable for deciding
+        // preprocessor execution order.
+        // [1]: https://doc.rust-lang.org/stable/std/cmp/trait.Ord.html#impl-Ord-14
+        names.sort();
+        for name in names {
+            let preprocessor: Box<dyn Preprocessor> = match name.as_str() {
+                "links" => Box::new(LinkPreprocessor::new()),
+                "index" => Box::new(IndexPreprocessor::new()),
+                _ => {
+                    // The only way to request a custom preprocessor is through the `preprocessor`
+                    // table, so it must exist, be a table, and contain the key.
+                    let table = &config.get("preprocessor").unwrap().as_table().unwrap()[&name];
+                    let command = get_custom_preprocessor_cmd(&name, table);
+                    Box::new(CmdPreprocessor::new(name, command))
+                }
+            };
+            preprocessors.push(preprocessor);
+        }
+    }
+
+    // "If `pop_all` returns an empty vector and `len` is not 0, there are cyclic dependencies."
+    // Normally, `len() == 0` is equivalent to `is_empty()`, so we'll use that.
+    if preprocessor_names.is_empty() {
         Ok(preprocessors)
+    } else {
+        Err(Error::msg("Cyclic dependency detected in preprocessors"))
+    }
 }
 
-fn interpret_custom_renderer(key: &str, table: &Value) -> Box<Renderer> {
+fn get_custom_preprocessor_cmd(key: &str, table: &Value) -> String {
+    table
+        .get("command")
+        .and_then(Value::as_str)
+        .map(ToString::to_string)
+        .unwrap_or_else(|| format!("mdbook-{}", key))
+}
+
+fn interpret_custom_renderer(key: &str, table: &Value) -> Box<CmdRenderer> {
     // look for the `command` field, falling back to using the key
     // prepended by "mdbook-"
     let table_dot_command = table
         .get("command")
-        .and_then(|c| c.as_str())
-        .map(|s| s.to_string());
+        .and_then(Value::as_str)
+        .map(ToString::to_string);
 
     let command = table_dot_command.unwrap_or_else(|| format!("mdbook-{}", key));
 
-    Box::new(CmdRenderer::new(key.to_string(), command.to_string()))
+    Box::new(CmdRenderer::new(key.to_string(), command))
+}
+
+/// Check whether we should run a particular `Preprocessor` in combination
+/// with the renderer, falling back to `Preprocessor::supports_renderer()`
+/// method if the user doesn't say anything.
+///
+/// The `build.use-default-preprocessors` config option can be used to ensure
+/// default preprocessors always run if they support the renderer.
+fn preprocessor_should_run(
+    preprocessor: &dyn Preprocessor,
+    renderer: &dyn Renderer,
+    cfg: &Config,
+) -> bool {
+    // default preprocessors should be run by default (if supported)
+    if cfg.build.use_default_preprocessors && is_default_preprocessor(preprocessor) {
+        return preprocessor.supports_renderer(renderer.name());
+    }
+
+    let key = format!("preprocessor.{}.renderers", preprocessor.name());
+    let renderer_name = renderer.name();
+
+    if let Some(Value::Array(ref explicit_renderers)) = cfg.get(&key) {
+        return explicit_renderers
+            .iter()
+            .filter_map(Value::as_str)
+            .any(|name| name == renderer_name);
+    }
+
+    preprocessor.supports_renderer(renderer_name)
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
-    use toml::value::{Table, Value};
+    use std::str::FromStr;
+    use toml::value::Table;
 
     #[test]
     fn config_defaults_to_html_renderer_if_empty() {
@@ -413,59 +671,229 @@ mod tests {
     fn config_defaults_to_link_and_index_preprocessor_if_not_set() {
         let cfg = Config::default();
 
-        // make sure we haven't got anything in the `output` table
-        assert!(cfg.build.preprocess.is_none());
+        // make sure we haven't got anything in the `preprocessor` table
+        assert!(cfg.get("preprocessor").is_none());
 
         let got = determine_preprocessors(&cfg);
 
         assert!(got.is_ok());
         assert_eq!(got.as_ref().unwrap().len(), 2);
-        assert_eq!(got.as_ref().unwrap()[0].name(), "links");
-        assert_eq!(got.as_ref().unwrap()[1].name(), "index");
+        assert_eq!(got.as_ref().unwrap()[0].name(), "index");
+        assert_eq!(got.as_ref().unwrap()[1].name(), "links");
     }
 
     #[test]
-    fn config_doesnt_default_if_empty() {
-        let cfg_str: &'static str = r#"
+    fn use_default_preprocessors_works() {
+        let mut cfg = Config::default();
+        cfg.build.use_default_preprocessors = false;
+
+        let got = determine_preprocessors(&cfg).unwrap();
+
+        assert_eq!(got.len(), 0);
+    }
+
+    #[test]
+    fn can_determine_third_party_preprocessors() {
+        let cfg_str = r#"
         [book]
         title = "Some Book"
 
+        [preprocessor.random]
+
         [build]
         build-dir = "outputs"
         create-missing = false
-        preprocess = []
         "#;
 
         let cfg = Config::from_str(cfg_str).unwrap();
 
-        // make sure we have something in the `output` table
-        assert!(cfg.build.preprocess.is_some());
+        // make sure the `preprocessor.random` table exists
+        assert!(cfg.get_preprocessor("random").is_some());
 
-        let got = determine_preprocessors(&cfg);
+        let got = determine_preprocessors(&cfg).unwrap();
 
-        assert!(got.is_ok());
-        assert!(got.unwrap().is_empty());
+        assert!(got.into_iter().any(|p| p.name() == "random"));
     }
 
     #[test]
-    fn config_complains_if_unimplemented_preprocessor() {
-        let cfg_str: &'static str = r#"
-        [book]
-        title = "Some Book"
-
-        [build]
-        build-dir = "outputs"
-        create-missing = false
-        preprocess = ["random"]
+    fn preprocessors_can_provide_their_own_commands() {
+        let cfg_str = r#"
+        [preprocessor.random]
+        command = "python random.py"
         "#;
 
         let cfg = Config::from_str(cfg_str).unwrap();
 
-        // make sure we have something in the `output` table
-        assert!(cfg.build.preprocess.is_some());
+        // make sure the `preprocessor.random` table exists
+        let random = cfg.get_preprocessor("random").unwrap();
+        let random = get_custom_preprocessor_cmd("random", &Value::Table(random.clone()));
 
-        let got = determine_preprocessors(&cfg);
+        assert_eq!(random, "python random.py");
+    }
 
-        assert!(got.is_err());
+    #[test]
+    fn preprocessor_before_must_be_array() {
+        let cfg_str = r#"
+        [preprocessor.random]
+        before = 0
+        "#;
+
+        let cfg = Config::from_str(cfg_str).unwrap();
+
+        assert!(determine_preprocessors(&cfg).is_err());
+    }
+
+    #[test]
+    fn preprocessor_after_must_be_array() {
+        let cfg_str = r#"
+        [preprocessor.random]
+        after = 0
+        "#;
+
+        let cfg = Config::from_str(cfg_str).unwrap();
+
+        assert!(determine_preprocessors(&cfg).is_err());
+    }
+
+    #[test]
+    fn preprocessor_order_is_honored() {
+        let cfg_str = r#"
+        [preprocessor.random]
+        before = [ "last" ]
+        after = [ "index" ]
+
+        [preprocessor.last]
+        after = [ "links", "index" ]
+        "#;
+
+        let cfg = Config::from_str(cfg_str).unwrap();
+
+        let preprocessors = determine_preprocessors(&cfg).unwrap();
+        let index = |name| {
+            preprocessors
+                .iter()
+                .enumerate()
+                .find(|(_, preprocessor)| preprocessor.name() == name)
+                .unwrap()
+                .0
+        };
+        let assert_before = |before, after| {
+            if index(before) >= index(after) {
+                eprintln!("Preprocessor order:");
+                for preprocessor in &preprocessors {
+                    eprintln!("  {}", preprocessor.name());
+                }
+                panic!("{} should come before {}", before, after);
+            }
+        };
+
+        assert_before("index", "random");
+        assert_before("index", "last");
+        assert_before("random", "last");
+        assert_before("links", "last");
+    }
+
+    #[test]
+    fn cyclic_dependencies_are_detected() {
+        let cfg_str = r#"
+        [preprocessor.links]
+        before = [ "index" ]
+
+        [preprocessor.index]
+        before = [ "links" ]
+        "#;
+
+        let cfg = Config::from_str(cfg_str).unwrap();
+
+        assert!(determine_preprocessors(&cfg).is_err());
+    }
+
+    #[test]
+    fn dependencies_dont_register_undefined_preprocessors() {
+        let cfg_str = r#"
+        [preprocessor.links]
+        before = [ "random" ]
+        "#;
+
+        let cfg = Config::from_str(cfg_str).unwrap();
+
+        let preprocessors = determine_preprocessors(&cfg).unwrap();
+
+        assert!(!preprocessors
+            .iter()
+            .any(|preprocessor| preprocessor.name() == "random"));
+    }
+
+    #[test]
+    fn dependencies_dont_register_builtin_preprocessors_if_disabled() {
+        let cfg_str = r#"
+        [preprocessor.random]
+        before = [ "links" ]
+
+        [build]
+        use-default-preprocessors = false
+        "#;
+
+        let cfg = Config::from_str(cfg_str).unwrap();
+
+        let preprocessors = determine_preprocessors(&cfg).unwrap();
+
+        assert!(!preprocessors
+            .iter()
+            .any(|preprocessor| preprocessor.name() == "links"));
+    }
+
+    #[test]
+    fn config_respects_preprocessor_selection() {
+        let cfg_str = r#"
+        [preprocessor.links]
+        renderers = ["html"]
+        "#;
+
+        let cfg = Config::from_str(cfg_str).unwrap();
+
+        // double-check that we can access preprocessor.links.renderers[0]
+        let html = cfg
+            .get_preprocessor("links")
+            .and_then(|links| links.get("renderers"))
+            .and_then(Value::as_array)
+            .and_then(|renderers| renderers.get(0))
+            .and_then(Value::as_str)
+            .unwrap();
+        assert_eq!(html, "html");
+        let html_renderer = HtmlHandlebars::default();
+        let pre = LinkPreprocessor::new();
+
+        let should_run = preprocessor_should_run(&pre, &html_renderer, &cfg);
+        assert!(should_run);
+    }
+
+    struct BoolPreprocessor(bool);
+    impl Preprocessor for BoolPreprocessor {
+        fn name(&self) -> &str {
+            "bool-preprocessor"
+        }
+
+        fn run(&self, _ctx: &PreprocessorContext, _book: Book) -> Result<Book> {
+            unimplemented!()
+        }
+
+        fn supports_renderer(&self, _renderer: &str) -> bool {
+            self.0
+        }
+    }
+
+    #[test]
+    fn preprocessor_should_run_falls_back_to_supports_renderer_method() {
+        let cfg = Config::default();
+        let html = HtmlHandlebars::new();
+
+        let should_be = true;
+        let got = preprocessor_should_run(&BoolPreprocessor(should_be), &html, &cfg);
+        assert_eq!(got, should_be);
+
+        let should_be = false;
+        let got = preprocessor_should_run(&BoolPreprocessor(should_be), &html, &cfg);
+        assert_eq!(got, should_be);
     }
 }

src/book/summary.rs

@@ -1,8 +1,9 @@
-use errors::*;
-use memchr::{self, Memchr};
-use pulldown_cmark::{self, Event, Tag};
+use crate::errors::*;
+use log::{debug, trace, warn};
+use memchr::Memchr;
+use pulldown_cmark::{DefaultBrokenLinkCallback, Event, HeadingLevel, Tag, TagEnd};
+use serde::{Deserialize, Serialize};
 use std::fmt::{self, Display, Formatter};
-use std::iter::FromIterator;
 use std::ops::{Deref, DerefMut};
 use std::path::{Path, PathBuf};
 
@@ -25,12 +26,17 @@ use std::path::{Path, PathBuf};
 /// [Title of prefix element](relative/path/to/markdown.md)
 /// ```
 ///
+/// **Part Title:** An optional title for the next collect of numbered chapters. The numbered
+/// chapters can be broken into as many parts as desired.
+///
 /// **Numbered Chapter:** Numbered chapters are the main content of the book,
 /// they
 /// will be numbered and can be nested, resulting in a nice hierarchy (chapters,
 /// sub-chapters, etc.)
 ///
 /// ```markdown
+/// # Title of Part
+///
 /// - [Title of the Chapter](relative/path/to/markdown.md)
 /// ```
 ///
@@ -55,7 +61,7 @@ pub struct Summary {
     pub title: Option<String>,
     /// Chapters before the main text (e.g. an introduction).
     pub prefix_chapters: Vec<SummaryItem>,
-    /// The main chapters in the document.
+    /// The main numbered chapters of the book, broken into one or more possibly named parts.
     pub numbered_chapters: Vec<SummaryItem>,
     /// Items which come after the main document (e.g. a conclusion).
     pub suffix_chapters: Vec<SummaryItem>,
@@ -71,7 +77,7 @@ pub struct Link {
     pub name: String,
     /// The location of the chapter's source file, taking the book's `src`
     /// directory as the root.
-    pub location: PathBuf,
+    pub location: Option<PathBuf>,
     /// The section number, if this chapter is in the numbered section.
     pub number: Option<SectionNumber>,
     /// Any nested items this chapter may contain.
@@ -83,7 +89,7 @@ impl Link {
     pub fn new<S: Into<String>, P: AsRef<Path>>(name: S, location: P) -> Link {
         Link {
             name: name.into(),
-            location: location.as_ref().to_path_buf(),
+            location: Some(location.as_ref().to_path_buf()),
             number: None,
             nested_items: Vec::new(),
         }
@@ -94,7 +100,7 @@ impl Default for Link {
     fn default() -> Self {
         Link {
             name: String::new(),
-            location: PathBuf::new(),
+            location: Some(PathBuf::new()),
             number: None,
             nested_items: Vec::new(),
         }
@@ -108,6 +114,8 @@ pub enum SummaryItem {
     Link(Link),
     /// A separator (`---`).
     Separator,
+    /// A part title.
+    PartTitle(String),
 }
 
 impl SummaryItem {
@@ -139,7 +147,8 @@ impl From<Link> for SummaryItem {
 ///                     | EPSILON
 /// prefix_chapters   ::= item*
 /// suffix_chapters   ::= item*
-/// numbered_chapters ::= dotted_item+
+/// numbered_chapters ::= part+
+/// part              ::= title dotted_item+
 /// dotted_item       ::= INDENT* DOT_POINT item
 /// item              ::= link
 ///                     | separator
@@ -153,14 +162,19 @@ impl From<Link> for SummaryItem {
 /// > match the following regex: "[^<>\n[]]+".
 struct SummaryParser<'a> {
     src: &'a str,
-    stream: pulldown_cmark::Parser<'a>,
+    stream: pulldown_cmark::OffsetIter<'a, DefaultBrokenLinkCallback>,
+    offset: usize,
+
+    /// We can't actually put an event back into the `OffsetIter` stream, so instead we store it
+    /// here until somebody calls `next_event` again.
+    back: Option<Event<'a>>,
 }
 
 /// Reads `Events` from the provided stream until the corresponding
 /// `Event::End` is encountered which matches the `$delimiter` pattern.
 ///
 /// This is the equivalent of doing
-/// `$stream.take_while(|e| e != $delimeter).collect()` but it allows you to
+/// `$stream.take_while(|e| e != $delimiter).collect()` but it allows you to
 /// use pattern matching and you won't get errors because `take_while()`
 /// moves `$stream` out of self.
 macro_rules! collect_events {
@@ -174,7 +188,7 @@ macro_rules! collect_events {
         let mut events = Vec::new();
 
         loop {
-            let event = $stream.next();
+            let event = $stream.next().map(|(ev, _range)| ev);
             trace!("Next event: {:?}", event);
 
             match event {
@@ -195,24 +209,24 @@ macro_rules! collect_events {
 }
 
 impl<'a> SummaryParser<'a> {
-    fn new(text: &str) -> SummaryParser {
-        let pulldown_parser = pulldown_cmark::Parser::new(text);
+    fn new(text: &'a str) -> SummaryParser<'a> {
+        let pulldown_parser = pulldown_cmark::Parser::new(text).into_offset_iter();
 
         SummaryParser {
             src: text,
             stream: pulldown_parser,
+            offset: 0,
+            back: None,
         }
     }
 
     /// Get the current line and column to give the user more useful error
     /// messages.
     fn current_location(&self) -> (usize, usize) {
-        let byte_offset = self.stream.get_offset();
-
-        let previous_text = self.src[..byte_offset].as_bytes();
+        let previous_text = self.src[..self.offset].as_bytes();
         let line = Memchr::new(b'\n', previous_text).count() + 1;
         let start_of_line = memchr::memrchr(b'\n', previous_text).unwrap_or(0);
-        let col = self.src[start_of_line..byte_offset].chars().count();
+        let col = self.src[start_of_line..self.offset].chars().count();
 
         (line, col)
     }
@@ -223,13 +237,13 @@ impl<'a> SummaryParser<'a> {
 
         let prefix_chapters = self
             .parse_affix(true)
-            .chain_err(|| "There was an error parsing the prefix chapters")?;
+            .with_context(|| "There was an error parsing the prefix chapters")?;
         let numbered_chapters = self
-            .parse_numbered()
-            .chain_err(|| "There was an error parsing the numbered chapters")?;
+            .parse_parts()
+            .with_context(|| "There was an error parsing the numbered chapters")?;
         let suffix_chapters = self
             .parse_affix(false)
-            .chain_err(|| "There was an error parsing the suffix chapters")?;
+            .with_context(|| "There was an error parsing the suffix chapters")?;
 
         Ok(Summary {
             title,
@@ -239,8 +253,7 @@ impl<'a> SummaryParser<'a> {
         })
     }
 
-    /// Parse the affix chapters. This expects the first event (start of
-    /// paragraph) to have already been consumed by the previous parser.
+    /// Parse the affix chapters.
     fn parse_affix(&mut self, is_prefix: bool) -> Result<Vec<SummaryItem>> {
         let mut items = Vec::new();
         debug!(
@@ -250,20 +263,27 @@ impl<'a> SummaryParser<'a> {
 
         loop {
             match self.next_event() {
-                Some(Event::Start(Tag::List(..))) => {
+                Some(ev @ Event::Start(Tag::List(..)))
+                | Some(
+                    ev @ Event::Start(Tag::Heading {
+                        level: HeadingLevel::H1,
+                        ..
+                    }),
+                ) => {
                     if is_prefix {
                         // we've finished prefix chapters and are at the start
                         // of the numbered section.
+                        self.back(ev);
                         break;
                     } else {
                         bail!(self.parse_error("Suffix chapters cannot be followed by a list"));
                     }
                 }
-                Some(Event::Start(Tag::Link(href, _))) => {
-                    let link = self.parse_link(href.to_string())?;
+                Some(Event::Start(Tag::Link { dest_url, .. })) => {
+                    let link = self.parse_link(dest_url.to_string());
                     items.push(SummaryItem::Link(link));
                 }
-                Some(Event::Start(Tag::Rule)) => items.push(SummaryItem::Separator),
+                Some(Event::Rule) => items.push(SummaryItem::Separator),
                 Some(_) => {}
                 None => break,
             }
@@ -272,85 +292,164 @@ impl<'a> SummaryParser<'a> {
         Ok(items)
     }
 
-    fn parse_link(&mut self, href: String) -> Result<Link> {
-        let link_content = collect_events!(self.stream, end Tag::Link(..));
-        let name = stringify_events(link_content);
+    fn parse_parts(&mut self) -> Result<Vec<SummaryItem>> {
+        let mut parts = vec![];
 
-        if href.is_empty() {
-            Err(self.parse_error("You can't have an empty link."))
-        } else {
-            Ok(Link {
-                name: name,
-                location: PathBuf::from(href.to_string()),
-                number: None,
-                nested_items: Vec::new(),
-            })
-        }
-    }
-
-    /// Parse the numbered chapters. This assumes the opening list tag has
-    /// already been consumed by a previous parser.
-    fn parse_numbered(&mut self) -> Result<Vec<SummaryItem>> {
-        let mut items = Vec::new();
-        let root_number = SectionNumber::default();
-
-        // we need to do this funny loop-match-if-let dance because a rule will
-        // close off any currently running list. Therefore we try to read the
-        // list items before the rule, then if we encounter a rule we'll add a
-        // separator and try to resume parsing numbered chapters if we start a
-        // list immediately afterwards.
-        //
-        // If you can think of a better way to do this then please make a PR :)
+        // We want the section numbers to be continues through all parts.
+        let mut root_number = SectionNumber::default();
+        let mut root_items = 0;
 
         loop {
-            let mut bunch_of_items = self.parse_nested_numbered(&root_number)?;
+            // Possibly match a title or the end of the "numbered chapters part".
+            let title = match self.next_event() {
+                Some(ev @ Event::Start(Tag::Paragraph)) => {
+                    // we're starting the suffix chapters
+                    self.back(ev);
+                    break;
+                }
+
+                Some(Event::Start(Tag::Heading {
+                    level: HeadingLevel::H1,
+                    ..
+                })) => {
+                    debug!("Found a h1 in the SUMMARY");
+
+                    let tags = collect_events!(self.stream, end TagEnd::Heading(HeadingLevel::H1));
+                    Some(stringify_events(tags))
+                }
+
+                Some(ev) => {
+                    self.back(ev);
+                    None
+                }
+
+                None => break, // EOF, bail...
+            };
+
+            // Parse the rest of the part.
+            let numbered_chapters = self
+                .parse_numbered(&mut root_items, &mut root_number)
+                .with_context(|| "There was an error parsing the numbered chapters")?;
+
+            if let Some(title) = title {
+                parts.push(SummaryItem::PartTitle(title));
+            }
+            parts.extend(numbered_chapters);
+        }
+
+        Ok(parts)
+    }
+
+    /// Finishes parsing a link once the `Event::Start(Tag::Link(..))` has been opened.
+    fn parse_link(&mut self, href: String) -> Link {
+        let href = href.replace("%20", " ");
+        let link_content = collect_events!(self.stream, end TagEnd::Link);
+        let name = stringify_events(link_content);
+
+        let path = if href.is_empty() {
+            None
+        } else {
+            Some(PathBuf::from(href))
+        };
+
+        Link {
+            name,
+            location: path,
+            number: None,
+            nested_items: Vec::new(),
+        }
+    }
+
+    /// Parse the numbered chapters.
+    fn parse_numbered(
+        &mut self,
+        root_items: &mut u32,
+        root_number: &mut SectionNumber,
+    ) -> Result<Vec<SummaryItem>> {
+        let mut items = Vec::new();
+
+        // For the first iteration, we want to just skip any opening paragraph tags, as that just
+        // marks the start of the list. But after that, another opening paragraph indicates that we
+        // have started a new part or the suffix chapters.
+        let mut first = true;
+
+        loop {
+            match self.next_event() {
+                Some(ev @ Event::Start(Tag::Paragraph)) => {
+                    if !first {
+                        // we're starting the suffix chapters
+                        self.back(ev);
+                        break;
+                    }
+                }
+                // The expectation is that pulldown cmark will terminate a paragraph before a new
+                // heading, so we can always count on this to return without skipping headings.
+                Some(
+                    ev @ Event::Start(Tag::Heading {
+                        level: HeadingLevel::H1,
+                        ..
+                    }),
+                ) => {
+                    // we're starting a new part
+                    self.back(ev);
+                    break;
+                }
+                Some(ev @ Event::Start(Tag::List(..))) => {
+                    self.back(ev);
+                    let mut bunch_of_items = self.parse_nested_numbered(root_number)?;
 
                     // if we've resumed after something like a rule the root sections
                     // will be numbered from 1. We need to manually go back and update
                     // them
-            update_section_numbers(&mut bunch_of_items, 0, items.len() as u32);
+                    update_section_numbers(&mut bunch_of_items, 0, *root_items);
+                    *root_items += bunch_of_items.len() as u32;
                     items.extend(bunch_of_items);
-
-            match self.next_event() {
-                Some(Event::Start(Tag::Paragraph)) => {
-                    // we're starting the suffix chapters
-                    break;
                 }
                 Some(Event::Start(other_tag)) => {
-                    if other_tag == Tag::Rule {
-                        items.push(SummaryItem::Separator);
-                    }
                     trace!("Skipping contents of {:?}", other_tag);
 
                     // Skip over the contents of this tag
                     while let Some(event) = self.next_event() {
-                        if event == Event::End(other_tag.clone()) {
+                        if event == Event::End(other_tag.clone().into()) {
+                            break;
+                        }
+                    }
+                }
+                Some(Event::Rule) => {
+                    items.push(SummaryItem::Separator);
+                }
+
+                // something else... ignore
+                Some(_) => {}
+
+                // EOF, bail...
+                None => {
                     break;
                 }
             }
 
-                    if let Some(Event::Start(Tag::List(..))) = self.next_event() {
-                        continue;
-                    } else {
-                        break;
-                    }
-                }
-                Some(_) => {
-                    // something else... ignore
-                    continue;
-                }
-                None => {
-                    // EOF, bail...
-                    break;
-                }
-            }
+            // From now on, we cannot accept any new paragraph opening tags.
+            first = false;
         }
 
         Ok(items)
     }
 
+    /// Push an event back to the tail of the stream.
+    fn back(&mut self, ev: Event<'a>) {
+        assert!(self.back.is_none());
+        trace!("Back: {:?}", ev);
+        self.back = Some(ev);
+    }
+
     fn next_event(&mut self) -> Option<Event<'a>> {
-        let next = self.stream.next();
+        let next = self.back.take().or_else(|| {
+            self.stream.next().map(|(ev, range)| {
+                self.offset = range.start;
+                ev
+            })
+        });
+
         trace!("Next event: {:?}", next);
 
         next
@@ -367,6 +466,10 @@ impl<'a> SummaryParser<'a> {
                     items.push(item);
                 }
                 Some(Event::Start(Tag::List(..))) => {
+                    // Skip this tag after comment because it is not nested.
+                    if items.is_empty() {
+                        continue;
+                    }
                     // recurse to parse the nested list
                     let (_, last_item) = get_last_link(&mut items)?;
                     let last_item_number = last_item
@@ -378,7 +481,7 @@ impl<'a> SummaryParser<'a> {
 
                     last_item.nested_items = sub_items;
                 }
-                Some(Event::End(Tag::List(..))) => break,
+                Some(Event::End(TagEnd::List(..))) => break,
                 Some(_) => {}
                 None => break,
             }
@@ -395,8 +498,8 @@ impl<'a> SummaryParser<'a> {
         loop {
             match self.next_event() {
                 Some(Event::Start(Tag::Paragraph)) => continue,
-                Some(Event::Start(Tag::Link(href, _))) => {
-                    let mut link = self.parse_link(href.to_string())?;
+                Some(Event::Start(Tag::Link { dest_url, .. })) => {
+                    let mut link = self.parse_link(dest_url.to_string());
 
                     let mut number = parent.clone();
                     number.0.push(num_existing_items as u32 + 1);
@@ -404,7 +507,10 @@ impl<'a> SummaryParser<'a> {
                         "Found chapter: {} {} ({})",
                         number,
                         link.name,
-                        link.location.display()
+                        link.location
+                            .as_ref()
+                            .map(|p| p.to_str().unwrap_or(""))
+                            .unwrap_or("[draft]")
                     );
 
                     link.number = Some(number);
@@ -423,19 +529,37 @@ impl<'a> SummaryParser<'a> {
 
     fn parse_error<D: Display>(&self, msg: D) -> Error {
         let (line, col) = self.current_location();
-
-        ErrorKind::ParseError(line, col, msg.to_string()).into()
+        anyhow::anyhow!(
+            "failed to parse SUMMARY.md line {}, column {}: {}",
+            line,
+            col,
+            msg
+        )
     }
 
     /// Try to parse the title line.
     fn parse_title(&mut self) -> Option<String> {
-        if let Some(Event::Start(Tag::Header(1))) = self.next_event() {
+        loop {
+            match self.next_event() {
+                Some(Event::Start(Tag::Heading {
+                    level: HeadingLevel::H1,
+                    ..
+                })) => {
                     debug!("Found a h1 in the SUMMARY");
 
-            let tags = collect_events!(self.stream, end Tag::Header(1));
-            Some(stringify_events(tags))
-        } else {
-            None
+                    let tags = collect_events!(self.stream, end TagEnd::Heading(HeadingLevel::H1));
+                    return Some(stringify_events(tags));
+                }
+                // Skip a HTML element such as a comment line.
+                Some(Event::Html(_) | Event::InlineHtml(_))
+                | Some(Event::Start(Tag::HtmlBlock) | Event::End(TagEnd::HtmlBlock)) => {}
+                // Otherwise, no title.
+                Some(ev) => {
+                    self.back(ev);
+                    return None;
+                }
+                _ => return None,
+            }
         }
     }
 }
@@ -461,21 +585,22 @@ fn get_last_link(links: &mut [SummaryItem]) -> Result<(usize, &mut Link)> {
         .filter_map(|(i, item)| item.maybe_link_mut().map(|l| (i, l)))
         .rev()
         .next()
-        .ok_or_else(|| {
-            "Unable to get last link because the list of SummaryItems doesn't contain any Links"
-                .into()
-        })
+        .ok_or_else(||
+            anyhow::anyhow!("Unable to get last link because the list of SummaryItems doesn't contain any Links")
+            )
 }
 
 /// Removes the styling from a list of Markdown events and returns just the
 /// plain text.
-fn stringify_events(events: Vec<Event>) -> String {
+fn stringify_events(events: Vec<Event<'_>>) -> String {
     events
         .into_iter()
         .filter_map(|t| match t {
-            Event::Text(text) => Some(text.into_owned()),
+            Event::Text(text) | Event::Code(text) => Some(text.into_string()),
+            Event::SoftBreak => Some(String::from(" ")),
             _ => None,
-        }).collect()
+        })
+        .collect()
 }
 
 /// A section number like "1.2.3", basically just a newtype'd `Vec<u32>` with
@@ -484,7 +609,7 @@ fn stringify_events(events: Vec<Event>) -> String {
 pub struct SectionNumber(pub Vec<u32>);
 
 impl Display for SectionNumber {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         if self.0.is_empty() {
             write!(f, "0")
         } else {
@@ -544,6 +669,18 @@ mod tests {
         assert_eq!(got, should_be);
     }
 
+    #[test]
+    fn no_initial_title() {
+        let src = "[Link]()";
+        let mut parser = SummaryParser::new(src);
+
+        assert!(parser.parse_title().is_none());
+        assert!(matches!(
+            parser.next_event(),
+            Some(Event::Start(Tag::Paragraph))
+        ));
+    }
+
     #[test]
     fn parse_title_with_styling() {
         let src = "# My **Awesome** Summary";
@@ -574,17 +711,16 @@ mod tests {
         let should_be = vec![
             SummaryItem::Link(Link {
                 name: String::from("First"),
-                location: PathBuf::from("./first.md"),
+                location: Some(PathBuf::from("./first.md")),
                 ..Default::default()
             }),
             SummaryItem::Link(Link {
                 name: String::from("Second"),
-                location: PathBuf::from("./second.md"),
+                location: Some(PathBuf::from("./second.md")),
                 ..Default::default()
             }),
         ];
 
-        let _ = parser.stream.next(); // step past first event
         let got = parser.parse_affix(true).unwrap();
 
         assert_eq!(got, should_be);
@@ -595,7 +731,6 @@ mod tests {
         let src = "[First](./first.md)\n\n---\n\n[Second](./second.md)\n";
         let mut parser = SummaryParser::new(src);
 
-        let _ = parser.stream.next(); // step past first event
         let got = parser.parse_affix(true).unwrap();
 
         assert_eq!(got.len(), 3);
@@ -607,7 +742,6 @@ mod tests {
         let src = "[First](./first.md)\n- [Second](./second.md)\n";
         let mut parser = SummaryParser::new(src);
 
-        let _ = parser.stream.next(); // step past first event
         let got = parser.parse_affix(false);
 
         assert!(got.is_err());
@@ -618,19 +752,19 @@ mod tests {
         let src = "[First](./first.md)";
         let should_be = Link {
             name: String::from("First"),
-            location: PathBuf::from("./first.md"),
+            location: Some(PathBuf::from("./first.md")),
             ..Default::default()
         };
 
         let mut parser = SummaryParser::new(src);
-        let _ = parser.stream.next(); // skip past start of paragraph
+        let _ = parser.stream.next(); // Discard opening paragraph
 
         let href = match parser.stream.next() {
-            Some(Event::Start(Tag::Link(href, _))) => href.to_string(),
+            Some((Event::Start(Tag::Link { dest_url, .. }), _range)) => dest_url.to_string(),
             other => panic!("Unreachable, {:?}", other),
         };
 
-        let got = parser.parse_link(href).unwrap();
+        let got = parser.parse_link(href);
         assert_eq!(got, should_be);
     }
 
@@ -639,16 +773,16 @@ mod tests {
         let src = "- [First](./first.md)\n";
         let link = Link {
             name: String::from("First"),
-            location: PathBuf::from("./first.md"),
+            location: Some(PathBuf::from("./first.md")),
             number: Some(SectionNumber(vec![1])),
             ..Default::default()
         };
         let should_be = vec![SummaryItem::Link(link)];
 
         let mut parser = SummaryParser::new(src);
-        let _ = parser.stream.next();
-
-        let got = parser.parse_numbered().unwrap();
+        let got = parser
+            .parse_numbered(&mut 0, &mut SectionNumber::default())
+            .unwrap();
 
         assert_eq!(got, should_be);
     }
@@ -660,27 +794,92 @@ mod tests {
         let should_be = vec![
             SummaryItem::Link(Link {
                 name: String::from("First"),
-                location: PathBuf::from("./first.md"),
+                location: Some(PathBuf::from("./first.md")),
                 number: Some(SectionNumber(vec![1])),
                 nested_items: vec![SummaryItem::Link(Link {
                     name: String::from("Nested"),
-                    location: PathBuf::from("./nested.md"),
+                    location: Some(PathBuf::from("./nested.md")),
                     number: Some(SectionNumber(vec![1, 1])),
                     nested_items: Vec::new(),
                 })],
             }),
             SummaryItem::Link(Link {
                 name: String::from("Second"),
-                location: PathBuf::from("./second.md"),
+                location: Some(PathBuf::from("./second.md")),
                 number: Some(SectionNumber(vec![2])),
                 nested_items: Vec::new(),
             }),
         ];
 
         let mut parser = SummaryParser::new(src);
-        let _ = parser.stream.next();
+        let got = parser
+            .parse_numbered(&mut 0, &mut SectionNumber::default())
+            .unwrap();
 
-        let got = parser.parse_numbered().unwrap();
+        assert_eq!(got, should_be);
+    }
+
+    #[test]
+    fn parse_numbered_chapters_separated_by_comment() {
+        let src = "- [First](./first.md)\n<!-- this is a comment -->\n- [Second](./second.md)";
+
+        let should_be = vec![
+            SummaryItem::Link(Link {
+                name: String::from("First"),
+                location: Some(PathBuf::from("./first.md")),
+                number: Some(SectionNumber(vec![1])),
+                nested_items: Vec::new(),
+            }),
+            SummaryItem::Link(Link {
+                name: String::from("Second"),
+                location: Some(PathBuf::from("./second.md")),
+                number: Some(SectionNumber(vec![2])),
+                nested_items: Vec::new(),
+            }),
+        ];
+
+        let mut parser = SummaryParser::new(src);
+        let got = parser
+            .parse_numbered(&mut 0, &mut SectionNumber::default())
+            .unwrap();
+
+        assert_eq!(got, should_be);
+    }
+
+    #[test]
+    fn parse_titled_parts() {
+        let src = "- [First](./first.md)\n- [Second](./second.md)\n\
+                   # Title 2\n- [Third](./third.md)\n\t- [Fourth](./fourth.md)";
+
+        let should_be = vec![
+            SummaryItem::Link(Link {
+                name: String::from("First"),
+                location: Some(PathBuf::from("./first.md")),
+                number: Some(SectionNumber(vec![1])),
+                nested_items: Vec::new(),
+            }),
+            SummaryItem::Link(Link {
+                name: String::from("Second"),
+                location: Some(PathBuf::from("./second.md")),
+                number: Some(SectionNumber(vec![2])),
+                nested_items: Vec::new(),
+            }),
+            SummaryItem::PartTitle(String::from("Title 2")),
+            SummaryItem::Link(Link {
+                name: String::from("Third"),
+                location: Some(PathBuf::from("./third.md")),
+                number: Some(SectionNumber(vec![3])),
+                nested_items: vec![SummaryItem::Link(Link {
+                    name: String::from("Fourth"),
+                    location: Some(PathBuf::from("./fourth.md")),
+                    number: Some(SectionNumber(vec![3, 1])),
+                    nested_items: Vec::new(),
+                })],
+            }),
+        ];
+
+        let mut parser = SummaryParser::new(src);
+        let got = parser.parse_parts().unwrap();
 
         assert_eq!(got, should_be);
     }
@@ -695,33 +894,221 @@ mod tests {
         let should_be = vec![
             SummaryItem::Link(Link {
                 name: String::from("First"),
-                location: PathBuf::from("./first.md"),
+                location: Some(PathBuf::from("./first.md")),
                 number: Some(SectionNumber(vec![1])),
                 nested_items: Vec::new(),
             }),
             SummaryItem::Link(Link {
                 name: String::from("Second"),
-                location: PathBuf::from("./second.md"),
+                location: Some(PathBuf::from("./second.md")),
                 number: Some(SectionNumber(vec![2])),
                 nested_items: Vec::new(),
             }),
         ];
 
         let mut parser = SummaryParser::new(src);
-        let _ = parser.stream.next();
-
-        let got = parser.parse_numbered().unwrap();
+        let got = parser
+            .parse_numbered(&mut 0, &mut SectionNumber::default())
+            .unwrap();
 
         assert_eq!(got, should_be);
     }
 
     #[test]
-    fn an_empty_link_location_is_an_error() {
+    fn an_empty_link_location_is_a_draft_chapter() {
         let src = "- [Empty]()\n";
         let mut parser = SummaryParser::new(src);
-        parser.stream.next();
 
-        let got = parser.parse_numbered();
-        assert!(got.is_err());
+        let got = parser.parse_numbered(&mut 0, &mut SectionNumber::default());
+        let should_be = vec![SummaryItem::Link(Link {
+            name: String::from("Empty"),
+            location: None,
+            number: Some(SectionNumber(vec![1])),
+            nested_items: Vec::new(),
+        })];
+
+        assert!(got.is_ok());
+        assert_eq!(got.unwrap(), should_be);
+    }
+
+    /// Regression test for https://github.com/rust-lang/mdBook/issues/779
+    /// Ensure section numbers are correctly incremented after a horizontal separator.
+    #[test]
+    fn keep_numbering_after_separator() {
+        let src =
+            "- [First](./first.md)\n---\n- [Second](./second.md)\n---\n- [Third](./third.md)\n";
+        let should_be = vec![
+            SummaryItem::Link(Link {
+                name: String::from("First"),
+                location: Some(PathBuf::from("./first.md")),
+                number: Some(SectionNumber(vec![1])),
+                nested_items: Vec::new(),
+            }),
+            SummaryItem::Separator,
+            SummaryItem::Link(Link {
+                name: String::from("Second"),
+                location: Some(PathBuf::from("./second.md")),
+                number: Some(SectionNumber(vec![2])),
+                nested_items: Vec::new(),
+            }),
+            SummaryItem::Separator,
+            SummaryItem::Link(Link {
+                name: String::from("Third"),
+                location: Some(PathBuf::from("./third.md")),
+                number: Some(SectionNumber(vec![3])),
+                nested_items: Vec::new(),
+            }),
+        ];
+
+        let mut parser = SummaryParser::new(src);
+        let got = parser
+            .parse_numbered(&mut 0, &mut SectionNumber::default())
+            .unwrap();
+
+        assert_eq!(got, should_be);
+    }
+
+    /// Regression test for https://github.com/rust-lang/mdBook/issues/1218
+    /// Ensure chapter names spread across multiple lines have spaces between all the words.
+    #[test]
+    fn add_space_for_multi_line_chapter_names() {
+        let src = "- [Chapter\ntitle](./chapter.md)";
+        let should_be = vec![SummaryItem::Link(Link {
+            name: String::from("Chapter title"),
+            location: Some(PathBuf::from("./chapter.md")),
+            number: Some(SectionNumber(vec![1])),
+            nested_items: Vec::new(),
+        })];
+
+        let mut parser = SummaryParser::new(src);
+        let got = parser
+            .parse_numbered(&mut 0, &mut SectionNumber::default())
+            .unwrap();
+
+        assert_eq!(got, should_be);
+    }
+
+    #[test]
+    fn allow_space_in_link_destination() {
+        let src = "- [test1](./test%20link1.md)\n- [test2](<./test link2.md>)";
+        let should_be = vec![
+            SummaryItem::Link(Link {
+                name: String::from("test1"),
+                location: Some(PathBuf::from("./test link1.md")),
+                number: Some(SectionNumber(vec![1])),
+                nested_items: Vec::new(),
+            }),
+            SummaryItem::Link(Link {
+                name: String::from("test2"),
+                location: Some(PathBuf::from("./test link2.md")),
+                number: Some(SectionNumber(vec![2])),
+                nested_items: Vec::new(),
+            }),
+        ];
+        let mut parser = SummaryParser::new(src);
+        let got = parser
+            .parse_numbered(&mut 0, &mut SectionNumber::default())
+            .unwrap();
+
+        assert_eq!(got, should_be);
+    }
+
+    #[test]
+    fn skip_html_comments() {
+        let src = r#"<!--
+# Title - En
+-->
+# Title - Local
+
+<!--
+[Prefix 00-01 - En](ch00-01.md)
+[Prefix 00-02 - En](ch00-02.md)
+-->
+[Prefix 00-01 - Local](ch00-01.md)
+[Prefix 00-02 - Local](ch00-02.md)
+
+<!--
+## Section Title - En
+-->
+## Section Title - Localized
+
+<!--
+- [Ch 01-00 - En](ch01-00.md)
+    - [Ch 01-01 - En](ch01-01.md)
+    - [Ch 01-02 - En](ch01-02.md)
+-->
+- [Ch 01-00 - Local](ch01-00.md)
+    - [Ch 01-01 - Local](ch01-01.md)
+    - [Ch 01-02 - Local](ch01-02.md)
+
+<!--
+- [Ch 02-00 - En](ch02-00.md)
+-->
+- [Ch 02-00 - Local](ch02-00.md)
+
+<!--
+[Appendix A - En](appendix-01.md)
+[Appendix B - En](appendix-02.md)
+-->`
+[Appendix A - Local](appendix-01.md)
+[Appendix B - Local](appendix-02.md)
+"#;
+
+        let mut parser = SummaryParser::new(src);
+
+        // ---- Title ----
+        let title = parser.parse_title();
+        assert_eq!(title, Some(String::from("Title - Local")));
+
+        // ---- Prefix Chapters ----
+
+        let new_affix_item = |name, location| {
+            SummaryItem::Link(Link {
+                name: String::from(name),
+                location: Some(PathBuf::from(location)),
+                ..Default::default()
+            })
+        };
+
+        let should_be = vec![
+            new_affix_item("Prefix 00-01 - Local", "ch00-01.md"),
+            new_affix_item("Prefix 00-02 - Local", "ch00-02.md"),
+        ];
+
+        let got = parser.parse_affix(true).unwrap();
+        assert_eq!(got, should_be);
+
+        // ---- Numbered Chapters ----
+
+        let new_numbered_item = |name, location, numbers: &[u32], nested_items| {
+            SummaryItem::Link(Link {
+                name: String::from(name),
+                location: Some(PathBuf::from(location)),
+                number: Some(SectionNumber(numbers.to_vec())),
+                nested_items,
+            })
+        };
+
+        let ch01_nested = vec![
+            new_numbered_item("Ch 01-01 - Local", "ch01-01.md", &[1, 1], vec![]),
+            new_numbered_item("Ch 01-02 - Local", "ch01-02.md", &[1, 2], vec![]),
+        ];
+
+        let should_be = vec![
+            new_numbered_item("Ch 01-00 - Local", "ch01-00.md", &[1], ch01_nested),
+            new_numbered_item("Ch 02-00 - Local", "ch02-00.md", &[2], vec![]),
+        ];
+        let got = parser.parse_parts().unwrap();
+        assert_eq!(got, should_be);
+
+        // ---- Suffix Chapters ----
+
+        let should_be = vec![
+            new_affix_item("Appendix A - Local", "appendix-01.md"),
+            new_affix_item("Appendix B - Local", "appendix-02.md"),
+        ];
+
+        let got = parser.parse_affix(false).unwrap();
+        assert_eq!(got, should_be);
     }
 }

src/cmd/build.rs

@@ -1,35 +1,37 @@
-use clap::{App, ArgMatches, SubCommand};
+use super::command_prelude::*;
+use crate::{get_book_dir, open};
 use mdbook::errors::Result;
 use mdbook::MDBook;
-use {get_book_dir, open};
+use std::path::PathBuf;
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'a, 'b>() -> App<'a, 'b> {
-    SubCommand::with_name("build")
+pub fn make_subcommand() -> Command {
+    Command::new("build")
         .about("Builds a book from its markdown files")
-        .arg_from_usage(
-            "-d, --dest-dir=[dest-dir] 'Output directory for the book{n}\
-             (If omitted, uses build.build-dir from book.toml or defaults to ./book)'",
-        ).arg_from_usage(
-            "[dir] 'Root directory for the book{n}\
-             (Defaults to the Current Directory when omitted)'",
-        ).arg_from_usage("-o, --open 'Opens the compiled book in a web browser'")
+        .arg_dest_dir()
+        .arg_root_dir()
+        .arg_open()
 }
 
 // Build command implementation
 pub fn execute(args: &ArgMatches) -> Result<()> {
     let book_dir = get_book_dir(args);
-    let mut book = MDBook::load(&book_dir)?;
+    let mut book = MDBook::load(book_dir)?;
 
-    if let Some(dest_dir) = args.value_of("dest-dir") {
+    if let Some(dest_dir) = args.get_one::<PathBuf>("dest-dir") {
         book.config.build.build_dir = dest_dir.into();
     }
 
     book.build()?;
 
-    if args.is_present("open") {
+    if args.get_flag("open") {
         // FIXME: What's the right behaviour if we don't use the HTML renderer?
-        open(book.build_dir_for("html").join("index.html"));
+        let path = book.build_dir_for("html").join("index.html");
+        if !path.exists() {
+            error!("No chapter available to open");
+            std::process::exit(1)
+        }
+        open(path);
     }
 
     Ok(())

src/cmd/clean.rs

@@ -1,32 +1,32 @@
-use clap::{App, ArgMatches, SubCommand};
-use get_book_dir;
-use mdbook::errors::*;
+use super::command_prelude::*;
+use crate::get_book_dir;
+use anyhow::Context;
 use mdbook::MDBook;
 use std::fs;
+use std::path::PathBuf;
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'a, 'b>() -> App<'a, 'b> {
-    SubCommand::with_name("clean")
+pub fn make_subcommand() -> Command {
+    Command::new("clean")
         .about("Deletes a built book")
-        .arg_from_usage(
-            "-d, --dest-dir=[dest-dir] 'Output directory for the book{n}\
-             (If omitted, uses build.build-dir from book.toml or defaults to ./book)'",
-        ).arg_from_usage(
-            "[dir] 'Root directory for the book{n}\
-             (Defaults to the Current Directory when omitted)'",
-        )
+        .arg_dest_dir()
+        .arg_root_dir()
 }
 
 // Clean command implementation
-pub fn execute(args: &ArgMatches) -> ::mdbook::errors::Result<()> {
+pub fn execute(args: &ArgMatches) -> mdbook::errors::Result<()> {
     let book_dir = get_book_dir(args);
-    let book = MDBook::load(&book_dir)?;
+    let book = MDBook::load(book_dir)?;
 
-    let dir_to_remove = match args.value_of("dest-dir") {
+    let dir_to_remove = match args.get_one::<PathBuf>("dest-dir") {
         Some(dest_dir) => dest_dir.into(),
         None => book.root.join(&book.config.build.build_dir),
     };
-    fs::remove_dir_all(&dir_to_remove).chain_err(|| "Unable to remove the build directory")?;
+
+    if dir_to_remove.exists() {
+        fs::remove_dir_all(&dir_to_remove)
+            .with_context(|| "Unable to remove the build directory")?;
+    }
 
     Ok(())
 }

src/cmd/command_prelude.rs

@@ -0,0 +1,45 @@
+//! Helpers for building the command-line arguments for commands.
+
+pub use clap::{arg, Arg, ArgMatches, Command};
+use std::path::PathBuf;
+
+pub trait CommandExt: Sized {
+    fn _arg(self, arg: Arg) -> Self;
+
+    fn arg_dest_dir(self) -> Self {
+        self._arg(
+            Arg::new("dest-dir")
+                .short('d')
+                .long("dest-dir")
+                .value_name("dest-dir")
+                .value_parser(clap::value_parser!(PathBuf))
+                .help(
+                    "Output directory for the book\n\
+                    Relative paths are interpreted relative to the book's root directory.\n\
+                    If omitted, mdBook uses build.build-dir from book.toml \
+                    or defaults to `./book`.",
+                ),
+        )
+    }
+
+    fn arg_root_dir(self) -> Self {
+        self._arg(
+            Arg::new("dir")
+                .help(
+                    "Root directory for the book\n\
+                    (Defaults to the current directory when omitted)",
+                )
+                .value_parser(clap::value_parser!(PathBuf)),
+        )
+    }
+
+    fn arg_open(self) -> Self {
+        self._arg(arg!(-o --open "Opens the compiled book in a web browser"))
+    }
+}
+
+impl CommandExt for Command {
+    fn _arg(self, arg: Arg) -> Self {
+        self.arg(arg)
+    }
+}

src/cmd/init.rs

@@ -1,5 +1,5 @@
-use clap::{App, ArgMatches, SubCommand};
-use get_book_dir;
+use crate::get_book_dir;
+use clap::{arg, ArgMatches, Command as ClapCommand};
 use mdbook::config;
 use mdbook::errors::Result;
 use mdbook::MDBook;
@@ -8,14 +8,23 @@ use std::io::Write;
 use std::process::Command;
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'a, 'b>() -> App<'a, 'b> {
-    SubCommand::with_name("init")
+pub fn make_subcommand() -> ClapCommand {
+    ClapCommand::new("init")
         .about("Creates the boilerplate structure and files for a new book")
-        // the {n} denotes a newline which will properly aligned in all help messages
-        .arg_from_usage("[dir] 'Directory to create the book in{n}\
-            (Defaults to the Current Directory when omitted)'")
-        .arg_from_usage("--theme 'Copies the default theme into your source folder'")
-        .arg_from_usage("--force 'Skips confirmation prompts'")
+        .arg(
+            arg!([dir]
+                "Directory to create the book in\n\
+                (Defaults to the current directory when omitted)"
+            )
+            .value_parser(clap::value_parser!(std::path::PathBuf)),
+        )
+        .arg(arg!(--theme "Copies the default theme into your source folder"))
+        .arg(arg!(--force "Skips confirmation prompts"))
+        .arg(arg!(--title <title> "Sets the book title"))
+        .arg(
+            arg!(--ignore <ignore> "Creates a VCS ignore file (i.e. .gitignore)")
+                .value_parser(["none", "git"]),
+        )
 }
 
 // Init command implementation
@@ -23,18 +32,13 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
     let book_dir = get_book_dir(args);
     let mut builder = MDBook::init(&book_dir);
     let mut config = config::Config::default();
-
     // If flag `--theme` is present, copy theme to src
-    if args.is_present("theme") {
-        config.set("output.html.theme", "src/theme")?;
-        // Skip this if `--force` is present
-        if !args.is_present("force") {
-            // Print warning
+    if args.get_flag("theme") {
+        let theme_dir = book_dir.join("theme");
         println!();
-            println!(
-                "Copying the default theme to {}",
-                builder.config().book.src.display()
-            );
+        println!("Copying the default theme to {}", theme_dir.display());
+        // Skip this if `--force` is present
+        if !args.get_flag("force") && theme_dir.exists() {
             println!("This could potentially overwrite files already present in that directory.");
             print!("\nAre you sure you want to continue? (y/n) ");
 
@@ -47,13 +51,25 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
         }
     }
 
+    if let Some(ignore) = args.get_one::<String>("ignore").map(|s| s.as_str()) {
+        match ignore {
+            "git" => builder.create_gitignore(true),
+            _ => builder.create_gitignore(false),
+        };
+    } else if !args.get_flag("force") {
         println!("\nDo you want a .gitignore to be created? (y/n)");
-
         if confirm() {
             builder.create_gitignore(true);
         }
+    }
 
-    config.book.title = request_book_title();
+    config.book.title = if args.contains_id("title") {
+        args.get_one::<String>("title").map(String::from)
+    } else if args.get_flag("force") {
+        None
+    } else {
+        request_book_title()
+    };
 
     if let Some(author) = get_author_name() {
         debug!("Obtained user name from gitconfig: {:?}", author);
@@ -70,7 +86,7 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
 /// Obtains author name from git config file by running the `git config` command.
 fn get_author_name() -> Option<String> {
     let output = Command::new("git")
-        .args(&["config", "--get", "user.name"])
+        .args(["config", "--get", "user.name"])
         .output()
         .ok()?;
 
@@ -100,8 +116,5 @@ fn confirm() -> bool {
     io::stdout().flush().unwrap();
     let mut s = String::new();
     io::stdin().read_line(&mut s).ok();
-    match &*s.trim() {
-        "Y" | "y" | "yes" | "Yes" => true,
-        _ => false,
-    }
+    matches!(s.trim(), "Y" | "y" | "yes" | "Yes")
 }

src/cmd/mod.rs

@@ -2,6 +2,7 @@
 
 pub mod build;
 pub mod clean;
+pub mod command_prelude;
 pub mod init;
 #[cfg(feature = "serve")]
 pub mod serve;

src/cmd/serve.rs

@@ -1,109 +1,92 @@
-extern crate iron;
-extern crate staticfile;
-extern crate ws;
-
-use self::iron::{
-    status, AfterMiddleware, Chain, Iron, IronError, IronResult, Request, Response, Set,
-};
+use super::command_prelude::*;
 #[cfg(feature = "watch")]
 use super::watch;
-use clap::{App, Arg, ArgMatches, SubCommand};
+use crate::{get_book_dir, open};
+use clap::builder::NonEmptyStringValueParser;
+use futures_util::sink::SinkExt;
+use futures_util::StreamExt;
 use mdbook::errors::*;
 use mdbook::utils;
+use mdbook::utils::fs::get_404_output_file;
 use mdbook::MDBook;
-use std;
-use {get_book_dir, open};
+use std::net::{SocketAddr, ToSocketAddrs};
+use std::path::PathBuf;
+use tokio::sync::broadcast;
+use warp::ws::Message;
+use warp::Filter;
 
-struct ErrorRecover;
+/// The HTTP endpoint for the websocket used to trigger reloads when a file changes.
+const LIVE_RELOAD_ENDPOINT: &str = "__livereload";
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'a, 'b>() -> App<'a, 'b> {
-    SubCommand::with_name("serve")
+pub fn make_subcommand() -> Command {
+    Command::new("serve")
         .about("Serves a book at http://localhost:3000, and rebuilds it on changes")
-        .arg_from_usage(
-            "-d, --dest-dir=[dest-dir] 'Output directory for the book{n}\
-             (If omitted, uses build.build-dir from book.toml or defaults to ./book)'",
-        )
-        .arg_from_usage(
-            "[dir] 'Root directory for the book{n}\
-             (Defaults to the Current Directory when omitted)'",
-        )
+        .arg_dest_dir()
+        .arg_root_dir()
         .arg(
-            Arg::with_name("hostname")
-                .short("n")
+            Arg::new("hostname")
+                .short('n')
                 .long("hostname")
-                .takes_value(true)
+                .num_args(1)
                 .default_value("localhost")
-                .empty_values(false)
+                .value_parser(NonEmptyStringValueParser::new())
                 .help("Hostname to listen on for HTTP connections"),
         )
         .arg(
-            Arg::with_name("port")
-                .short("p")
+            Arg::new("port")
+                .short('p')
                 .long("port")
-                .takes_value(true)
+                .num_args(1)
                 .default_value("3000")
-                .empty_values(false)
+                .value_parser(NonEmptyStringValueParser::new())
                 .help("Port to use for HTTP connections"),
         )
-        .arg(
-            Arg::with_name("websocket-hostname")
-                .long("websocket-hostname")
-                .takes_value(true)
-                .empty_values(false)
-                .help(
-                    "Hostname to connect to for WebSockets connections (Defaults to the HTTP hostname)",
-                ),
-        )
-        .arg(
-            Arg::with_name("websocket-port")
-                .short("w")
-                .long("websocket-port")
-                .takes_value(true)
-                .default_value("3001")
-                .empty_values(false)
-                .help("Port to use for WebSockets livereload connections"),
-        )
-        .arg_from_usage("-o, --open 'Opens the book server in a web browser'")
+        .arg_open()
 }
 
-// Watch command implementation
+// Serve command implementation
 pub fn execute(args: &ArgMatches) -> Result<()> {
     let book_dir = get_book_dir(args);
-    let mut book = MDBook::load(&book_dir)?;
+    let mut book = MDBook::load(book_dir)?;
 
-    let port = args.value_of("port").unwrap();
-    let ws_port = args.value_of("websocket-port").unwrap();
-    let hostname = args.value_of("hostname").unwrap();
-    let public_address = args.value_of("websocket-address").unwrap_or(hostname);
-    let open_browser = args.is_present("open");
+    let port = args.get_one::<String>("port").unwrap();
+    let hostname = args.get_one::<String>("hostname").unwrap();
+    let open_browser = args.get_flag("open");
 
     let address = format!("{}:{}", hostname, port);
-    let ws_address = format!("{}:{}", hostname, ws_port);
 
-    let livereload_url = format!("ws://{}:{}", public_address, ws_port);
+    let update_config = |book: &mut MDBook| {
         book.config
-        .set("output.html.livereload-url", &livereload_url)?;
-
-    if let Some(dest_dir) = args.value_of("dest-dir") {
+            .set("output.html.live-reload-endpoint", LIVE_RELOAD_ENDPOINT)
+            .expect("live-reload-endpoint update failed");
+        if let Some(dest_dir) = args.get_one::<PathBuf>("dest-dir") {
             book.config.build.build_dir = dest_dir.into();
         }
-
+        // Override site-url for local serving of the 404 file
+        book.config.set("output.html.site-url", "/").unwrap();
+    };
+    update_config(&mut book);
     book.build()?;
 
-    let mut chain = Chain::new(staticfile::Static::new(book.build_dir_for("html")));
-    chain.link_after(ErrorRecover);
-    let _iron = Iron::new(chain)
-        .http(&*address)
-        .chain_err(|| "Unable to launch the server")?;
+    let sockaddr: SocketAddr = address
+        .to_socket_addrs()?
+        .next()
+        .ok_or_else(|| anyhow::anyhow!("no address found for {}", address))?;
+    let build_dir = book.build_dir_for("html");
+    let input_404 = book
+        .config
+        .get("output.html.input-404")
+        .and_then(toml::Value::as_str)
+        .map(ToString::to_string);
+    let file_404 = get_404_output_file(&input_404);
 
-    let ws_server =
-        ws::WebSocket::new(|_| |_| Ok(())).chain_err(|| "Unable to start the websocket")?;
+    // A channel used to broadcast to any websockets to reload when a file changes.
+    let (tx, _rx) = tokio::sync::broadcast::channel::<Message>(100);
 
-    let broadcaster = ws_server.broadcaster();
-
-    std::thread::spawn(move || {
-        ws_server.listen(&*ws_address).unwrap();
+    let reload_tx = tx.clone();
+    let thread_handle = std::thread::spawn(move || {
+        serve(build_dir, sockaddr, reload_tx, &file_404);
     });
 
     let serving_url = format!("http://{}", address);
@@ -114,36 +97,68 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
     }
 
     #[cfg(feature = "watch")]
-    watch::trigger_on_change(&mut book, move |path, book_dir| {
-        info!("File changed: {:?}", path);
+    watch::trigger_on_change(&book, move |paths, book_dir| {
+        info!("Files changed: {:?}", paths);
         info!("Building book...");
 
         // FIXME: This area is really ugly because we need to re-set livereload :(
-
-        let result = MDBook::load(&book_dir)
-            .and_then(|mut b| {
-                b.config
-                    .set("output.html.livereload-url", &livereload_url)?;
-                Ok(b)
-            }).and_then(|b| b.build());
+        let result = MDBook::load(book_dir).and_then(|mut b| {
+            update_config(&mut b);
+            b.build()
+        });
 
         if let Err(e) = result {
             error!("Unable to load the book");
             utils::log_backtrace(&e);
         } else {
-            let _ = broadcaster.send("reload");
+            let _ = tx.send(Message::text("reload"));
         }
     });
 
+    let _ = thread_handle.join();
+
     Ok(())
 }
 
-impl AfterMiddleware for ErrorRecover {
-    fn catch(&self, _: &mut Request, err: IronError) -> IronResult<Response> {
-        match err.response.status {
-            // each error will result in 404 response
-            Some(_) => Ok(err.response.set(status::NotFound)),
-            _ => Err(err),
-        }
+#[tokio::main]
+async fn serve(
+    build_dir: PathBuf,
+    address: SocketAddr,
+    reload_tx: broadcast::Sender<Message>,
+    file_404: &str,
+) {
+    // A warp Filter which captures `reload_tx` and provides an `rx` copy to
+    // receive reload messages.
+    let sender = warp::any().map(move || reload_tx.subscribe());
+
+    // A warp Filter to handle the livereload endpoint. This upgrades to a
+    // websocket, and then waits for any filesystem change notifications, and
+    // relays them over the websocket.
+    let livereload = warp::path(LIVE_RELOAD_ENDPOINT)
+        .and(warp::ws())
+        .and(sender)
+        .map(|ws: warp::ws::Ws, mut rx: broadcast::Receiver<Message>| {
+            ws.on_upgrade(move |ws| async move {
+                let (mut user_ws_tx, _user_ws_rx) = ws.split();
+                trace!("websocket got connection");
+                if let Ok(m) = rx.recv().await {
+                    trace!("notify of reload");
+                    let _ = user_ws_tx.send(m).await;
                 }
+            })
+        });
+    // A warp Filter that serves from the filesystem.
+    let book_route = warp::fs::dir(build_dir.clone());
+    // The fallback route for 404 errors
+    let fallback_route = warp::fs::file(build_dir.join(file_404))
+        .map(|reply| warp::reply::with_status(reply, warp::http::StatusCode::NOT_FOUND));
+    let routes = livereload.or(book_route).or(fallback_route);
+
+    std::panic::set_hook(Box::new(move |panic_info| {
+        // exit if serve panics
+        error!("Unable to serve: {}", panic_info);
+        std::process::exit(1);
+    }));
+
+    warp::serve(routes).run(address).await;
 }

src/cmd/test.rs

@@ -1,45 +1,58 @@
-use clap::{App, Arg, ArgMatches, SubCommand};
-use get_book_dir;
+use super::command_prelude::*;
+use crate::get_book_dir;
+use clap::builder::NonEmptyStringValueParser;
+use clap::ArgAction;
 use mdbook::errors::Result;
 use mdbook::MDBook;
+use std::path::PathBuf;
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'a, 'b>() -> App<'a, 'b> {
-    SubCommand::with_name("test")
+pub fn make_subcommand() -> Command {
+    Command::new("test")
         .about("Tests that a book's Rust code samples compile")
-        .arg_from_usage(
-            "-d, --dest-dir=[dest-dir] 'Output directory for the book{n}\
-             (If omitted, uses build.build-dir from book.toml or defaults to ./book)'",
+        // FIXME: --dest-dir is unused by the test command, it should be removed
+        .arg_dest_dir()
+        .arg_root_dir()
+        .arg(
+            Arg::new("chapter")
+                .short('c')
+                .long("chapter")
+                .value_name("chapter"),
         )
-        .arg_from_usage(
-            "[dir] 'Root directory for the book{n}\
-             (Defaults to the Current Directory when omitted)'",
-        )
-        .arg(Arg::with_name("library-path")
-            .short("L")
+        .arg(
+            Arg::new("library-path")
+                .short('L')
                 .long("library-path")
                 .value_name("dir")
-            .takes_value(true)
-            .require_delimiter(true)
-            .multiple(true)
-            .empty_values(false)
-            .help("A comma-separated list of directories to add to {n}the crate search path when building tests"))
+                .value_delimiter(',')
+                .value_parser(NonEmptyStringValueParser::new())
+                .action(ArgAction::Append)
+                .help(
+                    "A comma-separated list of directories to add to the crate \
+                    search path when building tests",
+                ),
+        )
 }
 
 // test command implementation
 pub fn execute(args: &ArgMatches) -> Result<()> {
     let library_paths: Vec<&str> = args
-        .values_of("library-path")
-        .map(|v| v.collect())
+        .get_many("library-path")
+        .map(|it| it.map(String::as_str).collect())
         .unwrap_or_default();
+
+    let chapter: Option<&str> = args.get_one::<String>("chapter").map(|s| s.as_str());
+
     let book_dir = get_book_dir(args);
-    let mut book = MDBook::load(&book_dir)?;
+    let mut book = MDBook::load(book_dir)?;
 
-    if let Some(dest_dir) = args.value_of("dest-dir") {
-        book.config.build.build_dir = dest_dir.into();
+    if let Some(dest_dir) = args.get_one::<PathBuf>("dest-dir") {
+        book.config.build.build_dir = dest_dir.to_path_buf();
     }
-
-    book.test(library_paths)?;
+    match chapter {
+        Some(_) => book.test_chapter(library_paths, chapter),
+        None => book.test(library_paths),
+    }?;
 
     Ok(())
 }

src/cmd/watch.rs

@@ -1,41 +1,52 @@
-extern crate notify;
-
-use self::notify::Watcher;
-use clap::{App, ArgMatches, SubCommand};
+use super::command_prelude::*;
+use crate::{get_book_dir, open};
+use ignore::gitignore::Gitignore;
 use mdbook::errors::Result;
 use mdbook::utils;
 use mdbook::MDBook;
-use std::path::Path;
+use pathdiff::diff_paths;
+use std::path::{Path, PathBuf};
 use std::sync::mpsc::channel;
+use std::thread::sleep;
 use std::time::Duration;
-use {get_book_dir, open};
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'a, 'b>() -> App<'a, 'b> {
-    SubCommand::with_name("watch")
+pub fn make_subcommand() -> Command {
+    Command::new("watch")
         .about("Watches a book's files and rebuilds it on changes")
-        .arg_from_usage(
-            "-d, --dest-dir=[dest-dir] 'Output directory for the book{n}\
-             (If omitted, uses build.build-dir from book.toml or defaults to ./book)'",
-        ).arg_from_usage(
-            "[dir] 'Root directory for the book{n}\
-             (Defaults to the Current Directory when omitted)'",
-        ).arg_from_usage("-o, --open 'Open the compiled book in a web browser'")
+        .arg_dest_dir()
+        .arg_root_dir()
+        .arg_open()
 }
 
 // Watch command implementation
 pub fn execute(args: &ArgMatches) -> Result<()> {
     let book_dir = get_book_dir(args);
-    let book = MDBook::load(&book_dir)?;
+    let mut book = MDBook::load(book_dir)?;
 
-    if args.is_present("open") {
+    let update_config = |book: &mut MDBook| {
+        if let Some(dest_dir) = args.get_one::<PathBuf>("dest-dir") {
+            book.config.build.build_dir = dest_dir.into();
+        }
+    };
+    update_config(&mut book);
+
+    if args.get_flag("open") {
         book.build()?;
-        open(book.build_dir_for("html").join("index.html"));
+        let path = book.build_dir_for("html").join("index.html");
+        if !path.exists() {
+            error!("No chapter available to open");
+            std::process::exit(1)
+        }
+        open(path);
     }
 
-    trigger_on_change(&book, |path, book_dir| {
-        info!("File changed: {:?}\nBuilding book...\n", path);
-        let result = MDBook::load(&book_dir).and_then(|b| b.build());
+    trigger_on_change(&book, |paths, book_dir| {
+        info!("Files changed: {:?}\nBuilding book...\n", paths);
+        let result = MDBook::load(book_dir).and_then(|mut b| {
+            update_config(&mut b);
+            b.build()
+        });
 
         if let Err(e) = result {
             error!("Unable to build the book");
@@ -46,45 +57,173 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
     Ok(())
 }
 
+fn remove_ignored_files(book_root: &Path, paths: &[PathBuf]) -> Vec<PathBuf> {
+    if paths.is_empty() {
+        return vec![];
+    }
+
+    match find_gitignore(book_root) {
+        Some(gitignore_path) => {
+            let (ignore, err) = Gitignore::new(&gitignore_path);
+            if let Some(err) = err {
+                warn!(
+                    "error reading gitignore `{}`: {err}",
+                    gitignore_path.display()
+                );
+            }
+            filter_ignored_files(ignore, paths)
+        }
+        None => {
+            // There is no .gitignore file.
+            paths.iter().map(|path| path.to_path_buf()).collect()
+        }
+    }
+}
+
+fn find_gitignore(book_root: &Path) -> Option<PathBuf> {
+    book_root
+        .ancestors()
+        .map(|p| p.join(".gitignore"))
+        .find(|p| p.exists())
+}
+
+// Note: The usage of `canonicalize` may encounter occasional failures on the Windows platform, presenting a potential risk.
+// For more details, refer to [Pull Request #2229](https://github.com/rust-lang/mdBook/pull/2229#discussion_r1408665981).
+fn filter_ignored_files(ignore: Gitignore, paths: &[PathBuf]) -> Vec<PathBuf> {
+    let ignore_root = ignore
+        .path()
+        .canonicalize()
+        .expect("ignore root canonicalize error");
+
+    paths
+        .iter()
+        .filter(|path| {
+            let relative_path =
+                diff_paths(&path, &ignore_root).expect("One of the paths should be an absolute");
+            !ignore
+                .matched_path_or_any_parents(&relative_path, relative_path.is_dir())
+                .is_ignore()
+        })
+        .map(|path| path.to_path_buf())
+        .collect()
+}
+
 /// Calls the closure when a book source file is changed, blocking indefinitely.
 pub fn trigger_on_change<F>(book: &MDBook, closure: F)
 where
-    F: Fn(&Path, &Path),
+    F: Fn(Vec<PathBuf>, &Path),
 {
-    use self::notify::DebouncedEvent::*;
-    use self::notify::RecursiveMode::*;
+    use notify::RecursiveMode::*;
 
     // Create a channel to receive the events.
     let (tx, rx) = channel();
 
-    let mut watcher = match notify::watcher(tx, Duration::from_secs(1)) {
-        Ok(w) => w,
+    let mut debouncer = match notify_debouncer_mini::new_debouncer(Duration::from_secs(1), tx) {
+        Ok(d) => d,
         Err(e) => {
             error!("Error while trying to watch the files:\n\n\t{:?}", e);
-            ::std::process::exit(1)
+            std::process::exit(1)
         }
     };
+    let watcher = debouncer.watcher();
 
     // Add the source directory to the watcher
-    if let Err(e) = watcher.watch(book.source_dir(), Recursive) {
+    if let Err(e) = watcher.watch(&book.source_dir(), Recursive) {
         error!("Error while watching {:?}:\n    {:?}", book.source_dir(), e);
-        ::std::process::exit(1);
+        std::process::exit(1);
     };
 
-    let _ = watcher.watch(book.theme_dir(), Recursive);
+    let _ = watcher.watch(&book.theme_dir(), Recursive);
 
     // Add the book.toml file to the watcher if it exists
-    let _ = watcher.watch(book.root.join("book.toml"), NonRecursive);
+    let _ = watcher.watch(&book.root.join("book.toml"), NonRecursive);
+
+    for dir in &book.config.build.extra_watch_dirs {
+        let path = book.root.join(dir);
+        let canonical_path = path.canonicalize().unwrap_or_else(|e| {
+            error!("Error while watching extra directory {path:?}:\n    {e}");
+            std::process::exit(1);
+        });
+
+        if let Err(e) = watcher.watch(&canonical_path, Recursive) {
+            error!(
+                "Error while watching extra directory {:?}:\n    {:?}",
+                canonical_path, e
+            );
+            std::process::exit(1);
+        }
+    }
 
     info!("Listening for changes...");
 
-    for event in rx.iter() {
-        debug!("Received filesystem event: {:?}", event);
-        match event {
-            Create(path) | Write(path) | Remove(path) | Rename(_, path) => {
-                closure(&path, &book.root);
+    loop {
+        let first_event = rx.recv().unwrap();
+        sleep(Duration::from_millis(50));
+        let other_events = rx.try_iter();
+
+        let all_events = std::iter::once(first_event).chain(other_events);
+
+        let paths: Vec<_> = all_events
+            .filter_map(|event| match event {
+                Ok(events) => Some(events),
+                Err(error) => {
+                    log::warn!("error while watching for changes: {error}");
+                    None
                 }
-            _ => {}
+            })
+            .flatten()
+            .map(|event| event.path)
+            .collect();
+
+        // If we are watching files outside the current repository (via extra-watch-dirs), then they are definitionally
+        // ignored by gitignore. So we handle this case by including such files into the watched paths list.
+        let any_external_paths = paths.iter().filter(|p| !p.starts_with(&book.root)).cloned();
+        let mut paths = remove_ignored_files(&book.root, &paths[..]);
+        paths.extend(any_external_paths);
+
+        if !paths.is_empty() {
+            closure(paths, &book.root);
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ignore::gitignore::GitignoreBuilder;
+    use std::env;
+
+    #[test]
+    fn test_filter_ignored_files() {
+        let current_dir = env::current_dir().unwrap();
+
+        let ignore = GitignoreBuilder::new(&current_dir)
+            .add_line(None, "*.html")
+            .unwrap()
+            .build()
+            .unwrap();
+        let should_remain = current_dir.join("record.text");
+        let should_filter = current_dir.join("index.html");
+
+        let remain = filter_ignored_files(ignore, &[should_remain.clone(), should_filter]);
+        assert_eq!(remain, vec![should_remain])
+    }
+
+    #[test]
+    fn filter_ignored_files_should_handle_parent_dir() {
+        let current_dir = env::current_dir().unwrap();
+
+        let ignore = GitignoreBuilder::new(&current_dir)
+            .add_line(None, "*.html")
+            .unwrap()
+            .build()
+            .unwrap();
+
+        let parent_dir = current_dir.join("..");
+        let should_remain = parent_dir.join("record.text");
+        let should_filter = parent_dir.join("index.html");
+
+        let remain = filter_ignored_files(ignore, &[should_remain.clone(), should_filter]);
+        assert_eq!(remain, vec![should_remain])
+    }
+}

src/lib.rs

@@ -75,37 +75,13 @@
 //! directly, making deserializing the `RenderContext` easy and giving you
 //! access to the various methods for working with the [`Config`].
 //!
-//! [user guide]: https://rust-lang-nursery.github.io/mdBook/
-//! [`RenderContext`]: renderer/struct.RenderContext.html
-//! [relevant chapter]: https://rust-lang-nursery.github.io/mdBook/for_developers/backends.html
-//! [`Config`]: config/struct.Config.html
+//! [user guide]: https://rust-lang.github.io/mdBook/
+//! [`RenderContext`]: renderer::RenderContext
+//! [relevant chapter]: https://rust-lang.github.io/mdBook/for_developers/backends.html
+//! [`Config`]: config::Config
 
 #![deny(missing_docs)]
-
-#[macro_use]
-extern crate error_chain;
-extern crate handlebars;
-extern crate itertools;
-#[macro_use]
-extern crate lazy_static;
-#[macro_use]
-extern crate log;
-extern crate memchr;
-extern crate pulldown_cmark;
-extern crate regex;
-extern crate serde;
-#[macro_use]
-extern crate serde_derive;
-#[macro_use]
-extern crate serde_json;
-extern crate shlex;
-extern crate tempfile;
-extern crate toml;
-extern crate toml_query;
-
-#[cfg(test)]
-#[macro_use]
-extern crate pretty_assertions;
+#![deny(rust_2018_idioms)]
 
 pub mod book;
 pub mod config;
@@ -114,53 +90,19 @@ pub mod renderer;
 pub mod theme;
 pub mod utils;
 
-pub use book::BookItem;
-pub use book::MDBook;
-pub use config::Config;
-pub use renderer::Renderer;
+/// The current version of `mdbook`.
+///
+/// This is provided as a way for custom preprocessors and renderers to do
+/// compatibility checks.
+pub const MDBOOK_VERSION: &str = env!("CARGO_PKG_VERSION");
+
+pub use crate::book::BookItem;
+pub use crate::book::MDBook;
+pub use crate::config::Config;
+pub use crate::renderer::Renderer;
 
 /// The error types used through out this crate.
 pub mod errors {
-    use std::path::PathBuf;
-
-    error_chain!{
-        foreign_links {
-            Io(::std::io::Error) #[doc = "A wrapper around `std::io::Error`"];
-            HandlebarsRender(::handlebars::RenderError) #[doc = "Handlebars rendering failed"];
-            HandlebarsTemplate(Box<::handlebars::TemplateError>) #[doc = "Unable to parse the template"];
-            Utf8(::std::string::FromUtf8Error) #[doc = "Invalid UTF-8"];
-            SerdeJson(::serde_json::Error) #[doc = "JSON conversion failed"];
-        }
-
-        links {
-            TomlQuery(::toml_query::error::Error, ::toml_query::error::ErrorKind) #[doc = "A TomlQuery error"];
-        }
-
-        errors {
-            /// A subprocess exited with an unsuccessful return code.
-            Subprocess(message: String, output: ::std::process::Output) {
-                description("A subprocess failed")
-                display("{}: {}", message, String::from_utf8_lossy(&output.stdout))
-            }
-
-            /// An error was encountered while parsing the `SUMMARY.md` file.
-            ParseError(line: usize, col: usize, message: String) {
-                description("A SUMMARY.md parsing error")
-                display("Error at line {}, column {}: {}", line, col, message)
-            }
-
-            /// The user tried to use a reserved filename.
-            ReservedFilenameError(filename: PathBuf) {
-                description("Reserved Filename")
-                display("{} is reserved for internal use", filename.display())
-            }
-        }
-    }
-
-    // Box to halve the size of Error
-    impl From<::handlebars::TemplateError> for Error {
-        fn from(e: ::handlebars::TemplateError) -> Error {
-            From::from(Box::new(e))
-        }
-    }
+    pub(crate) use anyhow::{bail, ensure, Context};
+    pub use anyhow::{Error, Result};
 }

src/main.rs

@@ -1,70 +1,97 @@
-extern crate chrono;
 #[macro_use]
 extern crate clap;
-extern crate env_logger;
-extern crate error_chain;
 #[macro_use]
 extern crate log;
-extern crate mdbook;
-extern crate open;
 
+use anyhow::anyhow;
 use chrono::Local;
-use clap::{App, AppSettings, ArgMatches};
+use clap::{Arg, ArgMatches, Command};
+use clap_complete::Shell;
 use env_logger::Builder;
 use log::LevelFilter;
 use mdbook::utils;
 use std::env;
 use std::ffi::OsStr;
 use std::io::Write;
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
 
 mod cmd;
 
-const NAME: &'static str = "mdBook";
-const VERSION: &'static str = concat!("v", crate_version!());
+const VERSION: &str = concat!("v", crate_version!());
 
 fn main() {
     init_logger();
 
-    // Create a list of valid arguments and sub-commands
-    let app = App::new(NAME)
-        .about("Creates a book from markdown files")
+    let command = create_clap_command();
+
+    // Check which subcommand the user ran...
+    let res = match command.get_matches().subcommand() {
+        Some(("init", sub_matches)) => cmd::init::execute(sub_matches),
+        Some(("build", sub_matches)) => cmd::build::execute(sub_matches),
+        Some(("clean", sub_matches)) => cmd::clean::execute(sub_matches),
+        #[cfg(feature = "watch")]
+        Some(("watch", sub_matches)) => cmd::watch::execute(sub_matches),
+        #[cfg(feature = "serve")]
+        Some(("serve", sub_matches)) => cmd::serve::execute(sub_matches),
+        Some(("test", sub_matches)) => cmd::test::execute(sub_matches),
+        Some(("completions", sub_matches)) => (|| {
+            let shell = sub_matches
+                .get_one::<Shell>("shell")
+                .ok_or_else(|| anyhow!("Shell name missing."))?;
+
+            let mut complete_app = create_clap_command();
+            clap_complete::generate(
+                *shell,
+                &mut complete_app,
+                "mdbook",
+                &mut std::io::stdout().lock(),
+            );
+            Ok(())
+        })(),
+        _ => unreachable!(),
+    };
+
+    if let Err(e) = res {
+        utils::log_backtrace(&e);
+
+        std::process::exit(101);
+    }
+}
+
+/// Create a list of valid arguments and sub-commands
+fn create_clap_command() -> Command {
+    let app = Command::new(crate_name!())
+        .about(crate_description!())
         .author("Mathieu David <mathieudavid@mathieudavid.org>")
         .version(VERSION)
-        .setting(AppSettings::GlobalVersion)
-        .setting(AppSettings::ArgRequiredElseHelp)
+        .propagate_version(true)
+        .arg_required_else_help(true)
         .after_help(
             "For more information about a specific command, try `mdbook <command> --help`\n\
-             The source code for mdBook is available at: https://github.com/rust-lang-nursery/mdBook",
+             The source code for mdBook is available at: https://github.com/rust-lang/mdBook",
         )
         .subcommand(cmd::init::make_subcommand())
         .subcommand(cmd::build::make_subcommand())
         .subcommand(cmd::test::make_subcommand())
-        .subcommand(cmd::clean::make_subcommand());
+        .subcommand(cmd::clean::make_subcommand())
+        .subcommand(
+            Command::new("completions")
+                .about("Generate shell completions for your shell to stdout")
+                .arg(
+                    Arg::new("shell")
+                        .value_parser(clap::value_parser!(Shell))
+                        .help("the shell to generate completions for")
+                        .value_name("SHELL")
+                        .required(true),
+                ),
+        );
 
     #[cfg(feature = "watch")]
     let app = app.subcommand(cmd::watch::make_subcommand());
     #[cfg(feature = "serve")]
     let app = app.subcommand(cmd::serve::make_subcommand());
 
-    // Check which subcomamnd the user ran...
-    let res = match app.get_matches().subcommand() {
-        ("init", Some(sub_matches)) => cmd::init::execute(sub_matches),
-        ("build", Some(sub_matches)) => cmd::build::execute(sub_matches),
-        ("clean", Some(sub_matches)) => cmd::clean::execute(sub_matches),
-        #[cfg(feature = "watch")]
-        ("watch", Some(sub_matches)) => cmd::watch::execute(sub_matches),
-        #[cfg(feature = "serve")]
-        ("serve", Some(sub_matches)) => cmd::serve::execute(sub_matches),
-        ("test", Some(sub_matches)) => cmd::test::execute(sub_matches),
-        (_, _) => unreachable!(),
-    };
-
-    if let Err(e) = res {
-        utils::log_backtrace(&e);
-
-        ::std::process::exit(101);
-    }
+    app
 }
 
 fn init_logger() {
@@ -82,7 +109,7 @@ fn init_logger() {
     });
 
     if let Ok(var) = env::var("RUST_LOG") {
-        builder.parse(&var);
+        builder.parse_filters(&var);
     } else {
         // if no RUST_LOG provided, default to logging at the Info level
         builder.filter(None, LevelFilter::Info);
@@ -94,11 +121,10 @@ fn init_logger() {
 }
 
 fn get_book_dir(args: &ArgMatches) -> PathBuf {
-    if let Some(dir) = args.value_of("dir") {
+    if let Some(p) = args.get_one::<PathBuf>("dir") {
         // Check if path is relative from current dir, or absolute...
-        let p = Path::new(dir);
         if p.is_relative() {
-            env::current_dir().unwrap().join(dir)
+            env::current_dir().unwrap().join(p)
         } else {
             p.to_path_buf()
         }
@@ -108,7 +134,13 @@ fn get_book_dir(args: &ArgMatches) -> PathBuf {
 }
 
 fn open<P: AsRef<OsStr>>(path: P) {
-    if let Err(e) = open::that(path) {
+    info!("Opening web browser");
+    if let Err(e) = opener::open(path) {
         error!("Error opening web browser: {}", e);
     }
 }
+
+#[test]
+fn verify_app() {
+    create_clap_command().debug_assert();
+}

src/preprocess/cmd.rs

@@ -0,0 +1,208 @@
+use super::{Preprocessor, PreprocessorContext};
+use crate::book::Book;
+use crate::errors::*;
+use log::{debug, trace, warn};
+use shlex::Shlex;
+use std::io::{self, Read, Write};
+use std::process::{Child, Command, Stdio};
+
+/// A custom preprocessor which will shell out to a 3rd-party program.
+///
+/// # Preprocessing Protocol
+///
+/// When the `supports_renderer()` method is executed, `CmdPreprocessor` will
+/// execute the shell command `$cmd supports $renderer`. If the renderer is
+/// supported, custom preprocessors should exit with a exit code of `0`,
+/// any other exit code be considered as unsupported.
+///
+/// The `run()` method is implemented by passing a `(PreprocessorContext, Book)`
+/// tuple to the spawned command (`$cmd`) as JSON via `stdin`. Preprocessors
+/// should then "return" a processed book by printing it to `stdout` as JSON.
+/// For convenience, the `CmdPreprocessor::parse_input()` function can be used
+/// to parse the input provided by `mdbook`.
+///
+/// Exiting with a non-zero exit code while preprocessing is considered an
+/// error. `stderr` is passed directly through to the user, so it can be used
+/// for logging or emitting warnings if desired.
+///
+/// # Examples
+///
+/// An example preprocessor is available in this project's `examples/`
+/// directory.
+#[derive(Debug, Clone, PartialEq)]
+pub struct CmdPreprocessor {
+    name: String,
+    cmd: String,
+}
+
+impl CmdPreprocessor {
+    /// Create a new `CmdPreprocessor`.
+    pub fn new(name: String, cmd: String) -> CmdPreprocessor {
+        CmdPreprocessor { name, cmd }
+    }
+
+    /// A convenience function custom preprocessors can use to parse the input
+    /// written to `stdin` by a `CmdRenderer`.
+    pub fn parse_input<R: Read>(reader: R) -> Result<(PreprocessorContext, Book)> {
+        serde_json::from_reader(reader).with_context(|| "Unable to parse the input")
+    }
+
+    fn write_input_to_child(&self, child: &mut Child, book: &Book, ctx: &PreprocessorContext) {
+        let stdin = child.stdin.take().expect("Child has stdin");
+
+        if let Err(e) = self.write_input(stdin, book, ctx) {
+            // Looks like the backend hung up before we could finish
+            // sending it the render context. Log the error and keep going
+            warn!("Error writing the RenderContext to the backend, {}", e);
+        }
+    }
+
+    fn write_input<W: Write>(
+        &self,
+        writer: W,
+        book: &Book,
+        ctx: &PreprocessorContext,
+    ) -> Result<()> {
+        serde_json::to_writer(writer, &(ctx, book)).map_err(Into::into)
+    }
+
+    /// The command this `Preprocessor` will invoke.
+    pub fn cmd(&self) -> &str {
+        &self.cmd
+    }
+
+    fn command(&self) -> Result<Command> {
+        let mut words = Shlex::new(&self.cmd);
+        let executable = match words.next() {
+            Some(e) => e,
+            None => bail!("Command string was empty"),
+        };
+
+        let mut cmd = Command::new(executable);
+
+        for arg in words {
+            cmd.arg(arg);
+        }
+
+        Ok(cmd)
+    }
+}
+
+impl Preprocessor for CmdPreprocessor {
+    fn name(&self) -> &str {
+        &self.name
+    }
+
+    fn run(&self, ctx: &PreprocessorContext, book: Book) -> Result<Book> {
+        let mut cmd = self.command()?;
+
+        let mut child = cmd
+            .stdin(Stdio::piped())
+            .stdout(Stdio::piped())
+            .stderr(Stdio::inherit())
+            .spawn()
+            .with_context(|| {
+                format!(
+                    "Unable to start the \"{}\" preprocessor. Is it installed?",
+                    self.name()
+                )
+            })?;
+
+        self.write_input_to_child(&mut child, &book, ctx);
+
+        let output = child.wait_with_output().with_context(|| {
+            format!(
+                "Error waiting for the \"{}\" preprocessor to complete",
+                self.name
+            )
+        })?;
+
+        trace!("{} exited with output: {:?}", self.cmd, output);
+        ensure!(
+            output.status.success(),
+            format!(
+                "The \"{}\" preprocessor exited unsuccessfully with {} status",
+                self.name, output.status
+            )
+        );
+
+        serde_json::from_slice(&output.stdout).with_context(|| {
+            format!(
+                "Unable to parse the preprocessed book from \"{}\" processor",
+                self.name
+            )
+        })
+    }
+
+    fn supports_renderer(&self, renderer: &str) -> bool {
+        debug!(
+            "Checking if the \"{}\" preprocessor supports \"{}\"",
+            self.name(),
+            renderer
+        );
+
+        let mut cmd = match self.command() {
+            Ok(c) => c,
+            Err(e) => {
+                warn!(
+                    "Unable to create the command for the \"{}\" preprocessor, {}",
+                    self.name(),
+                    e
+                );
+                return false;
+            }
+        };
+
+        let outcome = cmd
+            .arg("supports")
+            .arg(renderer)
+            .stdin(Stdio::null())
+            .stdout(Stdio::inherit())
+            .stderr(Stdio::inherit())
+            .status()
+            .map(|status| status.code() == Some(0));
+
+        if let Err(ref e) = outcome {
+            if e.kind() == io::ErrorKind::NotFound {
+                warn!(
+                    "The command wasn't found, is the \"{}\" preprocessor installed?",
+                    self.name
+                );
+                warn!("\tCommand: {}", self.cmd);
+            }
+        }
+
+        outcome.unwrap_or(false)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::MDBook;
+    use std::path::Path;
+
+    fn guide() -> MDBook {
+        let example = Path::new(env!("CARGO_MANIFEST_DIR")).join("guide");
+        MDBook::load(example).unwrap()
+    }
+
+    #[test]
+    fn round_trip_write_and_parse_input() {
+        let cmd = CmdPreprocessor::new("test".to_string(), "test".to_string());
+        let md = guide();
+        let ctx = PreprocessorContext::new(
+            md.root.clone(),
+            md.config.clone(),
+            "some-renderer".to_string(),
+        );
+
+        let mut buffer = Vec::new();
+        cmd.write_input(&mut buffer, &md.book, &ctx).unwrap();
+
+        let (got_ctx, got_book) = CmdPreprocessor::parse_input(buffer.as_slice()).unwrap();
+
+        assert_eq!(got_book, md.book);
+        assert_eq!(got_ctx, ctx);
+    }
+}

src/preprocess/index.rs

@@ -1,16 +1,20 @@
 use regex::Regex;
 use std::path::Path;
 
-use errors::*;
-
 use super::{Preprocessor, PreprocessorContext};
-use book::{Book, BookItem};
+use crate::book::{Book, BookItem};
+use crate::errors::*;
+use log::warn;
+use once_cell::sync::Lazy;
 
 /// A preprocessor for converting file name `README.md` to `index.md` since
-/// `README.md` is the de facto index file in a markdown-based documentation.
+/// `README.md` is the de facto index file in markdown-based documentation.
+#[derive(Default)]
 pub struct IndexPreprocessor;
 
 impl IndexPreprocessor {
+    pub(crate) const NAME: &'static str = "index";
+
     /// Create a new `IndexPreprocessor`.
     pub fn new() -> Self {
         IndexPreprocessor
@@ -19,31 +23,36 @@ impl IndexPreprocessor {
 
 impl Preprocessor for IndexPreprocessor {
     fn name(&self) -> &str {
-        "index"
+        Self::NAME
     }
 
-    fn run(&self, ctx: &PreprocessorContext, book: &mut Book) -> Result<()> {
+    fn run(&self, ctx: &PreprocessorContext, mut book: Book) -> Result<Book> {
         let source_dir = ctx.root.join(&ctx.config.book.src);
         book.for_each_mut(|section: &mut BookItem| {
             if let BookItem::Chapter(ref mut ch) = *section {
-                if is_readme_file(&ch.path) {
-                    let index_md = source_dir.join(ch.path.with_file_name("index.md"));
+                if let Some(ref mut path) = ch.path {
+                    if is_readme_file(&path) {
+                        let mut index_md = source_dir.join(path.with_file_name("index.md"));
                         if index_md.exists() {
-                        warn_readme_name_conflict(&ch.path, &index_md);
+                            warn_readme_name_conflict(&path, &&mut index_md);
                         }
 
-                    ch.path.set_file_name("index.md");
+                        path.set_file_name("index.md");
+                    }
                 }
             }
         });
 
-        Ok(())
+        Ok(book)
     }
 }
 
 fn warn_readme_name_conflict<P: AsRef<Path>>(readme_path: P, index_path: P) {
     let file_name = readme_path.as_ref().file_name().unwrap_or_default();
-    let parent_dir = index_path.as_ref().parent().unwrap_or(index_path.as_ref());
+    let parent_dir = index_path
+        .as_ref()
+        .parent()
+        .unwrap_or_else(|| index_path.as_ref());
     warn!(
         "It seems that there are both {:?} and index.md under \"{}\".",
         file_name,
@@ -59,13 +68,12 @@ fn warn_readme_name_conflict<P: AsRef<Path>>(readme_path: P, index_path: P) {
 }
 
 fn is_readme_file<P: AsRef<Path>>(path: P) -> bool {
-    lazy_static! {
-        static ref RE: Regex = Regex::new(r"(?i)^readme$").unwrap();
-    }
+    static RE: Lazy<Regex> = Lazy::new(|| Regex::new(r"(?i)^readme$").unwrap());
+
     RE.is_match(
         path.as_ref()
             .file_stem()
-            .and_then(|s| s.to_str())
+            .and_then(std::ffi::OsStr::to_str)
             .unwrap_or_default(),
     )
 }

src/preprocess/links.rs

@@ -1,21 +1,37 @@
-use errors::*;
+use crate::errors::*;
+use crate::utils::{
+    take_anchored_lines, take_lines, take_rustdoc_include_anchored_lines,
+    take_rustdoc_include_lines,
+};
 use regex::{CaptureMatches, Captures, Regex};
-use std::ops::{Range, RangeFrom, RangeFull, RangeTo};
+use std::fs;
+use std::ops::{Bound, Range, RangeBounds, RangeFrom, RangeFull, RangeTo};
 use std::path::{Path, PathBuf};
-use utils::fs::file_to_string;
-use utils::take_lines;
 
 use super::{Preprocessor, PreprocessorContext};
-use book::{Book, BookItem};
+use crate::book::{Book, BookItem};
+use log::{error, warn};
+use once_cell::sync::Lazy;
 
 const ESCAPE_CHAR: char = '\\';
 const MAX_LINK_NESTED_DEPTH: usize = 10;
 
-/// A preprocessor for expanding the `{{# playpen}}` and `{{# include}}`
-/// helpers in a chapter.
+/// A preprocessor for expanding helpers in a chapter. Supported helpers are:
+///
+/// - `{{# include}}` - Insert an external file of any type. Include the whole file, only particular
+///.  lines, or only between the specified anchors.
+/// - `{{# rustdoc_include}}` - Insert an external Rust file, showing the particular lines
+///.  specified or the lines between specified anchors, and include the rest of the file behind `#`.
+///   This hides the lines from initial display but shows them when the reader expands the code
+///   block and provides them to Rustdoc for testing.
+/// - `{{# playground}}` - Insert runnable Rust files
+/// - `{{# title}}` - Override \<title\> of a webpage.
+#[derive(Default)]
 pub struct LinkPreprocessor;
 
 impl LinkPreprocessor {
+    pub(crate) const NAME: &'static str = "links";
+
     /// Create a new `LinkPreprocessor`.
     pub fn new() -> Self {
         LinkPreprocessor
@@ -24,30 +40,44 @@ impl LinkPreprocessor {
 
 impl Preprocessor for LinkPreprocessor {
     fn name(&self) -> &str {
-        "links"
+        Self::NAME
     }
 
-    fn run(&self, ctx: &PreprocessorContext, book: &mut Book) -> Result<()> {
+    fn run(&self, ctx: &PreprocessorContext, mut book: Book) -> Result<Book> {
         let src_dir = ctx.root.join(&ctx.config.book.src);
 
         book.for_each_mut(|section: &mut BookItem| {
             if let BookItem::Chapter(ref mut ch) = *section {
-                let base = ch
-                    .path
+                if let Some(ref chapter_path) = ch.path {
+                    let base = chapter_path
                         .parent()
                         .map(|dir| src_dir.join(dir))
                         .expect("All book items have a parent");
 
-                let content = replace_all(&ch.content, base, &ch.path, 0);
+                    let mut chapter_title = ch.name.clone();
+                    let content =
+                        replace_all(&ch.content, base, chapter_path, 0, &mut chapter_title);
                     ch.content = content;
+                    if chapter_title != ch.name {
+                        ctx.chapter_titles
+                            .borrow_mut()
+                            .insert(chapter_path.clone(), chapter_title);
+                    }
+                }
             }
         });
 
-        Ok(())
+        Ok(book)
     }
 }
 
-fn replace_all<P1, P2>(s: &str, path: P1, source: P2, depth: usize) -> String
+fn replace_all<P1, P2>(
+    s: &str,
+    path: P1,
+    source: P2,
+    depth: usize,
+    chapter_title: &mut String,
+) -> String
 where
     P1: AsRef<Path>,
     P2: AsRef<Path>,
@@ -60,14 +90,20 @@ where
     let mut previous_end_index = 0;
     let mut replaced = String::new();
 
-    for playpen in find_links(s) {
-        replaced.push_str(&s[previous_end_index..playpen.start_index]);
+    for link in find_links(s) {
+        replaced.push_str(&s[previous_end_index..link.start_index]);
 
-        match playpen.render_with_path(&path) {
+        match link.render_with_path(path, chapter_title) {
             Ok(new_content) => {
                 if depth < MAX_LINK_NESTED_DEPTH {
-                    if let Some(rel_path) = playpen.link.relative_path(path) {
-                        replaced.push_str(&replace_all(&new_content, rel_path, source, depth + 1));
+                    if let Some(rel_path) = link.link_type.relative_path(path) {
+                        replaced.push_str(&replace_all(
+                            &new_content,
+                            rel_path,
+                            source,
+                            depth + 1,
+                            chapter_title,
+                        ));
                     } else {
                         replaced.push_str(&new_content);
                     }
@@ -77,13 +113,17 @@ where
                         source.display()
                     );
                 }
-                previous_end_index = playpen.end_index;
+                previous_end_index = link.end_index;
             }
             Err(e) => {
-                error!("Error updating \"{}\", {}", playpen.link_text, e);
+                error!("Error updating \"{}\", {}", link.link_text, e);
+                for cause in e.chain().skip(1) {
+                    warn!("Caused By: {}", cause);
+                }
+
                 // This should make sure we include the raw `{{# ... }}` snippet
                 // in the page content if there are any errors.
-                previous_end_index = playpen.start_index;
+                previous_end_index = link.start_index;
             }
         }
     }
@@ -95,11 +135,70 @@ where
 #[derive(PartialEq, Debug, Clone)]
 enum LinkType<'a> {
     Escaped,
-    IncludeRange(PathBuf, Range<usize>),
-    IncludeRangeFrom(PathBuf, RangeFrom<usize>),
-    IncludeRangeTo(PathBuf, RangeTo<usize>),
-    IncludeRangeFull(PathBuf, RangeFull),
-    Playpen(PathBuf, Vec<&'a str>),
+    Include(PathBuf, RangeOrAnchor),
+    Playground(PathBuf, Vec<&'a str>),
+    RustdocInclude(PathBuf, RangeOrAnchor),
+    Title(&'a str),
+}
+
+#[derive(PartialEq, Debug, Clone)]
+enum RangeOrAnchor {
+    Range(LineRange),
+    Anchor(String),
+}
+
+// A range of lines specified with some include directive.
+#[allow(clippy::enum_variant_names)] // The prefix can't be removed, and is meant to mirror the contained type
+#[derive(PartialEq, Debug, Clone)]
+enum LineRange {
+    Range(Range<usize>),
+    RangeFrom(RangeFrom<usize>),
+    RangeTo(RangeTo<usize>),
+    RangeFull(RangeFull),
+}
+
+impl RangeBounds<usize> for LineRange {
+    fn start_bound(&self) -> Bound<&usize> {
+        match self {
+            LineRange::Range(r) => r.start_bound(),
+            LineRange::RangeFrom(r) => r.start_bound(),
+            LineRange::RangeTo(r) => r.start_bound(),
+            LineRange::RangeFull(r) => r.start_bound(),
+        }
+    }
+
+    fn end_bound(&self) -> Bound<&usize> {
+        match self {
+            LineRange::Range(r) => r.end_bound(),
+            LineRange::RangeFrom(r) => r.end_bound(),
+            LineRange::RangeTo(r) => r.end_bound(),
+            LineRange::RangeFull(r) => r.end_bound(),
+        }
+    }
+}
+
+impl From<Range<usize>> for LineRange {
+    fn from(r: Range<usize>) -> LineRange {
+        LineRange::Range(r)
+    }
+}
+
+impl From<RangeFrom<usize>> for LineRange {
+    fn from(r: RangeFrom<usize>) -> LineRange {
+        LineRange::RangeFrom(r)
+    }
+}
+
+impl From<RangeTo<usize>> for LineRange {
+    fn from(r: RangeTo<usize>) -> LineRange {
+        LineRange::RangeTo(r)
+    }
+}
+
+impl From<RangeFull> for LineRange {
+    fn from(r: RangeFull) -> LineRange {
+        LineRange::RangeFull(r)
+    }
 }
 
 impl<'a> LinkType<'a> {
@@ -107,11 +206,10 @@ impl<'a> LinkType<'a> {
         let base = base.as_ref();
         match self {
             LinkType::Escaped => None,
-            LinkType::IncludeRange(p, _) => Some(return_relative_path(base, &p)),
-            LinkType::IncludeRangeFrom(p, _) => Some(return_relative_path(base, &p)),
-            LinkType::IncludeRangeTo(p, _) => Some(return_relative_path(base, &p)),
-            LinkType::IncludeRangeFull(p, _) => Some(return_relative_path(base, &p)),
-            LinkType::Playpen(p, _) => Some(return_relative_path(base, &p)),
+            LinkType::Include(p, _) => Some(return_relative_path(base, &p)),
+            LinkType::Playground(p, _) => Some(return_relative_path(base, &p)),
+            LinkType::RustdocInclude(p, _) => Some(return_relative_path(base, &p)),
+            LinkType::Title(_) => None,
         }
     }
 }
@@ -123,56 +221,68 @@ fn return_relative_path<P: AsRef<Path>>(base: P, relative: P) -> PathBuf {
         .to_path_buf()
 }
 
-fn parse_include_path(path: &str) -> LinkType<'static> {
-    let mut parts = path.split(':');
-    let path = parts.next().unwrap().into();
+fn parse_range_or_anchor(parts: Option<&str>) -> RangeOrAnchor {
+    let mut parts = parts.unwrap_or("").splitn(3, ':').fuse();
+
+    let next_element = parts.next();
+    let start = if let Some(value) = next_element.and_then(|s| s.parse::<usize>().ok()) {
         // subtract 1 since line numbers usually begin with 1
-    let start = parts
-        .next()
-        .and_then(|s| s.parse::<usize>().ok())
-        .map(|val| val.saturating_sub(1));
-    let end = parts.next();
-    let has_end = end.is_some();
-    let end = end.and_then(|s| s.parse::<usize>().ok());
-    match start {
-        Some(start) => match end {
-            Some(end) => LinkType::IncludeRange(
-                path,
-                Range {
-                    start: start,
-                    end: end,
-                },
-            ),
-            None => if has_end {
-                LinkType::IncludeRangeFrom(path, RangeFrom { start: start })
+        Some(value.saturating_sub(1))
+    } else if let Some("") = next_element {
+        None
+    } else if let Some(anchor) = next_element {
+        return RangeOrAnchor::Anchor(String::from(anchor));
     } else {
-                LinkType::IncludeRange(
-                    path,
-                    Range {
-                        start: start,
-                        end: start + 1,
-                    },
-                )
-            },
-        },
-        None => match end {
-            Some(end) => LinkType::IncludeRangeTo(path, RangeTo { end: end }),
-            None => LinkType::IncludeRangeFull(path, RangeFull),
-        },
+        None
+    };
+
+    let end = parts.next();
+    // If `end` is empty string or any other value that can't be parsed as a usize, treat this
+    // include as a range with only a start bound. However, if end isn't specified, include only
+    // the single line specified by `start`.
+    let end = end.map(|s| s.parse::<usize>());
+
+    match (start, end) {
+        (Some(start), Some(Ok(end))) => RangeOrAnchor::Range(LineRange::from(start..end)),
+        (Some(start), Some(Err(_))) => RangeOrAnchor::Range(LineRange::from(start..)),
+        (Some(start), None) => RangeOrAnchor::Range(LineRange::from(start..start + 1)),
+        (None, Some(Ok(end))) => RangeOrAnchor::Range(LineRange::from(..end)),
+        (None, None) | (None, Some(Err(_))) => RangeOrAnchor::Range(LineRange::from(RangeFull)),
     }
 }
 
+fn parse_include_path(path: &str) -> LinkType<'static> {
+    let mut parts = path.splitn(2, ':');
+
+    let path = parts.next().unwrap().into();
+    let range_or_anchor = parse_range_or_anchor(parts.next());
+
+    LinkType::Include(path, range_or_anchor)
+}
+
+fn parse_rustdoc_include_path(path: &str) -> LinkType<'static> {
+    let mut parts = path.splitn(2, ':');
+
+    let path = parts.next().unwrap().into();
+    let range_or_anchor = parse_range_or_anchor(parts.next());
+
+    LinkType::RustdocInclude(path, range_or_anchor)
+}
+
 #[derive(PartialEq, Debug, Clone)]
 struct Link<'a> {
     start_index: usize,
     end_index: usize,
-    link: LinkType<'a>,
+    link_type: LinkType<'a>,
     link_text: &'a str,
 }
 
 impl<'a> Link<'a> {
     fn from_capture(cap: Captures<'a>) -> Option<Link<'a>> {
         let link_type = match (cap.get(0), cap.get(1), cap.get(2)) {
+            (_, Some(typ), Some(title)) if typ.as_str() == "title" => {
+                Some(LinkType::Title(title.as_str()))
+            }
             (_, Some(typ), Some(rest)) => {
                 let mut path_props = rest.as_str().split_whitespace();
                 let file_arg = path_props.next();
@@ -180,7 +290,16 @@ impl<'a> Link<'a> {
 
                 match (typ.as_str(), file_arg) {
                     ("include", Some(pth)) => Some(parse_include_path(pth)),
-                    ("playpen", Some(pth)) => Some(LinkType::Playpen(pth.into(), props)),
+                    ("playground", Some(pth)) => Some(LinkType::Playground(pth.into(), props)),
+                    ("playpen", Some(pth)) => {
+                        warn!(
+                            "the {{{{#playpen}}}} expression has been \
+                            renamed to {{{{#playground}}}}, \
+                            please update your book to use the new name"
+                        );
+                        Some(LinkType::Playground(pth.into(), props))
+                    }
+                    ("rustdoc_include", Some(pth)) => Some(parse_rustdoc_include_path(pth)),
                     _ => None,
                 }
             }
@@ -190,43 +309,86 @@ impl<'a> Link<'a> {
             _ => None,
         };
 
-        link_type.and_then(|lnk| {
+        link_type.and_then(|lnk_type| {
             cap.get(0).map(|mat| Link {
                 start_index: mat.start(),
                 end_index: mat.end(),
-                link: lnk,
+                link_type: lnk_type,
                 link_text: mat.as_str(),
             })
         })
     }
 
-    fn render_with_path<P: AsRef<Path>>(&self, base: P) -> Result<String> {
+    fn render_with_path<P: AsRef<Path>>(
+        &self,
+        base: P,
+        chapter_title: &mut String,
+    ) -> Result<String> {
         let base = base.as_ref();
-        match self.link {
+        match self.link_type {
             // omit the escape char
-            LinkType::Escaped => Ok((&self.link_text[1..]).to_owned()),
-            LinkType::IncludeRange(ref pat, ref range) => file_to_string(base.join(pat))
-                .map(|s| take_lines(&s, range.clone()))
-                .chain_err(|| format!("Could not read file for link {}", self.link_text)),
-            LinkType::IncludeRangeFrom(ref pat, ref range) => file_to_string(base.join(pat))
-                .map(|s| take_lines(&s, range.clone()))
-                .chain_err(|| format!("Could not read file for link {}", self.link_text)),
-            LinkType::IncludeRangeTo(ref pat, ref range) => file_to_string(base.join(pat))
-                .map(|s| take_lines(&s, range.clone()))
-                .chain_err(|| format!("Could not read file for link {}", self.link_text)),
-            LinkType::IncludeRangeFull(ref pat, _) => file_to_string(base.join(pat))
-                .chain_err(|| format!("Could not read file for link {}", self.link_text)),
-            LinkType::Playpen(ref pat, ref attrs) => {
-                let contents = file_to_string(base.join(pat))
-                    .chain_err(|| format!("Could not read file for link {}", self.link_text))?;
+            LinkType::Escaped => Ok(self.link_text[1..].to_owned()),
+            LinkType::Include(ref pat, ref range_or_anchor) => {
+                let target = base.join(pat);
+
+                fs::read_to_string(&target)
+                    .map(|s| match range_or_anchor {
+                        RangeOrAnchor::Range(range) => take_lines(&s, range.clone()),
+                        RangeOrAnchor::Anchor(anchor) => take_anchored_lines(&s, anchor),
+                    })
+                    .with_context(|| {
+                        format!(
+                            "Could not read file for link {} ({})",
+                            self.link_text,
+                            target.display(),
+                        )
+                    })
+            }
+            LinkType::RustdocInclude(ref pat, ref range_or_anchor) => {
+                let target = base.join(pat);
+
+                fs::read_to_string(&target)
+                    .map(|s| match range_or_anchor {
+                        RangeOrAnchor::Range(range) => {
+                            take_rustdoc_include_lines(&s, range.clone())
+                        }
+                        RangeOrAnchor::Anchor(anchor) => {
+                            take_rustdoc_include_anchored_lines(&s, anchor)
+                        }
+                    })
+                    .with_context(|| {
+                        format!(
+                            "Could not read file for link {} ({})",
+                            self.link_text,
+                            target.display(),
+                        )
+                    })
+            }
+            LinkType::Playground(ref pat, ref attrs) => {
+                let target = base.join(pat);
+
+                let mut contents = fs::read_to_string(&target).with_context(|| {
+                    format!(
+                        "Could not read file for link {} ({})",
+                        self.link_text,
+                        target.display()
+                    )
+                })?;
                 let ftype = if !attrs.is_empty() { "rust," } else { "rust" };
+                if !contents.ends_with('\n') {
+                    contents.push('\n');
+                }
                 Ok(format!(
-                    "```{}{}\n{}\n```\n",
+                    "```{}{}\n{}```\n",
                     ftype,
                     attrs.join(","),
                     contents
                 ))
             }
+            LinkType::Title(title) => {
+                *chapter_title = title.to_owned();
+                Ok(String::new())
+            }
         }
     }
 }
@@ -245,21 +407,23 @@ impl<'a> Iterator for LinkIter<'a> {
     }
 }
 
-fn find_links(contents: &str) -> LinkIter {
+fn find_links(contents: &str) -> LinkIter<'_> {
     // lazily compute following regex
-    // r"\\\{\{#.*\}\}|\{\{#([a-zA-Z0-9]+)\s*([a-zA-Z0-9_.\-:/\\\s]+)\}\}")?;
-    lazy_static! {
-        static ref RE: Regex = Regex::new(
+    // r"\\\{\{#.*\}\}|\{\{#([a-zA-Z0-9]+)\s*([^}]+)\}\}")?;
+    static RE: Lazy<Regex> = Lazy::new(|| {
+        Regex::new(
             r"(?x)              # insignificant whitespace mode
         \\\{\{\#.*\}\}      # match escaped link
         |                   # or
         \{\{\s*             # link opening parens and whitespace
-            \#([a-zA-Z0-9]+)           # link type
+        \#([a-zA-Z0-9_]+)   # link type
         \s+                 # separating whitespace
-            ([a-zA-Z0-9\s_.\-:/\\]+)   # link target path and space separated properties
-            \s*\}\}                    # whitespace and link closing parens"
-        ).unwrap();
-    }
+        ([^}]+)             # link target path and space separated properties
+        \}\}                # link closing parens",
+        )
+        .unwrap()
+    });
+
     LinkIter(RE.captures_iter(contents))
 }
 
@@ -279,7 +443,21 @@ mod tests {
         ```hbs
         {{#include file.rs}} << an escaped link!
         ```";
-        assert_eq!(replace_all(start, "", "", 0), end);
+        let mut chapter_title = "test_replace_all_escaped".to_owned();
+        assert_eq!(replace_all(start, "", "", 0, &mut chapter_title), end);
+    }
+
+    #[test]
+    fn test_set_chapter_title() {
+        let start = r"{{#title My Title}}
+        # My Chapter
+        ";
+        let end = r"
+        # My Chapter
+        ";
+        let mut chapter_title = "test_set_chapter_title".to_owned();
+        assert_eq!(replace_all(start, "", "", 0, &mut chapter_title), end);
+        assert_eq!(chapter_title, "My Title");
     }
 
     #[test]
@@ -290,7 +468,7 @@ mod tests {
 
     #[test]
     fn test_find_links_partial_link() {
-        let s = "Some random text with {{#playpen...";
+        let s = "Some random text with {{#playground...";
         assert!(find_links(s).collect::<Vec<_>>() == vec![]);
         let s = "Some random text with {{#include...";
         assert!(find_links(s).collect::<Vec<_>>() == vec![]);
@@ -300,19 +478,19 @@ mod tests {
 
     #[test]
     fn test_find_links_empty_link() {
-        let s = "Some random text with {{#playpen}} and {{#playpen   }} {{}} {{#}}...";
+        let s = "Some random text with {{#playground}} and {{#playground   }} {{}} {{#}}...";
         assert!(find_links(s).collect::<Vec<_>>() == vec![]);
     }
 
     #[test]
     fn test_find_links_unknown_link_type() {
-        let s = "Some random text with {{#playpenz ar.rs}} and {{#incn}} {{baz}} {{#bar}}...";
+        let s = "Some random text with {{#playgroundz ar.rs}} and {{#incn}} {{baz}} {{#bar}}...";
         assert!(find_links(s).collect::<Vec<_>>() == vec![]);
     }
 
     #[test]
     fn test_find_links_simple_link() {
-        let s = "Some random text with {{#playpen file.rs}} and {{#playpen test.rs }}...";
+        let s = "Some random text with {{#playground file.rs}} and {{#playground test.rs }}...";
 
         let res = find_links(s).collect::<Vec<_>>();
         println!("\nOUTPUT: {:?}\n", res);
@@ -322,20 +500,38 @@ mod tests {
             vec![
                 Link {
                     start_index: 22,
-                    end_index: 42,
-                    link: LinkType::Playpen(PathBuf::from("file.rs"), vec![]),
-                    link_text: "{{#playpen file.rs}}",
+                    end_index: 45,
+                    link_type: LinkType::Playground(PathBuf::from("file.rs"), vec![]),
+                    link_text: "{{#playground file.rs}}",
                 },
                 Link {
-                    start_index: 47,
-                    end_index: 68,
-                    link: LinkType::Playpen(PathBuf::from("test.rs"), vec![]),
-                    link_text: "{{#playpen test.rs }}",
+                    start_index: 50,
+                    end_index: 74,
+                    link_type: LinkType::Playground(PathBuf::from("test.rs"), vec![]),
+                    link_text: "{{#playground test.rs }}",
                 },
             ]
         );
     }
 
+    #[test]
+    fn test_find_links_with_special_characters() {
+        let s = "Some random text with {{#playground foo-bar\\baz/_c++.rs}}...";
+
+        let res = find_links(s).collect::<Vec<_>>();
+        println!("\nOUTPUT: {:?}\n", res);
+
+        assert_eq!(
+            res,
+            vec![Link {
+                start_index: 22,
+                end_index: 57,
+                link_type: LinkType::Playground(PathBuf::from("foo-bar\\baz/_c++.rs"), vec![]),
+                link_text: "{{#playground foo-bar\\baz/_c++.rs}}",
+            },]
+        );
+    }
+
     #[test]
     fn test_find_links_with_range() {
         let s = "Some random text with {{#include file.rs:10:20}}...";
@@ -346,7 +542,10 @@ mod tests {
             vec![Link {
                 start_index: 22,
                 end_index: 48,
-                link: LinkType::IncludeRange(PathBuf::from("file.rs"), 9..20),
+                link_type: LinkType::Include(
+                    PathBuf::from("file.rs"),
+                    RangeOrAnchor::Range(LineRange::from(9..20))
+                ),
                 link_text: "{{#include file.rs:10:20}}",
             }]
         );
@@ -362,7 +561,10 @@ mod tests {
             vec![Link {
                 start_index: 22,
                 end_index: 45,
-                link: LinkType::IncludeRange(PathBuf::from("file.rs"), 9..10),
+                link_type: LinkType::Include(
+                    PathBuf::from("file.rs"),
+                    RangeOrAnchor::Range(LineRange::from(9..10))
+                ),
                 link_text: "{{#include file.rs:10}}",
             }]
         );
@@ -378,7 +580,10 @@ mod tests {
             vec![Link {
                 start_index: 22,
                 end_index: 46,
-                link: LinkType::IncludeRangeFrom(PathBuf::from("file.rs"), 9..),
+                link_type: LinkType::Include(
+                    PathBuf::from("file.rs"),
+                    RangeOrAnchor::Range(LineRange::from(9..))
+                ),
                 link_text: "{{#include file.rs:10:}}",
             }]
         );
@@ -394,7 +599,10 @@ mod tests {
             vec![Link {
                 start_index: 22,
                 end_index: 46,
-                link: LinkType::IncludeRangeTo(PathBuf::from("file.rs"), ..20),
+                link_type: LinkType::Include(
+                    PathBuf::from("file.rs"),
+                    RangeOrAnchor::Range(LineRange::from(..20))
+                ),
                 link_text: "{{#include file.rs::20}}",
             }]
         );
@@ -410,7 +618,10 @@ mod tests {
             vec![Link {
                 start_index: 22,
                 end_index: 44,
-                link: LinkType::IncludeRangeFull(PathBuf::from("file.rs"), ..),
+                link_type: LinkType::Include(
+                    PathBuf::from("file.rs"),
+                    RangeOrAnchor::Range(LineRange::from(..))
+                ),
                 link_text: "{{#include file.rs::}}",
             }]
         );
@@ -426,15 +637,37 @@ mod tests {
             vec![Link {
                 start_index: 22,
                 end_index: 42,
-                link: LinkType::IncludeRangeFull(PathBuf::from("file.rs"), ..),
+                link_type: LinkType::Include(
+                    PathBuf::from("file.rs"),
+                    RangeOrAnchor::Range(LineRange::from(..))
+                ),
                 link_text: "{{#include file.rs}}",
             }]
         );
     }
 
+    #[test]
+    fn test_find_links_with_anchor() {
+        let s = "Some random text with {{#include file.rs:anchor}}...";
+        let res = find_links(s).collect::<Vec<_>>();
+        println!("\nOUTPUT: {:?}\n", res);
+        assert_eq!(
+            res,
+            vec![Link {
+                start_index: 22,
+                end_index: 49,
+                link_type: LinkType::Include(
+                    PathBuf::from("file.rs"),
+                    RangeOrAnchor::Anchor(String::from("anchor"))
+                ),
+                link_text: "{{#include file.rs:anchor}}",
+            }]
+        );
+    }
+
     #[test]
     fn test_find_links_escaped_link() {
-        let s = "Some random text with escaped playpen \\{{#playpen file.rs editable}} ...";
+        let s = "Some random text with escaped playground \\{{#playground file.rs editable}} ...";
 
         let res = find_links(s).collect::<Vec<_>>();
         println!("\nOUTPUT: {:?}\n", res);
@@ -442,18 +675,19 @@ mod tests {
         assert_eq!(
             res,
             vec![Link {
-                start_index: 38,
-                end_index: 68,
-                link: LinkType::Escaped,
-                link_text: "\\{{#playpen file.rs editable}}",
+                start_index: 41,
+                end_index: 74,
+                link_type: LinkType::Escaped,
+                link_text: "\\{{#playground file.rs editable}}",
             }]
         );
     }
 
     #[test]
-    fn test_find_playpens_with_properties() {
-        let s = "Some random text with escaped playpen {{#playpen file.rs editable }} and some \
-                 more\n text {{#playpen my.rs editable no_run should_panic}} ...";
+    fn test_find_playgrounds_with_properties() {
+        let s =
+            "Some random text with escaped playground {{#playground file.rs editable }} and some \
+                 more\n text {{#playground my.rs editable no_run should_panic}} ...";
 
         let res = find_links(s).collect::<Vec<_>>();
         println!("\nOUTPUT: {:?}\n", res);
@@ -461,19 +695,19 @@ mod tests {
             res,
             vec![
                 Link {
-                    start_index: 38,
-                    end_index: 68,
-                    link: LinkType::Playpen(PathBuf::from("file.rs"), vec!["editable"]),
-                    link_text: "{{#playpen file.rs editable }}",
+                    start_index: 41,
+                    end_index: 74,
+                    link_type: LinkType::Playground(PathBuf::from("file.rs"), vec!["editable"]),
+                    link_text: "{{#playground file.rs editable }}",
                 },
                 Link {
-                    start_index: 89,
-                    end_index: 136,
-                    link: LinkType::Playpen(
+                    start_index: 95,
+                    end_index: 145,
+                    link_type: LinkType::Playground(
                         PathBuf::from("my.rs"),
                         vec!["editable", "no_run", "should_panic"],
                     ),
-                    link_text: "{{#playpen my.rs editable no_run should_panic}}",
+                    link_text: "{{#playground my.rs editable no_run should_panic}}",
                 },
             ]
         );
@@ -481,8 +715,9 @@ mod tests {
 
     #[test]
     fn test_find_all_link_types() {
-        let s = "Some random text with escaped playpen {{#include file.rs}} and \\{{#contents are \
-                 insignifficant in escaped link}} some more\n text  {{#playpen my.rs editable \
+        let s =
+            "Some random text with escaped playground {{#include file.rs}} and \\{{#contents are \
+                 insignifficant in escaped link}} some more\n text  {{#playground my.rs editable \
                  no_run should_panic}} ...";
 
         let res = find_links(s).collect::<Vec<_>>();
@@ -491,33 +726,215 @@ mod tests {
         assert_eq!(
             res[0],
             Link {
-                start_index: 38,
-                end_index: 58,
-                link: LinkType::IncludeRangeFull(PathBuf::from("file.rs"), ..),
+                start_index: 41,
+                end_index: 61,
+                link_type: LinkType::Include(
+                    PathBuf::from("file.rs"),
+                    RangeOrAnchor::Range(LineRange::from(..))
+                ),
                 link_text: "{{#include file.rs}}",
             }
         );
         assert_eq!(
             res[1],
             Link {
-                start_index: 63,
-                end_index: 112,
-                link: LinkType::Escaped,
+                start_index: 66,
+                end_index: 115,
+                link_type: LinkType::Escaped,
                 link_text: "\\{{#contents are insignifficant in escaped link}}",
             }
         );
         assert_eq!(
             res[2],
             Link {
-                start_index: 130,
-                end_index: 177,
-                link: LinkType::Playpen(
+                start_index: 133,
+                end_index: 183,
+                link_type: LinkType::Playground(
                     PathBuf::from("my.rs"),
                     vec!["editable", "no_run", "should_panic"]
                 ),
-                link_text: "{{#playpen my.rs editable no_run should_panic}}",
+                link_text: "{{#playground my.rs editable no_run should_panic}}",
             }
         );
     }
 
+    #[test]
+    fn parse_without_colon_includes_all() {
+        let link_type = parse_include_path("arbitrary");
+        assert_eq!(
+            link_type,
+            LinkType::Include(
+                PathBuf::from("arbitrary"),
+                RangeOrAnchor::Range(LineRange::from(RangeFull))
+            )
+        );
+    }
+
+    #[test]
+    fn parse_with_nothing_after_colon_includes_all() {
+        let link_type = parse_include_path("arbitrary:");
+        assert_eq!(
+            link_type,
+            LinkType::Include(
+                PathBuf::from("arbitrary"),
+                RangeOrAnchor::Range(LineRange::from(RangeFull))
+            )
+        );
+    }
+
+    #[test]
+    fn parse_with_two_colons_includes_all() {
+        let link_type = parse_include_path("arbitrary::");
+        assert_eq!(
+            link_type,
+            LinkType::Include(
+                PathBuf::from("arbitrary"),
+                RangeOrAnchor::Range(LineRange::from(RangeFull))
+            )
+        );
+    }
+
+    #[test]
+    fn parse_with_garbage_after_two_colons_includes_all() {
+        let link_type = parse_include_path("arbitrary::NaN");
+        assert_eq!(
+            link_type,
+            LinkType::Include(
+                PathBuf::from("arbitrary"),
+                RangeOrAnchor::Range(LineRange::from(RangeFull))
+            )
+        );
+    }
+
+    #[test]
+    fn parse_with_one_number_after_colon_only_that_line() {
+        let link_type = parse_include_path("arbitrary:5");
+        assert_eq!(
+            link_type,
+            LinkType::Include(
+                PathBuf::from("arbitrary"),
+                RangeOrAnchor::Range(LineRange::from(4..5))
+            )
+        );
+    }
+
+    #[test]
+    fn parse_with_one_based_start_becomes_zero_based() {
+        let link_type = parse_include_path("arbitrary:1");
+        assert_eq!(
+            link_type,
+            LinkType::Include(
+                PathBuf::from("arbitrary"),
+                RangeOrAnchor::Range(LineRange::from(0..1))
+            )
+        );
+    }
+
+    #[test]
+    fn parse_with_zero_based_start_stays_zero_based_but_is_probably_an_error() {
+        let link_type = parse_include_path("arbitrary:0");
+        assert_eq!(
+            link_type,
+            LinkType::Include(
+                PathBuf::from("arbitrary"),
+                RangeOrAnchor::Range(LineRange::from(0..1))
+            )
+        );
+    }
+
+    #[test]
+    fn parse_start_only_range() {
+        let link_type = parse_include_path("arbitrary:5:");
+        assert_eq!(
+            link_type,
+            LinkType::Include(
+                PathBuf::from("arbitrary"),
+                RangeOrAnchor::Range(LineRange::from(4..))
+            )
+        );
+    }
+
+    #[test]
+    fn parse_start_with_garbage_interpreted_as_start_only_range() {
+        let link_type = parse_include_path("arbitrary:5:NaN");
+        assert_eq!(
+            link_type,
+            LinkType::Include(
+                PathBuf::from("arbitrary"),
+                RangeOrAnchor::Range(LineRange::from(4..))
+            )
+        );
+    }
+
+    #[test]
+    fn parse_end_only_range() {
+        let link_type = parse_include_path("arbitrary::5");
+        assert_eq!(
+            link_type,
+            LinkType::Include(
+                PathBuf::from("arbitrary"),
+                RangeOrAnchor::Range(LineRange::from(..5))
+            )
+        );
+    }
+
+    #[test]
+    fn parse_start_and_end_range() {
+        let link_type = parse_include_path("arbitrary:5:10");
+        assert_eq!(
+            link_type,
+            LinkType::Include(
+                PathBuf::from("arbitrary"),
+                RangeOrAnchor::Range(LineRange::from(4..10))
+            )
+        );
+    }
+
+    #[test]
+    fn parse_with_negative_interpreted_as_anchor() {
+        let link_type = parse_include_path("arbitrary:-5");
+        assert_eq!(
+            link_type,
+            LinkType::Include(
+                PathBuf::from("arbitrary"),
+                RangeOrAnchor::Anchor("-5".to_string())
+            )
+        );
+    }
+
+    #[test]
+    fn parse_with_floating_point_interpreted_as_anchor() {
+        let link_type = parse_include_path("arbitrary:-5.7");
+        assert_eq!(
+            link_type,
+            LinkType::Include(
+                PathBuf::from("arbitrary"),
+                RangeOrAnchor::Anchor("-5.7".to_string())
+            )
+        );
+    }
+
+    #[test]
+    fn parse_with_anchor_followed_by_colon() {
+        let link_type = parse_include_path("arbitrary:some-anchor:this-gets-ignored");
+        assert_eq!(
+            link_type,
+            LinkType::Include(
+                PathBuf::from("arbitrary"),
+                RangeOrAnchor::Anchor("some-anchor".to_string())
+            )
+        );
+    }
+
+    #[test]
+    fn parse_with_more_than_three_colons_ignores_everything_after_third_colon() {
+        let link_type = parse_include_path("arbitrary:5:10:17:anything:");
+        assert_eq!(
+            link_type,
+            LinkType::Include(
+                PathBuf::from("arbitrary"),
+                RangeOrAnchor::Range(LineRange::from(4..10))
+            )
+        );
+    }
 }

src/preprocess/mod.rs

@@ -1,30 +1,51 @@
 //! Book preprocessing.
 
+pub use self::cmd::CmdPreprocessor;
 pub use self::index::IndexPreprocessor;
 pub use self::links::LinkPreprocessor;
 
+mod cmd;
 mod index;
 mod links;
 
-use book::Book;
-use config::Config;
-use errors::*;
+use crate::book::Book;
+use crate::config::Config;
+use crate::errors::*;
 
+use serde::{Deserialize, Serialize};
+use std::cell::RefCell;
+use std::collections::HashMap;
 use std::path::PathBuf;
 
 /// Extra information for a `Preprocessor` to give them more context when
 /// processing a book.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 pub struct PreprocessorContext {
     /// The location of the book directory on disk.
     pub root: PathBuf,
     /// The book configuration (`book.toml`).
     pub config: Config,
+    /// The `Renderer` this preprocessor is being used with.
+    pub renderer: String,
+    /// The calling `mdbook` version.
+    pub mdbook_version: String,
+    #[serde(skip)]
+    pub(crate) chapter_titles: RefCell<HashMap<PathBuf, String>>,
+    #[serde(skip)]
+    __non_exhaustive: (),
 }
 
 impl PreprocessorContext {
     /// Create a new `PreprocessorContext`.
-    pub(crate) fn new(root: PathBuf, config: Config) -> Self {
-        PreprocessorContext { root, config }
+    pub(crate) fn new(root: PathBuf, config: Config, renderer: String) -> Self {
+        PreprocessorContext {
+            root,
+            config,
+            renderer,
+            mdbook_version: crate::MDBOOK_VERSION.to_string(),
+            chapter_titles: RefCell::new(HashMap::new()),
+            __non_exhaustive: (),
+        }
     }
 }
 
@@ -36,5 +57,13 @@ pub trait Preprocessor {
 
     /// Run this `Preprocessor`, allowing it to update the book before it is
     /// given to a renderer.
-    fn run(&self, ctx: &PreprocessorContext, book: &mut Book) -> Result<()>;
+    fn run(&self, ctx: &PreprocessorContext, book: Book) -> Result<Book>;
+
+    /// A hint to `MDBook` whether this preprocessor is compatible with a
+    /// particular renderer.
+    ///
+    /// By default, always returns `true`.
+    fn supports_renderer(&self, _renderer: &str) -> bool {
+        true
+    }
 }

src/renderer/html_handlebars/helpers/mod.rs

@@ -1,2 +1,3 @@
 pub mod navigation;
+pub mod theme;
 pub mod toc;

src/renderer/html_handlebars/helpers/navigation.rs

@@ -1,10 +1,13 @@
 use std::collections::BTreeMap;
 use std::path::Path;
 
-use handlebars::{Context, Handlebars, Helper, Output, RenderContext, RenderError, Renderable};
-use serde_json;
+use handlebars::{
+    Context, Handlebars, Helper, Output, RenderContext, RenderError, RenderErrorReason, Renderable,
+};
 
-use utils;
+use crate::utils;
+use log::{debug, trace};
+use serde_json::json;
 
 type StringMap = BTreeMap<String, String>;
 
@@ -18,23 +21,23 @@ impl Target {
     /// Returns target if found.
     fn find(
         &self,
-        base_path: &String,
-        current_path: &String,
+        base_path: &str,
+        current_path: &str,
         current_item: &StringMap,
         previous_item: &StringMap,
     ) -> Result<Option<StringMap>, RenderError> {
-        match self {
-            &Target::Next => {
-                let previous_path = previous_item
-                    .get("path")
-                    .ok_or_else(|| RenderError::new("No path found for chapter in JSON data"))?;
+        match *self {
+            Target::Next => {
+                let previous_path = previous_item.get("path").ok_or_else(|| {
+                    RenderErrorReason::Other("No path found for chapter in JSON data".to_owned())
+                })?;
 
                 if previous_path == base_path {
                     return Ok(Some(current_item.clone()));
                 }
             }
 
-            &Target::Previous => {
+            Target::Previous => {
                 if current_path == base_path {
                     return Ok(Some(previous_item.clone()));
                 }
@@ -47,21 +50,45 @@ impl Target {
 
 fn find_chapter(
     ctx: &Context,
-    rc: &mut RenderContext,
+    rc: &mut RenderContext<'_, '_>,
     target: Target,
 ) -> Result<Option<StringMap>, RenderError> {
     debug!("Get data from context");
 
-    let chapters = rc.evaluate_absolute(ctx, "chapters", true).and_then(|c| {
-        serde_json::value::from_value::<Vec<StringMap>>(c.clone())
-            .map_err(|_| RenderError::new("Could not decode the JSON data"))
+    let chapters = rc.evaluate(ctx, "@root/chapters").and_then(|c| {
+        serde_json::value::from_value::<Vec<StringMap>>(c.as_json().clone()).map_err(|_| {
+            RenderErrorReason::Other("Could not decode the JSON data".to_owned()).into()
+        })
     })?;
 
     let base_path = rc
-        .evaluate_absolute(ctx, "path", true)?
+        .evaluate(ctx, "@root/path")?
+        .as_json()
         .as_str()
-        .ok_or_else(|| RenderError::new("Type error for `path`, string expected"))?
-        .replace("\"", "");
+        .ok_or_else(|| {
+            RenderErrorReason::Other("Type error for `path`, string expected".to_owned())
+        })?
+        .replace('\"', "");
+
+    if !rc.evaluate(ctx, "@root/is_index")?.is_missing() {
+        // Special case for index.md which may be a synthetic page.
+        // Target::find won't match because there is no page with the path
+        // "index.md" (unless there really is an index.md in SUMMARY.md).
+        match target {
+            Target::Previous => return Ok(None),
+            Target::Next => match chapters
+                .iter()
+                .filter(|chapter| {
+                    // Skip things like "spacer"
+                    chapter.contains_key("path")
+                })
+                .nth(1)
+            {
+                Some(chapter) => return Ok(Some(chapter.clone())),
+                None => return Ok(None),
+            },
+        }
+    }
 
     let mut previous: Option<StringMap> = None;
 
@@ -71,12 +98,12 @@ fn find_chapter(
         match item.get("path") {
             Some(path) if !path.is_empty() => {
                 if let Some(previous) = previous {
-                    if let Some(item) = target.find(&base_path, &path, &item, &previous)? {
+                    if let Some(item) = target.find(&base_path, path, &item, &previous)? {
                         return Ok(Some(item));
                     }
                 }
 
-                previous = Some(item.clone());
+                previous = Some(item);
             }
             _ => continue,
         }
@@ -86,62 +113,68 @@ fn find_chapter(
 }
 
 fn render(
-    _h: &Helper,
-    r: &Handlebars,
+    _h: &Helper<'_>,
+    r: &Handlebars<'_>,
     ctx: &Context,
-    rc: &mut RenderContext,
-    out: &mut Output,
+    rc: &mut RenderContext<'_, '_>,
+    out: &mut dyn Output,
     chapter: &StringMap,
 ) -> Result<(), RenderError> {
     trace!("Creating BTreeMap to inject in context");
 
     let mut context = BTreeMap::new();
     let base_path = rc
-        .evaluate_absolute(ctx, "path", false)?
+        .evaluate(ctx, "@root/path")?
+        .as_json()
         .as_str()
-        .ok_or_else(|| RenderError::new("Type error for `path`, string expected"))?
-        .replace("\"", "");
+        .ok_or_else(|| {
+            RenderErrorReason::Other("Type error for `path`, string expected".to_owned())
+        })?
+        .replace('\"', "");
 
     context.insert(
         "path_to_root".to_owned(),
-        json!(utils::fs::path_to_root(&base_path)),
+        json!(utils::fs::path_to_root(base_path)),
     );
 
     chapter
         .get("name")
-        .ok_or_else(|| RenderError::new("No title found for chapter in JSON data"))
+        .ok_or_else(|| {
+            RenderErrorReason::Other("No title found for chapter in JSON data".to_owned())
+        })
         .map(|name| context.insert("title".to_owned(), json!(name)))?;
 
     chapter
         .get("path")
-        .ok_or_else(|| RenderError::new("No path found for chapter in JSON data"))
+        .ok_or_else(|| {
+            RenderErrorReason::Other("No path found for chapter in JSON data".to_owned())
+        })
         .and_then(|p| {
             Path::new(p)
                 .with_extension("html")
                 .to_str()
-                .ok_or_else(|| RenderError::new("Link could not be converted to str"))
-                .map(|p| context.insert("link".to_owned(), json!(p.replace("\\", "/"))))
+                .ok_or_else(|| {
+                    RenderErrorReason::Other("Link could not be converted to str".to_owned())
+                })
+                .map(|p| context.insert("link".to_owned(), json!(p.replace('\\', "/"))))
         })?;
 
     trace!("Render template");
 
-    _h.template()
-        .ok_or_else(|| RenderError::new("Error with the handlebars template"))
-        .and_then(|t| {
-            let mut local_rc = rc.new_for_block();
+    let t = _h
+        .template()
+        .ok_or_else(|| RenderErrorReason::Other("Error with the handlebars template".to_owned()))?;
     let local_ctx = Context::wraps(&context)?;
+    let mut local_rc = rc.clone();
     t.render(r, &local_ctx, &mut local_rc, out)
-        })?;
-
-    Ok(())
 }
 
 pub fn previous(
-    _h: &Helper,
-    r: &Handlebars,
+    _h: &Helper<'_>,
+    r: &Handlebars<'_>,
     ctx: &Context,
-    rc: &mut RenderContext,
-    out: &mut Output,
+    rc: &mut RenderContext<'_, '_>,
+    out: &mut dyn Output,
 ) -> Result<(), RenderError> {
     trace!("previous (handlebars helper)");
 
@@ -153,11 +186,11 @@ pub fn previous(
 }
 
 pub fn next(
-    _h: &Helper,
-    r: &Handlebars,
+    _h: &Helper<'_>,
+    r: &Handlebars<'_>,
     ctx: &Context,
-    rc: &mut RenderContext,
-    out: &mut Output,
+    rc: &mut RenderContext<'_, '_>,
+    out: &mut dyn Output,
 ) -> Result<(), RenderError> {
     trace!("next (handlebars helper)");
 
@@ -172,7 +205,7 @@ pub fn next(
 mod tests {
     use super::*;
 
-    static TEMPLATE: &'static str =
+    static TEMPLATE: &str =
         "{{#previous}}{{title}}: {{link}}{{/previous}}|{{#next}}{{title}}: {{link}}{{/next}}";
 
     #[test]

src/renderer/html_handlebars/helpers/theme.rs

@@ -0,0 +1,38 @@
+use handlebars::{
+    Context, Handlebars, Helper, Output, RenderContext, RenderError, RenderErrorReason,
+};
+use log::trace;
+
+pub fn theme_option(
+    h: &Helper<'_>,
+    _r: &Handlebars<'_>,
+    ctx: &Context,
+    rc: &mut RenderContext<'_, '_>,
+    out: &mut dyn Output,
+) -> Result<(), RenderError> {
+    trace!("theme_option (handlebars helper)");
+
+    let param = h.param(0).and_then(|v| v.value().as_str()).ok_or_else(|| {
+        RenderErrorReason::ParamTypeMismatchForName(
+            "theme_option",
+            "0".to_owned(),
+            "string".to_owned(),
+        )
+    })?;
+
+    let default_theme = rc.evaluate(ctx, "@root/default_theme")?;
+    let default_theme_name = default_theme.as_json().as_str().ok_or_else(|| {
+        RenderErrorReason::ParamTypeMismatchForName(
+            "theme_option",
+            "default_theme".to_owned(),
+            "string".to_owned(),
+        )
+    })?;
+
+    out.write(param)?;
+    if param.to_lowercase() == default_theme_name.to_lowercase() {
+        out.write(" (default)")?;
+    }
+
+    Ok(())
+}

src/renderer/html_handlebars/helpers/toc.rs

@@ -1,11 +1,12 @@
-use std::collections::BTreeMap;
 use std::path::Path;
+use std::{cmp::Ordering, collections::BTreeMap};
 
-use utils;
+use crate::utils;
+use crate::utils::bracket_escape;
 
-use handlebars::{Context, Handlebars, Helper, HelperDef, Output, RenderContext, RenderError};
-use pulldown_cmark::{html, Event, Parser, Tag};
-use serde_json;
+use handlebars::{
+    Context, Handlebars, Helper, HelperDef, Output, RenderContext, RenderError, RenderErrorReason,
+};
 
 // Handlebars helper to construct TOC
 #[derive(Clone, Copy)]
@@ -16,28 +17,61 @@ pub struct RenderToc {
 impl HelperDef for RenderToc {
     fn call<'reg: 'rc, 'rc>(
         &self,
-        _h: &Helper,
-        _: &Handlebars,
-        ctx: &Context,
-        rc: &mut RenderContext,
-        out: &mut Output,
+        _h: &Helper<'rc>,
+        _r: &'reg Handlebars<'_>,
+        ctx: &'rc Context,
+        rc: &mut RenderContext<'reg, 'rc>,
+        out: &mut dyn Output,
     ) -> Result<(), RenderError> {
         // get value from context data
         // rc.get_path() is current json parent path, you should always use it like this
         // param is the key of value you want to display
-        let chapters = rc.evaluate_absolute(ctx, "chapters", true).and_then(|c| {
-            serde_json::value::from_value::<Vec<BTreeMap<String, String>>>(c.clone())
-                .map_err(|_| RenderError::new("Could not decode the JSON data"))
+        let chapters = rc.evaluate(ctx, "@root/chapters").and_then(|c| {
+            serde_json::value::from_value::<Vec<BTreeMap<String, String>>>(c.as_json().clone())
+                .map_err(|_| {
+                    RenderErrorReason::Other("Could not decode the JSON data".to_owned()).into()
+                })
         })?;
-        let current = rc
-            .evaluate_absolute(ctx, "path", true)?
+        let current_path = rc
+            .evaluate(ctx, "@root/path")?
+            .as_json()
             .as_str()
-            .ok_or_else(|| RenderError::new("Type error for `path`, string expected"))?
-            .replace("\"", "");
+            .ok_or_else(|| {
+                RenderErrorReason::Other("Type error for `path`, string expected".to_owned())
+            })?
+            .replace('\"', "");
+
+        let current_section = rc
+            .evaluate(ctx, "@root/section")?
+            .as_json()
+            .as_str()
+            .map(str::to_owned)
+            .unwrap_or_default();
+
+        let fold_enable = rc
+            .evaluate(ctx, "@root/fold_enable")?
+            .as_json()
+            .as_bool()
+            .ok_or_else(|| {
+                RenderErrorReason::Other("Type error for `fold_enable`, bool expected".to_owned())
+            })?;
+
+        let fold_level = rc
+            .evaluate(ctx, "@root/fold_level")?
+            .as_json()
+            .as_u64()
+            .ok_or_else(|| {
+                RenderErrorReason::Other("Type error for `fold_level`, u64 expected".to_owned())
+            })?;
 
         out.write("<ol class=\"chapter\">")?;
 
         let mut current_level = 1;
+        // The "index" page, which has this attribute set, is supposed to alias the first chapter in
+        // the book, i.e. the first link. There seems to be no easy way to determine which chapter
+        // the "index" is aliasing from within the renderer, so this is used instead to force the
+        // first link to be active. See further below.
+        let mut is_first_chapter = ctx.data().get("is_index").is_some();
 
         for item in chapters {
             // Spacer
@@ -46,97 +80,109 @@ impl HelperDef for RenderToc {
                 continue;
             }
 
-            let level = if let Some(s) = item.get("section") {
-                s.matches('.').count()
+            let (section, level) = if let Some(s) = item.get("section") {
+                (s.as_str(), s.matches('.').count())
             } else {
-                1
+                ("", 1)
             };
 
-            if level > current_level {
+            let is_expanded =
+                if !fold_enable || (!section.is_empty() && current_section.starts_with(section)) {
+                    // Expand if folding is disabled, or if the section is an
+                    // ancestor or the current section itself.
+                    true
+                } else {
+                    // Levels that are larger than this would be folded.
+                    level - 1 < fold_level as usize
+                };
+
+            match level.cmp(&current_level) {
+                Ordering::Greater => {
                     while level > current_level {
                         out.write("<li>")?;
                         out.write("<ol class=\"section\">")?;
                         current_level += 1;
                     }
-                out.write("<li>")?;
-            } else if level < current_level {
+                    write_li_open_tag(out, is_expanded, false)?;
+                }
+                Ordering::Less => {
                     while level < current_level {
                         out.write("</ol>")?;
                         out.write("</li>")?;
                         current_level -= 1;
                     }
-                out.write("<li>")?;
-            } else {
-                out.write("<li")?;
-                if item.get("section").is_none() {
-                    out.write(" class=\"affix\"")?;
+                    write_li_open_tag(out, is_expanded, false)?;
                 }
-                out.write(">")?;
+                Ordering::Equal => {
+                    write_li_open_tag(out, is_expanded, item.get("section").is_none())?;
+                }
+            }
+
+            // Part title
+            if let Some(title) = item.get("part") {
+                out.write("<li class=\"part-title\">")?;
+                out.write(&bracket_escape(title))?;
+                out.write("</li>")?;
+                continue;
             }
 
             // Link
-            let path_exists = if let Some(path) = item.get("path") {
-                if !path.is_empty() {
+            let path_exists: bool;
+            match item.get("path") {
+                Some(path) if !path.is_empty() => {
                     out.write("<a href=\"")?;
-
-                    let tmp = Path::new(item.get("path").expect("Error: path should be Some(_)"))
+                    let tmp = Path::new(path)
                         .with_extension("html")
                         .to_str()
                         .unwrap()
                         // Hack for windows who tends to use `\` as separator instead of `/`
-                        .replace("\\", "/");
+                        .replace('\\', "/");
 
                     // Add link
-                    out.write(&utils::fs::path_to_root(&current))?;
+                    out.write(&utils::fs::path_to_root(&current_path))?;
                     out.write(&tmp)?;
                     out.write("\"")?;
 
-                    if path == &current {
+                    if path == &current_path || is_first_chapter {
+                        is_first_chapter = false;
                         out.write(" class=\"active\"")?;
                     }
 
                     out.write(">")?;
-                    true
-                } else {
-                    false
+                    path_exists = true;
+                }
+                _ => {
+                    out.write("<div>")?;
+                    path_exists = false;
+                }
             }
-            } else {
-                false
-            };
 
             if !self.no_section_label {
                 // Section does not necessarily exist
                 if let Some(section) = item.get("section") {
                     out.write("<strong aria-hidden=\"true\">")?;
-                    out.write(&section)?;
+                    out.write(section)?;
                     out.write("</strong> ")?;
                 }
             }
 
             if let Some(name) = item.get("name") {
-                // Render only inline code blocks
-
-                // filter all events that are not inline code blocks
-                let parser = Parser::new(name).filter(|event| match *event {
-                    Event::Start(Tag::Code)
-                    | Event::End(Tag::Code)
-                    | Event::InlineHtml(_)
-                    | Event::Text(_) => true,
-                    _ => false,
-                });
-
-                // render markdown to html
-                let mut markdown_parsed_name = String::with_capacity(name.len() * 3 / 2);
-                html::push_html(&mut markdown_parsed_name, parser);
-
-                // write to the handlebars template
-                out.write(&markdown_parsed_name)?;
+                out.write(&bracket_escape(name))?
             }
 
             if path_exists {
                 out.write("</a>")?;
+            } else {
+                out.write("</div>")?;
             }
 
+            // Render expand/collapse toggle
+            if let Some(flag) = item.get("has_sub_items") {
+                let has_sub_items = flag.parse::<bool>().unwrap_or_default();
+                if fold_enable && has_sub_items {
+                    out.write("<a class=\"toggle\"><div>❱</div></a>")?;
+                }
+            }
             out.write("</li>")?;
         }
         while current_level > 1 {
@@ -149,3 +195,19 @@ impl HelperDef for RenderToc {
         Ok(())
     }
 }
+
+fn write_li_open_tag(
+    out: &mut dyn Output,
+    is_expanded: bool,
+    is_affix: bool,
+) -> Result<(), std::io::Error> {
+    let mut li = String::from("<li class=\"chapter-item ");
+    if is_expanded {
+        li.push_str("expanded ");
+    }
+    if is_affix {
+        li.push_str("affix ");
+    }
+    li.push_str("\">");
+    out.write(&li)
+}

src/renderer/html_handlebars/search.rs

@@ -1,30 +1,45 @@
-extern crate ammonia;
-extern crate elasticlunr;
-
 use std::borrow::Cow;
 use std::collections::{HashMap, HashSet};
 use std::path::Path;
 
-use self::elasticlunr::Index;
+use elasticlunr::{Index, IndexBuilder};
+use once_cell::sync::Lazy;
 use pulldown_cmark::*;
-use serde_json;
 
-use book::{Book, BookItem};
-use config::Search;
-use errors::*;
-use theme::searcher;
-use utils;
+use crate::book::{Book, BookItem};
+use crate::config::Search;
+use crate::errors::*;
+use crate::theme::searcher;
+use crate::utils;
+use log::{debug, warn};
+use serde::Serialize;
+
+const MAX_WORD_LENGTH_TO_INDEX: usize = 80;
+
+/// Tokenizes in the same way as elasticlunr-rs (for English), but also drops long tokens.
+fn tokenize(text: &str) -> Vec<String> {
+    text.split(|c: char| c.is_whitespace() || c == '-')
+        .filter(|s| !s.is_empty())
+        .map(|s| s.trim().to_lowercase())
+        .filter(|s| s.len() <= MAX_WORD_LENGTH_TO_INDEX)
+        .collect()
+}
 
 /// Creates all files required for search.
 pub fn create_files(search_config: &Search, destination: &Path, book: &Book) -> Result<()> {
-    let mut index = Index::new(&["title", "body", "breadcrumbs"]);
+    let mut index = IndexBuilder::new()
+        .add_field_with_tokenizer("title", Box::new(&tokenize))
+        .add_field_with_tokenizer("body", Box::new(&tokenize))
+        .add_field_with_tokenizer("breadcrumbs", Box::new(&tokenize))
+        .build();
+
     let mut doc_urls = Vec::with_capacity(book.sections.len());
 
     for item in book.iter() {
-        render_item(&mut index, &search_config, &mut doc_urls, item)?;
+        render_item(&mut index, search_config, &mut doc_urls, item)?;
     }
 
-    let index = write_to_json(index, &search_config, doc_urls)?;
+    let index = write_to_json(index, search_config, doc_urls)?;
     debug!("Writing search index ✓");
     if index.len() > 10_000_000 {
         warn!("searchindex.json is very large ({} bytes)", index.len());
@@ -35,7 +50,7 @@ pub fn create_files(search_config: &Search, destination: &Path, book: &Book) ->
         utils::fs::write_file(
             destination,
             "searchindex.js",
-            format!("window.search = {};", index).as_bytes(),
+            format!("Object.assign(window.search, {});", index).as_bytes(),
         )?;
         utils::fs::write_file(destination, "searcher.js", searcher::JS)?;
         utils::fs::write_file(destination, "mark.min.js", searcher::MARK_JS)?;
@@ -51,10 +66,23 @@ fn add_doc(
     index: &mut Index,
     doc_urls: &mut Vec<String>,
     anchor_base: &str,
-    section_id: &Option<String>,
+    heading: &str,
+    id_counter: &mut HashMap<String, usize>,
+    section_id: &Option<CowStr<'_>>,
     items: &[&str],
 ) {
-    let url = if let &Some(ref id) = section_id {
+    // Either use the explicit section id the user specified, or generate one
+    // from the heading content.
+    let section_id = section_id.as_ref().map(|id| id.to_string()).or_else(|| {
+        if heading.is_empty() {
+            // In the case where a chapter has no heading, don't set a section id.
+            None
+        } else {
+            Some(utils::unique_id_from_content(heading, id_counter))
+        }
+    });
+
+    let url = if let Some(id) = section_id {
         Cow::Owned(format!("{}#{}", anchor_base, id))
     } else {
         Cow::Borrowed(anchor_base)
@@ -74,95 +102,132 @@ fn render_item(
     doc_urls: &mut Vec<String>,
     item: &BookItem,
 ) -> Result<()> {
-    let chapter = match item {
-        &BookItem::Chapter(ref ch) => ch,
+    let chapter = match *item {
+        BookItem::Chapter(ref ch) if !ch.is_draft_chapter() => ch,
         _ => return Ok(()),
     };
 
-    let filepath = Path::new(&chapter.path).with_extension("html");
+    let chapter_path = chapter
+        .path
+        .as_ref()
+        .expect("Checked that path exists above");
+    let filepath = Path::new(&chapter_path).with_extension("html");
     let filepath = filepath
         .to_str()
-        .chain_err(|| "Could not convert HTML path to str")?;
+        .with_context(|| "Could not convert HTML path to str")?;
     let anchor_base = utils::fs::normalize_path(filepath);
 
-    let mut opts = Options::empty();
-    opts.insert(OPTION_ENABLE_TABLES);
-    opts.insert(OPTION_ENABLE_FOOTNOTES);
-    let p = Parser::new_ext(&chapter.content, opts);
+    let mut p = utils::new_cmark_parser(&chapter.content, false).peekable();
 
-    let mut in_header = false;
-    let max_section_depth = search_config.heading_split_level as i32;
+    let mut in_heading = false;
+    let max_section_depth = u32::from(search_config.heading_split_level);
     let mut section_id = None;
     let mut heading = String::new();
     let mut body = String::new();
     let mut breadcrumbs = chapter.parent_names.clone();
     let mut footnote_numbers = HashMap::new();
 
-    for event in p {
+    breadcrumbs.push(chapter.name.clone());
+
+    let mut id_counter = HashMap::new();
+    while let Some(event) = p.next() {
         match event {
-            Event::Start(Tag::Header(i)) if i <= max_section_depth => {
-                if heading.len() > 0 {
-                    // Section finished, the next header is following now
+            Event::Start(Tag::Heading { level, id, .. }) if level as u32 <= max_section_depth => {
+                if !heading.is_empty() {
+                    // Section finished, the next heading is following now
                     // Write the data to the index, and clear it for the next section
                     add_doc(
                         index,
                         doc_urls,
                         &anchor_base,
+                        &heading,
+                        &mut id_counter,
                         &section_id,
                         &[&heading, &body, &breadcrumbs.join(" » ")],
                     );
-                    section_id = None;
                     heading.clear();
                     body.clear();
                     breadcrumbs.pop();
                 }
 
-                in_header = true;
+                section_id = id;
+                in_heading = true;
             }
-            Event::End(Tag::Header(i)) if i <= max_section_depth => {
-                in_header = false;
-                section_id = Some(utils::id_from_content(&heading));
+            Event::End(TagEnd::Heading(level)) if level as u32 <= max_section_depth => {
+                in_heading = false;
                 breadcrumbs.push(heading.clone());
             }
             Event::Start(Tag::FootnoteDefinition(name)) => {
                 let number = footnote_numbers.len() + 1;
                 footnote_numbers.entry(name).or_insert(number);
             }
-            Event::Start(_) | Event::End(_) | Event::SoftBreak | Event::HardBreak => {
-                // Insert spaces where HTML output would usually seperate text
+            Event::Html(html) => {
+                let mut html_block = html.into_string();
+
+                // As of pulldown_cmark 0.6, html events are no longer contained
+                // in an HtmlBlock tag. We must collect consecutive Html events
+                // into a block ourselves.
+                while let Some(Event::Html(html)) = p.peek() {
+                    html_block.push_str(html);
+                    p.next();
+                }
+                body.push_str(&clean_html(&html_block));
+            }
+            Event::InlineHtml(html) => {
+                // This is not capable of cleaning inline tags like
+                // `foo <script>…</script>`. The `<script>` tags show up as
+                // individual InlineHtml events, and the content inside is
+                // just a regular Text event. There isn't a very good way to
+                // know how to collect all the content in-between. I'm not
+                // sure if this is easily fixable. It should be extremely
+                // rare, since script and style tags should almost always be
+                // blocks, and worse case you have some noise in the index.
+                body.push_str(&clean_html(&html));
+            }
+            Event::Start(_) | Event::End(_) | Event::Rule | Event::SoftBreak | Event::HardBreak => {
+                // Insert spaces where HTML output would usually separate text
                 // to ensure words don't get merged together
-                if in_header {
+                if in_heading {
                     heading.push(' ');
                 } else {
                     body.push(' ');
                 }
             }
-            Event::Text(text) => {
-                if in_header {
+            Event::Text(text) | Event::Code(text) => {
+                if in_heading {
                     heading.push_str(&text);
                 } else {
                     body.push_str(&text);
                 }
             }
-            Event::Html(html) | Event::InlineHtml(html) => {
-                body.push_str(&clean_html(&html));
-            }
             Event::FootnoteReference(name) => {
                 let len = footnote_numbers.len() + 1;
                 let number = footnote_numbers.entry(name).or_insert(len);
                 body.push_str(&format!(" [{}] ", number));
             }
+            Event::TaskListMarker(_checked) => {}
         }
     }
 
-    if heading.len() > 0 {
+    if !body.is_empty() || !heading.is_empty() {
+        let title = if heading.is_empty() {
+            if let Some(chapter) = breadcrumbs.first() {
+                chapter
+            } else {
+                ""
+            }
+        } else {
+            &heading
+        };
         // Make sure the last section is added to the index
         add_doc(
             index,
             doc_urls,
             &anchor_base,
+            &heading,
+            &mut id_counter,
             &section_id,
-            &[&heading, &body, &breadcrumbs.join(" » ")],
+            &[title, &body, &breadcrumbs.join(" » ")],
         );
     }
 
@@ -170,7 +235,7 @@ fn render_item(
 }
 
 fn write_to_json(index: Index, search_config: &Search, doc_urls: Vec<String>) -> Result<String> {
-    use self::elasticlunr::config::{SearchBool, SearchOptions, SearchOptionsField};
+    use elasticlunr::config::{SearchBool, SearchOptions, SearchOptionsField};
     use std::collections::BTreeMap;
 
     #[derive(Serialize)]
@@ -193,12 +258,13 @@ fn write_to_json(index: Index, search_config: &Search, doc_urls: Vec<String>) ->
 
     let mut fields = BTreeMap::new();
     let mut opt = SearchOptionsField::default();
-    opt.boost = Some(search_config.boost_title);
-    fields.insert("title".into(), opt);
-    opt.boost = Some(search_config.boost_paragraph);
-    fields.insert("body".into(), opt);
-    opt.boost = Some(search_config.boost_hierarchy);
-    fields.insert("breadcrumbs".into(), opt);
+    let mut insert_boost = |key: &str, boost| {
+        opt.boost = Some(boost);
+        fields.insert(key.into(), opt);
+    };
+    insert_boost("title", search_config.boost_title);
+    insert_boost("body", search_config.boost_paragraph);
+    insert_boost("breadcrumbs", search_config.boost_hierarchy);
 
     let search_options = SearchOptions {
         bool: if search_config.use_boolean_and {
@@ -231,8 +297,7 @@ fn write_to_json(index: Index, search_config: &Search, doc_urls: Vec<String>) ->
 }
 
 fn clean_html(html: &str) -> String {
-    lazy_static! {
-        static ref AMMONIA: ammonia::Builder<'static> = {
+    static AMMONIA: Lazy<ammonia::Builder<'static>> = Lazy::new(|| {
         let mut clean_content = HashSet::new();
         clean_content.insert("script");
         clean_content.insert("style");
@@ -245,7 +310,6 @@ fn clean_html(html: &str) -> String {
             .allowed_classes(HashMap::new())
             .clean_content_tags(clean_content);
         builder
-        };
-    }
+    });
     AMMONIA.clean(html).to_string()
 }

src/renderer/markdown_renderer.rs

@@ -0,0 +1,52 @@
+use crate::book::BookItem;
+use crate::errors::*;
+use crate::renderer::{RenderContext, Renderer};
+use crate::utils;
+use log::trace;
+use std::fs;
+
+#[derive(Default)]
+/// A renderer to output the Markdown after the preprocessors have run. Mostly useful
+/// when debugging preprocessors.
+pub struct MarkdownRenderer;
+
+impl MarkdownRenderer {
+    /// Create a new `MarkdownRenderer` instance.
+    pub fn new() -> Self {
+        MarkdownRenderer
+    }
+}
+
+impl Renderer for MarkdownRenderer {
+    fn name(&self) -> &str {
+        "markdown"
+    }
+
+    fn render(&self, ctx: &RenderContext) -> Result<()> {
+        let destination = &ctx.destination;
+        let book = &ctx.book;
+
+        if destination.exists() {
+            utils::fs::remove_dir_content(destination)
+                .with_context(|| "Unable to remove stale Markdown output")?;
+        }
+
+        trace!("markdown render");
+        for item in book.iter() {
+            if let BookItem::Chapter(ref ch) = *item {
+                if !ch.is_draft_chapter() {
+                    utils::fs::write_file(
+                        &ctx.destination,
+                        ch.path.as_ref().expect("Checked path exists before"),
+                        ch.content.as_bytes(),
+                    )?;
+                }
+            }
+        }
+
+        fs::create_dir_all(destination)
+            .with_context(|| "Unexpected error when constructing destination path")?;
+
+        Ok(())
+    }
+}

src/renderer/mod.rs

@@ -8,25 +8,29 @@
 //!
 //! The definition for [RenderContext] may be useful though.
 //!
-//! [For Developers]: https://rust-lang-nursery.github.io/mdBook/lib/index.html
+//! [For Developers]: https://rust-lang.github.io/mdBook/for_developers/index.html
 //! [RenderContext]: struct.RenderContext.html
 
 pub use self::html_handlebars::HtmlHandlebars;
+pub use self::markdown_renderer::MarkdownRenderer;
 
 mod html_handlebars;
+mod markdown_renderer;
 
-use serde_json;
 use shlex::Shlex;
+use std::collections::HashMap;
 use std::fs;
-use std::io::{self, Read};
-use std::path::PathBuf;
+use std::io::{self, ErrorKind, Read};
+use std::path::{Path, PathBuf};
 use std::process::{Command, Stdio};
 
-use book::Book;
-use config::Config;
-use errors::*;
+use crate::book::Book;
+use crate::config::Config;
+use crate::errors::*;
+use log::{error, info, trace, warn};
+use toml::Value;
 
-const MDBOOK_VERSION: &str = env!("CARGO_PKG_VERSION");
+use serde::{Deserialize, Serialize};
 
 /// An arbitrary `mdbook` backend.
 ///
@@ -34,12 +38,9 @@ const MDBOOK_VERSION: &str = env!("CARGO_PKG_VERSION");
 /// provide your own renderer, there are two main renderer implementations that
 /// 99% of users will ever use:
 ///
-/// - [HtmlHandlebars] - the built-in HTML renderer
-/// - [CmdRenderer] - a generic renderer which shells out to a program to do the
+/// - [`HtmlHandlebars`] - the built-in HTML renderer
+/// - [`CmdRenderer`] - a generic renderer which shells out to a program to do the
 ///   actual rendering
-///
-/// [HtmlHandlebars]: struct.HtmlHandlebars.html
-/// [CmdRenderer]: struct.CmdRenderer.html
 pub trait Renderer {
     /// The `Renderer`'s name.
     fn name(&self) -> &str;
@@ -66,6 +67,10 @@ pub struct RenderContext {
     /// renderers to cache intermediate results, this directory is not
     /// guaranteed to be empty or even exist.
     pub destination: PathBuf,
+    #[serde(skip)]
+    pub(crate) chapter_titles: HashMap<PathBuf, String>,
+    #[serde(skip)]
+    __non_exhaustive: (),
 }
 
 impl RenderContext {
@@ -76,11 +81,13 @@ impl RenderContext {
         Q: Into<PathBuf>,
     {
         RenderContext {
-            book: book,
-            config: config,
-            version: MDBOOK_VERSION.to_string(),
+            book,
+            config,
+            version: crate::MDBOOK_VERSION.to_string(),
             root: root.into(),
             destination: destination.into(),
+            chapter_titles: HashMap::new(),
+            __non_exhaustive: (),
         }
     }
 
@@ -91,7 +98,7 @@ impl RenderContext {
 
     /// Load a `RenderContext` from its JSON representation.
     pub fn from_json<R: Read>(reader: R) -> Result<RenderContext> {
-        serde_json::from_reader(reader).chain_err(|| "Unable to deserialize the `RenderContext`")
+        serde_json::from_reader(reader).with_context(|| "Unable to deserialize the `RenderContext`")
     }
 }
 
@@ -130,14 +137,44 @@ impl CmdRenderer {
         CmdRenderer { name, cmd }
     }
 
-    fn compose_command(&self) -> Result<Command> {
+    fn compose_command(&self, root: &Path, destination: &Path) -> Result<Command> {
         let mut words = Shlex::new(&self.cmd);
-        let executable = match words.next() {
-            Some(e) => e,
+        let exe = match words.next() {
+            Some(e) => PathBuf::from(e),
             None => bail!("Command string was empty"),
         };
 
-        let mut cmd = Command::new(executable);
+        let exe = if exe.components().count() == 1 {
+            // Search PATH for the executable.
+            exe
+        } else {
+            // Relative paths are preferred to be relative to the book root.
+            let abs_exe = root.join(&exe);
+            if abs_exe.exists() {
+                abs_exe
+            } else {
+                // Historically paths were relative to the destination, but
+                // this is not the preferred way.
+                let legacy_path = destination.join(&exe);
+                if legacy_path.exists() {
+                    warn!(
+                        "Renderer command `{}` uses a path relative to the \
+                        renderer output directory `{}`. This was previously \
+                        accepted, but has been deprecated. Relative executable \
+                        paths should be relative to the book root.",
+                        exe.display(),
+                        destination.display()
+                    );
+                    legacy_path
+                } else {
+                    // Let this bubble through to later be handled by
+                    // handle_render_command_error.
+                    abs_exe
+                }
+            }
+        };
+
+        let mut cmd = Command::new(exe);
 
         for arg in words {
             cmd.arg(arg);
@@ -147,6 +184,40 @@ impl CmdRenderer {
     }
 }
 
+impl CmdRenderer {
+    fn handle_render_command_error(&self, ctx: &RenderContext, error: io::Error) -> Result<()> {
+        if let ErrorKind::NotFound = error.kind() {
+            // Look for "output.{self.name}.optional".
+            // If it exists and is true, treat this as a warning.
+            // Otherwise, fail the build.
+
+            let optional_key = format!("output.{}.optional", self.name);
+
+            let is_optional = match ctx.config.get(&optional_key) {
+                Some(Value::Boolean(value)) => *value,
+                _ => false,
+            };
+
+            if is_optional {
+                warn!(
+                    "The command `{}` for backend `{}` was not found, \
+                    but was marked as optional.",
+                    self.cmd, self.name
+                );
+                return Ok(());
+            } else {
+                error!(
+                    "The command `{0}` wasn't found, is the \"{1}\" backend installed? \
+                    If you want to ignore this error when the \"{1}\" backend is not installed, \
+                    set `optional = true` in the `[output.{1}]` section of the book.toml configuration file.",
+                    self.cmd, self.name
+                );
+            }
+        }
+        Err(error).with_context(|| "Unable to start the backend")?
+    }
+}
+
 impl Renderer for CmdRenderer {
     fn name(&self) -> &str {
         &self.name
@@ -158,7 +229,7 @@ impl Renderer for CmdRenderer {
         let _ = fs::create_dir_all(&ctx.destination);
 
         let mut child = match self
-            .compose_command()?
+            .compose_command(&ctx.root, &ctx.destination)?
             .stdin(Stdio::piped())
             .stdout(Stdio::inherit())
             .stderr(Stdio::inherit())
@@ -166,20 +237,9 @@ impl Renderer for CmdRenderer {
             .spawn()
         {
             Ok(c) => c,
-            Err(ref e) if e.kind() == io::ErrorKind::NotFound => {
-                warn!(
-                    "The command wasn't found, is the \"{}\" backend installed?",
-                    self.name
-                );
-                warn!("\tCommand: {}", self.cmd);
-                return Ok(());
-            }
-            Err(e) => {
-                return Err(e).chain_err(|| "Unable to start the backend")?;
-            }
+            Err(e) => return self.handle_render_command_error(ctx, e),
         };
 
-        {
         let mut stdin = child.stdin.take().expect("Child has stdin");
         if let Err(e) = serde_json::to_writer(&mut stdin, &ctx) {
             // Looks like the backend hung up before we could finish
@@ -189,11 +249,10 @@ impl Renderer for CmdRenderer {
 
         // explicitly close the `stdin` file handle
         drop(stdin);
-        }
 
         let status = child
             .wait()
-            .chain_err(|| "Error waiting for the backend to complete")?;
+            .with_context(|| "Error waiting for the backend to complete")?;
 
         trace!("{} exited with output: {:?}", self.cmd, status);