version 0.2.3

Fixing links in print.html

CONTRIBUTING.md

@@ -48,6 +48,54 @@ mdBook builds on stable Rust, if you want to build mdBook from source, here are
 
 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-nursery/rustfmt) has a lot more information on the project.
+The quick guide is
+
+1. Install it
+    ```
+    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 crate.
+
+For more information, such as running it from your favourite editor, please see the `rustfmt` project. [rustfmt](https://github.com/rust-lang-nursery/rustfmt)
+
+
+#### Finding Issues with Clippy
+
+Clippy is a code analyser/linter detecting mistakes, and therfore 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.
+
+The best documentation can be found over at [rust-clippy](https://github.com/rust-lang-nursery/rust-clippy)
+
+1. To install
+    ```
+    rustup component add clippy
+    ```
+2. Running clippy
+    ```
+    cargo clippy
+    ```
+
+Clippy has an ever growing list of checks, that are managed in [lint files](https://rust-lang-nursery.github.io/rust-clippy/master/index.html).
+
 ### Making a pull-request
 
 When you feel comfortable that your changes could be integrated into mdBook, you can create a pull-request on GitHub.

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mdbook"
-version = "0.2.2-alpha.0"
+version = "0.2.3"
 authors = [
     "Mathieu David <mathieudavid@mathieudavid.org>", 
     "Michael-F-Bryan <michaelfbryan@gmail.com>",
@@ -26,7 +26,7 @@ pulldown-cmark = "0.1.2"
 lazy_static = "1.0"
 log = "0.4"
 env_logger = "0.5"
-toml = "0.4"
+toml = "0.4.8"
 memchr = "2.0"
 open = "1.1"
 regex = "1.0.0"

README.md

@@ -145,6 +145,57 @@ explanation, check out the [User Guide].
 
     Delete directory in which generated book is located.
 
+### 3rd Party Plugins
+
+The way a book is loaded and rendered can be configured by the user via third
+party plugins. These plugins are just programs which will be invoked during the
+build process and are split into roughly two categories, *preprocessors* and
+*renderers*.
+
+Preprocessors are used to transform a book before it is sent to a renderer. 
+One example would be to replace all occurrences of 
+`{{#include some_file.ext}}` with the contents of that file. Some existing 
+preprocessors are:
+
+- `index` - a built-in preprocessor (enabled by default) which will transform
+  all `README.md` chapters to `index.md` so `foo/README.md` can be accessed via
+  the url `foo/` when published to a browser
+- `links` - a built-in preprocessor (enabled by default) for expanding the
+  `{{# playpen}}` and `{{# include}}` helpers in a chapter.
+
+Renderers are given the final book so they can do something with it. This is
+typically used for, as the name suggests, rendering the document in a particular
+format, however there's nothing stopping a renderer from doing static analysis
+of a book in order to validate links or run tests. Some existing renderers are:
+
+- `html` - the built-in renderer which will generate a HTML version of the book
+- [`linkcheck`] - a backend which will check that all links are valid
+- [`epub`] - an experimental EPUB generator
+
+> **Note for Developers:** Feel free to send us a PR if you've developed your
+> own plugin and want it mentioned here.
+
+A preprocessor or renderer is enabled by installing the appropriate program and
+then mentioning it in the book's `book.toml` file.
+
+```console
+$ cargo install mdbook-linkcheck
+$ edit book.toml && cat book.toml
+[book]
+title = "My Awesome Book"
+authors = ["Michael-F-Bryan"]
+
+[output.html]
+
+[output.linkcheck]  # enable the "mdbook-linkcheck" renderer
+
+$ mdbook build
+2018-10-20 13:57:51 [INFO] (mdbook::book): Book building has started
+2018-10-20 13:57:51 [INFO] (mdbook::book): Running the html backend
+2018-10-20 13:57:53 [INFO] (mdbook::book): Running the linkcheck backend
+```
+
+For more information on the plugin system, consult the [User Guide].
 
 ### As a library
 
@@ -189,3 +240,5 @@ All the code in this repository is released under the ***Mozilla Public License
 [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/
+[`linkcheck`]: https://crates.io/crates/mdbook-linkcheck
+[`epub`]: https://crates.io/crates/mdbook-epub

book-example/src/cli/README.md

@@ -18,7 +18,7 @@ mdBook can also be installed from source
 
 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.
+ahead and [install it](https://www.rust-lang.org/tools/install) now.
 
 ### Install Crates.io version
 

book-example/src/cli/build.md

@@ -29,8 +29,9 @@ 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`.
 
 -------------------
 

book-example/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

book-example/src/cli/serve.md

@@ -5,6 +5,9 @@ The serve command is used to preview a book by serving it over HTTP at
 changes, rebuilding the book and refreshing clients for each change. 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
@@ -40,10 +43,6 @@ 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. 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`.

book-example/src/cli/test.md

@@ -48,5 +48,6 @@ comma-delimited list (`-L foo,bar`).
 #### --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`.

book-example/src/cli/watch.md

@@ -22,5 +22,6 @@ 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. 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`.

book-example/src/continuous-integration.md

@@ -26,7 +26,7 @@ before_script:
   - cargo install-update -a
 
 script:
-  - cd path/to/mybook && mdbook build && mdbook test
+  - mdbook build path/to/mybook && mdbook test path/to/mybook
 ```
 
 ## Deploying Your Book to GitHub Pages

book-example/src/for_developers/README.md

@@ -42,5 +42,5 @@ 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/
+[API Docs]: https://docs.rs/mdbook/*/mdbook/
 [config]: file:///home/michael/Documents/forks/mdBook/target/doc/mdbook/config/index.html

book-example/src/for_developers/preprocessors.md

@@ -11,65 +11,79 @@ the book. Possible use cases are:
   mathjax equivalents
 
 
-## Implementing a Preprocessor
+## Hooking Into MDBook
 
-A preprocessor is represented by the `Preprocessor` trait.
+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.
 
-```rust
-pub trait Preprocessor {
-    fn name(&self) -> &str;
-    fn run(&self, ctx: &PreprocessorContext, book: &mut Book) -> Result<()>;
-}
+While preprocessors can be hard-coded to specify which backend it should be run
+for (e.g. it doesn't make sense for MathJax to be used for non-HTML renderers)
+with the `preprocessor.foo.renderer` key.
+
+```toml
+[book]
+title = "My Book"
+authors = ["Michael-F-Bryan"]
+
+[preprocessor.foo]
+# The command can also be specified manually
+command = "python3 /path/to/foo.py"
+# Only run the `foo` preprocessor for the HTML and EPUB renderer
+renderer = ["html", "epub"]
 ```
 
-Where the `PreprocessorContext` is defined as
+In typical unix style, all inputs to the plugin will be written to `stdin` as
+JSON and `mdbook` will read from `stdout` if it is expecting output.
+
+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
-pub struct PreprocessorContext {
-    pub root: PathBuf,
-    pub config: Config,
-}
+// nop-preprocessors.rs
+
+{{#include ../../../examples/nop-preprocessor.rs}}
 ```
+</details>
 
-## A complete Example
+## Hints For Implementing A Preprocessor
 
-The magic happens within the `run(...)` method of the
-[`Preprocessor`][preprocessor-docs] trait implementation.
+By pulling in `mdbook` as a library, preprocessors can have access to the
+existing infrastructure for dealing with books.
 
-As direct access to the chapters is not possible, you will probably end up
-iterating them using `for_each_mut(...)`:
+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] 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
-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> {
+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)
@@ -83,15 +97,19 @@ fn remove_emphasis(num_removed_items: &mut i32, chapter: &mut Chapter) -> Result
         }
         should_keep
     });
-    cmark(events, &mut buf, None)
-        .map(|_| buf)
-        .map_err(|err| Error::from(format!("Markdown serialization failed: {}", err)))
+
+    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
+[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-nursery/mdBook/blob/master/examples/de-emphasize.rs
+[an example no-op preprocessor]: https://github.com/rust-lang-nursery/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

book-example/src/format/config.md

@@ -14,6 +14,10 @@ description = "The example book covers examples."
 build-dir = "my-example-book"
 create-missing = false
 
+[preprocess.index]
+
+[preprocess.links]
+
 [output.html]
 additional-css = ["custom.css"]
 
@@ -27,7 +31,6 @@ 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.
@@ -59,15 +62,25 @@ This controls the build process of your book.
   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.
+- **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.
+
+## Configuring Preprocessors
 
 The following preprocessors are available and included by default:
 
-- `links`: Expand the `{{# playpen}}` and `{{# include}}` handlebars helpers in
-  a chapter.
+- `links`: Expand the `{{ #playpen }}` and `{{ #include }}` handlebars
+  helpers in a chapter to include the contents of a file.
 - `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.
@@ -78,10 +91,53 @@ The following preprocessors are available and included by default:
 [build]
 build-dir = "build"
 create-missing = false
-preprocess = ["links", "index"]
+
+[preprocess.links]
+
+[preprocess.index]
 ```
 
+### Custom Preprocessor Configuration
+
+Like renderers, preprocessor will need to be given its own table (e.g.
+`[preprocessor.mathjax]`). In the section, you may then pass extra
+configuration to the preprocessor by adding key-value pairs to the table.
+
+For example
+
+```
+[preprocess.links]
+# set the renderers this preprocessor will run for
+renderers = ["html"]
+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.
+
+```
+[preprocessor.mathjax]
+renderers = ["html"]  # mathjax only makes sense 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` executa`ble. 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"
+```
+
+## Configuring Renderers
+
 ### 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]`.
 
@@ -90,6 +146,8 @@ 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`.
 - **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
@@ -107,6 +165,10 @@ The following configuration options are available:
 - **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).
+- **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`.
 
 Available configuration options for the `[output.html.playpen]` table:
 
@@ -139,7 +201,8 @@ Available configuration options for the `[output.html.search]` table:
 - **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**:
+This shows all available HTML output options in the **book.toml**:
+
 ```toml
 [book]
 title = "Example book"
@@ -176,6 +239,16 @@ heading-split-level = 3
 copy-js = true
 ```
 
+### Custom Renderers
+
+A custom renderer can be enabled by adding a `[output.foo]` table to your 
+`book.toml`. Similar to [preprocessors](#configuring-preprocessors) this will 
+instruct `mdbook` to pass a representation of the book to `mdbook-foo` for 
+rendering.
+
+Custom renderers will have access to all configuration within their table
+(i.e. anything under `[output.foo]`), and the command to be invoked can be 
+manually specified with the `command` field.
 
 ## Environment Variables
 
@@ -214,4 +287,4 @@ book's title without needing to touch your `book.toml`.
 
 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.
+building.

examples/de-emphasize.rs

@@ -1,4 +1,6 @@
-//! This program removes all forms of emphasis from the markdown of the book.
+//! An example preprocessor for removing all forms of emphasis from a markdown
+//! book.
+
 extern crate mdbook;
 extern crate pulldown_cmark;
 extern crate pulldown_cmark_to_cmark;
@@ -6,89 +8,73 @@ 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;
+const NAME: &str = "md-links-to-html-links";
 
+fn main() {
+    panic!("This example is intended to be part of a library");
+}
+
+#[allow(dead_code)]
 struct Deemphasize;
 
 impl Preprocessor for Deemphasize {
     fn name(&self) -> &str {
-        "md-links-to-html-links"
+        NAME
     }
 
-    fn run(&self, _ctx: &PreprocessorContext, book: &mut Book) -> Result<()> {
+    fn run(&self, _ctx: &PreprocessorContext, mut book: Book) -> Result<Book> {
         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),
-                    },
-                );
-            }
-        });
+
+        process(&mut book.sections, &mut num_removed_items)?;
+
         eprintln!(
             "{}: removed {} events from markdown stream.",
             self.name(),
             num_removed_items
         );
-        match res {
-            Some(res) => res,
-            None => Ok(()),
+
+        Ok(book)
+    }
+}
+
+fn process<'a, I>(items: I, num_removed_items: &mut usize) -> Result<()>
+where
+    I: IntoIterator<Item = &'a mut BookItem> + 'a,
+{
+    for item in items {
+        if let BookItem::Chapter(ref mut chapter) = *item {
+            eprintln!("{}: processing chapter '{}'", NAME, chapter.name);
+
+            let md = remove_emphasis(num_removed_items, chapter)?;
+            chapter.content = md;
         }
     }
+
+    Ok(())
 }
 
-fn do_it(book: OsString) -> Result<()> {
-    let mut book = MDBook::load(book)?;
-    book.with_preprecessor(Deemphasize);
-    book.build()
-}
+fn remove_emphasis(num_removed_items: &mut usize, chapter: &mut Chapter) -> Result<String> {
+    let mut buf = String::with_capacity(chapter.content.len());
 
-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);
-    }
-}
+    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
+    });
 
-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)))
-    }
+    cmark(events, &mut buf, None)
+        .map(|_| buf)
+        .map_err(|err| Error::from(format!("Markdown serialization failed: {}", err)))
 }

examples/nop-preprocessor.rs

@@ -0,0 +1,108 @@
+extern crate clap;
+extern crate mdbook;
+extern crate serde_json;
+
+use clap::{App, Arg, ArgMatches, SubCommand};
+use mdbook::book::Book;
+use mdbook::errors::Error;
+use mdbook::preprocess::{CmdPreprocessor, Preprocessor, PreprocessorContext};
+use nop_lib::Nop;
+use std::io;
+use std::process;
+
+pub fn make_app() -> App<'static, 'static> {
+    App::new("nop-preprocessor")
+        .about("A mdbook preprocessor which does precisely nothing")
+        .subcommand(
+            SubCommand::with_name("supports")
+                .arg(Arg::with_name("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())?;
+
+    if ctx.mdbook_version != mdbook::MDBOOK_VERSION {
+        // We should probably use the `semver` crate to check compatibility
+        // here...
+        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.value_of("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") {
+                    return Err("Boom!!1!".into());
+                }
+            }
+
+            // we *are* a no-op preprocessor after all
+            Ok(book)
+        }
+
+        fn supports_renderer(&self, renderer: &str) -> bool {
+            renderer != "not-supported"
+        }
+    }
+}

src/book/book.rs

@@ -167,9 +167,9 @@ impl Chapter {
     ) -> Chapter {
         Chapter {
             name: name.to_string(),
-            content: content,
+            content,
             path: path.into(),
-            parent_names: parent_names,
+            parent_names,
             ..Default::default()
         }
     }
@@ -210,7 +210,7 @@ fn load_summary_item<P: AsRef<Path>>(
     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)
         }
     }
 }

src/book/init.rs

@@ -175,7 +175,7 @@ impl BookBuilder {
         let summary = src_dir.join("SUMMARY.md");
         let mut f = File::create(&summary).chain_err(|| "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");

src/book/mod.rs

@@ -20,7 +20,9 @@ use tempfile::Builder as TempFileBuilder;
 use toml::Value;
 
 use errors::*;
-use preprocess::{IndexPreprocessor, LinkPreprocessor, Preprocessor, PreprocessorContext};
+use preprocess::{
+    CmdPreprocessor, IndexPreprocessor, LinkPreprocessor, Preprocessor, PreprocessorContext,
+};
 use renderer::{CmdRenderer, HtmlHandlebars, RenderContext, Renderer};
 use utils;
 
@@ -149,23 +151,36 @@ 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<()> {
+    /// Run the entire build process for a particular `Renderer`.
+    fn execute_build_process(&self, renderer: &Renderer) -> Result<()> {
+        let mut preprocessed_book = self.book.clone();
+        let preprocess_ctx = PreprocessorContext::new(
+            self.root.clone(),
+            self.config.clone(),
+            renderer.name().to_string(),
+        );
+
+        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)?;
+            }
+        }
+
+        info!("Running the {} backend", renderer.name());
+        self.render(&preprocessed_book, renderer)?;
+
+        Ok(())
+    }
+
+    fn render(&self, preprocessed_book: &Book, renderer: &Renderer) -> Result<()> {
         let name = renderer.name();
         let build_dir = self.build_dir_for(name);
         if build_dir.exists() {
@@ -215,13 +230,15 @@ impl MDBook {
 
         let temp_dir = TempFileBuilder::new().prefix("mdbook-").tempdir()?;
 
-        let preprocess_context = PreprocessorContext::new(self.root.clone(), self.config.clone());
+        // FIXME: Is "test" the proper renderer name to use here?
+        let preprocess_context =
+            PreprocessorContext::new(self.root.clone(), self.config.clone(), "test".to_string());
 
-        LinkPreprocessor::new().run(&preprocess_context, &mut self.book)?;
+        let book = LinkPreprocessor::new().run(&preprocess_context, self.book.clone())?;
         // Index Preprocessor is disabled so that chapter paths continue to point to the
         // actual markdown files.
 
-        for item in self.iter() {
+        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);
@@ -330,30 +347,46 @@ fn default_preprocessors() -> Vec<Box<Preprocessor>> {
     ]
 }
 
+fn is_default_preprocessor(pre: &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()),
-    };
+    let mut preprocessors = Vec::new();
 
-    let mut preprocessors: Vec<Box<Preprocessor>> = Vec::new();
+    if config.build.use_default_preprocessors {
+        preprocessors.extend(default_preprocessors());
+    }
 
-    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 let Some(preprocessor_table) = config.get("preprocessor").and_then(|v| v.as_table()) {
+        for key in preprocessor_table.keys() {
+            match key.as_ref() {
+                "links" => preprocessors.push(Box::new(LinkPreprocessor::new())),
+                "index" => preprocessors.push(Box::new(IndexPreprocessor::new())),
+                name => preprocessors.push(interpret_custom_preprocessor(
+                    name,
+                    &preprocessor_table[name],
+                )),
+            }
         }
     }
 
     Ok(preprocessors)
 }
 
-fn interpret_custom_renderer(key: &str, table: &Value) -> Box<Renderer> {
+fn interpret_custom_preprocessor(key: &str, table: &Value) -> Box<CmdPreprocessor> {
+    let command = table
+        .get("command")
+        .and_then(|c| c.as_str())
+        .map(|s| s.to_string())
+        .unwrap_or_else(|| format!("mdbook-{}", key));
+
+    Box::new(CmdPreprocessor::new(key.to_string(), command.to_string()))
+}
+
+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
@@ -366,6 +399,31 @@ fn interpret_custom_renderer(key: &str, table: &Value) -> Box<Renderer> {
     Box::new(CmdRenderer::new(key.to_string(), command.to_string()))
 }
 
+/// 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: &Preprocessor, renderer: &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(|val| val.as_str())
+            .any(|name| name == renderer_name);
+    }
+
+    preprocessor.supports_renderer(renderer_name)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -413,8 +471,8 @@ 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);
 
@@ -425,47 +483,105 @@ mod tests {
     }
 
     #[test]
-    fn config_doesnt_default_if_empty() {
-        let cfg_str: &'static str = r#"
-        [book]
-        title = "Some Book"
+    fn use_default_preprocessors_works() {
+        let mut cfg = Config::default();
+        cfg.build.use_default_preprocessors = false;
 
-        [build]
-        build-dir = "outputs"
-        create-missing = false
-        preprocess = []
-        "#;
+        let got = determine_preprocessors(&cfg).unwrap();
 
-        let cfg = Config::from_str(cfg_str).unwrap();
-
-        // make sure we have something in the `output` table
-        assert!(cfg.build.preprocess.is_some());
-
-        let got = determine_preprocessors(&cfg);
-
-        assert!(got.is_ok());
-        assert!(got.unwrap().is_empty());
+        assert_eq!(got.len(), 0);
     }
 
     #[test]
-    fn config_complains_if_unimplemented_preprocessor() {
+    fn can_determine_third_party_preprocessors() {
         let cfg_str: &'static str = r#"
         [book]
         title = "Some Book"
 
+        [preprocessor.random]
+
         [build]
         build-dir = "outputs"
         create-missing = false
-        preprocess = ["random"]
         "#;
 
         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_err());
+        assert!(got.into_iter().any(|p| p.name() == "random"));
+    }
+
+    #[test]
+    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 the `preprocessor.random` table exists
+        let random = cfg.get_preprocessor("random").unwrap();
+        let random = interpret_custom_preprocessor("random", &Value::Table(random.clone()));
+
+        assert_eq!(random.cmd(), "python random.py");
+    }
+
+    #[test]
+    fn config_respects_preprocessor_selection() {
+        let cfg_str: &'static 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(|renderers| renderers.as_array())
+            .and_then(|renderers| renderers.get(0))
+            .and_then(|renderer| renderer.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

@@ -280,7 +280,7 @@ impl<'a> SummaryParser<'a> {
             Err(self.parse_error("You can't have an empty link."))
         } else {
             Ok(Link {
-                name: name,
+                name,
                 location: PathBuf::from(href.to_string()),
                 number: None,
                 nested_items: Vec::new(),
@@ -292,6 +292,7 @@ impl<'a> SummaryParser<'a> {
     /// already been consumed by a previous parser.
     fn parse_numbered(&mut self) -> Result<Vec<SummaryItem>> {
         let mut items = Vec::new();
+        let mut root_items = 0;
         let root_number = SectionNumber::default();
 
         // we need to do this funny loop-match-if-let dance because a rule will
@@ -308,7 +309,8 @@ impl<'a> SummaryParser<'a> {
             // 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() {
@@ -724,4 +726,41 @@ mod tests {
         let got = parser.parse_numbered();
         assert!(got.is_err());
     }
+
+    /// Regression test for https://github.com/rust-lang-nursery/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: PathBuf::from("./first.md"),
+                number: Some(SectionNumber(vec![1])),
+                nested_items: Vec::new(),
+            }),
+            SummaryItem::Separator,
+            SummaryItem::Link(Link {
+                name: String::from("Second"),
+                location: PathBuf::from("./second.md"),
+                number: Some(SectionNumber(vec![2])),
+                nested_items: Vec::new(),
+            }),
+            SummaryItem::Separator,
+            SummaryItem::Link(Link {
+                name: String::from("Third"),
+                location: PathBuf::from("./third.md"),
+                number: Some(SectionNumber(vec![3])),
+                nested_items: Vec::new(),
+            }),
+        ];
+
+        let mut parser = SummaryParser::new(src);
+        let _ = parser.stream.next();
+
+        let got = parser.parse_numbered().unwrap();
+
+        assert_eq!(got, should_be);
+    }
 }

src/cmd/build.rs

@@ -9,7 +9,8 @@ pub fn make_subcommand<'a, 'b>() -> App<'a, 'b> {
         .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)'",
+             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`.'",
         ).arg_from_usage(
             "[dir] 'Root directory for the book{n}\
              (Defaults to the Current Directory when omitted)'",

src/cmd/clean.rs

@@ -10,7 +10,9 @@ pub fn make_subcommand<'a, 'b>() -> App<'a, 'b> {
         .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)'",
+             Relative paths are interpreted relative to the book's root directory.{n}\
+             Running this command deletes this directory.{n}\
+             If omitted, mdBook 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)'",

src/cmd/init.rs

@@ -12,9 +12,10 @@ pub fn make_subcommand<'a, 'b>() -> App<'a, 'b> {
     SubCommand::with_name("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(
+            "[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'")
 }
 

src/cmd/serve.rs

@@ -22,7 +22,8 @@ pub fn make_subcommand<'a, 'b>() -> App<'a, 'b> {
         .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)'",
+             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`.'",
         )
         .arg_from_usage(
             "[dir] 'Root directory for the book{n}\
@@ -75,7 +76,7 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
     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 public_address = args.value_of("websocket-hostname").unwrap_or(hostname);
     let open_browser = args.is_present("open");
 
     let address = format!("{}:{}", hostname, port);
@@ -114,7 +115,7 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
     }
 
     #[cfg(feature = "watch")]
-    watch::trigger_on_change(&mut book, move |path, book_dir| {
+    watch::trigger_on_change(&book, move |path, book_dir| {
         info!("File changed: {:?}", path);
         info!("Building book...");
 

src/cmd/test.rs

@@ -9,7 +9,8 @@ pub fn make_subcommand<'a, 'b>() -> App<'a, 'b> {
         .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)'",
+             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`.'",
         )
         .arg_from_usage(
             "[dir] 'Root directory for the book{n}\

src/cmd/watch.rs

@@ -16,7 +16,8 @@ pub fn make_subcommand<'a, 'b>() -> App<'a, 'b> {
         .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)'",
+             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`.'",
         ).arg_from_usage(
             "[dir] 'Root directory for the book{n}\
              (Defaults to the Current Directory when omitted)'",

src/config.rs

@@ -209,6 +209,18 @@ impl Config {
         Ok(())
     }
 
+    /// Get the table associated with a particular renderer.
+    pub fn get_renderer<I: AsRef<str>>(&self, index: I) -> Option<&Table> {
+        let key = format!("output.{}", index.as_ref());
+        self.get(&key).and_then(|v| v.as_table())
+    }
+
+    /// Get the table associated with a particular preprocessor.
+    pub fn get_preprocessor<I: AsRef<str>>(&self, index: I) -> Option<&Table> {
+        let key = format!("preprocessor.{}", index.as_ref());
+        self.get(&key).and_then(|v| v.as_table())
+    }
+
     fn from_legacy(mut table: Value) -> Config {
         let mut cfg = Config::default();
 
@@ -289,8 +301,8 @@ impl<'de> Deserialize<'de> for Config {
             .unwrap_or_default();
 
         Ok(Config {
-            book: book,
-            build: build,
+            book,
+            build,
             rest: Value::Table(table),
         })
     }
@@ -382,8 +394,9 @@ pub struct BuildConfig {
     /// Should non-existent markdown files specified in `SETTINGS.md` be created
     /// if they don't exist?
     pub create_missing: bool,
-    /// Which preprocessors should be applied
-    pub preprocess: Option<Vec<String>>,
+    /// Should the default preprocessors always be used when they are
+    /// compatible with the renderer?
+    pub use_default_preprocessors: bool,
 }
 
 impl Default for BuildConfig {
@@ -391,7 +404,7 @@ impl Default for BuildConfig {
         BuildConfig {
             build_dir: PathBuf::from("book"),
             create_missing: true,
-            preprocess: None,
+            use_default_preprocessors: true,
         }
     }
 }
@@ -402,6 +415,8 @@ impl Default for BuildConfig {
 pub struct HtmlConfig {
     /// The theme directory, if specified.
     pub theme: Option<PathBuf>,
+    /// The default theme to use, defaults to 'light'
+    pub default_theme: Option<String>,
     /// Use "smart quotes" instead of the usual `"` character.
     pub curly_quotes: bool,
     /// Should mathjax be enabled?
@@ -423,10 +438,15 @@ pub struct HtmlConfig {
     /// This config item *should not be edited* by the end user.
     #[doc(hidden)]
     pub livereload_url: Option<String>,
-    /// Should section labels be rendered?
+    /// Don't render section labels.
     pub no_section_label: bool,
     /// Search settings. If `None`, the default will be used.
     pub search: Option<Search>,
+    /// Git repository url. If `None`, the git button will not be shown.
+    pub git_repository_url: Option<String>,
+    /// FontAwesome icon class to use for the Git repository link.
+    /// Defaults to `fa-github` if `None`.
+    pub git_repository_icon: Option<String>,
 }
 
 impl HtmlConfig {
@@ -551,17 +571,24 @@ mod tests {
         [build]
         build-dir = "outputs"
         create-missing = false
-        preprocess = ["first_preprocessor", "second_preprocessor"]
+        use-default-preprocessors = true
 
         [output.html]
         theme = "./themedir"
+        default-theme = "rust"
         curly-quotes = true
         google-analytics = "123456"
         additional-css = ["./foo/bar/baz.css"]
+        git-repository-url = "https://foo.com/"
+        git-repository-icon = "fa-code-fork"
 
         [output.html.playpen]
         editable = true
         editor = "ace"
+
+        [preprocess.first]
+
+        [preprocess.second]
         "#;
 
     #[test]
@@ -579,10 +606,7 @@ mod tests {
         let build_should_be = BuildConfig {
             build_dir: PathBuf::from("outputs"),
             create_missing: false,
-            preprocess: Some(vec![
-                "first_preprocessor".to_string(),
-                "second_preprocessor".to_string(),
-            ]),
+            use_default_preprocessors: true,
         };
         let playpen_should_be = Playpen {
             editable: true,
@@ -593,7 +617,10 @@ mod tests {
             google_analytics: Some(String::from("123456")),
             additional_css: vec![PathBuf::from("./foo/bar/baz.css")],
             theme: Some(PathBuf::from("./themedir")),
+            default_theme: Some(String::from("rust")),
             playpen: playpen_should_be,
+            git_repository_url: Some(String::from("https://foo.com/")),
+            git_repository_icon: Some(String::from("fa-code-fork")),
             ..Default::default()
         };
 
@@ -684,7 +711,7 @@ mod tests {
         let build_should_be = BuildConfig {
             build_dir: PathBuf::from("my-book"),
             create_missing: true,
-            preprocess: None,
+            use_default_preprocessors: true,
         };
 
         let html_should_be = HtmlConfig {

src/lib.rs

@@ -114,6 +114,12 @@ pub mod renderer;
 pub mod theme;
 pub mod utils;
 
+/// 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 book::BookItem;
 pub use book::MDBook;
 pub use config::Config;

src/main.rs

@@ -20,8 +20,8 @@ use std::path::{Path, PathBuf};
 
 mod cmd;
 
-const NAME: &'static str = "mdBook";
-const VERSION: &'static str = concat!("v", crate_version!());
+const NAME: &str = "mdBook";
+const VERSION: &str = concat!("v", crate_version!());
 
 fn main() {
     init_logger();

src/preprocess/cmd.rs

@@ -0,0 +1,197 @@
+use super::{Preprocessor, PreprocessorContext};
+use book::Book;
+use errors::*;
+use serde_json;
+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).chain_err(|| "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()
+            .chain_err(|| {
+                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()
+            .chain_err(|| "Error waiting for the preprocessor to complete")?;
+
+        trace!("{} exited with output: {:?}", self.cmd, output);
+        ensure!(
+            output.status.success(),
+            "The preprocessor exited unsuccessfully"
+        );
+
+        serde_json::from_slice(&output.stdout).chain_err(|| "Unable to parse the preprocessed book")
+    }
+
+    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 std::path::Path;
+    use MDBook;
+
+    fn book_example() -> MDBook {
+        let example = Path::new(env!("CARGO_MANIFEST_DIR")).join("book-example");
+        MDBook::load(example).unwrap()
+    }
+
+    #[test]
+    fn round_trip_write_and_parse_input() {
+        let cmd = CmdPreprocessor::new("test".to_string(), "test".to_string());
+        let md = book_example();
+        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

@@ -7,10 +7,12 @@ use super::{Preprocessor, PreprocessorContext};
 use book::{Book, BookItem};
 
 /// 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.
 pub struct IndexPreprocessor;
 
 impl IndexPreprocessor {
+    pub(crate) const NAME: &'static str = "index";
+
     /// Create a new `IndexPreprocessor`.
     pub fn new() -> Self {
         IndexPreprocessor
@@ -19,10 +21,10 @@ 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 {
@@ -37,7 +39,7 @@ impl Preprocessor for IndexPreprocessor {
             }
         });
 
-        Ok(())
+        Ok(book)
     }
 }
 

src/preprocess/links.rs

@@ -16,6 +16,8 @@ const MAX_LINK_NESTED_DEPTH: usize = 10;
 pub struct LinkPreprocessor;
 
 impl LinkPreprocessor {
+    pub(crate) const NAME: &'static str = "links";
+
     /// Create a new `LinkPreprocessor`.
     pub fn new() -> Self {
         LinkPreprocessor
@@ -24,10 +26,10 @@ 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| {
@@ -43,7 +45,7 @@ impl Preprocessor for LinkPreprocessor {
             }
         });
 
-        Ok(())
+        Ok(book)
     }
 }
 
@@ -81,6 +83,10 @@ where
             }
             Err(e) => {
                 error!("Error updating \"{}\", {}", playpen.link_text, e);
+                for cause in e.iter().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;
@@ -136,27 +142,21 @@ fn parse_include_path(path: &str) -> LinkType<'static> {
     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,
-                },
-            ),
+            Some(end) => LinkType::IncludeRange(path, Range { start, end }),
             None => if has_end {
-                LinkType::IncludeRangeFrom(path, RangeFrom { start: start })
+                LinkType::IncludeRangeFrom(path, RangeFrom { start })
             } else {
                 LinkType::IncludeRange(
                     path,
                     Range {
-                        start: start,
+                        start,
                         end: start + 1,
                     },
                 )
             },
         },
         None => match end {
-            Some(end) => LinkType::IncludeRangeTo(path, RangeTo { end: end }),
+            Some(end) => LinkType::IncludeRangeTo(path, RangeTo { end }),
             None => LinkType::IncludeRangeFull(path, RangeFull),
         },
     }
@@ -205,20 +205,66 @@ impl<'a> Link<'a> {
         match self.link {
             // 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::IncludeRange(ref pat, ref range) => {
+                let target = base.join(pat);
+
+                file_to_string(&target)
+                    .map(|s| take_lines(&s, range.clone()))
+                    .chain_err(|| {
+                        format!(
+                            "Could not read file for link {} ({})",
+                            self.link_text,
+                            target.display(),
+                        )
+                    })
+            }
+            LinkType::IncludeRangeFrom(ref pat, ref range) => {
+                let target = base.join(pat);
+
+                file_to_string(&target)
+                    .map(|s| take_lines(&s, range.clone()))
+                    .chain_err(|| {
+                        format!(
+                            "Could not read file for link {} ({})",
+                            self.link_text,
+                            target.display(),
+                        )
+                    })
+            }
+            LinkType::IncludeRangeTo(ref pat, ref range) => {
+                let target = base.join(pat);
+
+                file_to_string(&target)
+                    .map(|s| take_lines(&s, *range))
+                    .chain_err(|| {
+                        format!(
+                            "Could not read file for link {} ({})",
+                            self.link_text,
+                            target.display(),
+                        )
+                    })
+            }
+            LinkType::IncludeRangeFull(ref pat, _) => {
+                let target = base.join(pat);
+
+                file_to_string(&target).chain_err(|| {
+                    format!(
+                        "Could not read file for link {} ({})",
+                        self.link_text,
+                        target.display()
+                    )
+                })
+            }
             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))?;
+                let target = base.join(pat);
+
+                let contents = file_to_string(&target).chain_err(|| {
+                    format!(
+                        "Could not read file for link {} ({})",
+                        self.link_text,
+                        target.display()
+                    )
+                })?;
                 let ftype = if !attrs.is_empty() { "rust," } else { "rust" };
                 Ok(format!(
                     "```{}{}\n{}\n```\n",

src/preprocess/mod.rs

@@ -1,8 +1,10 @@
 //! Book preprocessing.
 
+pub use self::cmd::CmdPreprocessor;
 pub use self::index::IndexPreprocessor;
 pub use self::links::LinkPreprocessor;
 
+mod cmd;
 mod index;
 mod links;
 
@@ -14,17 +16,30 @@ 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)]
+    __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: ::MDBOOK_VERSION.to_string(),
+            __non_exhaustive: (),
+        }
     }
 }
 
@@ -36,5 +51,13 @@ 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/hbs_renderer.rs

@@ -30,75 +30,71 @@ impl HtmlHandlebars {
         print_content: &mut String,
     ) -> Result<()> {
         // FIXME: This should be made DRY-er and rely less on mutable state
-        match *item {
-            BookItem::Chapter(ref ch) => {
-                let content = ch.content.clone();
-                let content = utils::render_markdown(&content, ctx.html_config.curly_quotes);
-                print_content.push_str(&content);
+        if let BookItem::Chapter(ref ch) = *item {
+            let content = ch.content.clone();
+            let content = utils::render_markdown(&content, ctx.html_config.curly_quotes);
 
-                // Update the context with data for this file
-                let path = ch
-                    .path
-                    .to_str()
-                    .chain_err(|| "Could not convert path to str")?;
-                let filepath = Path::new(&ch.path).with_extension("html");
+            let string_path = ch.path.parent().unwrap().display().to_string();
 
-                // "print.html" is used for the print page.
-                if ch.path == Path::new("print.md") {
-                    bail!(ErrorKind::ReservedFilenameError(ch.path.clone()));
-                };
+            let fixed_content = utils::render_markdown_with_base(&ch.content, ctx.html_config.curly_quotes, &string_path);
+            print_content.push_str(&fixed_content);
 
-                // Non-lexical lifetimes needed :'(
-                let title: String;
-                {
-                    let book_title = ctx
-                        .data
-                        .get("book_title")
-                        .and_then(serde_json::Value::as_str)
-                        .unwrap_or("");
-                    title = ch.name.clone() + " - " + book_title;
-                }
+            // Update the context with data for this file
+            let path = ch
+                .path
+                .to_str()
+                .chain_err(|| "Could not convert path to str")?;
+            let filepath = Path::new(&ch.path).with_extension("html");
 
-                ctx.data.insert("path".to_owned(), json!(path));
-                ctx.data.insert("content".to_owned(), json!(content));
-                ctx.data.insert("chapter_title".to_owned(), json!(ch.name));
-                ctx.data.insert("title".to_owned(), json!(title));
-                ctx.data.insert(
-                    "path_to_root".to_owned(),
-                    json!(utils::fs::path_to_root(&ch.path)),
-                );
+            // "print.html" is used for the print page.
+            if ch.path == Path::new("print.md") {
+                bail!(ErrorKind::ReservedFilenameError(ch.path.clone()));
+            };
 
-                // Render the handlebars template with the data
-                debug!("Render template");
-                let rendered = ctx.handlebars.render("index", &ctx.data)?;
-
-                let rendered = self.post_process(rendered, &ctx.html_config.playpen);
-
-                // Write to file
-                debug!("Creating {}", filepath.display());
-                utils::fs::write_file(&ctx.destination, &filepath, rendered.as_bytes())?;
-
-                if ctx.is_index {
-                    ctx.data.insert("path".to_owned(), json!("index.html"));
-                    ctx.data.insert("path_to_root".to_owned(), json!(""));
-                    let rendered_index = ctx.handlebars.render("index", &ctx.data)?;
-                    let rendered_index =
-                        self.post_process(rendered_index, &ctx.html_config.playpen);
-                    debug!("Creating index.html from {}", path);
-                    utils::fs::write_file(
-                        &ctx.destination,
-                        "index.html",
-                        rendered_index.as_bytes(),
-                    )?;
-                }
+            // Non-lexical lifetimes needed :'(
+            let title: String;
+            {
+                let book_title = ctx
+                    .data
+                    .get("book_title")
+                    .and_then(serde_json::Value::as_str)
+                    .unwrap_or("");
+                title = ch.name.clone() + " - " + book_title;
+            }
+
+            ctx.data.insert("path".to_owned(), json!(path));
+            ctx.data.insert("content".to_owned(), json!(content));
+            ctx.data.insert("chapter_title".to_owned(), json!(ch.name));
+            ctx.data.insert("title".to_owned(), json!(title));
+            ctx.data.insert(
+                "path_to_root".to_owned(),
+                json!(utils::fs::path_to_root(&ch.path)),
+            );
+
+            // Render the handlebars template with the data
+            debug!("Render template");
+            let rendered = ctx.handlebars.render("index", &ctx.data)?;
+
+            let rendered = self.post_process(rendered, &ctx.html_config.playpen);
+
+            // Write to file
+            debug!("Creating {}", filepath.display());
+            utils::fs::write_file(&ctx.destination, &filepath, rendered.as_bytes())?;
+
+            if ctx.is_index {
+                ctx.data.insert("path".to_owned(), json!("index.html"));
+                ctx.data.insert("path_to_root".to_owned(), json!(""));
+                let rendered_index = ctx.handlebars.render("index", &ctx.data)?;
+                let rendered_index = self.post_process(rendered_index, &ctx.html_config.playpen);
+                debug!("Creating index.html from {}", path);
+                utils::fs::write_file(&ctx.destination, "index.html", rendered_index.as_bytes())?;
             }
-            _ => {}
         }
 
         Ok(())
     }
 
-    #[cfg_attr(feature = "cargo-clippy", allow(let_and_return))]
+    #[cfg_attr(feature = "cargo-clippy", allow(clippy::let_and_return))]
     fn post_process(&self, rendered: String, playpen_config: &Playpen) -> String {
         let rendered = build_header_links(&rendered);
         let rendered = fix_code_blocks(&rendered);
@@ -214,6 +210,7 @@ impl HtmlHandlebars {
         );
         handlebars.register_helper("previous", Box::new(helpers::navigation::previous));
         handlebars.register_helper("next", Box::new(helpers::navigation::next));
+        handlebars.register_helper("theme_option", Box::new(helpers::theme::theme_option));
     }
 
     /// Copy across any additional CSS and JavaScript files which the book
@@ -327,7 +324,7 @@ impl Renderer for HtmlHandlebars {
                 handlebars: &handlebars,
                 destination: destination.to_path_buf(),
                 data: data.clone(),
-                is_index: is_index,
+                is_index,
                 html_config: html_config.clone(),
             };
             self.render_item(item, ctx, &mut print_content)?;
@@ -395,6 +392,12 @@ fn make_data(
         data.insert("livereload".to_owned(), json!(livereload));
     }
 
+    let default_theme = match html_config.default_theme {
+        Some(ref theme) => theme,
+        None => "light",
+    };
+    data.insert("default_theme".to_owned(), json!(default_theme));
+
     // Add google analytics tag
     if let Some(ref ga) = config.html_config().and_then(|html| html.google_analytics) {
         data.insert("google_analytics".to_owned(), json!(ga));
@@ -454,6 +457,15 @@ fn make_data(
         )
     }
 
+    if let Some(ref git_repository_url) = html_config.git_repository_url {
+        data.insert("git_repository_url".to_owned(), json!(git_repository_url));
+    }
+    let git_repository_icon = match html_config.git_repository_icon {
+        Some(ref git_repository_icon) => git_repository_icon,
+        None => "fa-github",
+    };
+    data.insert("git_repository_icon".to_owned(), json!(git_repository_icon));
+
     let mut chapters = vec![];
 
     for item in book.iter() {

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

@@ -18,13 +18,13 @@ 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 => {
+        match *self {
+            Target::Next => {
                 let previous_path = previous_item
                     .get("path")
                     .ok_or_else(|| RenderError::new("No path found for chapter in JSON data"))?;
@@ -34,7 +34,7 @@ impl Target {
                 }
             }
 
-            &Target::Previous => {
+            Target::Previous => {
                 if current_path == base_path {
                     return Ok(Some(previous_item.clone()));
                 }

src/renderer/html_handlebars/helpers/theme.rs

@@ -0,0 +1,30 @@
+use handlebars::{Context, Handlebars, Helper, Output, RenderContext, RenderError};
+
+pub fn theme_option(
+    h: &Helper,
+    _r: &Handlebars,
+    ctx: &Context,
+    rc: &mut RenderContext,
+    out: &mut Output,
+) -> Result<(), RenderError> {
+    trace!("theme_option (handlebars helper)");
+
+    let param = h
+        .param(0)
+        .and_then(|v| v.value().as_str())
+        .ok_or(RenderError::new(
+            "Param 0 with String type is required for theme_option helper.",
+        ))?;
+
+    let theme_name = rc
+        .evaluate_absolute(ctx, "default_theme", true)?
+        .as_str()
+        .ok_or_else(|| RenderError::new("Type error for `default_theme`, string expected"))?;
+
+    out.write(param)?;
+    if param.to_lowercase() == theme_name.to_lowercase() {
+        out.write(" (default)")?;
+    }
+
+    Ok(())
+}

src/renderer/html_handlebars/search.rs

@@ -54,7 +54,7 @@ fn add_doc(
     section_id: &Option<String>,
     items: &[&str],
 ) {
-    let url = if let &Some(ref id) = section_id {
+    let url = if let Some(ref id) = *section_id {
         Cow::Owned(format!("{}#{}", anchor_base, id))
     } else {
         Cow::Borrowed(anchor_base)
@@ -74,8 +74,8 @@ 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) => ch,
         _ => return Ok(()),
     };
 
@@ -101,7 +101,7 @@ fn render_item(
     for event in p {
         match event {
             Event::Start(Tag::Header(i)) if i <= max_section_depth => {
-                if heading.len() > 0 {
+                if !heading.is_empty() {
                     // Section finished, the next header is following now
                     // Write the data to the index, and clear it for the next section
                     add_doc(
@@ -155,7 +155,7 @@ fn render_item(
         }
     }
 
-    if heading.len() > 0 {
+    if !heading.is_empty() {
         // Make sure the last section is added to the index
         add_doc(
             index,

src/renderer/mod.rs

@@ -8,7 +8,7 @@
 //!
 //! 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-nursery.github.io/mdBook/for_developers/index.html
 //! [RenderContext]: struct.RenderContext.html
 
 pub use self::html_handlebars::HtmlHandlebars;
@@ -26,8 +26,6 @@ use book::Book;
 use config::Config;
 use errors::*;
 
-const MDBOOK_VERSION: &str = env!("CARGO_PKG_VERSION");
-
 /// An arbitrary `mdbook` backend.
 ///
 /// Although it's quite possible for you to import `mdbook` as a library and
@@ -66,6 +64,8 @@ pub struct RenderContext {
     /// renderers to cache intermediate results, this directory is not
     /// guaranteed to be empty or even exist.
     pub destination: PathBuf,
+    #[serde(skip)]
+    __non_exhaustive: (),
 }
 
 impl RenderContext {
@@ -76,11 +76,12 @@ impl RenderContext {
         Q: Into<PathBuf>,
     {
         RenderContext {
-            book: book,
-            config: config,
-            version: MDBOOK_VERSION.to_string(),
+            book,
+            config,
+            version: ::MDBOOK_VERSION.to_string(),
             root: root.into(),
             destination: destination.into(),
+            __non_exhaustive: (),
         }
     }
 

src/theme/book.js

@@ -352,7 +352,7 @@ function playpen_text(playpen) {
 
         var previousTheme;
         try { previousTheme = localStorage.getItem('mdbook-theme'); } catch (e) { }
-        if (previousTheme === null || previousTheme === undefined) { previousTheme = 'light'; }
+        if (previousTheme === null || previousTheme === undefined) { previousTheme = default_theme; }
 
         try { localStorage.setItem('mdbook-theme', theme); } catch (e) { }
 
@@ -364,7 +364,7 @@ function playpen_text(playpen) {
     // Set theme
     var theme;
     try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
-    if (theme === null || theme === undefined) { theme = 'light'; }
+    if (theme === null || theme === undefined) { theme = default_theme; }
 
     set_theme(theme);
 

src/theme/css/chrome.css

@@ -63,9 +63,12 @@ a > .hljs {
     margin: 0;
 }
 
-#print-button {
+.right-buttons {
     margin: 0 15px;
 }
+.right-buttons a {
+    text-decoration: none;
+}
 
 html:not(.sidebar-visible) #menu-bar:not(:hover).folded > #menu-bar-sticky-container {
     transform: translateY(-60px);

src/theme/index.hbs

@@ -27,7 +27,7 @@
 
         <!-- Custom theme stylesheets -->
         {{#each additional_css}}
-        <link rel="stylesheet" href="{{ this }}">
+        <link rel="stylesheet" href="{{ ../path_to_root }}{{ this }}">
         {{/each}}
 
         {{#if mathjax_support}}
@@ -35,9 +35,12 @@
         <script async type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
         {{/if}}
     </head>
-    <body class="light">
+    <body class="{{ default_theme }}">
         <!-- Provide site root to javascript -->
-        <script type="text/javascript">var path_to_root = "{{ path_to_root }}";</script>
+        <script type="text/javascript">
+            var path_to_root = "{{ path_to_root }}";
+            var default_theme = "{{ default_theme }}";
+        </script>
 
         <!-- Work around some values being stored in localStorage wrapped in quotes -->
         <script type="text/javascript">
@@ -59,7 +62,7 @@
         <script type="text/javascript">
             var theme;
             try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { } 
-            if (theme === null || theme === undefined) { theme = 'light'; }
+            if (theme === null || theme === undefined) { theme = default_theme; }
             document.body.className = theme;
             document.querySelector('html').className = theme + ' js';
         </script>
@@ -94,11 +97,11 @@
                                 <i class="fa fa-paint-brush"></i>
                             </button>
                             <ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
-                                <li role="none"><button role="menuitem" class="theme" id="light">Light <span class="default">(default)</span></button></li>
-                                <li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
-                                <li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
-                                <li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
-                                <li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
+                                <li role="none"><button role="menuitem" class="theme" id="light">{{ theme_option "Light" }}</button></li>
+                                <li role="none"><button role="menuitem" class="theme" id="rust">{{ theme_option "Rust" }}</button></li>
+                                <li role="none"><button role="menuitem" class="theme" id="coal">{{ theme_option "Coal" }}</button></li>
+                                <li role="none"><button role="menuitem" class="theme" id="navy">{{ theme_option "Navy" }}</button></li>
+                                <li role="none"><button role="menuitem" class="theme" id="ayu">{{ theme_option "Ayu" }}</button></li>
                             </ul>
                             {{#if search_enabled}}
                             <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
@@ -113,6 +116,11 @@
                             <a href="{{ path_to_root }}print.html" title="Print this book" aria-label="Print this book">
                                 <i id="print-button" class="fa fa-print"></i>
                             </a>
+                            {{#if git_repository_url}}
+                            <a href="{{git_repository_url}}" title="Git repository" aria-label="Git repository">
+                                <i id="git-repository-button" class="fa {{git_repository_icon}}"></i>
+                            </a>
+                            {{/if}}
                         </div>
                     </div>
                 </div>
@@ -235,7 +243,7 @@
 
         <!-- Custom JS scripts -->
         {{#each additional_js}}
-        <script type="text/javascript" src="{{ path_to_root }}{{this}}"></script>
+        <script type="text/javascript" src="{{ ../path_to_root }}{{this}}"></script>
         {{/each}}
 
         {{#if is_print}}

src/utils/mod.rs

@@ -21,9 +21,10 @@ pub fn collapse_whitespace<'a>(text: &'a str) -> Cow<'a, str> {
     RE.replace_all(text, " ")
 }
 
-/// Convert the given string to a valid HTML element ID
+/// Convert the given string to a valid HTML element ID.
+/// The only restriction is that the ID must not contain any ASCII whitespace.
 pub fn normalize_id(content: &str) -> String {
-    let mut ret = content
+    content
         .chars()
         .filter_map(|ch| {
             if ch.is_alphanumeric() || ch == '_' || ch == '-' {
@@ -33,16 +34,7 @@ pub fn normalize_id(content: &str) -> String {
             } else {
                 None
             }
-        }).collect::<String>();
-    // Ensure that the first character is [A-Za-z]
-    if ret
-        .chars()
-        .next()
-        .map_or(false, |c| !c.is_ascii_alphabetic())
-    {
-        ret.insert(0, 'a');
-    }
-    ret
+        }).collect::<String>()
 }
 
 /// Generate an ID for use with anchors which is derived from a "normalised"
@@ -74,15 +66,21 @@ pub fn id_from_content(content: &str) -> String {
     normalize_id(trimmed)
 }
 
-fn adjust_links(event: Event) -> Event {
+fn adjust_links<'a>(event: Event<'a>, with_base: &str) -> Event<'a> {
     lazy_static! {
         static ref HTTP_LINK: Regex = Regex::new("^https?://").unwrap();
-        static ref MD_LINK: Regex = Regex::new("(?P<link>.*).md(?P<anchor>#.*)?").unwrap();
+        static ref MD_LINK: Regex = Regex::new(r"(?P<link>.*)\.md(?P<anchor>#.*)?").unwrap();
     }
 
     match event {
         Event::Start(Tag::Link(dest, title)) => {
             if !HTTP_LINK.is_match(&dest) {
+                let dest = if !with_base.is_empty() {
+                    format!("{}/{}", with_base, dest)
+                } else {
+                    dest.clone().into_owned()
+                };
+
                 if let Some(caps) = MD_LINK.captures(&dest) {
                     let mut html_link = [&caps["link"], ".html"].concat();
 
@@ -102,6 +100,10 @@ fn adjust_links(event: Event) -> Event {
 
 /// Wrapper around the pulldown-cmark parser for rendering markdown to HTML.
 pub fn render_markdown(text: &str, curly_quotes: bool) -> String {
+    render_markdown_with_base(text, curly_quotes, "")
+}
+
+pub fn render_markdown_with_base(text: &str, curly_quotes: bool, base: &str) -> String {
     let mut s = String::with_capacity(text.len() * 3 / 2);
 
     let mut opts = Options::empty();
@@ -112,7 +114,7 @@ pub fn render_markdown(text: &str, curly_quotes: bool) -> String {
     let mut converter = EventQuoteConverter::new(curly_quotes);
     let events = p
         .map(clean_codeblock_headers)
-        .map(adjust_links)
+        .map(|event| adjust_links(event, base))
         .map(|event| converter.convert(event));
 
     html::push_html(&mut s, events);
@@ -127,7 +129,7 @@ struct EventQuoteConverter {
 impl EventQuoteConverter {
     fn new(enabled: bool) -> Self {
         EventQuoteConverter {
-            enabled: enabled,
+            enabled,
             convert_text: true,
         }
     }
@@ -228,6 +230,12 @@ mod tests {
                 render_markdown("[example_anchor](example.md#anchor)", false),
                 "<p><a href=\"example.html#anchor\">example_anchor</a></p>\n"
             );
+
+            // this anchor contains 'md' inside of it
+            assert_eq!(
+                render_markdown("[phantom data](foo.html#phantomdata)", false),
+                "<p><a href=\"foo.html#phantomdata\">phantom data</a></p>\n"
+            );
         }
 
         #[test]
@@ -328,28 +336,42 @@ more text with spaces
 
         #[test]
         fn it_generates_anchors() {
-            assert_eq!(
-                id_from_content("## `--passes`: add more rustdoc passes"),
-                "a--passes-add-more-rustdoc-passes"
-            );
             assert_eq!(
                 id_from_content("## Method-call expressions"),
                 "method-call-expressions"
             );
+            assert_eq!(id_from_content("## **Bold** title"), "bold-title");
+            assert_eq!(id_from_content("## `Code` title"), "code-title");
+        }
+
+        #[test]
+        fn it_generates_anchors_from_non_ascii_initial() {
+            assert_eq!(
+                id_from_content("## `--passes`: add more rustdoc passes"),
+                "--passes-add-more-rustdoc-passes"
+            );
+            assert_eq!(
+                id_from_content("## 中文標題 CJK title"),
+                "中文標題-cjk-title"
+            );
+            assert_eq!(id_from_content("## Über"), "Über");
         }
 
         #[test]
         fn it_normalizes_ids() {
             assert_eq!(
                 normalize_id("`--passes`: add more rustdoc passes"),
-                "a--passes-add-more-rustdoc-passes"
+                "--passes-add-more-rustdoc-passes"
             );
             assert_eq!(
                 normalize_id("Method-call 🐙 expressions \u{1f47c}"),
                 "method-call--expressions-"
             );
-            assert_eq!(normalize_id("_-_12345"), "a_-_12345");
-            assert_eq!(normalize_id("12345"), "a12345");
+            assert_eq!(normalize_id("_-_12345"), "_-_12345");
+            assert_eq!(normalize_id("12345"), "12345");
+            assert_eq!(normalize_id("中文"), "中文");
+            assert_eq!(normalize_id("にほんご"), "にほんご");
+            assert_eq!(normalize_id("한국어"), "한국어");
             assert_eq!(normalize_id(""), "");
         }
     }

tests/alternate_backends.rs

@@ -11,14 +11,14 @@ use tempfile::{Builder as TempFileBuilder, TempDir};
 
 #[test]
 fn passing_alternate_backend() {
-    let (md, _temp) = dummy_book_with_backend("passing", "true");
+    let (md, _temp) = dummy_book_with_backend("passing", success_cmd());
 
     md.build().unwrap();
 }
 
 #[test]
 fn failing_alternate_backend() {
-    let (md, _temp) = dummy_book_with_backend("failing", "false");
+    let (md, _temp) = dummy_book_with_backend("failing", fail_cmd());
 
     md.build().unwrap_err();
 }
@@ -84,3 +84,19 @@ fn dummy_book_with_backend(name: &str, command: &str) -> (MDBook, TempDir) {
 
     (md, temp)
 }
+
+fn fail_cmd() -> &'static str {
+    if cfg!(windows) {
+        r#"cmd.exe /c "exit 1""#
+    } else {
+        "false"
+    }
+}
+
+fn success_cmd() -> &'static str {
+    if cfg!(windows) {
+        r#"cmd.exe /c "exit 0""#
+    } else {
+        "true"
+    }
+}

tests/build_process.rs

@@ -0,0 +1,80 @@
+extern crate mdbook;
+
+mod dummy_book;
+
+use dummy_book::DummyBook;
+use mdbook::book::Book;
+use mdbook::config::Config;
+use mdbook::errors::*;
+use mdbook::preprocess::{Preprocessor, PreprocessorContext};
+use mdbook::renderer::{RenderContext, Renderer};
+use mdbook::MDBook;
+use std::sync::{Arc, Mutex};
+
+struct Spy(Arc<Mutex<Inner>>);
+
+#[derive(Debug, Default)]
+struct Inner {
+    run_count: usize,
+    rendered_with: Vec<String>,
+}
+
+impl Preprocessor for Spy {
+    fn name(&self) -> &str {
+        "dummy"
+    }
+
+    fn run(&self, ctx: &PreprocessorContext, book: Book) -> Result<Book> {
+        let mut inner = self.0.lock().unwrap();
+        inner.run_count += 1;
+        inner.rendered_with.push(ctx.renderer.clone());
+        Ok(book)
+    }
+}
+
+impl Renderer for Spy {
+    fn name(&self) -> &str {
+        "dummy"
+    }
+
+    fn render(&self, _ctx: &RenderContext) -> Result<()> {
+        let mut inner = self.0.lock().unwrap();
+        inner.run_count += 1;
+        Ok(())
+    }
+}
+
+#[test]
+fn mdbook_runs_preprocessors() {
+    let spy: Arc<Mutex<Inner>> = Default::default();
+
+    let temp = DummyBook::new().build().unwrap();
+    let cfg = Config::default();
+
+    let mut book = MDBook::load_with_config(temp.path(), cfg).unwrap();
+    book.with_preprecessor(Spy(Arc::clone(&spy)));
+    book.build().unwrap();
+
+    let inner = spy.lock().unwrap();
+    assert_eq!(inner.run_count, 1);
+    assert_eq!(inner.rendered_with.len(), 1);
+    assert_eq!(
+        "html", inner.rendered_with[0],
+        "We should have been run with the default HTML renderer"
+    );
+}
+
+#[test]
+fn mdbook_runs_renderers() {
+    let spy: Arc<Mutex<Inner>> = Default::default();
+
+    let temp = DummyBook::new().build().unwrap();
+    let cfg = Config::default();
+
+    let mut book = MDBook::load_with_config(temp.path(), cfg).unwrap();
+    book.with_renderer(Spy(Arc::clone(&spy)));
+    book.build().unwrap();
+
+    let inner = spy.lock().unwrap();
+    assert_eq!(inner.run_count, 1);
+}

tests/custom_preprocessors.rs

@@ -0,0 +1,58 @@
+extern crate mdbook;
+
+mod dummy_book;
+
+use dummy_book::DummyBook;
+use mdbook::preprocess::{CmdPreprocessor, Preprocessor};
+use mdbook::MDBook;
+
+fn example() -> CmdPreprocessor {
+    CmdPreprocessor::new(
+        "nop-preprocessor".to_string(),
+        "cargo run --example nop-preprocessor --".to_string(),
+    )
+}
+
+#[test]
+fn example_supports_whatever() {
+    let cmd = example();
+
+    let got = cmd.supports_renderer("whatever");
+
+    assert_eq!(got, true);
+}
+
+#[test]
+fn example_doesnt_support_not_supported() {
+    let cmd = example();
+
+    let got = cmd.supports_renderer("not-supported");
+
+    assert_eq!(got, false);
+}
+
+#[test]
+fn ask_the_preprocessor_to_blow_up() {
+    let dummy_book = DummyBook::new();
+    let temp = dummy_book.build().unwrap();
+    let mut md = MDBook::load(temp.path()).unwrap();
+    md.with_preprecessor(example());
+
+    md.config
+        .set("preprocessor.nop-preprocessor.blow-up", true)
+        .unwrap();
+
+    let got = md.build();
+
+    assert!(got.is_err());
+}
+
+#[test]
+fn process_the_dummy_book() {
+    let dummy_book = DummyBook::new();
+    let temp = dummy_book.build().unwrap();
+    let mut md = MDBook::load(temp.path()).unwrap();
+    md.with_preprecessor(example());
+
+    md.build().unwrap();
+}

tests/dummy_book/src/SUMMARY.md

@@ -8,6 +8,7 @@
     - [Includes](first/includes.md)
     - [Recursive](first/recursive.md)
 - [Second Chapter](second.md)
+    - [Nested Chapter](second/nested.md)
 
 ---
 

tests/dummy_book/src/second/nested.md

@@ -0,0 +1,4 @@
+# Testing relative links for the print page
+
+When we link to [the first section](../first/nested.md), it should work on
+both the print page and the non-print page.

tests/rendered_output.rs

@@ -31,7 +31,7 @@ const TOC_TOP_LEVEL: &[&'static str] = &[
     "Introduction",
 ];
 const TOC_SECOND_LEVEL: &[&'static str] =
-    &["1.1. Nested Chapter", "1.2. Includes", "1.3. Recursive"];
+    &["1.1. Nested Chapter", "1.2. Includes", "2.1. Nested Chapter", "1.3. Recursive"];
 
 /// Make sure you can load the dummy book and build it without panicking.
 #[test]
@@ -109,6 +109,20 @@ fn check_correct_cross_links_in_nested_dir() {
     );
 }
 
+#[test]
+fn check_correct_relative_links_in_print_page() {
+    let temp = DummyBook::new().build().unwrap();
+    let md = MDBook::load(temp.path()).unwrap();
+    md.build().unwrap();
+
+    let first = temp.path().join("book");
+
+    assert_contains_strings(
+        first.join("print.html"),
+        &[r##"<a href="second/../first/nested.html">the first section</a>,"##],
+    );
+}
+
 #[test]
 fn rendered_code_has_playpen_stuff() {
     let temp = DummyBook::new().build().unwrap();
@@ -443,7 +457,7 @@ mod search {
         assert_eq!(docs[&some_section]["body"], "");
         assert_eq!(
             docs[&summary]["body"],
-            "Dummy Book Introduction First Chapter Nested Chapter Includes Recursive Second Chapter Conclusion"
+            "Dummy Book Introduction First Chapter Nested Chapter Includes Recursive Second Chapter Nested Chapter Conclusion"
         );
         assert_eq!(docs[&summary]["breadcrumbs"], "First Chapter » Summary");
         assert_eq!(docs[&conclusion]["body"], "I put &lt;HTML&gt; in here!");

tests/searchindex_fixture.json

@@ -9,6 +9,7 @@
     "first/includes.html#includes",
     "first/includes.html#summary",
     "second.html#second-chapter",
+    "second/nested.html#testing-relative-links-for-the-print-page",
     "conclusion.html#conclusion"
   ],
   "index": {
@@ -24,6 +25,11 @@
           "breadcrumbs": 1,
           "title": 1
         },
+        "10": {
+          "body": 3,
+          "breadcrumbs": 1,
+          "title": 1
+        },
         "2": {
           "body": 2,
           "breadcrumbs": 2,
@@ -50,7 +56,7 @@
           "title": 1
         },
         "7": {
-          "body": 12,
+          "body": 14,
           "breadcrumbs": 3,
           "title": 1
         },
@@ -60,9 +66,9 @@
           "title": 2
         },
         "9": {
-          "body": 3,
-          "breadcrumbs": 1,
-          "title": 1
+          "body": 10,
+          "breadcrumbs": 7,
+          "title": 5
         }
       },
       "docs": {
@@ -78,6 +84,12 @@
           "id": "1",
           "title": "Introduction"
         },
+        "10": {
+          "body": "I put <HTML> in here!",
+          "breadcrumbs": "Conclusion",
+          "id": "10",
+          "title": "Conclusion"
+        },
         "2": {
           "body": "more text.",
           "breadcrumbs": "First Chapter",
@@ -109,7 +121,7 @@
           "title": "Includes"
         },
         "7": {
-          "body": "Dummy Book Introduction First Chapter Nested Chapter Includes Recursive Second Chapter Conclusion",
+          "body": "Dummy Book Introduction First Chapter Nested Chapter Includes Recursive Second Chapter Nested Chapter Conclusion",
           "breadcrumbs": "First Chapter » Summary",
           "id": "7",
           "title": "Summary"
@@ -121,13 +133,13 @@
           "title": "Second Chapter"
         },
         "9": {
-          "body": "I put <HTML> in here!",
-          "breadcrumbs": "Conclusion",
+          "body": "When we link to the first section , it should work on both the print page and the non-print page.",
+          "breadcrumbs": "Second Chapter » Testing relative links for the print page",
           "id": "9",
-          "title": "Conclusion"
+          "title": "Testing relative links for the print page"
         }
       },
-      "length": 10,
+      "length": 11,
       "save": true
     },
     "fields": [
@@ -206,6 +218,18 @@
                     }
                   }
                 }
+              },
+              "t": {
+                "df": 0,
+                "docs": {},
+                "h": {
+                  "df": 1,
+                  "docs": {
+                    "9": {
+                      "tf": 1.0
+                    }
+                  }
+                }
               }
             }
           },
@@ -251,7 +275,7 @@
                             "tf": 1.0
                           },
                           "7": {
-                            "tf": 1.7320508075688773
+                            "tf": 2.0
                           },
                           "8": {
                             "tf": 1.0
@@ -296,10 +320,10 @@
                       "s": {
                         "df": 2,
                         "docs": {
-                          "7": {
+                          "10": {
                             "tf": 1.0
                           },
-                          "9": {
+                          "7": {
                             "tf": 1.0
                           }
                         }
@@ -420,13 +444,16 @@
                   "df": 0,
                   "docs": {},
                   "t": {
-                    "df": 2,
+                    "df": 3,
                     "docs": {
                       "2": {
                         "tf": 1.0
                       },
                       "7": {
                         "tf": 1.0
+                      },
+                      "9": {
+                        "tf": 1.0
                       }
                     }
                   }
@@ -485,7 +512,7 @@
                     "0": {
                       "tf": 1.0
                     },
-                    "9": {
+                    "10": {
                       "tf": 1.0
                     }
                   }
@@ -683,6 +710,14 @@
                       "tf": 1.0
                     }
                   }
+                },
+                "k": {
+                  "df": 1,
+                  "docs": {
+                    "9": {
+                      "tf": 1.4142135623730951
+                    }
+                  }
                 }
               }
             },
@@ -709,7 +744,7 @@
                             "t": {
                               "df": 1,
                               "docs": {
-                                "9": {
+                                "10": {
                                   "tf": 1.0
                                 }
                               }
@@ -791,14 +826,42 @@
                       "tf": 1.0
                     },
                     "7": {
-                      "tf": 1.0
+                      "tf": 1.4142135623730951
                     }
                   }
                 }
               }
+            },
+            "o": {
+              "df": 0,
+              "docs": {},
+              "n": {
+                "df": 1,
+                "docs": {
+                  "9": {
+                    "tf": 1.0
+                  }
+                }
+              }
             }
           },
           "p": {
+            "a": {
+              "df": 0,
+              "docs": {},
+              "g": {
+                "df": 0,
+                "docs": {},
+                "e": {
+                  "df": 1,
+                  "docs": {
+                    "9": {
+                      "tf": 1.7320508075688772
+                    }
+                  }
+                }
+              }
+            },
             "df": 0,
             "docs": {},
             "r": {
@@ -871,8 +934,12 @@
                   "df": 0,
                   "docs": {},
                   "t": {
-                    "df": 0,
-                    "docs": {},
+                    "df": 1,
+                    "docs": {
+                      "9": {
+                        "tf": 1.7320508075688772
+                      }
+                    },
                     "l": {
                       "df": 0,
                       "docs": {},
@@ -935,7 +1002,7 @@
               "t": {
                 "df": 1,
                 "docs": {
-                  "9": {
+                  "10": {
                     "tf": 1.0
                   }
                 }
@@ -967,7 +1034,15 @@
                 }
               },
               "df": 0,
-              "docs": {}
+              "docs": {},
+              "l": {
+                "df": 1,
+                "docs": {
+                  "9": {
+                    "tf": 1.0
+                  }
+                }
+              }
             },
             "u": {
               "df": 0,
@@ -1050,13 +1125,16 @@
                       "df": 0,
                       "docs": {},
                       "n": {
-                        "df": 2,
+                        "df": 3,
                         "docs": {
                           "3": {
                             "tf": 1.0
                           },
                           "5": {
                             "tf": 1.0
+                          },
+                          "9": {
+                            "tf": 1.0
                           }
                         }
                       }
@@ -1170,8 +1248,12 @@
                     "df": 0,
                     "docs": {}
                   },
-                  "df": 0,
-                  "docs": {}
+                  "df": 1,
+                  "docs": {
+                    "9": {
+                      "tf": 1.0
+                    }
+                  }
                 }
               },
               "x": {
@@ -1200,6 +1282,14 @@
               "r": {
                 "df": 0,
                 "docs": {},
+                "k": {
+                  "df": 1,
+                  "docs": {
+                    "9": {
+                      "tf": 1.0
+                    }
+                  }
+                },
                 "l": {
                   "d": {
                     "df": 1,
@@ -1280,13 +1370,25 @@
                   "df": 2,
                   "docs": {
                     "0": {
-                      "tf": 1.4142135623730952
+                      "tf": 1.4142135623730951
                     },
                     "7": {
                       "tf": 1.0
                     }
                   }
                 }
+              },
+              "t": {
+                "df": 0,
+                "docs": {},
+                "h": {
+                  "df": 1,
+                  "docs": {
+                    "9": {
+                      "tf": 1.0
+                    }
+                  }
+                }
               }
             }
           },
@@ -1323,13 +1425,13 @@
                       "df": 0,
                       "docs": {},
                       "r": {
-                        "df": 6,
+                        "df": 7,
                         "docs": {
                           "2": {
-                            "tf": 1.4142135623730952
+                            "tf": 1.4142135623730951
                           },
                           "4": {
-                            "tf": 1.7320508075688773
+                            "tf": 1.7320508075688772
                           },
                           "5": {
                             "tf": 1.0
@@ -1338,10 +1440,13 @@
                             "tf": 1.0
                           },
                           "7": {
-                            "tf": 2.0
+                            "tf": 2.23606797749979
                           },
                           "8": {
-                            "tf": 1.4142135623730952
+                            "tf": 1.4142135623730951
+                          },
+                          "9": {
+                            "tf": 1.0
                           }
                         }
                       }
@@ -1383,11 +1488,11 @@
                       "s": {
                         "df": 2,
                         "docs": {
+                          "10": {
+                            "tf": 1.4142135623730951
+                          },
                           "7": {
                             "tf": 1.0
-                          },
-                          "9": {
-                            "tf": 1.4142135623730952
                           }
                         }
                       }
@@ -1419,7 +1524,7 @@
                     "df": 2,
                     "docs": {
                       "0": {
-                        "tf": 1.4142135623730952
+                        "tf": 1.4142135623730951
                       },
                       "7": {
                         "tf": 1.0
@@ -1507,10 +1612,10 @@
                   "df": 0,
                   "docs": {},
                   "t": {
-                    "df": 5,
+                    "df": 6,
                     "docs": {
                       "2": {
-                        "tf": 1.4142135623730952
+                        "tf": 1.4142135623730951
                       },
                       "4": {
                         "tf": 1.0
@@ -1522,7 +1627,10 @@
                         "tf": 1.0
                       },
                       "7": {
-                        "tf": 1.4142135623730952
+                        "tf": 1.4142135623730951
+                      },
+                      "9": {
+                        "tf": 1.0
                       }
                     }
                   }
@@ -1581,7 +1689,7 @@
                     "0": {
                       "tf": 1.0
                     },
-                    "9": {
+                    "10": {
                       "tf": 1.0
                     }
                   }
@@ -1636,7 +1744,7 @@
                       "df": 2,
                       "docs": {
                         "6": {
-                          "tf": 1.4142135623730952
+                          "tf": 1.4142135623730951
                         },
                         "7": {
                           "tf": 1.0
@@ -1728,7 +1836,7 @@
                             "df": 2,
                             "docs": {
                               "1": {
-                                "tf": 1.4142135623730952
+                                "tf": 1.4142135623730951
                               },
                               "7": {
                                 "tf": 1.0
@@ -1779,6 +1887,14 @@
                       "tf": 1.0
                     }
                   }
+                },
+                "k": {
+                  "df": 1,
+                  "docs": {
+                    "9": {
+                      "tf": 1.7320508075688772
+                    }
+                  }
                 }
               }
             },
@@ -1805,7 +1921,7 @@
                             "t": {
                               "df": 1,
                               "docs": {
-                                "9": {
+                                "10": {
                                   "tf": 1.0
                                 }
                               }
@@ -1884,17 +2000,45 @@
                   "df": 2,
                   "docs": {
                     "4": {
-                      "tf": 1.4142135623730952
+                      "tf": 1.4142135623730951
                     },
                     "7": {
-                      "tf": 1.0
+                      "tf": 1.4142135623730951
                     }
                   }
                 }
               }
+            },
+            "o": {
+              "df": 0,
+              "docs": {},
+              "n": {
+                "df": 1,
+                "docs": {
+                  "9": {
+                    "tf": 1.0
+                  }
+                }
+              }
             }
           },
           "p": {
+            "a": {
+              "df": 0,
+              "docs": {},
+              "g": {
+                "df": 0,
+                "docs": {},
+                "e": {
+                  "df": 1,
+                  "docs": {
+                    "9": {
+                      "tf": 2.0
+                    }
+                  }
+                }
+              }
+            },
             "df": 0,
             "docs": {},
             "r": {
@@ -1967,8 +2111,12 @@
                   "df": 0,
                   "docs": {},
                   "t": {
-                    "df": 0,
-                    "docs": {},
+                    "df": 1,
+                    "docs": {
+                      "9": {
+                        "tf": 2.0
+                      }
+                    },
                     "l": {
                       "df": 0,
                       "docs": {},
@@ -2031,7 +2179,7 @@
               "t": {
                 "df": 1,
                 "docs": {
-                  "9": {
+                  "10": {
                     "tf": 1.0
                   }
                 }
@@ -2063,7 +2211,15 @@
                 }
               },
               "df": 0,
-              "docs": {}
+              "docs": {},
+              "l": {
+                "df": 1,
+                "docs": {
+                  "9": {
+                    "tf": 1.4142135623730951
+                  }
+                }
+              }
             },
             "u": {
               "df": 0,
@@ -2122,13 +2278,16 @@
                   "docs": {},
                   "n": {
                     "d": {
-                      "df": 2,
+                      "df": 3,
                       "docs": {
                         "7": {
                           "tf": 1.0
                         },
                         "8": {
-                          "tf": 1.4142135623730952
+                          "tf": 1.4142135623730951
+                        },
+                        "9": {
+                          "tf": 1.0
                         }
                       }
                     },
@@ -2146,13 +2305,16 @@
                       "df": 0,
                       "docs": {},
                       "n": {
-                        "df": 2,
+                        "df": 3,
                         "docs": {
                           "3": {
-                            "tf": 1.4142135623730952
+                            "tf": 1.4142135623730951
                           },
                           "5": {
-                            "tf": 1.4142135623730952
+                            "tf": 1.4142135623730951
+                          },
+                          "9": {
+                            "tf": 1.0
                           }
                         }
                       }
@@ -2216,7 +2378,7 @@
                         "df": 1,
                         "docs": {
                           "7": {
-                            "tf": 1.4142135623730952
+                            "tf": 1.4142135623730951
                           }
                         }
                       }
@@ -2266,8 +2428,12 @@
                     "df": 0,
                     "docs": {}
                   },
-                  "df": 0,
-                  "docs": {}
+                  "df": 1,
+                  "docs": {
+                    "9": {
+                      "tf": 1.4142135623730951
+                    }
+                  }
                 }
               },
               "x": {
@@ -2296,6 +2462,14 @@
               "r": {
                 "df": 0,
                 "docs": {},
+                "k": {
+                  "df": 1,
+                  "docs": {
+                    "9": {
+                      "tf": 1.0
+                    }
+                  }
+                },
                 "l": {
                   "d": {
                     "df": 1,
@@ -2388,7 +2562,7 @@
                       "s": {
                         "df": 1,
                         "docs": {
-                          "9": {
+                          "10": {
                             "tf": 1.0
                           }
                         }
@@ -2511,6 +2685,26 @@
               }
             }
           },
+          "l": {
+            "df": 0,
+            "docs": {},
+            "i": {
+              "df": 0,
+              "docs": {},
+              "n": {
+                "df": 0,
+                "docs": {},
+                "k": {
+                  "df": 1,
+                  "docs": {
+                    "9": {
+                      "tf": 1.0
+                    }
+                  }
+                }
+              }
+            }
+          },
           "n": {
             "df": 0,
             "docs": {},
@@ -2531,6 +2725,62 @@
               }
             }
           },
+          "p": {
+            "a": {
+              "df": 0,
+              "docs": {},
+              "g": {
+                "df": 0,
+                "docs": {},
+                "e": {
+                  "df": 1,
+                  "docs": {
+                    "9": {
+                      "tf": 1.0
+                    }
+                  }
+                }
+              }
+            },
+            "df": 0,
+            "docs": {},
+            "r": {
+              "df": 0,
+              "docs": {},
+              "i": {
+                "df": 0,
+                "docs": {},
+                "n": {
+                  "df": 0,
+                  "docs": {},
+                  "t": {
+                    "df": 1,
+                    "docs": {
+                      "9": {
+                        "tf": 1.0
+                      }
+                    }
+                  }
+                }
+              }
+            }
+          },
+          "r": {
+            "df": 0,
+            "docs": {},
+            "e": {
+              "df": 0,
+              "docs": {},
+              "l": {
+                "df": 1,
+                "docs": {
+                  "9": {
+                    "tf": 1.0
+                  }
+                }
+              }
+            }
+          },
           "s": {
             "df": 0,
             "docs": {},
@@ -2609,6 +2859,26 @@
                 }
               }
             }
+          },
+          "t": {
+            "df": 0,
+            "docs": {},
+            "e": {
+              "df": 0,
+              "docs": {},
+              "s": {
+                "df": 0,
+                "docs": {},
+                "t": {
+                  "df": 1,
+                  "docs": {
+                    "9": {
+                      "tf": 1.0
+                    }
+                  }
+                }
+              }
+            }
           }
         }
       }

tests/testing.rs

@@ -4,14 +4,8 @@ mod dummy_book;
 
 use dummy_book::DummyBook;
 
-use mdbook::book::Book;
-use mdbook::config::Config;
-use mdbook::errors::*;
-use mdbook::preprocess::{Preprocessor, PreprocessorContext};
 use mdbook::MDBook;
 
-use std::sync::{Arc, Mutex};
-
 #[test]
 fn mdbook_can_correctly_test_a_passing_book() {
     let temp = DummyBook::new().with_passing_test(true).build().unwrap();
@@ -27,30 +21,3 @@ fn mdbook_detects_book_with_failing_tests() {
 
     assert!(md.test(vec![]).is_err());
 }
-
-#[test]
-fn mdbook_runs_preprocessors() {
-    let has_run: Arc<Mutex<bool>> = Arc::new(Mutex::new(false));
-
-    struct DummyPreprocessor(Arc<Mutex<bool>>);
-
-    impl Preprocessor for DummyPreprocessor {
-        fn name(&self) -> &str {
-            "dummy"
-        }
-
-        fn run(&self, _ctx: &PreprocessorContext, _book: &mut Book) -> Result<()> {
-            *self.0.lock().unwrap() = true;
-            Ok(())
-        }
-    }
-
-    let temp = DummyBook::new().build().unwrap();
-    let cfg = Config::default();
-
-    let mut book = MDBook::load_with_config(temp.path(), cfg).unwrap();
-    book.with_preprecessor(DummyPreprocessor(Arc::clone(&has_run)));
-    book.build().unwrap();
-
-    assert!(*has_run.lock().unwrap())
-}