Copied across the summary parser and Book structure (doesn't compile)

src/book/book.rs

@@ -0,0 +1,392 @@
+use std::fmt::{self, Display, Formatter};
+use std::path::{Path, PathBuf};
+use std::collections::VecDeque;
+use std::fs::File;
+use std::io::{Read, Write};
+
+use super::summary::{parse_summary, Summary, Link, SummaryItem, SectionNumber};
+use errors::*;
+
+
+/// Load a book into memory from its `src/` directory.
+pub fn load_book<P: AsRef<Path>>(src_dir: P, create_if_not_present: bool) -> Result<Book> {
+    let src_dir = src_dir.as_ref();
+    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")?
+        .read_to_string(&mut summary_content)?;
+
+    let summary = parse_summary(&summary_content).chain_err(|| "Summary parsing failed")?;
+
+    load_book_from_disk(&summary, src_dir, create_if_not_present)
+}
+
+
+/// A dumb tree structure representing a book.
+///
+/// For the moment a book is just a collection of `BookItems`.
+#[derive(Debug, Clone, Default, PartialEq, Serialize, Deserialize)]
+pub struct Book {
+    /// The sections in this book.
+    pub sections: Vec<BookItem>,
+}
+
+impl Book {
+    /// Create an empty book.
+    pub fn new() -> Self {
+        Default::default()
+    }
+
+    /// Get a depth-first iterator over the items in the book.
+    pub fn iter(&self) -> BookItems {
+        BookItems { items: self.sections.iter().collect() }
+    }
+}
+
+/// Enum representing any type of item which can be added to a book.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum BookItem {
+    /// A nested chapter.
+    Chapter(Chapter),
+    /// A section separator.
+    Separator,
+}
+
+/// The representation of a "chapter", usually mapping to a single file on
+/// disk however it may contain multiple sub-chapters.
+#[derive(Debug, Clone, Default, PartialEq, Serialize, Deserialize)]
+pub struct Chapter {
+    /// The chapter's name.
+    pub name: String,
+    /// The chapter's contents.
+    pub content: String,
+    /// The chapter's section number, if it has one.
+    pub number: Option<SectionNumber>,
+    /// Nested items.
+    pub sub_items: Vec<BookItem>,
+    /// The chapter's location, relative to the `SUMMARY.md` file.
+    pub path: PathBuf,
+}
+
+impl Chapter {
+    /// Create a new chapter with the provided content.
+    pub fn new<P: Into<PathBuf>>(name: &str, content: String, path: P) -> Chapter {
+        Chapter {
+            name: name.to_string(),
+            content: content,
+            path: path.into(),
+            ..Default::default()
+        }
+    }
+}
+
+/// 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, create_if_not_present: bool) -> Result<Book> {
+    debug!("[*] Loading the book from disk");
+    let src_dir = src_dir.as_ref();
+
+    let prefix = summary.prefix_chapters.iter();
+    let numbered = summary.numbered_chapters.iter();
+    let suffix = summary.suffix_chapters.iter();
+
+    let summary_items = prefix.chain(numbered).chain(suffix);
+
+    let mut chapters = Vec::new();
+
+    for summary_item in summary_items {
+        let chapter = load_summary_item(summary_item, src_dir, create_if_not_present)?;
+        chapters.push(chapter);
+    }
+
+    Ok(Book { sections: chapters })
+}
+
+fn load_summary_item<P: AsRef<Path>>(item: &SummaryItem, src_dir: P, create_if_not_present: bool) -> Result<BookItem> {
+    match *item {
+        SummaryItem::Separator => Ok(BookItem::Separator),
+        SummaryItem::Link(ref link) => {
+            let file = src_dir.as_ref().join(&link.location);
+
+            if create_if_not_present && !file.exists() {
+                let text = format!("# {}", link.name);
+                File::create(&file)?.write_all(text.as_bytes())?;
+            }
+
+            load_chapter(link, src_dir).map(|c| BookItem::Chapter(c))
+        },
+    }
+}
+
+fn load_chapter<P: AsRef<Path>>(link: &Link, src_dir: P) -> 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()
+    } else {
+        src_dir.join(&link.location)
+    };
+
+    let mut f = File::open(&location).chain_err(|| {
+        format!("Chapter file not found, {}", link.location.display())
+    })?;
+
+    let mut content = String::new();
+    f.read_to_string(&mut content)?;
+
+    let stripped = location.strip_prefix(&src_dir).expect("Chapters are always inside a book");
+
+    let mut ch = Chapter::new(&link.name, content, stripped);
+    ch.number = link.number.clone();
+
+    let sub_items = link.nested_items
+        .iter()
+        .map(|i| load_summary_item(i, src_dir, false))
+        .collect::<Result<Vec<_>>>()?;
+
+    ch.sub_items = sub_items;
+
+    Ok(ch)
+}
+
+/// A depth-first iterator over the items in a book.
+///
+/// # Note
+///
+/// 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>,
+}
+
+impl<'a> Iterator for BookItems<'a> {
+    type Item = &'a BookItem;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let item = self.items.pop_front();
+
+        if let Some(&BookItem::Chapter(ref 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);
+            }
+        }
+
+        item
+    }
+}
+
+impl Display for Chapter {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        if let Some(ref section_number) = self.number {
+            write!(f, "{} ", section_number)?;
+        }
+
+        write!(f, "{}", self.name)
+    }
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tempdir::TempDir;
+    use std::io::Write;
+    use std::fs;
+
+    const DUMMY_SRC: &'static str = "
+# Dummy Chapter
+
+this is some dummy text.
+
+And here is some more text.
+";
+
+    /// Create a dummy `Link` in a temporary directory.
+    fn dummy_link() -> (Link, TempDir) {
+        let temp = TempDir::new("book").unwrap();
+
+        let chapter_path = temp.path().join("chapter_1.md");
+        File::create(&chapter_path)
+            .unwrap()
+            .write(DUMMY_SRC.as_bytes())
+            .unwrap();
+
+        let link = Link::new("Chapter 1", chapter_path);
+
+        (link, temp)
+    }
+
+    /// Create a nested `Link` written to a temporary directory.
+    fn nested_links() -> (Link, TempDir) {
+        let (mut root, temp_dir) = dummy_link();
+
+        let second_path = temp_dir.path().join("second.md");
+
+        File::create(&second_path)
+            .unwrap()
+            .write_all("Hello World!".as_bytes())
+            .unwrap();
+
+
+        let mut second = Link::new("Nested Chapter 1", &second_path);
+        second.number = Some(SectionNumber(vec![1, 2]));
+
+        root.nested_items.push(second.clone().into());
+        root.nested_items.push(SummaryItem::Separator);
+        root.nested_items.push(second.clone().into());
+
+        (root, temp_dir)
+    }
+
+    #[test]
+    fn load_a_single_chapter_from_disk() {
+        let (link, temp_dir) = dummy_link();
+        let should_be = Chapter::new("Chapter 1", DUMMY_SRC.to_string(), "chapter_1.md");
+
+        let got = load_chapter(&link, temp_dir.path()).unwrap();
+        assert_eq!(got, should_be);
+    }
+
+    #[test]
+    fn cant_load_a_nonexistent_chapter() {
+        let link = Link::new("Chapter 1", "/foo/bar/baz.md");
+
+        let got = load_chapter(&link, "");
+        assert!(got.is_err());
+    }
+
+    #[test]
+    fn load_recursive_link_with_separators() {
+        let (root, temp) = nested_links();
+
+        let nested = Chapter {
+            name: String::from("Nested Chapter 1"),
+            content: String::from("Hello World!"),
+            number: Some(SectionNumber(vec![1, 2])),
+            path: PathBuf::from("second.md"),
+            sub_items: Vec::new(),
+        };
+        let should_be = BookItem::Chapter(Chapter {
+            name: String::from("Chapter 1"),
+            content: String::from(DUMMY_SRC),
+            number: None,
+            path: PathBuf::from("chapter_1.md"),
+            sub_items: vec![
+                BookItem::Chapter(nested.clone()),
+                BookItem::Separator,
+                BookItem::Chapter(nested.clone()),
+            ],
+        });
+
+        let got = load_summary_item(&SummaryItem::Link(root), temp.path(), false).unwrap();
+        assert_eq!(got, should_be);
+    }
+
+    #[test]
+    fn load_a_book_with_a_single_chapter() {
+        let (link, temp) = dummy_link();
+        let summary = Summary {
+            numbered_chapters: vec![SummaryItem::Link(link)],
+            ..Default::default()
+        };
+        let should_be = Book {
+            sections: vec![
+                BookItem::Chapter(Chapter {
+                    name: String::from("Chapter 1"),
+                    content: String::from(DUMMY_SRC),
+                    path: PathBuf::from("chapter_1.md"),
+                    ..Default::default()
+                }),
+            ],
+        };
+
+        let got = load_book_from_disk(&summary, temp.path(), false).unwrap();
+
+        assert_eq!(got, should_be);
+    }
+
+    #[test]
+    fn book_iter_iterates_over_sequential_items() {
+        let book = Book {
+            sections: vec![
+                BookItem::Chapter(Chapter {
+                    name: String::from("Chapter 1"),
+                    content: String::from(DUMMY_SRC),
+                    ..Default::default()
+                }),
+                BookItem::Separator,
+            ],
+        };
+
+        let should_be: Vec<_> = book.sections.iter().collect();
+
+        let got: Vec<_> = book.iter().collect();
+
+        assert_eq!(got, should_be);
+    }
+
+    #[test]
+    fn iterate_over_nested_book_items() {
+        let book = Book {
+            sections: vec![
+                BookItem::Chapter(Chapter {
+                    name: String::from("Chapter 1"),
+                    content: String::from(DUMMY_SRC),
+                    number: None,
+                    path: PathBuf::from("Chapter_1/index.md"),
+                    sub_items: vec![
+                        BookItem::Chapter(Chapter::new("Hello World", String::new(), "Chapter_1/hello.md")),
+                        BookItem::Separator,
+                        BookItem::Chapter(Chapter::new("Goodbye World", String::new(), "Chapter_1/goodbye.md")),
+                    ],
+                }),
+                BookItem::Separator,
+            ],
+        };
+
+
+        let got: Vec<_> = book.iter().collect();
+
+        assert_eq!(got.len(), 5);
+
+        // checking the chapter names are in the order should be sufficient here...
+        let chapter_names: Vec<String> = got.into_iter()
+            .filter_map(|i| match *i {
+                BookItem::Chapter(ref ch) => Some(ch.name.clone()),
+                _ => None,
+            })
+            .collect();
+        let should_be: Vec<_> = vec![
+            String::from("Chapter 1"),
+            String::from("Hello World"),
+            String::from("Goodbye World"),
+        ];
+
+        assert_eq!(chapter_names, should_be);
+    }
+
+    #[test]
+    fn create_missing_book_items() {
+        let (link, temp) = dummy_link();
+        let summary = Summary {
+            numbered_chapters: vec![SummaryItem::Link(link)],
+            ..Default::default()
+        };
+
+        let chapter_1 = temp.path().join("chapter_1.md");
+        fs::remove_file(&chapter_1).unwrap();
+        assert!(!chapter_1.exists());
+
+        load_book_from_disk(&summary, temp.path(), true).unwrap();
+
+        assert!(chapter_1.exists());
+    }
+}

src/book/bookitem.rs

@@ -1,86 +0,0 @@
-use serde::{Serialize, Serializer};
-use serde::ser::SerializeStruct;
-use std::path::PathBuf;
-
-
-#[derive(Debug, Clone)]
-pub enum BookItem {
-    Chapter(String, Chapter), // String = section
-    Affix(Chapter),
-    Spacer,
-}
-
-#[derive(Debug, Clone)]
-pub struct Chapter {
-    pub name: String,
-    pub path: PathBuf,
-    pub sub_items: Vec<BookItem>,
-}
-
-#[derive(Debug, Clone)]
-pub struct BookItems<'a> {
-    pub items: &'a [BookItem],
-    pub current_index: usize,
-    pub stack: Vec<(&'a [BookItem], usize)>,
-}
-
-
-impl Chapter {
-    pub fn new(name: String, path: PathBuf) -> Self {
-        Chapter {
-            name: name,
-            path: path,
-            sub_items: vec![],
-        }
-    }
-}
-
-
-impl Serialize for Chapter {
-    fn serialize<S>(&self, serializer: S) -> ::std::result::Result<S::Ok, S::Error>
-    where
-        S: Serializer,
-    {
-        let mut struct_ = serializer.serialize_struct("Chapter", 2)?;
-        struct_.serialize_field("name", &self.name)?;
-        struct_.serialize_field("path", &self.path)?;
-        struct_.end()
-    }
-}
-
-
-
-// Shamelessly copied from Rustbook
-// (https://github.com/rust-lang/rust/blob/master/src/rustbook/book.rs)
-impl<'a> Iterator for BookItems<'a> {
-    type Item = &'a BookItem;
-
-    fn next(&mut self) -> Option<&'a BookItem> {
-        loop {
-            if self.current_index >= self.items.len() {
-                match self.stack.pop() {
-                    None => return None,
-                    Some((parent_items, parent_idx)) => {
-                        self.items = parent_items;
-                        self.current_index = parent_idx + 1;
-                    }
-                }
-            } else {
-                let cur = &self.items[self.current_index];
-
-                match *cur {
-                    BookItem::Chapter(_, ref ch) | BookItem::Affix(ref ch) => {
-                        self.stack.push((self.items, self.current_index));
-                        self.items = &ch.sub_items[..];
-                        self.current_index = 0;
-                    }
-                    BookItem::Spacer => {
-                        self.current_index += 1;
-                    }
-                }
-
-                return Some(cur);
-            }
-        }
-    }
-}

src/book/summary.rs

@@ -0,0 +1,718 @@
+use std::fmt::{self, Formatter, Display};
+use std::ops::{Deref, DerefMut};
+use std::path::{Path, PathBuf};
+use pulldown_cmark::{self, Event, Tag};
+use errors::*;
+
+
+/// Parse the text from a `SUMMARY.md` file into a sort of "recipe" to be
+/// used when loading a book from disk.
+///
+/// # Summary Format
+///
+/// **Title:** It's common practice to begin with a title, generally
+/// "# Summary". But it is not mandatory, the parser just ignores it. So you
+/// can too if you feel like it.
+///
+/// **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)
+/// ```
+///
+/// **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.
+///
+/// **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.
+pub fn parse_summary(summary: &str) -> Result<Summary> {
+    let parser = SummaryParser::new(summary);
+    parser.parse()
+}
+
+/// The parsed `SUMMARY.md`, specifying how the book should be laid out.
+#[derive(Debug, Clone, Default, PartialEq, Serialize, Deserialize)]
+pub struct Summary {
+    /// An optional title for the `SUMMARY.md`, currently just ignored.
+    pub title: Option<String>,
+    /// Chapters before the main text (e.g. an introduction).
+    pub prefix_chapters: Vec<SummaryItem>,
+    /// The main chapters in the document.
+    pub numbered_chapters: Vec<SummaryItem>,
+    /// Items which come after the main document (e.g. a conclusion).
+    pub suffix_chapters: Vec<SummaryItem>,
+}
+
+/// A struct representing an entry in the `SUMMARY.md`, possibly with nested
+/// entries.
+///
+/// This is roughly the equivalent of `[Some section](./path/to/file.md)`.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct Link {
+    /// The name of the chapter.
+    pub name: String,
+    /// The location of the chapter's source file, taking the book's `src`
+    /// directory as the root.
+    pub location: PathBuf,
+    /// The section number, if this chapter is in the numbered section.
+    pub number: Option<SectionNumber>,
+    /// Any nested items this chapter may contain.
+    pub nested_items: Vec<SummaryItem>,
+}
+
+impl Link {
+    /// Create a new link with no nested items.
+    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(),
+            number: None,
+            nested_items: Vec::new(),
+        }
+    }
+}
+
+impl Default for Link {
+    fn default() -> Self {
+        Link {
+            name: String::new(),
+            location: PathBuf::new(),
+            number: None,
+            nested_items: Vec::new(),
+        }
+    }
+}
+
+/// An item in `SUMMARY.md` which could be either a separator or a `Link`.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum SummaryItem {
+    /// A link to a chapter.
+    Link(Link),
+    /// A separator (`---`).
+    Separator,
+}
+
+impl SummaryItem {
+    fn maybe_link_mut(&mut self) -> Option<&mut Link> {
+        match *self {
+            SummaryItem::Link(ref mut l) => Some(l),
+            _ => None,
+        }
+    }
+}
+
+impl From<Link> for SummaryItem {
+    fn from(other: Link) -> SummaryItem {
+        SummaryItem::Link(other)
+    }
+}
+
+#[derive(Debug, Copy, Clone, PartialEq)]
+enum State {
+    Begin,
+    PrefixChapters,
+    /// Numbered chapters, including the nesting level.
+    NumberedChapters(u32),
+    SuffixChapters,
+    End,
+}
+
+/// A state machine parser for parsing a `SUMMARY.md` file.
+///
+/// The parser has roughly 5 states,
+///
+/// - **Begin:** the initial state
+/// - **Prefix Chapters:** Parsing the prefix chapters
+/// - **Numbered Chapters:** Parsing the numbered chapters, using a `usize` to
+///   indicate the nesting level (because chapters can have sub-chapters)
+/// - **Suffix Chapters:** pretty much identical to the Prefix Chapters
+/// - **End:** The final state
+///
+/// The `parse()` method then continually invokes `step()` until it reaches the
+/// `End` state. Parsing is guaranteed to (eventually) finish because the next
+/// `Event` is read from the underlying `pulldown_cmark::Parser` and passed
+/// into the current state's associated method.
+///
+///
+/// # Grammar
+///
+/// The `SUMMARY.md` file has a grammar which looks something like this:
+///
+/// ```text
+/// summary           ::= title prefix_chapters numbered_chapters
+/// suffix_chapters
+/// title             ::= "# " TEXT
+///                     | EPSILON
+/// prefix_chapters   ::= item*
+/// suffix_chapters   ::= item*
+/// numbered_chapters ::= dotted_item+
+/// dotted_item       ::= INDENT* DOT_POINT item
+/// item              ::= link
+///                     | separator
+/// separator         ::= "---"
+/// link              ::= "[" TEXT "]" "(" TEXT ")"
+/// DOT_POINT         ::= "-"
+///                     | "*"
+/// ```
+///
+/// > **Note:** the `TEXT` terminal is "normal" text, and should (roughly)
+/// > match the following regex: "[^<>\n[]]+".
+struct SummaryParser<'a> {
+    stream: pulldown_cmark::Parser<'a>,
+    summary: Summary,
+    state: State,
+}
+
+/// 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 != $delimeter).collect()` but it allows you to
+/// use pattern matching and you won't get errors because `take_while()`
+/// moves `$stream` out of self.
+macro_rules! collect_events {
+    ($stream:expr, $delimiter:pat) => {
+        {
+            let mut events = Vec::new();
+
+            loop {
+                let event = $stream.next();
+                match event {
+                    Some(Event::End($delimiter)) => break,
+                    Some(other) => events.push(other),
+                    None => {
+                        debug!("Reached end of stream without finding the closing pattern, {}", stringify!($delimiter));
+                        break;
+                    }
+                }
+            }
+
+            events
+        }
+    }
+}
+
+impl<'a> SummaryParser<'a> {
+    fn new(text: &str) -> SummaryParser {
+        let pulldown_parser = pulldown_cmark::Parser::new(text);
+        let intermediate_summary = Summary::default();
+
+        SummaryParser {
+            stream: pulldown_parser,
+            summary: intermediate_summary,
+            state: State::Begin,
+        }
+    }
+
+    /// Parse the text the `SummaryParser` was created with.
+    fn parse(mut self) -> Result<Summary> {
+        self.summary.title = self.parse_title();
+
+        if let Some(ref title) = self.summary.title {
+            debug!("[*] Title is {:?}", title);
+        }
+
+        while self.state != State::End {
+            self.step()?;
+        }
+
+        Ok(self.summary)
+    }
+
+    fn step(&mut self) -> Result<()> {
+        if let Some(next_event) = self.stream.next() {
+            trace!("[*] Current state: {:?}, next event: {:?}", self.state, next_event);
+
+            match self.state {
+                State::Begin => self.step_start(next_event)?,
+                State::PrefixChapters | State::SuffixChapters => self.step_affix(next_event)?,
+                State::NumberedChapters(_) => self.step_numbered(next_event)?,
+                State::End => {},
+            }
+        } else {
+            trace!("[*] Reached end of SUMMARY.md");
+            self.state = State::End;
+        }
+
+        Ok(())
+    }
+
+    /// The very first state, we should see a `Begin Paragraph` token or
+    /// it's an error...
+    fn step_start(&mut self, event: Event<'a>) -> Result<()> {
+        match event {
+            Event::Start(Tag::Paragraph) => self.state = State::PrefixChapters,
+            Event::Start(Tag::List(_)) => self.state = State::NumberedChapters(0),
+            other => bail!("Expected a start of paragraph but got {:?}", other),
+        }
+
+        Ok(())
+    }
+
+    /// Try to step through an "affix" section (recognising prefix and suffix 
+    /// chapters).
+    ///
+    /// If we encounter a link or horizontal line, it'll get added to the 
+    /// section. If we encounter a list, we'll either change to 
+    /// `State::NumberedChapter` (for prefix) or throw an error (suffix chapters).
+    ///
+    /// Anything else will be ignored.
+    fn step_affix(&mut self, event: Event<'a>) -> Result<()> {
+
+        match event {
+            Event::Start(tag) => self.handle_start_tag_in_affix_chapter(tag)?,
+            Event::End(Tag::Rule) => {
+                debug!("[*] Found an affix chapter separator");
+                self.affix_chapter_list().push(SummaryItem::Separator);
+            },
+            other => {
+                trace!("[*] Skipping unexpected token in summary: {:?}", other);
+            },
+        }
+
+        Ok(())
+    }
+
+    /// A helper function to get the `SummaryItem` list we should add items to
+    /// when parsing an affix chapter (i.e. prefix or suffix chapters). 
+    fn affix_chapter_list(&mut self) -> &mut Vec<SummaryItem> {
+        match self.state {
+            State::PrefixChapters => &mut self.summary.prefix_chapters,
+            State::SuffixChapters => &mut self.summary.suffix_chapters,
+            other => panic!("affix_chapter_list() called with invalid state: {:?}", other),
+        }
+    }
+
+    fn handle_start_tag_in_affix_chapter(&mut self, tag: Tag) -> Result<()> {
+        match tag {
+                Tag::Link(location, _) => {
+                    let content = collect_events!(self.stream, Tag::Link(_, _));
+                    let text = stringify_events(content);
+                    let link = Link::new(text, location.as_ref());
+
+                    debug!("[*] Found an affix chapter: {:?}", link.name);
+                    self.affix_chapter_list().push(SummaryItem::Link(link));
+                },
+                Tag::List(_) => {
+                    match self.state {
+                        State::PrefixChapters => {
+                            debug!("[*] Changing from prefix chapters to numbered chapters");
+                            self.state = State::NumberedChapters(0);
+                        },
+                        State::SuffixChapters => bail!("Suffix chapters can't be followed by a list"),
+                        _ => unreachable!(),
+                    }
+                },
+                other => trace!("[*] Skipping unknown start tag while parsing affix chapters: {:?}", other),
+        }
+
+        Ok(())
+    }
+
+    /// Parse the numbered chapters.
+    ///
+    /// If the event is the start of a list item, consume the entire item and
+    /// add a new link to the summary with `push_numbered_section`.
+    ///
+    /// If the event is the start of a new list, bump the nesting level.
+    ///
+    /// If the event is the end of a list, decrement the nesting level. When
+    /// the nesting level would go negative, we've finished the numbered
+    /// section and need to parse the suffix section.
+    ///
+    /// Otherwise, ignore the event.
+    fn step_numbered(&mut self, event: Event) -> Result<()> {
+        match event {
+            Event::Start(Tag::Item) => {
+                let it = self.parse_item().chain_err(
+                    || "List items should only contain links",
+                )?;
+
+                debug!("[*] Found a chapter: {:?} ({})", it.name, it.location.display());
+                let section_number = self.push_numbered_section(SummaryItem::Link(it));
+                trace!("[*] Section number is {}", section_number);
+            },
+            Event::End(Tag::Rule) => {
+                debug!("[*] Found a numbered chapter separator");
+                self.summary.numbered_chapters.push(SummaryItem::Separator);
+                self.state = State::NumberedChapters(0);
+            },
+            Event::Start(Tag::List(_)) => {
+                if let State::NumberedChapters(n) = self.state {
+                    self.state = State::NumberedChapters(n + 1);
+                    trace!("[*] Nesting level increased to {}", n + 1);
+                }
+            },
+            Event::End(Tag::List(_)) => {
+                if let State::NumberedChapters(n) = self.state {
+                    if n == 0 {
+                        trace!("[*] Finished parsing the numbered chapters");
+                        self.state = State::SuffixChapters;
+                    } else {
+                        trace!("[*] Nesting level decreased to {}", n - 1);
+                        self.state = State::NumberedChapters(n - 1);
+                    }
+                }
+            },
+            other => {
+                trace!("[*] skipping unexpected token: {:?}", other);
+            },
+        }
+
+        Ok(())
+    }
+
+    /// Parse a single item (`[Some Chapter Name](./path/to/chapter.md)`).
+    fn parse_item(&mut self) -> Result<Link> {
+        let next = self.stream.next();
+
+        if let Some(Event::Start(Tag::Link(dest, _))) = next {
+            let content = collect_events!(self.stream, Tag::Link(..));
+
+            Ok(Link::new(stringify_events(content), dest.as_ref()))
+        } else {
+            bail!("Expected a link, got {:?}", next)
+        }
+    }
+
+    /// Try to parse the title line.
+    fn parse_title(&mut self) -> Option<String> {
+        if let Some(Event::Start(Tag::Header(1))) = self.stream.next() {
+            debug!("[*] Found a h1 in the SUMMARY");
+
+            let tags = collect_events!(self.stream, Tag::Header(1));
+
+            // TODO: How do we deal with headings like "# My **awesome** summary"?
+            // for now, I'm just going to scan through and concatenate the
+            // Event::Text tags, skipping any styling.
+            Some(stringify_events(tags))
+        } else {
+            None
+        }
+    }
+
+    /// Push a new section at the end of the current nesting level.
+    fn push_numbered_section(&mut self, item: SummaryItem) -> SectionNumber {
+        if let State::NumberedChapters(level) = self.state {
+            push_item_at_nesting_level(
+                &mut self.summary.numbered_chapters,
+                item,
+                level as usize,
+                SectionNumber::default(),
+            ).chain_err(|| {
+                format!("The parser should always ensure we add the next \
+                item at the correct level ({}:{})", module_path!(), line!())
+            })
+                .unwrap()
+        } else {
+            // this method should only ever be called when parsing a numbered
+            // section, therefore if we ever get here something has gone
+            // hideously wrong...
+            error!("Calling push_numbered_section() when not in a numbered section");
+            error!("Current state: {:?}", self.state);
+            error!("Item: {:?}", item);
+            error!("Summary:");
+            error!("{:#?}", self.summary);
+            panic!("Entered unreachable code, this is a bug");
+        }
+    }
+}
+
+/// Given a particular level (e.g. 3), go that many levels down the `Link`'s
+/// nested items then append the provided item to the last `Link` in the
+/// list.
+fn push_item_at_nesting_level(links: &mut Vec<SummaryItem>, mut item: SummaryItem, level: usize, mut section_number: SectionNumber)
+    -> Result<SectionNumber> {
+    if level == 0 {
+        // set the section number, if applicable
+        section_number.push(links.len() as u32 + 1);
+
+        if let SummaryItem::Link(ref mut l) = item {
+            l.number = Some(section_number.clone());
+        }
+
+        links.push(item);
+        Ok(section_number)
+    } else {
+        let (index, last_link) = get_last_link(links).chain_err(|| {
+            format!("The list of links needs to be {} levels deeper (current position {})", 
+                level, section_number)
+        })?;
+
+        section_number.push(index as u32 + 1);
+        push_item_at_nesting_level(&mut last_link.nested_items, item, level - 1, section_number)
+    }
+}
+
+/// Gets a pointer to the last `Link` in a list of `SummaryItem`s, and its
+/// index.
+fn get_last_link(links: &mut [SummaryItem]) -> Result<(usize, &mut Link)> {
+    // TODO: This should probably be integrated into `Link::push_item()`
+    links
+        .iter_mut()
+        .enumerate()
+        .filter_map(|(i, item)| item.maybe_link_mut().map(|l| (i, l)))
+        .rev()
+        .next()
+        .ok_or_else(|| "The list of SummaryItems doesn't contain any Links".into())
+}
+
+
+/// Removes the styling from a list of Markdown events and returns just the
+/// plain text.
+fn stringify_events(events: Vec<Event>) -> String {
+    events
+        .into_iter()
+        .filter_map(|t| match t {
+            Event::Text(text) => Some(text.into_owned()),
+            _ => None,
+        })
+        .collect()
+}
+
+/// A section number like "1.2.3", basically just a newtype'd `Vec<u32>` with
+/// a pretty `Display` impl.
+#[derive(Debug, PartialEq, Clone, Default, Serialize, Deserialize)]
+pub struct SectionNumber(pub Vec<u32>);
+
+impl Display for SectionNumber {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        for item in &self.0 {
+            write!(f, "{}.", item)?;
+        }
+        Ok(())
+    }
+}
+
+impl Deref for SectionNumber {
+    type Target = Vec<u32>;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl DerefMut for SectionNumber {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn section_number_has_correct_dotted_representation() {
+        let inputs = vec![
+            (vec![0], "0."),
+            (vec![1, 3], "1.3."),
+            (vec![1, 2, 3], "1.2.3."),
+        ];
+
+        for (input, should_be) in inputs {
+            let section_number = SectionNumber(input).to_string();
+            assert_eq!(section_number, should_be);
+        }
+    }
+
+    #[test]
+    fn parse_initial_title() {
+        let src = "# Summary";
+        let should_be = String::from("Summary");
+
+        let mut parser = SummaryParser::new(src);
+        let got = parser.parse_title().unwrap();
+
+        assert_eq!(got, should_be);
+    }
+
+    #[test]
+    fn parse_title_with_styling() {
+        let src = "# My **Awesome** Summary";
+        let should_be = String::from("My Awesome Summary");
+
+        let mut parser = SummaryParser::new(src);
+        let got = parser.parse_title().unwrap();
+
+        assert_eq!(got, should_be);
+    }
+
+    #[test]
+    fn parse_a_single_item() {
+        let src = "[A Chapter](./path/to/chapter)";
+        let should_be = Link {
+            name: String::from("A Chapter"),
+            location: PathBuf::from("./path/to/chapter"),
+            number: None,
+            nested_items: Vec::new(),
+        };
+
+        let mut parser = SummaryParser::new(src);
+        let _ = parser.stream.next(); // skip the opening paragraph tag
+        let got = parser.parse_item().unwrap();
+
+        assert_eq!(got, should_be);
+    }
+
+    #[test]
+    fn convert_markdown_events_to_a_string() {
+        let src = "Hello *World*, `this` is some text [and a link](./path/to/link)";
+        let should_be = "Hello World, this is some text and a link";
+
+        let events = pulldown_cmark::Parser::new(src).collect();
+        let got = stringify_events(events);
+
+        assert_eq!(got, should_be);
+
+    }
+
+    #[test]
+    fn can_step_past_first_token() {
+        let src = "hello world";
+        let should_be = State::PrefixChapters;
+
+        let mut parser = SummaryParser::new(src);
+        assert_eq!(parser.state, State::Begin);
+        parser.step().unwrap();
+        assert_eq!(parser.state, should_be);
+    }
+
+    #[test]
+    fn first_token_must_be_open_paragraph() {
+        let src = "hello world";
+
+        let mut parser = SummaryParser::new(src);
+        let _ = parser.stream.next(); // manually step past the Start Paragraph
+        assert!(parser.step().is_err());
+    }
+
+    #[test]
+    fn can_parse_prefix_chapter_links() {
+        let src = "[Hello World](./foo/bar/baz)";
+        let should_be = Link {
+            name: String::from("Hello World"),
+            location: PathBuf::from("./foo/bar/baz"),
+            number: None,
+            nested_items: Vec::new(),
+        };
+
+        let mut parser = SummaryParser::new(src);
+        parser.state = State::PrefixChapters;
+        assert!(parser.summary.prefix_chapters.is_empty());
+
+        let _ = parser.stream.next(); // manually step past the Start Paragraph
+        parser.step().unwrap();
+
+        assert_eq!(parser.summary.prefix_chapters.len(), 1);
+        assert_eq!(parser.summary.prefix_chapters[0], SummaryItem::Link(should_be));
+        assert_eq!(parser.state, State::PrefixChapters);
+    }
+
+    #[test]
+    fn can_parse_prefix_chapter_horizontal_rules() {
+        let src = "---";
+        let should_be = SummaryItem::Separator;
+
+        let mut parser = SummaryParser::new(src);
+        parser.state = State::PrefixChapters;
+        assert!(parser.summary.prefix_chapters.is_empty());
+
+        let _ = parser.stream.next(); // manually step past the Start Paragraph
+        parser.step().unwrap();
+
+        assert_eq!(parser.summary.prefix_chapters.len(), 1);
+        assert_eq!(parser.summary.prefix_chapters[0], should_be);
+        assert_eq!(parser.state, State::PrefixChapters);
+    }
+
+    #[test]
+    fn step_from_prefix_chapters_to_numbered() {
+        let src = "- foo";
+
+        let mut parser = SummaryParser::new(src);
+        parser.state = State::PrefixChapters;
+
+        // let _ = parser.stream.next(); // manually step past the Start Paragraph
+        parser.step().unwrap();
+
+        assert_eq!(parser.state, State::NumberedChapters(0));
+    }
+
+    #[test]
+    fn push_item_onto_empty_link() {
+        let root = Link::new("First", "/");
+        let mut links = vec![SummaryItem::Link(root)];
+
+        assert_eq!(links[0].maybe_link_mut().unwrap().nested_items.len(), 0);
+        let got = push_item_at_nesting_level(&mut links, SummaryItem::Separator, 1, SectionNumber::default()).unwrap();
+        assert_eq!(links[0].maybe_link_mut().unwrap().nested_items.len(), 1);
+        assert_eq!(*got, vec![1, 1]);
+    }
+
+    #[test]
+    fn push_item_onto_complex_link() {
+        let mut root = Link::new("First", "/first");
+        root.nested_items.push(SummaryItem::Separator);
+
+        let mut child = Link::new("Second", "/first/second");
+        child.nested_items.push(SummaryItem::Link(
+            Link::new("Third", "/first/second/third"),
+        ));
+        root.nested_items.push(SummaryItem::Link(child));
+        root.nested_items.push(SummaryItem::Separator);
+
+        let mut links = vec![SummaryItem::Link(root)];
+
+        // FIXME: This crap for getting a deeply nested member is just plain ugly :(
+        assert_eq!(links[0].maybe_link_mut().unwrap()
+            .nested_items[1].maybe_link_mut()
+            .unwrap()
+            .nested_items[0].maybe_link_mut()
+            .unwrap()
+            .nested_items.len() , 0);
+        let got = push_item_at_nesting_level(
+            &mut links,
+            SummaryItem::Link(Link::new("Dummy", "")),
+            3,
+            SectionNumber::default(),
+        ).unwrap();
+        assert_eq!(links[0].maybe_link_mut().unwrap()
+            .nested_items[1].maybe_link_mut()
+            .unwrap()
+            .nested_items[0].maybe_link_mut()
+            .unwrap()
+            .nested_items.len() , 1);
+        println!("{:#?}", links);
+        assert_eq!(*got, vec![1, 2, 1, 1]);
+    }
+
+    #[test]
+    fn parse_a_numbered_chapter() {
+        let src = "- [First](./second)";
+        let mut parser = SummaryParser::new(src);
+        let _ = parser.stream.next();
+
+        assert_eq!(parser.summary.numbered_chapters.len(), 0);
+
+        parser.state = State::NumberedChapters(0);
+        parser.step().unwrap();
+
+        assert_eq!(parser.summary.numbered_chapters.len(), 1);
+    }
+}

src/lib.rs

@@ -89,7 +89,6 @@ extern crate serde_json;
 extern crate tempdir;
 extern crate toml;
 
-mod parse;
 mod preprocess;
 pub mod book;
 pub mod config;

src/parse/mod.rs

@@ -1,3 +0,0 @@
-pub use self::summary::construct_bookitems;
-
-pub mod summary;

src/parse/summary.rs

@@ -1,239 +0,0 @@
-use std::path::PathBuf;
-use std::fs::File;
-use std::io::{Error, ErrorKind, Read, Result};
-use book::bookitem::{BookItem, Chapter};
-
-pub fn construct_bookitems(path: &PathBuf) -> Result<Vec<BookItem>> {
-    debug!("[fn]: construct_bookitems");
-    let mut summary = String::new();
-    File::open(path)?.read_to_string(&mut summary)?;
-
-    debug!("[*]: Parse SUMMARY.md");
-    let top_items = parse_level(&mut summary.split('\n').collect(), 0, vec![0])?;
-    debug!("[*]: Done parsing SUMMARY.md");
-    Ok(top_items)
-}
-
-fn parse_level(summary: &mut Vec<&str>,
-               current_level: i32,
-               mut section: Vec<i32>)
-               -> Result<Vec<BookItem>> {
-    debug!("[fn]: parse_level");
-    let mut items: Vec<BookItem> = vec![];
-
-    // Construct the book recursively
-    while !summary.is_empty() {
-        let item: BookItem;
-        // Indentation level of the line to parse
-        let level = level(summary[0], 4)?;
-
-        // if level < current_level we remove the last digit of section,
-        // exit the current function,
-        // and return the parsed level to the calling function.
-        if level < current_level {
-            break;
-        }
-
-        // if level > current_level we call ourselves to go one level deeper
-        if level > current_level {
-            // Level can not be root level !!
-            // Add a sub-number to section
-            section.push(0);
-            let last = items.pop().expect(
-                "There should be at least one item since this can't be the root level",
-            );
-
-            if let BookItem::Chapter(ref s, ref ch) = last {
-                let mut ch = ch.clone();
-                ch.sub_items = parse_level(summary, level, section.clone())?;
-                items.push(BookItem::Chapter(s.clone(), ch));
-
-                // Remove the last number from the section, because we got back to our level..
-                section.pop();
-                continue;
-            } else {
-                return Err(Error::new(
-                    ErrorKind::Other,
-                    "Your summary.md is messed up\n\n
-                        Prefix, \
-                                       Suffix and Spacer elements can only exist \
-                                       on the root level.\n
-                        \
-                                       Prefix elements can only exist before \
-                                       any chapter and there can be \
-                                       no chapters after suffix elements.",
-                ));
-            };
-        } else {
-            // level and current_level are the same, parse the line
-            item = if let Some(parsed_item) = parse_line(summary[0]) {
-                // Eliminate possible errors and set section to -1 after suffix
-                match parsed_item {
-                    // error if level != 0 and BookItem is != Chapter
-                    BookItem::Affix(_) | BookItem::Spacer if level > 0 => {
-                        return Err(Error::new(
-                            ErrorKind::Other,
-                            "Your summary.md is messed up\n\n
-                                \
-                                               Prefix, Suffix and Spacer elements \
-                                               can only exist on the root level.\n
-                                Prefix \
-                                               elements can only exist before any chapter and \
-                                               there can be no chapters after suffix elements.",
-                        ))
-                    }
-
-                    // error if BookItem == Chapter and section == -1
-                    BookItem::Chapter(_, _) if section[0] == -1 => {
-                        return Err(Error::new(
-                            ErrorKind::Other,
-                            "Your summary.md is messed up\n\n
-                                \
-                                               Prefix, Suffix and Spacer elements can only \
-                                               exist on the root level.\n
-                                Prefix \
-                                               elements can only exist before any chapter and \
-                                               there can be no chapters after suffix elements.",
-                        ))
-                    }
-
-                    // Set section = -1 after suffix
-                    BookItem::Affix(_) if section[0] > 0 => {
-                        section[0] = -1;
-                    }
-
-                    _ => {}
-                }
-
-                match parsed_item {
-                    BookItem::Chapter(_, ch) => {
-                        // Increment section
-                        let len = section.len() - 1;
-                        section[len] += 1;
-                        let s = section.iter()
-                                       .fold("".to_owned(), |s, i| s + &i.to_string() + ".");
-                        BookItem::Chapter(s, ch)
-                    }
-                    _ => parsed_item,
-                }
-            } else {
-                // If parse_line does not return Some(_) continue...
-                summary.remove(0);
-                continue;
-            };
-        }
-
-        summary.remove(0);
-        items.push(item)
-    }
-    debug!("[*]: Level: {:?}", items);
-    Ok(items)
-}
-
-
-fn level(line: &str, spaces_in_tab: i32) -> Result<i32> {
-    debug!("[fn]: level");
-    let mut spaces = 0;
-    let mut level = 0;
-
-    for ch in line.chars() {
-        match ch {
-            ' ' => spaces += 1,
-            '\t' => level += 1,
-            _ => break,
-        }
-        if spaces >= spaces_in_tab {
-            level += 1;
-            spaces = 0;
-        }
-    }
-
-    // If there are spaces left, there is an indentation error
-    if spaces > 0 {
-        debug!("[SUMMARY.md]:");
-        debug!("\t[line]: {}", line);
-        debug!("[*]: There is an indentation error on this line. Indentation should be {} spaces",
-               spaces_in_tab);
-        return Err(Error::new(ErrorKind::Other,
-                              format!("Indentation error on line:\n\n{}", line)));
-    }
-
-    Ok(level)
-}
-
-
-fn parse_line(l: &str) -> Option<BookItem> {
-    debug!("[fn]: parse_line");
-
-    // Remove leading and trailing spaces or tabs
-    let line = l.trim_matches(|c: char| c == ' ' || c == '\t');
-
-    // Spacers are "------"
-    if line.starts_with("--") {
-        debug!("[*]: Line is spacer");
-        return Some(BookItem::Spacer);
-    }
-
-    if let Some(c) = line.chars().nth(0) {
-        match c {
-            // List item
-            '-' | '*' => {
-                debug!("[*]: Line is list element");
-
-                if let Some((name, path)) = read_link(line) {
-                    return Some(BookItem::Chapter("0".to_owned(), Chapter::new(name, path)));
-                } else {
-                    return None;
-                }
-            }
-            // Non-list element
-            '[' => {
-                debug!("[*]: Line is a link element");
-
-                if let Some((name, path)) = read_link(line) {
-                    return Some(BookItem::Affix(Chapter::new(name, path)));
-                } else {
-                    return None;
-                }
-            }
-            _ => {}
-        }
-    }
-
-    None
-}
-
-fn read_link(line: &str) -> Option<(String, PathBuf)> {
-    let mut start_delimitor;
-    let mut end_delimitor;
-
-    // In the future, support for list item that is not a link
-    // Not sure if I should error on line I can't parse or just ignore them...
-    if let Some(i) = line.find('[') {
-        start_delimitor = i;
-    } else {
-        debug!("[*]: '[' not found, this line is not a link. Ignoring...");
-        return None;
-    }
-
-    if let Some(i) = line[start_delimitor..].find("](") {
-        end_delimitor = start_delimitor + i;
-    } else {
-        debug!("[*]: '](' not found, this line is not a link. Ignoring...");
-        return None;
-    }
-
-    let name = line[start_delimitor + 1..end_delimitor].to_owned();
-
-    start_delimitor = end_delimitor + 1;
-    if let Some(i) = line[start_delimitor..].find(')') {
-        end_delimitor = start_delimitor + i;
-    } else {
-        debug!("[*]: ')' not found, this line is not a link. Ignoring...");
-        return None;
-    }
-
-    let path = PathBuf::from(line[start_delimitor + 1..end_delimitor].to_owned());
-
-    Some((name, path))
-}