Update dependencies. (#1211)

* Removed the itertools dependency

* Removed an unused feature flag

* Stubbed out a toml_query replacement

* Update dependencies.

* Bump env_logger.

* Use warp instead of iron for http server.

Iron does not appear to be maintained anymore. warp/hyper seems to be
reasonably maintained. Unfortunately this takes a few seconds more
to compile, but shouldn't be too bad.

One benefit is that there is no longer a need for a separate websocket
port, which makes it easier to run multiple servers at once.

* Update pulldown-cmark to 0.7

* Switch from error-chain to anyhow.

* Bump MSRV to 1.39.

* Update elasticlunr-rs.

Co-authored-by: Michael Bryan <michaelfbryan@gmail.com>

.github/workflows/main.yml

@@ -31,7 +31,7 @@ jobs:
             rust: stable
           - build: msrv
             os: ubuntu-latest
-            rust: 1.35.0
+            rust: 1.39.0
     steps:
     - uses: actions/checkout@master
     - name: Install Rust

Cargo.toml

@@ -16,17 +16,16 @@ repository = "https://github.com/rust-lang/mdBook"
 description = "Creates a book from markdown files"
 
 [dependencies]
+anyhow = "1.0.28"
 chrono = "0.4"
 clap = "2.24"
-env_logger = "0.6"
+env_logger = "0.7.1"
-error-chain = "0.12"
 handlebars = "3.0"
-itertools = "0.8"
 lazy_static = "1.0"
 log = "0.4"
 memchr = "2.0"
 open = "1.1"
-pulldown-cmark = "0.6.1"
+pulldown-cmark = "0.7.0"
 regex = "1.0.0"
 serde = "1.0"
 serde_derive = "1.0"
@@ -34,16 +33,15 @@ serde_json = "1.0"
 shlex = "0.1"
 tempfile = "3.0"
 toml = "0.5.1"
-toml-query = "0.9"
 
 # Watch feature
 notify = { version = "4.0", optional = true }
 gitignore = { version = "1.0", optional = true }
 
 # Serve feature
-iron = { version = "0.6", optional = true }
+futures-util = { version = "0.3.4", optional = true }
-staticfile = { version = "0.5", optional = true }
+tokio = { version = "0.2.18", features = ["macros"], optional = true }
-ws = { version = "0.9", optional = true}
+warp = { version = "0.2.2", default-features = false, features = ["websocket"], optional = true }
 
 # Search feature
 elasticlunr-rs = { version = "2.3", optional = true, default-features = false }
@@ -55,11 +53,9 @@ pretty_assertions = "0.6"
 walkdir = "2.0"
 
 [features]
-default = ["output", "watch", "serve", "search"]
+default = ["watch", "serve", "search"]
-debug = []
-output = []
 watch = ["notify", "gitignore"]
-serve = ["iron", "staticfile", "ws"]
+serve = ["futures-util", "tokio", "warp"]
 search = ["elasticlunr-rs", "ammonia"]
 
 [[bin]]

README.md

@@ -24,7 +24,7 @@ There are multiple ways to install mdBook.
 
 2. **From Crates.io**
 
-   This requires at least [Rust] 1.35 and Cargo to be installed. Once you have installed
+   This requires at least [Rust] 1.39 and Cargo to be installed. Once you have installed
    Rust, type the following in the terminal:
 
    ```

examples/nop-preprocessor.rs

@@ -87,7 +87,7 @@ mod nop_lib {
             // particular config value
             if let Some(nop_cfg) = ctx.config.get_preprocessor(self.name()) {
                 if nop_cfg.contains_key("blow-up") {
-                    return Err("Boom!!1!".into());
+                    anyhow::bail!("Boom!!1!");
                 }
             }
 

src/book/book.rs

@@ -15,13 +15,13 @@ pub fn load_book<P: AsRef<Path>>(src_dir: P, cfg: &BuildConfig) -> Result<Book>
 
     let mut summary_content = String::new();
     File::open(summary_md)
-        .chain_err(|| "Couldn't open SUMMARY.md")?
+        .with_context(|| "Couldn't open SUMMARY.md")?
         .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(|| "Summary parsing failed")?;
 
     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)
@@ -257,11 +257,12 @@ fn load_chapter<P: AsRef<Path>>(
         };
 
         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)
+        f.read_to_string(&mut content).with_context(|| {
-            .chain_err(|| format!("Unable to read \"{}\" ({})", link.name, location.display()))?;
+            format!("Unable to read \"{}\" ({})", link.name, location.display())
+        })?;
 
         let stripped = location
             .strip_prefix(&src_dir)

src/book/init.rs

@@ -64,19 +64,19 @@ 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()?;
@@ -97,12 +97,12 @@ 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(())
     }
 
@@ -174,13 +174,14 @@ impl BookBuilder {
         let summary = src_dir.join("SUMMARY.md");
         if !summary.exists() {
             trace!("No summary found creating stub summary and chapter_1.md.");
-            let mut f = File::create(&summary).chain_err(|| "Unable to create SUMMARY.md")?;
+            let mut f = File::create(&summary).with_context(|| "Unable to create SUMMARY.md")?;
             writeln!(f, "# Summary")?;
             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.");

src/book/mod.rs

@@ -215,7 +215,7 @@ impl MDBook {
 
         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.
@@ -282,10 +282,12 @@ impl MDBook {
                 let output = cmd.output()?;
 
                 if !output.status.success() {
-                    bail!(ErrorKind::Subprocess(
+                    bail!(
-                        "Rustdoc returned an error".to_string(),
+                        "rustdoc returned an error:\n\
-                        output
+                        \n--- stdout\n{}\n--- stderr\n{}",
-                    ));
+                        String::from_utf8_lossy(&output.stdout),
+                        String::from_utf8_lossy(&output.stderr)
+                    );
                 }
             }
         }

src/book/summary.rs

@@ -236,13 +236,13 @@ 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_parts()
-            .chain_err(|| "There was an error parsing the numbered chapters")?;
+            .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,
@@ -320,7 +320,7 @@ impl<'a> SummaryParser<'a> {
             // Parse the rest of the part.
             let numbered_chapters = self
                 .parse_numbered(&mut root_items, &mut root_number)
-                .chain_err(|| "There was an error parsing the numbered chapters")?;
+                .with_context(|| "There was an error parsing the numbered chapters")?;
 
             if let Some(title) = title {
                 parts.push(SummaryItem::PartTitle(title));
@@ -514,8 +514,12 @@ impl<'a> SummaryParser<'a> {
 
     fn parse_error<D: Display>(&self, msg: D) -> Error {
         let (line, col) = self.current_location();
-
+        anyhow::anyhow!(
-        ErrorKind::ParseError(line, col, msg.to_string()).into()
+            "failed to parse SUMMARY.md line {}, column {}: {}",
+            line,
+            col,
+            msg
+        )
     }
 
     /// Try to parse the title line.
@@ -553,10 +557,9 @@ 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(|| {
+        .ok_or_else(||
-            "Unable to get last link because the list of SummaryItems doesn't contain any Links"
+            anyhow::anyhow!("Unable to get last link because the list of SummaryItems doesn't contain any Links")
-                .into()
+            )
-        })
 }
 
 /// Removes the styling from a list of Markdown events and returns just the

src/cmd/clean.rs

@@ -1,6 +1,6 @@
 use crate::get_book_dir;
+use anyhow::Context;
 use clap::{App, ArgMatches, SubCommand};
-use mdbook::errors::*;
 use mdbook::MDBook;
 use std::fs;
 
@@ -31,7 +31,8 @@ pub fn execute(args: &ArgMatches) -> mdbook::errors::Result<()> {
     };
 
     if dir_to_remove.exists() {
-        fs::remove_dir_all(&dir_to_remove).chain_err(|| "Unable to remove the build directory")?;
+        fs::remove_dir_all(&dir_to_remove)
+            .with_context(|| "Unable to remove the build directory")?;
     }
 
     Ok(())

src/cmd/serve.rs

@@ -2,15 +2,19 @@
 use super::watch;
 use crate::{get_book_dir, open};
 use clap::{App, Arg, ArgMatches, SubCommand};
-use iron::headers;
+use futures_util::sink::SinkExt;
-use iron::{status, AfterMiddleware, Chain, Iron, IronError, IronResult, Request, Response, Set};
+use futures_util::StreamExt;
 use mdbook::errors::*;
 use mdbook::utils;
 use mdbook::MDBook;
+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";
-struct NoCache;
 
 // Create clap subcommand arguments
 pub fn make_subcommand<'a, 'b>() -> App<'a, 'b> {
@@ -43,42 +47,21 @@ pub fn make_subcommand<'a, 'b>() -> App<'a, 'b> {
                 .empty_values(false)
                 .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'")
 }
 
-// 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 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-hostname").unwrap_or(hostname);
     let open_browser = args.is_present("open");
 
     let address = format!("{}:{}", hostname, port);
-    let ws_address = format!("{}:{}", hostname, ws_port);
 
-    let livereload_url = format!("ws://{}:{}", public_address, ws_port);
+    let livereload_url = format!("ws://{}/{}", address, LIVE_RELOAD_ENDPOINT);
     book.config
         .set("output.html.livereload-url", &livereload_url)?;
 
@@ -88,20 +71,18 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
 
     book.build()?;
 
-    let mut chain = Chain::new(staticfile::Static::new(book.build_dir_for("html")));
+    let sockaddr: SocketAddr = address
-    chain.link_after(NoCache);
+        .to_socket_addrs()?
-    chain.link_after(ErrorRecover);
+        .next()
-    let _iron = Iron::new(chain)
+        .ok_or_else(|| anyhow::anyhow!("no address found for {}", address))?;
-        .http(&*address)
+    let build_dir = book.build_dir_for("html");
-        .chain_err(|| "Unable to launch the server")?;
 
-    let ws_server =
+    // A channel used to broadcast to any websockets to reload when a file changes.
-        ws::WebSocket::new(|_| |_| Ok(())).chain_err(|| "Unable to start the websocket")?;
+    let (tx, _rx) = tokio::sync::broadcast::channel::<Message>(100);
 
-    let broadcaster = ws_server.broadcaster();
+    let reload_tx = tx.clone();
-
+    let thread_handle = std::thread::spawn(move || {
-    std::thread::spawn(move || {
+        serve(build_dir, sockaddr, reload_tx);
-        ws_server.listen(&*ws_address).unwrap();
     });
 
     let serving_url = format!("http://{}", address);
@@ -117,7 +98,6 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
         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
@@ -130,30 +110,39 @@ pub fn execute(args: &ArgMatches) -> 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 NoCache {
+#[tokio::main]
-    fn after(&self, _: &mut Request, mut res: Response) -> IronResult<Response> {
+async fn serve(build_dir: PathBuf, address: SocketAddr, reload_tx: broadcast::Sender<Message>) {
-        res.headers.set(headers::CacheControl(vec![
+    // A warp Filter which captures `reload_tx` and provides an `rx` copy to
-            headers::CacheDirective::NoStore,
+    // receive reload messages.
-            headers::CacheDirective::MaxAge(0u32),
+    let sender = warp::any().map(move || reload_tx.subscribe());
-        ]));
 
-        Ok(res)
+    // 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)
-impl AfterMiddleware for ErrorRecover {
+        .and(warp::ws())
-    fn catch(&self, _: &mut Request, err: IronError) -> IronResult<Response> {
+        .and(sender)
-        match err.response.status {
+        .map(|ws: warp::ws::Ws, mut rx: broadcast::Receiver<Message>| {
-            // each error will result in 404 response
+            ws.on_upgrade(move |ws| async move {
-            Some(_) => Ok(err.response.set(status::NotFound)),
+                let (mut user_ws_tx, _user_ws_rx) = ws.split();
-            _ => Err(err),
+                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);
+    let routes = livereload.or(book_route);
+    warp::serve(routes).run(address).await;
 }

src/config.rs

@@ -57,12 +57,9 @@ use std::path::{Path, PathBuf};
 use std::str::FromStr;
 use toml::value::Table;
 use toml::{self, Value};
-use toml_query::delete::TomlValueDeleteExt;
-use toml_query::insert::TomlValueInsertExt;
-use toml_query::read::TomlValueReadExt;
 
 use crate::errors::*;
-use crate::utils;
+use crate::utils::{self, toml_ext::TomlExt};
 
 /// The overall configuration object for MDBook, essentially an in-memory
 /// representation of `book.toml`.
@@ -82,7 +79,7 @@ impl FromStr for Config {
 
     /// Load a `Config` from some string.
     fn from_str(src: &str) -> Result<Self> {
-        toml::from_str(src).chain_err(|| Error::from("Invalid configuration file"))
+        toml::from_str(src).with_context(|| "Invalid configuration file")
     }
 }
 
@@ -91,9 +88,9 @@ impl Config {
     pub fn from_disk<P: AsRef<Path>>(config_file: P) -> Result<Config> {
         let mut buffer = String::new();
         File::open(config_file)
-            .chain_err(|| "Unable to open the configuration file")?
+            .with_context(|| "Unable to open the configuration file")?
             .read_to_string(&mut buffer)
-            .chain_err(|| "Couldn't read the file")?;
+            .with_context(|| "Couldn't read the file")?;
 
         Config::from_str(&buffer)
     }
@@ -163,15 +160,12 @@ impl Config {
     /// `output.html.playpen` will fetch the "playpen" out of the html output
     /// table).
     pub fn get(&self, key: &str) -> Option<&Value> {
-        self.rest.read(key).unwrap_or(None)
+        self.rest.read(key)
     }
 
     /// Fetch a value from the `Config` so you can mutate it.
     pub fn get_mut(&mut self, key: &str) -> Option<&mut Value> {
-        match self.rest.read_mut(key) {
+        self.rest.read_mut(key)
-            Ok(inner) => inner,
-            Err(_) => None,
-        }
     }
 
     /// Convenience method for getting the html renderer's configuration.
@@ -182,11 +176,14 @@ impl Config {
     /// HTML renderer is refactored to be less coupled to `mdbook` internals.
     #[doc(hidden)]
     pub fn html_config(&self) -> Option<HtmlConfig> {
-        match self.get_deserialized_opt("output.html") {
+        match self
+            .get_deserialized_opt("output.html")
+            .with_context(|| "Parsing configuration [output.html]")
+        {
             Ok(Some(config)) => Some(config),
             Ok(None) => None,
             Err(e) => {
-                utils::log_backtrace(&e.chain_err(|| "Parsing configuration [output.html]"));
+                utils::log_backtrace(&e);
                 None
             }
         }
@@ -214,7 +211,7 @@ impl Config {
                 value
                     .clone()
                     .try_into()
-                    .chain_err(|| "Couldn't deserialize the value")
+                    .with_context(|| "Couldn't deserialize the value")
             })
             .transpose()
     }
@@ -226,17 +223,15 @@ impl Config {
     pub fn set<S: Serialize, I: AsRef<str>>(&mut self, index: I, value: S) -> Result<()> {
         let index = index.as_ref();
 
-        let value =
+        let value = Value::try_from(value)
-            Value::try_from(value).chain_err(|| "Unable to represent the item as a JSON Value")?;
+            .with_context(|| "Unable to represent the item as a JSON Value")?;
 
         if index.starts_with("book.") {
             self.book.update_value(&index[5..], value);
         } else if index.starts_with("build.") {
             self.build.update_value(&index[6..], value);
         } else {
-            self.rest
+            self.rest.insert(index, value);
-                .insert(index, value)
-                .map_err(ErrorKind::TomlQueryError)?;
         }
 
         Ok(())
@@ -277,7 +272,7 @@ impl Config {
         get_and_insert!(table, "source" => cfg.book.src);
         get_and_insert!(table, "description" => cfg.book.description);
 
-        if let Ok(Some(dest)) = table.delete("output.html.destination") {
+        if let Some(dest) = table.delete("output.html.destination") {
             if let Ok(destination) = dest.try_into() {
                 cfg.build.build_dir = destination;
             }
@@ -363,8 +358,8 @@ impl Serialize for Config {
         };
         let rust_config = Value::try_from(&self.rust).expect("should always be serializable");
 
-        table.insert("book", book_config).expect("unreachable");
+        table.insert("book", book_config);
-        table.insert("rust", rust_config).expect("unreachable");
+        table.insert("rust", rust_config);
         table.serialize(s)
     }
 }
@@ -391,7 +386,7 @@ fn is_legacy_format(table: &Value) -> bool {
     ];
 
     for item in &legacy_items {
-        if let Ok(Some(_)) = table.read(item) {
+        if table.read(item).is_some() {
             return true;
         }
     }

src/lib.rs

@@ -84,8 +84,6 @@
 #![deny(rust_2018_idioms)]
 #![allow(clippy::comparison_chain)]
 
-#[macro_use]
-extern crate error_chain;
 #[macro_use]
 extern crate lazy_static;
 #[macro_use]
@@ -119,48 +117,6 @@ pub use crate::renderer::Renderer;
 
 /// The error types used through out this crate.
 pub mod errors {
-    use std::path::PathBuf;
+    pub(crate) use anyhow::{bail, ensure, Context};
-
+    pub use anyhow::{Error, Result};
-    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"];
-        }
-
-        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())
-            }
-
-            /// Error with a TOML file.
-            TomlQueryError(inner: toml_query::error::Error) {
-                description("toml_query error")
-                display("{}", inner)
-            }
-        }
-    }
-
-    // Box to halve the size of Error
-    impl From<handlebars::TemplateError> for Error {
-        fn from(e: handlebars::TemplateError) -> Error {
-            From::from(Box::new(e))
-        }
-    }
 }

src/preprocess/cmd.rs

@@ -43,7 +43,7 @@ impl CmdPreprocessor {
     /// 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).chain_err(|| "Unable to parse the input")
+        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) {
@@ -100,7 +100,7 @@ impl Preprocessor for CmdPreprocessor {
             .stdout(Stdio::piped())
             .stderr(Stdio::inherit())
             .spawn()
-            .chain_err(|| {
+            .with_context(|| {
                 format!(
                     "Unable to start the \"{}\" preprocessor. Is it installed?",
                     self.name()
@@ -111,7 +111,7 @@ impl Preprocessor for CmdPreprocessor {
 
         let output = child
             .wait_with_output()
-            .chain_err(|| "Error waiting for the preprocessor to complete")?;
+            .with_context(|| "Error waiting for the preprocessor to complete")?;
 
         trace!("{} exited with output: {:?}", self.cmd, output);
         ensure!(
@@ -119,7 +119,8 @@ impl Preprocessor for CmdPreprocessor {
             "The preprocessor exited unsuccessfully"
         );
 
-        serde_json::from_slice(&output.stdout).chain_err(|| "Unable to parse the preprocessed book")
+        serde_json::from_slice(&output.stdout)
+            .with_context(|| "Unable to parse the preprocessed book")
     }
 
     fn supports_renderer(&self, renderer: &str) -> bool {

src/preprocess/links.rs

@@ -95,7 +95,7 @@ where
             }
             Err(e) => {
                 error!("Error updating \"{}\", {}", link.link_text, e);
-                for cause in e.iter().skip(1) {
+                for cause in e.chain().skip(1) {
                     warn!("Caused By: {}", cause);
                 }
 
@@ -296,7 +296,7 @@ impl<'a> Link<'a> {
                         RangeOrAnchor::Range(range) => take_lines(&s, range.clone()),
                         RangeOrAnchor::Anchor(anchor) => take_anchored_lines(&s, anchor),
                     })
-                    .chain_err(|| {
+                    .with_context(|| {
                         format!(
                             "Could not read file for link {} ({})",
                             self.link_text,
@@ -316,7 +316,7 @@ impl<'a> Link<'a> {
                             take_rustdoc_include_anchored_lines(&s, anchor)
                         }
                     })
-                    .chain_err(|| {
+                    .with_context(|| {
                         format!(
                             "Could not read file for link {} ({})",
                             self.link_text,
@@ -327,7 +327,7 @@ impl<'a> Link<'a> {
             LinkType::Playpen(ref pat, ref attrs) => {
                 let target = base.join(pat);
 
-                let contents = fs::read_to_string(&target).chain_err(|| {
+                let contents = fs::read_to_string(&target).with_context(|| {
                     format!(
                         "Could not read file for link {} ({})",
                         self.link_text,

src/renderer/html_handlebars/hbs_renderer.rs

@@ -49,12 +49,12 @@ impl HtmlHandlebars {
         // Update the context with data for this file
         let ctx_path = path
             .to_str()
-            .chain_err(|| "Could not convert path to str")?;
+            .with_context(|| "Could not convert path to str")?;
         let filepath = Path::new(&ctx_path).with_extension("html");
 
         // "print.html" is used for the print page.
         if path == Path::new("print.md") {
-            bail!(ErrorKind::ReservedFilenameError(path.clone()));
+            bail!("{} is reserved for internal use", path.display());
         };
 
         let book_title = ctx
@@ -260,7 +260,7 @@ impl HtmlHandlebars {
             let output_location = destination.join(custom_file);
             if let Some(parent) = output_location.parent() {
                 fs::create_dir_all(parent)
-                    .chain_err(|| format!("Unable to create {}", parent.display()))?;
+                    .with_context(|| format!("Unable to create {}", parent.display()))?;
             }
             debug!(
                 "Copying {} -> {}",
@@ -268,7 +268,7 @@ impl HtmlHandlebars {
                 output_location.display()
             );
 
-            fs::copy(&input_location, &output_location).chain_err(|| {
+            fs::copy(&input_location, &output_location).with_context(|| {
                 format!(
                     "Unable to copy {} to {}",
                     input_location.display(),
@@ -314,7 +314,7 @@ impl Renderer for HtmlHandlebars {
 
         if destination.exists() {
             utils::fs::remove_dir_content(destination)
-                .chain_err(|| "Unable to remove stale HTML output")?;
+                .with_context(|| "Unable to remove stale HTML output")?;
         }
 
         trace!("render");
@@ -355,7 +355,7 @@ impl Renderer for HtmlHandlebars {
         let mut print_content = String::new();
 
         fs::create_dir_all(&destination)
-            .chain_err(|| "Unexpected error when constructing destination path")?;
+            .with_context(|| "Unexpected error when constructing destination path")?;
 
         let mut is_index = true;
         for item in book.iter() {
@@ -388,9 +388,9 @@ impl Renderer for HtmlHandlebars {
 
         debug!("Copy static files");
         self.copy_static_files(&destination, &theme, &html_config)
-            .chain_err(|| "Unable to copy across static files")?;
+            .with_context(|| "Unable to copy across static files")?;
         self.copy_additional_css_and_js(&html_config, &ctx.root, &destination)
-            .chain_err(|| "Unable to copy across additional CSS and JS")?;
+            .with_context(|| "Unable to copy across additional CSS and JS")?;
 
         // Render search index
         #[cfg(feature = "search")]
@@ -549,7 +549,7 @@ fn make_data(
                 if let Some(ref path) = ch.path {
                     let p = path
                         .to_str()
-                        .chain_err(|| "Could not convert path to str")?;
+                        .with_context(|| "Could not convert path to str")?;
                     chapter.insert("path".to_owned(), json!(p));
                 }
             }

src/renderer/html_handlebars/search.rs

@@ -82,7 +82,7 @@ fn render_item(
     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 p = utils::new_cmark_parser(&chapter.content).peekable();

src/renderer/markdown_renderer.rs

@@ -28,7 +28,7 @@ impl Renderer for MarkdownRenderer {
 
         if destination.exists() {
             utils::fs::remove_dir_content(destination)
-                .chain_err(|| "Unable to remove stale Markdown output")?;
+                .with_context(|| "Unable to remove stale Markdown output")?;
         }
 
         trace!("markdown render");
@@ -45,7 +45,7 @@ impl Renderer for MarkdownRenderer {
         }
 
         fs::create_dir_all(&destination)
-            .chain_err(|| "Unexpected error when constructing destination path")?;
+            .with_context(|| "Unexpected error when constructing destination path")?;
 
         Ok(())
     }

src/renderer/mod.rs

@@ -94,7 +94,7 @@ 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`")
     }
 }
 
@@ -178,7 +178,7 @@ impl CmdRenderer {
                 );
             }
         }
-        Err(error).chain_err(|| "Unable to start the backend")?
+        Err(error).with_context(|| "Unable to start the backend")?
     }
 }
 
@@ -216,7 +216,7 @@ impl Renderer for CmdRenderer {
 
         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);
 

src/utils/mod.rs

@@ -2,10 +2,11 @@
 
 pub mod fs;
 mod string;
+pub(crate) mod toml_ext;
 use crate::errors::Error;
 use regex::Regex;
 
-use pulldown_cmark::{html, CowStr, Event, Options, Parser, Tag};
+use pulldown_cmark::{html, CodeBlockKind, CowStr, Event, Options, Parser, Tag};
 
 use std::borrow::Cow;
 use std::fmt::Write;
@@ -226,10 +227,10 @@ impl EventQuoteConverter {
 
 fn clean_codeblock_headers(event: Event<'_>) -> Event<'_> {
     match event {
-        Event::Start(Tag::CodeBlock(ref info)) => {
+        Event::Start(Tag::CodeBlock(CodeBlockKind::Fenced(ref info))) => {
             let info: String = info.chars().filter(|ch| !ch.is_whitespace()).collect();
 
-            Event::Start(Tag::CodeBlock(CowStr::from(info)))
+            Event::Start(Tag::CodeBlock(CodeBlockKind::Fenced(CowStr::from(info))))
         }
         _ => event,
     }
@@ -271,7 +272,7 @@ fn convert_quotes_to_curly(original_text: &str) -> String {
 pub fn log_backtrace(e: &Error) {
     error!("Error: {}", e);
 
-    for cause in e.iter().skip(1) {
+    for cause in e.chain().skip(1) {
         error!("\tCaused By: {}", cause);
     }
 }

src/utils/string.rs

@@ -1,4 +1,3 @@
-use itertools::Itertools;
 use regex::Regex;
 use std::ops::Bound::{Excluded, Included, Unbounded};
 use std::ops::RangeBounds;
@@ -10,11 +9,17 @@ pub fn take_lines<R: RangeBounds<usize>>(s: &str, range: R) -> String {
         Included(&n) => n,
         Unbounded => 0,
     };
-    let mut lines = s.lines().skip(start);
+    let lines = s.lines().skip(start);
     match range.end_bound() {
-        Excluded(end) => lines.take(end.saturating_sub(start)).join("\n"),
+        Excluded(end) => lines
-        Included(end) => lines.take((end + 1).saturating_sub(start)).join("\n"),
+            .take(end.saturating_sub(start))
-        Unbounded => lines.join("\n"),
+            .collect::<Vec<_>>()
+            .join("\n"),
+        Included(end) => lines
+            .take((end + 1).saturating_sub(start))
+            .collect::<Vec<_>>()
+            .join("\n"),
+        Unbounded => lines.collect::<Vec<_>>().join("\n"),
     }
 }
 

src/utils/toml_ext.rs

@@ -0,0 +1,130 @@
+use toml::value::{Table, Value};
+
+pub(crate) trait TomlExt {
+    fn read(&self, key: &str) -> Option<&Value>;
+    fn read_mut(&mut self, key: &str) -> Option<&mut Value>;
+    fn insert(&mut self, key: &str, value: Value);
+    fn delete(&mut self, key: &str) -> Option<Value>;
+}
+
+impl TomlExt for Value {
+    fn read(&self, key: &str) -> Option<&Value> {
+        if let Some((head, tail)) = split(key) {
+            self.get(head)?.read(tail)
+        } else {
+            self.get(key)
+        }
+    }
+
+    fn read_mut(&mut self, key: &str) -> Option<&mut Value> {
+        if let Some((head, tail)) = split(key) {
+            self.get_mut(head)?.read_mut(tail)
+        } else {
+            self.get_mut(key)
+        }
+    }
+
+    fn insert(&mut self, key: &str, value: Value) {
+        if !self.is_table() {
+            *self = Value::Table(Table::new());
+        }
+
+        let table = self.as_table_mut().expect("unreachable");
+
+        if let Some((head, tail)) = split(key) {
+            table
+                .entry(head)
+                .or_insert_with(|| Value::Table(Table::new()))
+                .insert(tail, value);
+        } else {
+            table.insert(key.to_string(), value);
+        }
+    }
+
+    fn delete(&mut self, key: &str) -> Option<Value> {
+        if let Some((head, tail)) = split(key) {
+            self.get_mut(head)?.delete(tail)
+        } else if let Some(table) = self.as_table_mut() {
+            table.remove(key)
+        } else {
+            None
+        }
+    }
+}
+
+fn split(key: &str) -> Option<(&str, &str)> {
+    let ix = key.find(".")?;
+
+    let (head, tail) = key.split_at(ix);
+    // splitting will leave the "."
+    let tail = &tail[1..];
+
+    Some((head, tail))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::str::FromStr;
+
+    #[test]
+    fn read_simple_table() {
+        let src = "[table]";
+        let value = Value::from_str(src).unwrap();
+
+        let got = value.read("table").unwrap();
+
+        assert!(got.is_table());
+    }
+
+    #[test]
+    fn read_nested_item() {
+        let src = "[table]\nnested=true";
+        let value = Value::from_str(src).unwrap();
+
+        let got = value.read("table.nested").unwrap();
+
+        assert_eq!(got, &Value::Boolean(true));
+    }
+
+    #[test]
+    fn insert_item_at_top_level() {
+        let mut value = Value::Table(Table::default());
+        let item = Value::Boolean(true);
+
+        value.insert("first", item.clone());
+
+        assert_eq!(value.get("first").unwrap(), &item);
+    }
+
+    #[test]
+    fn insert_nested_item() {
+        let mut value = Value::Table(Table::default());
+        let item = Value::Boolean(true);
+
+        value.insert("first.second", item.clone());
+
+        let inserted = value.read("first.second").unwrap();
+        assert_eq!(inserted, &item);
+    }
+
+    #[test]
+    fn delete_a_top_level_item() {
+        let src = "top = true";
+        let mut value = Value::from_str(src).unwrap();
+
+        let got = value.delete("top").unwrap();
+
+        assert_eq!(got, Value::Boolean(true));
+    }
+
+    #[test]
+    fn delete_a_nested_item() {
+        let src = "[table]\n nested = true";
+        let mut value = Value::from_str(src).unwrap();
+
+        let got = value.delete("table.nested").unwrap();
+
+        assert_eq!(got, Value::Boolean(true));
+    }
+}

tests/dummy_book/mod.rs

@@ -4,12 +4,12 @@
 // Not all features are used in all test crates, so...
 #![allow(dead_code, unused_variables, unused_imports, unused_extern_crates)]
 
+use anyhow::Context;
 use mdbook::errors::*;
+use mdbook::MDBook;
 use std::fs::{self, File};
 use std::io::{Read, Write};
 use std::path::Path;
-
-use mdbook::MDBook;
 use tempfile::{Builder as TempFileBuilder, TempDir};
 use walkdir::WalkDir;
 
@@ -43,10 +43,10 @@ impl DummyBook {
         let temp = TempFileBuilder::new()
             .prefix("dummy_book-")
             .tempdir()
-            .chain_err(|| "Unable to create temp directory")?;
+            .with_context(|| "Unable to create temp directory")?;
 
         let dummy_book_root = Path::new(env!("CARGO_MANIFEST_DIR")).join("tests/dummy_book");
-        recursive_copy(&dummy_book_root, temp.path()).chain_err(|| {
+        recursive_copy(&dummy_book_root, temp.path()).with_context(|| {
             "Couldn't copy files into a \
              temporary directory"
         })?;
@@ -113,7 +113,7 @@ fn recursive_copy<A: AsRef<Path>, B: AsRef<Path>>(from: A, to: B) -> Result<()>
     let to = to.as_ref();
 
     for entry in WalkDir::new(&from) {
-        let entry = entry.chain_err(|| "Unable to inspect directory entry")?;
+        let entry = entry.with_context(|| "Unable to inspect directory entry")?;
 
         let original_location = entry.path();
         let relative = original_location
@@ -123,11 +123,11 @@ fn recursive_copy<A: AsRef<Path>, B: AsRef<Path>>(from: A, to: B) -> Result<()>
 
         if original_location.is_file() {
             if let Some(parent) = new_location.parent() {
-                fs::create_dir_all(parent).chain_err(|| "Couldn't create directory")?;
+                fs::create_dir_all(parent).with_context(|| "Couldn't create directory")?;
             }
 
             fs::copy(&original_location, &new_location)
-                .chain_err(|| "Unable to copy file contents")?;
+                .with_context(|| "Unable to copy file contents")?;
         }
     }
 

tests/parse_existing_summary_files.rs

@@ -28,11 +28,9 @@ macro_rules! summary_md_test {
                 .unwrap();
 
             if let Err(e) = book::parse_summary(&content) {
-                use error_chain::ChainedError;
-
                 eprintln!("Error parsing {}", filename.display());
                 eprintln!();
-                eprintln!("{}", e.display_chain());
+                eprintln!("{:?}", e);
                 panic!();
             }
         }

tests/rendered_output.rs

@@ -5,6 +5,7 @@ mod dummy_book;
 
 use crate::dummy_book::{assert_contains_strings, assert_doesnt_contain_strings, DummyBook};
 
+use anyhow::Context;
 use mdbook::config::Config;
 use mdbook::errors::*;
 use mdbook::utils::fs::write_file;
@@ -247,13 +248,13 @@ fn entry_ends_with(entry: &DirEntry, ending: &str) -> bool {
 fn root_index_html() -> Result<Document> {
     let temp = DummyBook::new()
         .build()
-        .chain_err(|| "Couldn't create the dummy book")?;
+        .with_context(|| "Couldn't create the dummy book")?;
     MDBook::load(temp.path())?
         .build()
-        .chain_err(|| "Book building failed")?;
+        .with_context(|| "Book building failed")?;
 
     let index_page = temp.path().join("book").join("index.html");
-    let html = fs::read_to_string(&index_page).chain_err(|| "Unable to read index.html")?;
+    let html = fs::read_to_string(&index_page).with_context(|| "Unable to read index.html")?;
 
     Ok(Document::from(html.as_str()))
 }

tests/searchindex_fixture.json

@@ -6350,6 +6350,7 @@
         }
       }
     },
+    "lang": "English",
     "pipeline": [
       "trimmer",
       "stopWordFilter",