Merge pull request #2389 from ehuss/bump-version

Update to 0.4.40

.github/workflows/deploy.yml

@@ -3,18 +3,18 @@ on:
   release:
     types: [created]
 
+defaults:
+  run:
+    shell: bash
+
+permissions:
+  contents: write
+
 jobs:
   release:
-    name: Deploy Release
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        target:
-          - aarch64-unknown-linux-musl
-          - x86_64-unknown-linux-gnu
-          - x86_64-unknown-linux-musl
-          - x86_64-apple-darwin
-          - x86_64-pc-windows-msvc
         include:
           - target: aarch64-unknown-linux-musl
             os: ubuntu-20.04
@@ -26,24 +26,22 @@ jobs:
             os: macos-latest
           - target: x86_64-pc-windows-msvc
             os: windows-latest
+    name: Deploy ${{ matrix.target }}
     steps:
-    - uses: actions/checkout@master
-    - name: Install hub
-      run: ci/install-hub.sh ${{ matrix.os }}
-      shell: bash
+    - uses: actions/checkout@v4
     - name: Install Rust
       run: ci/install-rust.sh stable ${{ matrix.target }}
-      shell: bash
-    - name: Build and deploy artifacts
+    - name: Build asset
+      run: ci/make-release-asset.sh ${{ matrix.os }} ${{ matrix.target }}
+    - name: Update release with new asset
       env:
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-      run: ci/make-release.sh ${{ matrix.os }} ${{ matrix.target }}
-      shell: bash
+      run: gh release upload $MDBOOK_TAG $MDBOOK_ASSET
   pages:
     name: GitHub Pages
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v4
     - name: Install Rust (rustup)
       run: rustup update stable --no-self-update && rustup default stable
     - name: Build book
@@ -56,3 +54,14 @@ jobs:
         curl -LsSf https://raw.githubusercontent.com/rust-lang/simpleinfra/master/setup-deploy-keys/src/deploy.rs | rustc - -o /tmp/deploy
         cd guide/book
         /tmp/deploy
+  publish:
+    name: Publish to crates.io
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust (rustup)
+        run: rustup update stable --no-self-update && rustup default stable
+      - name: Publish
+        env:
+          CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}
+        run: cargo publish --no-verify

.github/workflows/main.yml

@@ -1,52 +1,88 @@
 name: CI
 on:
-  # Only run when merging to master, or open/synchronize/reopen a PR.
-  push:
-    branches:
-      - master
   pull_request:
+  merge_group:
 
 jobs:
   test:
-    name: Test
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        build: [stable, beta, nightly, macos, windows, msrv]
         include:
-          - build: stable
+          - name: stable linux
             os: ubuntu-latest
             rust: stable
-          - build: beta
+            target: x86_64-unknown-linux-gnu
+          - name: beta linux
             os: ubuntu-latest
             rust: beta
-          - build: nightly
+            target: x86_64-unknown-linux-gnu
+          - name: nightly linux
             os: ubuntu-latest
             rust: nightly
-          - build: macos
+            target: x86_64-unknown-linux-gnu
+          - name: stable x86_64-unknown-linux-musl
+            os: ubuntu-20.04
+            rust: stable
+            target: x86_64-unknown-linux-musl
+          - name: stable x86_64 macos
             os: macos-latest
             rust: stable
-          - build: windows
+            target: x86_64-apple-darwin
+          - name: stable aarch64 macos
+            os: macos-latest
+            rust: stable
+            target: aarch64-apple-darwin
+          - name: stable windows-msvc
             os: windows-latest
             rust: stable
-          - build: msrv
+            target: x86_64-pc-windows-msvc
+          - name: msrv
             os: ubuntu-20.04
             # sync MSRV with docs: guide/src/guide/installation.md and Cargo.toml
-            rust: 1.65.0
+            rust: 1.74.0
+            target: x86_64-unknown-linux-gnu
+    name: ${{ matrix.name }}
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Install Rust
-      run: bash ci/install-rust.sh ${{ matrix.rust }}
+      run: bash ci/install-rust.sh ${{ matrix.rust }} ${{ matrix.target }}
     - name: Build and run tests
-      run: cargo test --locked
+      run: cargo test --locked --target ${{ matrix.target }}
     - name: Test no default
-      run: cargo test --no-default-features
+      run: cargo test --no-default-features --target ${{ matrix.target }}
+
+  aarch64-cross-builds:
+    runs-on: ubuntu-20.04
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install Rust
+      run: bash ci/install-rust.sh stable aarch64-unknown-linux-musl
+    - name: Build
+      run: cargo build --locked --target aarch64-unknown-linux-musl
 
   rustfmt:
     name: Rustfmt
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Install Rust
       run: rustup update stable && rustup default stable && rustup component add rustfmt
     - run: cargo fmt --check
+
+  # The success job is here to consolidate the total success/failure state of
+  # all other jobs. This job is then included in the GitHub branch protection
+  # rule which prevents merges unless all other jobs are passing. This makes
+  # it easier to manage the list of jobs via this yml file and to prevent
+  # accidentally adding new jobs without also updating the branch protections.
+  success:
+    name: Success gate
+    if: always()
+    needs:
+      - test
+      - rustfmt
+    runs-on: ubuntu-latest
+    steps:
+      - run: jq --exit-status 'all(.result == "success")' <<< '${{ toJson(needs) }}'
+      - name: Done
+        run: exit 0

CHANGELOG.md

@@ -1,10 +1,187 @@
 # Changelog
 
+## mdBook 0.4.40
+[v0.4.39...v0.4.40](https://github.com/rust-lang/mdBook/compare/v0.4.39...v0.4.40)
+
+### Fixed
+
+- Reverted the update to pulldown-cmark which broke the semver API.
+  [#2388](https://github.com/rust-lang/mdBook/pull/2388)
+
+## mdBook 0.4.39
+[v0.4.38...v0.4.39](https://github.com/rust-lang/mdBook/compare/v0.4.38...v0.4.39)
+
+### Fixed
+
+- Fixed the automatic deploy broken in the previous release.
+  [#2383](https://github.com/rust-lang/mdBook/pull/2383)
+
+## mdBook 0.4.38
+[v0.4.37...v0.4.38](https://github.com/rust-lang/mdBook/compare/v0.4.37...v0.4.38)
+
+### Added
+
+- Added `nix` to the default set of languages supported for syntax highlighting.
+  [#2262](https://github.com/rust-lang/mdBook/pull/2262)
+
+### Changed
+
+- The `output.html.curly-quotes` option has been renamed to `output.html.smart-punctuation` to better reflect what it does. The old option `curly-quotes` is kept for compatibility, but may be removed in the future.
+  [#2327](https://github.com/rust-lang/mdBook/pull/2327)
+- The file-watcher used in `mdbook serve` and `mdbook watch` now uses a poll-based watcher instead of the native operating system notifications. This should fix issues on various systems and environments, and more accurately detect when files change. The native watcher can still be used with the `--watcher native` CLI option.
+  [#2325](https://github.com/rust-lang/mdBook/pull/2325)
+- `mdbook test` output now includes color, and shows relative paths to the source.
+  [#2259](https://github.com/rust-lang/mdBook/pull/2259)
+- Updated dependencies, MSRV raised to 1.74
+  [#2350](https://github.com/rust-lang/mdBook/pull/2350)
+  [#2351](https://github.com/rust-lang/mdBook/pull/2351)
+  [#2378](https://github.com/rust-lang/mdBook/pull/2378)
+  [#2381](https://github.com/rust-lang/mdBook/pull/2381)
+
+### Fixed
+
+- Reduced memory allocation when copying files.
+  [#2355](https://github.com/rust-lang/mdBook/pull/2355)
+- Fixed the horizontal divider in `SUMMARY.md` from being indented into the previous nested section.
+  [#2364](https://github.com/rust-lang/mdBook/pull/2364)
+- Removed unnecessary `@import` in the CSS.
+  [#2260](https://github.com/rust-lang/mdBook/pull/2260)
+
+## mdBook 0.4.37
+[v0.4.36...v0.4.37](https://github.com/rust-lang/mdBook/compare/v0.4.36...v0.4.37)
+
+### Changed
+- ❗️ Updated the markdown parser. This brings in many changes to more closely follow the CommonMark spec. This may cause some small rendering changes. It is recommended to compare the output of the old and new version to check for changes. See <https://github.com/raphlinus/pulldown-cmark/releases/tag/v0.10.0> for more information.
+  [#2308](https://github.com/rust-lang/mdBook/pull/2308)
+- The warning about the legacy `src/theme` directory has been removed.
+  [#2263](https://github.com/rust-lang/mdBook/pull/2263)
+- Updated dependencies. MSRV raised to 1.71.0.
+  [#2283](https://github.com/rust-lang/mdBook/pull/2283)
+  [#2293](https://github.com/rust-lang/mdBook/pull/2293)
+  [#2297](https://github.com/rust-lang/mdBook/pull/2297)
+  [#2310](https://github.com/rust-lang/mdBook/pull/2310)
+  [#2309](https://github.com/rust-lang/mdBook/pull/2309)
+- Some internal performance/memory improvements.
+  [#2273](https://github.com/rust-lang/mdBook/pull/2273)
+  [#2290](https://github.com/rust-lang/mdBook/pull/2290)
+- Made the `pathdiff` dependency optional based on the `watch` feature.
+  [#2291](https://github.com/rust-lang/mdBook/pull/2291)
+
+### Fixed
+- The `s` shortcut key handler should not trigger when focus is in an HTML form.
+  [#2311](https://github.com/rust-lang/mdBook/pull/2311)
+
+## mdBook 0.4.36
+[v0.4.35...v0.4.36](https://github.com/rust-lang/mdBook/compare/v0.4.35...v0.4.36)
+
+### Added
+- Added Nim to the default highlighted languages.
+  [#2232](https://github.com/rust-lang/mdBook/pull/2232)
+- Added a small indicator for the sidebar resize handle.
+  [#2209](https://github.com/rust-lang/mdBook/pull/2209)
+
+### Changed
+- Updated dependencies. MSRV raised to 1.70.0.
+  [#2173](https://github.com/rust-lang/mdBook/pull/2173)
+  [#2250](https://github.com/rust-lang/mdBook/pull/2250)
+  [#2252](https://github.com/rust-lang/mdBook/pull/2252)
+
+### Fixed
+- Fixed blank column in print page when the sidebar was visible.
+  [#2235](https://github.com/rust-lang/mdBook/pull/2235)
+- Fixed indentation of code blocks when Javascript is disabled.
+  [#2162](https://github.com/rust-lang/mdBook/pull/2162)
+- Fixed a panic when `mdbook serve` or `mdbook watch` were given certain kinds of paths.
+  [#2229](https://github.com/rust-lang/mdBook/pull/2229)
+
+## mdBook 0.4.35
+[v0.4.34...v0.4.35](https://github.com/rust-lang/mdBook/compare/v0.4.34...v0.4.35)
+
+### Added
+- Added the `book.text-direction` setting for explicit support for right-to-left languages.
+  [#1641](https://github.com/rust-lang/mdBook/pull/1641)
+- Added `rel=prefetch` to the "next" links to potentially improve browser performance.
+  [#2168](https://github.com/rust-lang/mdBook/pull/2168)
+- Added a `.warning` CSS class which is styled for displaying warning blocks.
+  [#2187](https://github.com/rust-lang/mdBook/pull/2187)
+
+### Changed
+- Better support of the sidebar when JavaScript is disabled.
+  [#2175](https://github.com/rust-lang/mdBook/pull/2175)
+
+## mdBook 0.4.34
+[v0.4.33...v0.4.34](https://github.com/rust-lang/mdBook/compare/v0.4.33...v0.4.34)
+
+### Fixed
+- Fixed file change watcher failing on macOS with a large number of files.
+  [#2157](https://github.com/rust-lang/mdBook/pull/2157)
+
+## mdBook 0.4.33
+[v0.4.32...v0.4.33](https://github.com/rust-lang/mdBook/compare/v0.4.32...v0.4.33)
+
+### Added
+- The `color-scheme` CSS property is now set based on the light/dark theme, which applies some slight color differences in browser elements like scroll bars on some browsers.
+  [#2134](https://github.com/rust-lang/mdBook/pull/2134)
+
+### Fixed
+- Fixed watching of extra-watch-dirs when not running in the book root directory.
+  [#2146](https://github.com/rust-lang/mdBook/pull/2146)
+- Reverted the dependency update to the `toml` crate (again!). This was an unintentional breaking change in 0.4.32.
+  [#2021](https://github.com/rust-lang/mdBook/pull/2021)
+- Changed macOS change notifications to use the kqueue implementation which should fix some issues with repeated rebuilds when a file changed.
+  [#2152](https://github.com/rust-lang/mdBook/pull/2152)
+- Don't set a background color in the print page for code blocks in a header.
+  [#2150](https://github.com/rust-lang/mdBook/pull/2150)
+
+## mdBook 0.4.32
+[v0.4.31...v0.4.32](https://github.com/rust-lang/mdBook/compare/v0.4.31...v0.4.32)
+
+### Fixed
+- Fixed theme-color meta tag not syncing with the theme.
+  [#2118](https://github.com/rust-lang/mdBook/pull/2118)
+
+### Changed
+- Updated all dependencies.
+  [#2121](https://github.com/rust-lang/mdBook/pull/2121)
+  [#2122](https://github.com/rust-lang/mdBook/pull/2122)
+  [#2123](https://github.com/rust-lang/mdBook/pull/2123)
+  [#2124](https://github.com/rust-lang/mdBook/pull/2124)
+  [#2125](https://github.com/rust-lang/mdBook/pull/2125)
+  [#2126](https://github.com/rust-lang/mdBook/pull/2126)
+
+## mdBook 0.4.31
+[v0.4.30...v0.4.31](https://github.com/rust-lang/mdBook/compare/v0.4.30...v0.4.31)
+
+### Fixed
+- Fixed menu border render flash during page navigation.
+  [#2101](https://github.com/rust-lang/mdBook/pull/2101)
+- Fixed flicker setting sidebar scroll position.
+  [#2104](https://github.com/rust-lang/mdBook/pull/2104)
+- Fixed compile error with proc-macro2 on latest Rust nightly.
+  [#2109](https://github.com/rust-lang/mdBook/pull/2109)
+
+## mdBook 0.4.30
+[v0.4.29...v0.4.30](https://github.com/rust-lang/mdBook/compare/v0.4.29...v0.4.30)
+
+### Added
+- Added support for heading attributes.
+  Attributes are specified in curly braces just after the heading text.
+  An HTML ID can be specified with `#` and classes with `.`.
+  For example: `## My heading {#custom-id .class1 .class2}`
+  [#2013](https://github.com/rust-lang/mdBook/pull/2013)
+- Added support for hidden code lines for languages other than Rust.
+  The `output.html.code.hidelines` table allows you to define the prefix character that will be used to hide code lines based on the language.
+  [#2093](https://github.com/rust-lang/mdBook/pull/2093)
+
+### Fixed
+- Fixed a few minor markdown rendering issues.
+  [#2092](https://github.com/rust-lang/mdBook/pull/2092)
+
 ## mdBook 0.4.29
 [v0.4.28...v0.4.29](https://github.com/rust-lang/mdBook/compare/v0.4.28...v0.4.29)
 
 ### Changed
-- Built-in fonts are no longer copied when `fonts/fonts.css` is overridded in the theme directory.
+- Built-in fonts are no longer copied when `fonts/fonts.css` is overridden in the theme directory.
   Additionally, the warning about `copy-fonts` has been removed if `fonts/fonts.css` is specified.
   [#2080](https://github.com/rust-lang/mdBook/pull/2080)
 - `mdbook init --force` now skips all interactive prompts as intended.
@@ -196,7 +373,7 @@
   [#1771](https://github.com/rust-lang/mdBook/pull/1771)
 - The 404 not-found page now includes the books title in the HTML title tag.
   [#1693](https://github.com/rust-lang/mdBook/pull/1693)
-- Migrated to clap 3.0 which which handles CLI option parsing.
+- Migrated to clap 3.0 which handles CLI option parsing.
   [#1731](https://github.com/rust-lang/mdBook/pull/1731)
 
 ### Fixed

CONTRIBUTING.md

@@ -148,8 +148,28 @@ The following are instructions for updating [highlight.js](https://highlightjs.o
 1. Clone the repository at <https://github.com/highlightjs/highlight.js>
 1. Check out a tagged release (like `10.1.1`).
 1. Run `npm install`
-1. Run `node tools/build.js :common apache armasm coffeescript d handlebars haskell http julia nginx properties r scala x86asm yaml`
+1. Run `node tools/build.js :common apache armasm coffeescript d handlebars haskell http julia nginx nim nix properties r scala x86asm yaml`
 1. Compare the language list that it spits out to the one in [`syntax-highlighting.md`](https://github.com/camelid/mdBook/blob/master/guide/src/format/theme/syntax-highlighting.md). If any are missing, add them to the list and rebuild (and update these docs). If any are added to the common set, add them to `syntax-highlighting.md`.
 1. Copy `build/highlight.min.js` to mdbook's directory [`highlight.js`](https://github.com/rust-lang/mdBook/blob/master/src/theme/highlight.js).
 1. Be sure to check the highlight.js [CHANGES](https://github.com/highlightjs/highlight.js/blob/main/CHANGES.md) for any breaking changes. Breaking changes that would affect users will need to wait until the next major release.
 1. Build mdbook with the new file and build some books with the new version and compare the output with a variety of languages to see if anything changes. The [test_book](https://github.com/rust-lang/mdBook/tree/master/test_book) contains a chapter with many languages to examine.
+
+## Publishing new releases
+
+Instructions for mdBook maintainers to publish a new release:
+
+1. Create a PR to update the version and update the CHANGELOG:
+    1. Update the version in `Cargo.toml`
+    2. Run `cargo test` to verify that everything is passing, and to update `Cargo.lock`.
+    3. Double-check for any SemVer breaking changes.
+       Try [`cargo-semver-checks`](https://crates.io/crates/cargo-semver-checks), though beware that the current version of mdBook isn't properly adhering to SemVer due to the lack of `#[non_exhaustive]` and other issues. See https://github.com/rust-lang/mdBook/issues/1835.
+    4. Update `CHANGELOG.md` with any changes that users may be interested in.
+    5. Update `continuous-integration.md` to update the version number for the installation instructions.
+    6. Commit the changes, and open a PR.
+2. After the PR has been merged, create a release in GitHub. This can either be done in the GitHub web UI, or on the command-line:
+   ```bash
+   MDBOOK_VERS="`cargo read-manifest | jq -r .version`" ; \
+    gh release create -R rust-lang/mdbook v$MDBOOK_VERS \
+        --title v$MDBOOK_VERS \
+        --notes "See https://github.com/rust-lang/mdBook/blob/master/CHANGELOG.md#mdbook-${MDBOOK_VERS//.} for a complete list of changes."
+   ```

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mdbook"
-version = "0.4.29"
+version = "0.4.40"
 authors = [
     "Mathieu David <mathieudavid@mathieudavid.org>",
     "Michael-F-Bryan <michaelfbryan@gmail.com>",
@@ -14,45 +14,47 @@ license = "MPL-2.0"
 readme = "README.md"
 repository = "https://github.com/rust-lang/mdBook"
 description = "Creates a book from markdown files"
-rust-version = "1.65"
+rust-version = "1.74"
 
 [dependencies]
 anyhow = "1.0.71"
 chrono = { version = "0.4.24", default-features = false, features = ["clock"] }
-clap = { version = "4.2.7", features = ["cargo", "wrap_help"] }
-clap_complete = "4.2.3"
+clap = { version = "4.3.12", features = ["cargo", "wrap_help"] }
+clap_complete = "4.3.2"
 once_cell = "1.17.1"
-env_logger = "0.10.0"
-handlebars = "4.3.7"
+env_logger = "0.11.1"
+handlebars = "5.0"
 log = "0.4.17"
 memchr = "2.5.0"
-opener = "0.5.2"
-pulldown-cmark = { version = "0.9.2", default-features = false }
+opener = "0.7.0"
+pulldown-cmark = { version = "0.10.0", default-features = false, features = ["html"] } # Do not update, part of the public api.
 regex = "1.8.1"
 serde = { version = "1.0.163", features = ["derive"] }
 serde_json = "1.0.96"
-shlex = "1.1.0"
+shlex = "1.3.0"
 tempfile = "3.4.0"
-toml = "0.5.11"
+toml = "0.5.11" # Do not update, see https://github.com/rust-lang/mdBook/issues/2037
 topological-sort = "0.2.2"
 
 # Watch feature
-notify = { version = "5.1.0", optional = true }
-notify-debouncer-mini = { version = "0.2.1", optional = true }
+notify = { version = "6.1.1", optional = true }
+notify-debouncer-mini = { version = "0.4.1", optional = true }
 ignore = { version = "0.4.20", optional = true }
+pathdiff = { version = "0.2.1", optional = true }
+walkdir = { version = "2.3.3", optional = true }
 
 # Serve feature
 futures-util = { version = "0.3.28", optional = true }
 tokio = { version = "1.28.1", features = ["macros", "rt-multi-thread"], optional = true }
-warp = { version = "0.3.5", default-features = false, features = ["websocket"], optional = true }
+warp = { version = "0.3.6", default-features = false, features = ["websocket"], optional = true }
 
 # Search feature
 elasticlunr-rs = { version = "3.0.2", optional = true }
-ammonia = { version = "3.3.0", optional = true }
+ammonia = { version = "4.0.0", optional = true }
 
 [dev-dependencies]
 assert_cmd = "2.0.11"
-predicates = "2.1.5"
+predicates = "3.0.3"
 select = "0.6.0"
 semver = "1.0.17"
 pretty_assertions = "1.3.0"
@@ -60,7 +62,7 @@ walkdir = "2.3.3"
 
 [features]
 default = ["watch", "serve", "search"]
-watch = ["dep:notify", "dep:notify-debouncer-mini", "dep:ignore"]
+watch = ["dep:notify", "dep:notify-debouncer-mini", "dep:ignore", "dep:pathdiff", "dep:walkdir"]
 serve = ["dep:futures-util", "dep:tokio", "dep:warp"]
 search = ["dep:elasticlunr-rs", "dep:ammonia"]
 

ci/install-hub.sh

@@ -1,24 +0,0 @@
-#!/usr/bin/env bash
-# Installs the `hub` executable into hub/bin
-set -ex
-case $1 in
-  ubuntu*)
-    curl -LsSf https://github.com/github/hub/releases/download/v2.12.8/hub-linux-amd64-2.12.8.tgz -o hub.tgz
-    mkdir hub
-    tar -xzvf hub.tgz --strip=1 -C hub
-    ;;
-  macos*)
-    curl -LsSf https://github.com/github/hub/releases/download/v2.12.8/hub-darwin-amd64-2.12.8.tgz -o hub.tgz
-    mkdir hub
-    tar -xzvf hub.tgz --strip=1 -C hub
-    ;;
-  windows*)
-    curl -LsSf https://github.com/github/hub/releases/download/v2.12.8/hub-windows-amd64-2.12.8.zip -o hub.zip
-    7z x hub.zip -ohub
-    ;;
-  *)
-    echo "OS should be first parameter, was: $1"
-    ;;
-esac
-
-echo "$PWD/hub/bin" >> $GITHUB_PATH

ci/install-rust.sh

@@ -22,6 +22,19 @@ then
         rustup component add llvm-tools-preview --toolchain=$TOOLCHAIN
         rustup component add rust-std-$TARGET --toolchain=$TOOLCHAIN
     fi
+    if [[ $TARGET == *"musl" ]]
+    then
+        # This is needed by libdbus-sys.
+        sudo apt update -y && sudo apt install musl-dev musl-tools -y
+    fi
+    if [[ $TARGET == "aarch64-unknown-linux-musl" ]]
+    then
+        echo CARGO_TARGET_AARCH64_UNKNOWN_LINUX_MUSL_LINKER=rust-lld >> $GITHUB_ENV
+        # This `CC` is some nonsense needed for libdbus-sys (via opener).
+        # I don't know if this is really the right thing to do, but it seems to work.
+        sudo apt install gcc-aarch64-linux-gnu -y
+        echo CC=aarch64-linux-gnu-gcc >> $GITHUB_ENV
+    fi
 fi
 
 rustup default $TOOLCHAIN

ci/make-release-asset.sh

@@ -12,10 +12,6 @@ TAG=${GITHUB_REF#*/tags/}
 
 host=$(rustc -Vv | grep ^host: | sed -e "s/host: //g")
 target=$2
-if [ "$host" != "$target" ]
-then
-  export "CARGO_TARGET_$(echo $target | tr a-z- A-Z_)_LINKER"=rust-lld
-fi
 export CARGO_PROFILE_RELEASE_LTO=true
 cargo build --locked --bin mdbook --release --target $target
 cd target/$target/release
@@ -44,9 +40,10 @@ case $1 in
 esac
 cd ../..
 
-if [[ -z "$GITHUB_TOKEN" ]]
+if [[ -z "$GITHUB_ENV" ]]
 then
-  echo "$GITHUB_TOKEN not set, skipping deploy."
+  echo "GITHUB_ENV not set, run: gh release upload $TAG target/$asset"
 else
-  hub release edit -m "" --attach $asset $TAG
+  echo "MDBOOK_TAG=$TAG" >> $GITHUB_ENV
+  echo "MDBOOK_ASSET=target/$asset" >> $GITHUB_ENV
 fi

guide/book.toml

@@ -8,6 +8,7 @@ language = "en"
 edition = "2018"
 
 [output.html]
+smart-punctuation = true
 mathjax-support = true
 site-url = "/mdBook/"
 git-repository-url = "https://github.com/rust-lang/mdBook/tree/master/guide"
@@ -17,6 +18,9 @@ edit-url-template = "https://github.com/rust-lang/mdBook/edit/master/guide/{path
 editable = true
 line-numbers = true
 
+[output.html.code.hidelines]
+python = "~"
+
 [output.html.search]
 limit-results = 20
 use-boolean-and = true

guide/src/cli/README.md

@@ -5,10 +5,10 @@ After you have [installed](../guide/installation.md) `mdbook`, you can run the `
 
 This following sections provide in-depth information on the different commands available.
 
-* [`mdbook init <directory>`](init.md) — Creates a new book with minimal boilerplate to start with.
-* [`mdbook build`](build.md) — Renders the book.
-* [`mdbook watch`](watch.md) — Rebuilds the book any time a source file changes.
-* [`mdbook serve`](serve.md) — Runs a web server to view the book, and rebuilds on changes.
-* [`mdbook test`](test.md) — Tests Rust code samples.
-* [`mdbook clean`](clean.md) — Deletes the rendered output.
-* [`mdbook completions`](completions.md) — Support for shell auto-completion.
+* [`mdbook init <directory>`](init.md) --- Creates a new book with minimal boilerplate to start with.
+* [`mdbook build`](build.md) --- Renders the book.
+* [`mdbook watch`](watch.md) --- Rebuilds the book any time a source file changes.
+* [`mdbook serve`](serve.md) --- Runs a web server to view the book, and rebuilds on changes.
+* [`mdbook test`](test.md) --- Tests Rust code samples.
+* [`mdbook clean`](clean.md) --- Deletes the rendered output.
+* [`mdbook completions`](completions.md) --- Support for shell auto-completion.

guide/src/cli/arg-watcher.md

@@ -0,0 +1,7 @@
+#### `--watcher`
+
+There are different backends used to determine when a file has changed.
+
+* `poll` (default) --- Checks for file modifications by scanning the filesystem every second.
+* `native` --- Uses the native operating system facilities to receive notifications when files change.
+  This can have less constant overhead, but may not be as reliable as the `poll` based watcher. See these issues for more information: [#383](https://github.com/rust-lang/mdBook/issues/383) [#1441](https://github.com/rust-lang/mdBook/issues/1441) [#1707](https://github.com/rust-lang/mdBook/issues/1707) [#2035](https://github.com/rust-lang/mdBook/issues/2035) [#2102](https://github.com/rust-lang/mdBook/issues/2102)

guide/src/cli/build.md

@@ -7,8 +7,8 @@ mdbook build
 ```
 
 It will try to parse your `SUMMARY.md` file to understand the structure of your
-book and fetch the corresponding files. Note that files mentioned in `SUMMARY.md`
-but not present will be created.
+book and fetch the corresponding files. Note that this will also create files
+mentioned in `SUMMARY.md` which are not yet present.
 
 The rendered output will maintain the same directory structure as the source for
 convenience. Large books will therefore remain structured when rendered.
@@ -22,12 +22,12 @@ root instead of the current working directory.
 mdbook build path/to/book
 ```
 
-#### --open
+#### `--open`
 
 When you use the `--open` (`-o`) flag, mdbook will open the rendered book in
 your default web browser after building it.
 
-#### --dest-dir
+#### `--dest-dir`
 
 The `--dest-dir` (`-d`) option allows you to change the output directory for the
 book. Relative paths are interpreted relative to the book's root directory. If

guide/src/cli/clean.md

@@ -16,7 +16,7 @@ root instead of the current working directory.
 mdbook clean path/to/book
 ```
 
-#### --dest-dir
+#### `--dest-dir`
 
 The `--dest-dir` (`-d`) option allows you to override the book's output
 directory, which will be deleted by this command. Relative paths are interpreted
@@ -27,4 +27,4 @@ value of the `build.build-dir` key in `book.toml`, or to `./book`.
 mdbook clean --dest-dir=path/to/book
 ```
 
-`path/to/book` could be absolute or relative.
+`path/to/book` could be absolute or relative.

guide/src/cli/completions.md

@@ -6,7 +6,11 @@ This means when you type `mdbook` in your shell, you can then press your shell's
 The completions first need to be installed for your shell:
 
 ```bash
+# bash
 mdbook completions bash > ~/.local/share/bash-completion/completions/mdbook
+# oh-my-zsh
+mdbook completions zsh > ~/.oh-my-zsh/completions/_mdbook
+autoload -U compinit && compinit
 ```
 
 The command prints a completion script for the given shell.

guide/src/cli/init.md

@@ -45,7 +45,7 @@ instead of the current working directory.
 mdbook init path/to/book
 ```
 
-#### --theme
+#### `--theme`
 
 When you use the `--theme` flag, the default theme will be copied into a
 directory called `theme` in your source directory so that you can modify it.
@@ -53,7 +53,7 @@ directory called `theme` in your source directory so that you can modify it.
 The theme is selectively overwritten, this means that if you don't want to
 overwrite a specific file, just delete it and the default file will be used.
 
-#### --title
+#### `--title`
 
 Specify a title for the book. If not supplied, an interactive prompt will ask for 
 a title. 
@@ -62,7 +62,7 @@ a title.
 mdbook init --title="my amazing book"
 ```
 
-#### --ignore
+#### `--ignore`
 
 Create a `.gitignore` file configured to ignore the `book` directory created when [building] a book. 
 If not supplied, an interactive prompt will ask whether it should be created.
@@ -77,6 +77,6 @@ mdbook init --ignore=git
 
 [building]: build.md
 
-#### --force
+#### `--force`
 
 Skip the prompts to create a `.gitignore` and for the title for the book.

guide/src/cli/serve.md

@@ -32,18 +32,20 @@ The `serve` hostname defaults to `localhost`, and the port defaults to `3000`. E
 mdbook serve path/to/book -p 8000 -n 127.0.0.1 
 ```
 
-#### --open
+#### `--open`
 
 When you use the `--open` (`-o`) flag, mdbook will open the book in your
 default web browser after starting the server.
 
-#### --dest-dir
+#### `--dest-dir`
 
 The `--dest-dir` (`-d`) option allows you to change the output directory for the
 book. Relative paths are interpreted relative to the book's root directory. If
 not specified it will default to the value of the `build.build-dir` key in
 `book.toml`, or to `./book`.
 
+{{#include arg-watcher.md}}
+
 #### Specify exclude patterns
 
 The `serve` command will not automatically trigger a build for files listed in

guide/src/cli/test.md

@@ -6,8 +6,7 @@ of code examples that could get outdated. Therefore it is very important for
 them to be able to automatically test these code examples.
 
 mdBook supports a `test` command that will run all available tests in a book. At
-the moment, only rustdoc tests are supported, but this may be expanded upon in
-the future.
+the moment, only Rust tests are supported.
 
 #### Disable tests on a code block
 
@@ -38,7 +37,7 @@ instead of the current working directory.
 mdbook test path/to/book
 ```
 
-#### --library-path
+#### `--library-path`
 
 The `--library-path` (`-L`) option allows you to add directories to the library
 search path used by `rustdoc` when it builds and tests the examples. Multiple
@@ -55,14 +54,14 @@ mdbook test my-book -L target/debug/deps/
 See the `rustdoc` command-line [documentation](https://doc.rust-lang.org/rustdoc/command-line-arguments.html#-l--library-path-where-to-look-for-dependencies)
 for more information.
 
-#### --dest-dir
+#### `--dest-dir`
 
 The `--dest-dir` (`-d`) option allows you to change the output directory for the
 book. Relative paths are interpreted relative to the book's root directory. If
 not specified it will default to the value of the `build.build-dir` key in
 `book.toml`, or to `./book`.
 
-#### --chapter
+#### `--chapter`
 
 The `--chapter` (`-c`) option allows you to test a specific chapter of the
-book using the chapter name or the relative path to the chapter.
+book using the chapter name or the relative path to the chapter.

guide/src/cli/watch.md

@@ -15,18 +15,19 @@ root instead of the current working directory.
 mdbook watch path/to/book
 ```
 
-#### --open
+#### `--open`
 
 When you use the `--open` (`-o`) option, mdbook will open the rendered book in
 your default web browser.
 
-#### --dest-dir
+#### `--dest-dir`
 
 The `--dest-dir` (`-d`) option allows you to change the output directory for the
 book. Relative paths are interpreted relative to the book's root directory. If
 not specified it will default to the value of the `build.build-dir` key in
 `book.toml`, or to `./book`.
 
+{{#include arg-watcher.md}}
 
 #### Specify exclude patterns
 

guide/src/continuous-integration.md

@@ -21,7 +21,7 @@ A simple approach would be to use the popular `curl` CLI tool to download the ex
 
 ```sh
 mkdir bin
-curl -sSL https://github.com/rust-lang/mdBook/releases/download/v0.4.29/mdbook-v0.4.29-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=bin
+curl -sSL https://github.com/rust-lang/mdBook/releases/download/v0.4.40/mdbook-v0.4.40-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=bin
 bin/mdbook build
 ```
 
@@ -51,13 +51,13 @@ cargo install mdbook --no-default-features --features search --vers "^0.4" --loc
 
 This includes several recommended options:
 
-* `--no-default-features` — Disables features like the HTTP server used by `mdbook serve` that is likely not needed on CI.
+* `--no-default-features` --- Disables features like the HTTP server used by `mdbook serve` that is likely not needed on CI.
   This will speed up the build time significantly.
-* `--features search` — Disabling default features means you should then manually enable features that you want, such as the built-in [search] capability.
-* `--vers "^0.4"` — This will install the most recent version of the `0.4` series.
+* `--features search` --- Disabling default features means you should then manually enable features that you want, such as the built-in [search] capability.
+* `--vers "^0.4"` --- This will install the most recent version of the `0.4` series.
   However, versions after like `0.5.0` won't be installed, as they may break your build.
   Cargo will automatically upgrade mdBook if you have an older version already installed.
-* `--locked` — This will use the dependencies that were used when mdBook was released.
+* `--locked` --- This will use the dependencies that were used when mdBook was released.
   Without `--locked`, it will use the latest version of all dependencies, which may include some fixes since the last release, but may also (rarely) cause build problems.
 
 You will likely want to investigate caching options, as building mdBook can be somewhat slow.

guide/src/for_developers/backends.md

@@ -287,7 +287,7 @@ like this:
 +             if cfg.deny_odds && num_words % 2 == 1 {
 +               eprintln!("{} has an odd number of words!", ch.name);
 +               process::exit(1);
-              }
++             }
           }
       }
   }

guide/src/format/configuration/general.md

@@ -46,6 +46,9 @@ This is general information about your book.
   `src` directly under the root folder. But this is configurable with the `src`
   key in the configuration file.
 - **language:** The main language of the book, which is used as a language attribute `<html lang="en">` for example.
+  This is also used to derive the direction of text (RTL, LTR) within the book.
+- **text-direction**: The direction of text in the book: Left-to-right (LTR) or Right-to-left (RTL). Possible values: `ltr`, `rtl`.
+  When not specified, the text direction is derived from the book's `language` attribute.
 
 **book.toml**
 ```toml
@@ -55,6 +58,7 @@ authors = ["John Doe", "Jane Doe"]
 description = "The example book covers examples."
 src = "my-src"  # the source files will be found in `root/my-src` instead of `root/src`
 language = "en"
+text-direction = "ltr"
 ```
 
 ### Rust options
@@ -68,7 +72,7 @@ edition = "2015"   # the default edition for code blocks
 ```
 
 - **edition**: Rust edition to use by default for the code snippets. Default
-  is "2015". Individual code blocks can be controlled with the `edition2015`, 
+  is `"2015"`. Individual code blocks can be controlled with the `edition2015`,
   `edition2018` or `edition2021` annotations, such as:
 
   ~~~text
@@ -97,7 +101,7 @@ extra-watch-dirs = []             # directories to watch for triggering builds
   will be created when the book is built (i.e. `create-missing = true`). If this
   is `false` then the build process will instead exit with an error if any files
   do not exist.
-- **use-default-preprocessors:** Disable the default preprocessors of (`links` &
+- **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
@@ -111,4 +115,4 @@ extra-watch-dirs = []             # directories to watch for triggering builds
     `use-default-preprocessors` that `links` it will run.
 - **extra-watch-dirs**: A list of paths to directories that will be watched in
   the `watch` and `serve` commands. Changes to files under these directories will
-  trigger rebuilds. Useful if your book depends on files outside its `src` directory.
+  trigger rebuilds. Useful if your book depends on files outside its `src` directory.

guide/src/format/configuration/preprocessors.md

@@ -35,7 +35,7 @@ For example, if you have a preprocessor called `mdbook-example`, then you can in
 With this table, mdBook will execute the `mdbook-example` preprocessor.
 
 This table can include additional key-value pairs that are specific to the preprocessor.
-For example, if our example prepocessor needed some extra configuration options:
+For example, if our example preprocessor needed some extra configuration options:
 
 ```toml
 [preprocessor.example]

guide/src/format/configuration/renderers.md

@@ -4,9 +4,9 @@ Renderers (also called "backends") are responsible for creating the output of th
 
 The following backends are built-in:
 
-* [`html`](#html-renderer-options) — This renders the book to HTML.
+* [`html`](#html-renderer-options) --- This renders the book to HTML.
   This is enabled by default if no other `[output]` tables are defined in `book.toml`.
-* [`markdown`](#markdown-renderer) — This outputs the book as markdown after running the preprocessors.
+* [`markdown`](#markdown-renderer) --- This outputs the book as markdown after running the preprocessors.
   This is useful for debugging preprocessors.
 
 The community has developed several backends.
@@ -97,7 +97,7 @@ description = "The example book covers examples."
 theme = "my-theme"
 default-theme = "light"
 preferred-dark-theme = "navy"
-curly-quotes = true
+smart-punctuation = true
 mathjax-support = false
 copy-fonts = true
 additional-css = ["custom.css", "custom2.css"]
@@ -120,10 +120,12 @@ The following configuration options are available:
   'Change Theme' dropdown. Defaults to `light`.
 - **preferred-dark-theme:** The default dark theme. This theme will be used if
   the browser requests the dark version of the site via the
-  ['prefers-color-scheme'](https://developer.mozilla.org/en-US/docs/Web/CSS/@media/prefers-color-scheme)
+  [`prefers-color-scheme`](https://developer.mozilla.org/en-US/docs/Web/CSS/@media/prefers-color-scheme)
   CSS media query. Defaults to `navy`.
-- **curly-quotes:** Convert straight quotes to curly quotes, except for those
-  that occur in code blocks and code spans. Defaults to `false`.
+- **smart-punctuation:** Converts quotes to curly quotes, `...` to `…`, `--` to en-dash, and `---` to em-dash.
+  See [Smart Punctuation].
+  Defaults to `false`.
+- **curly-quotes:** Deprecated alias for `smart-punctuation`.
 - **mathjax-support:** Adds support for [MathJax](../mathjax.md). Defaults to
   `false`.
 - **copy-fonts:** (**Deprecated**) If `true` (the default), mdBook uses its built-in fonts which are copied to the output directory.
@@ -150,9 +152,9 @@ The following configuration options are available:
 - **edit-url-template:** Edit url template, when provided shows a
   "Suggest an edit" button (which looks like <i class="fa fa-edit"></i>) for directly jumping to editing the currently
   viewed page. For e.g. GitHub projects set this to
-  `https://github.com/<owner>/<repo>/edit/master/{path}` or for
+  `https://github.com/<owner>/<repo>/edit/<branch>/{path}` or for
   Bitbucket projects set it to
-  `https://bitbucket.org/<owner>/<repo>/src/master/{path}?mode=edit`
+  `https://bitbucket.org/<owner>/<repo>/src/<branch>/{path}?mode=edit`
   where {path} will be replaced with the full path of the file in the
   repository.
 - **input-404:** The name of the markdown file used for missing files.
@@ -223,6 +225,20 @@ runnable = true          # displays a run button for rust code
 
 [Ace]: https://ace.c9.io/
 
+### `[output.html.code]`
+
+The `[output.html.code]` table provides options for controlling code blocks.
+
+```toml
+[output.html.code]
+# A prefix string per language (one or more chars).
+# Any line starting with whitespace+prefix is hidden.
+hidelines = { python = "~" }
+```
+
+- **hidelines:** A table that defines how [hidden code lines](../mdbook.md#hiding-code-lines) work for each language.
+  The key is the language and the value is a string that will cause code lines starting with that prefix to be hidden.
+
 ### `[output.html.search]`
 
 The `[output.html.search]` table provides options for controlling the built-in text [search].

guide/src/format/markdown.md

@@ -73,14 +73,14 @@ Linking to a URL or local file is easy:
 ```markdown
 Use [mdBook](https://github.com/rust-lang/mdBook). 
 
-Read about [mdBook](mdBook.md).
+Read about [mdBook](mdbook.md).
 
 A bare url: <https://www.rust-lang.org>.
 ```
 
 Use [mdBook](https://github.com/rust-lang/mdBook). 
 
-Read about [mdBook](mdBook.md).
+Read about [mdBook](mdbook.md).
 
 A bare url: <https://www.rust-lang.org>.
 
@@ -124,7 +124,7 @@ mdBook has several extensions beyond the standard CommonMark specification.
 ### Strikethrough
 
 Text may be rendered with a horizontal line through the center by wrapping the
-text with two tilde characters on each side:
+text with one or two tilde characters on each side:
 
 ```text
 An example of ~~strikethrough text~~.
@@ -214,9 +214,22 @@ characters:
 So, no need to manually enter those Unicode characters!
 
 This feature is disabled by default.
-To enable it, see the [`output.html.curly-quotes`] config option.
+To enable it, see the [`output.html.smart-punctuation`] config option.
 
 [strikethrough]: https://github.github.com/gfm/#strikethrough-extension-
 [tables]: https://github.github.com/gfm/#tables-extension-
 [task list extension]: https://github.github.com/gfm/#task-list-items-extension-
-[`output.html.curly-quotes`]: configuration/renderers.md#html-renderer-options
+[`output.html.smart-punctuation`]: configuration/renderers.md#html-renderer-options
+
+### Heading attributes
+
+Headings can have a custom HTML ID and classes. This lets you maintain the same ID even if you change the heading's text, it also lets you add multiple classes in the heading.
+
+Example:
+```md
+# Example heading { #first .class1 .class2 }
+```
+
+This makes the level 1 heading with the content `Example heading`, ID `first`, and classes `class1` and `class2`. Note that the attributes should be space-separated.
+
+More information can be found in the [heading attrs spec page](https://github.com/raphlinus/pulldown-cmark/blob/master/pulldown-cmark/specs/heading_attrs.txt).

guide/src/format/mdbook.md

@@ -2,11 +2,11 @@
 
 ## Hiding code lines
 
-There is a feature in mdBook that lets you hide code lines by prepending them
-with a `#` [like you would with Rustdoc][rustdoc-hide].
-This currently only works with Rust language code blocks.
+There is a feature in mdBook that lets you hide code lines by prepending them with a specific prefix.
 
-[rustdoc-hide]: https://doc.rust-lang.org/stable/rustdoc/documentation-tests.html#hiding-portions-of-the-example
+For the Rust language, you can use the `#` character as a prefix which will hide lines [like you would with Rustdoc][rustdoc-hide].
+
+[rustdoc-hide]: https://doc.rust-lang.org/stable/rustdoc/write-documentation/documentation-tests.html#hiding-portions-of-the-example
 
 ```bash
 # fn main() {
@@ -28,7 +28,47 @@ Will render as
 # }
 ```
 
-The code block has an eyeball icon (<i class="fa fa-eye"></i>) which will toggle the visibility of the hidden lines.
+When you tap or hover the mouse over the code block, there will be an eyeball icon (<i class="fa fa-eye"></i>) which will toggle the visibility of the hidden lines.
+
+By default, this only works for code examples that are annotated with `rust`.
+However, you can define custom prefixes for other languages by adding a new line-hiding prefix in your `book.toml` with the language name and prefix character(s):
+
+```toml
+[output.html.code.hidelines]
+python = "~"
+```
+
+The prefix will hide any lines that begin with the given prefix. With the python prefix shown above, this:
+
+```bash
+~hidden()
+nothidden():
+~    hidden()
+    ~hidden()
+    nothidden()
+```
+
+will render as
+
+```python
+~hidden()
+nothidden():
+~    hidden()
+    ~hidden()
+    nothidden()
+```
+
+This behavior can be overridden locally with a different prefix. This has the same effect as above:
+
+~~~markdown
+```python,hidelines=!!!
+!!!hidden()
+nothidden():
+!!!    hidden()
+    !!!hidden()
+    nothidden()
+```
+~~~
 
 ## Rust Playground
 
@@ -72,16 +112,16 @@ panic!("oops!");
 These are particularly important when using [`mdbook test`] to test Rust examples.
 These use the same attributes as [rustdoc attributes], with a few additions:
 
-* `editable` — Enables the [editor].
-* `noplayground` — Removes the play button, but will still be tested.
-* `mdbook-runnable` — Forces the play button to be displayed.
+* `editable` --- Enables the [editor].
+* `noplayground` --- Removes the play button, but will still be tested.
+* `mdbook-runnable` --- Forces the play button to be displayed.
   This is intended to be combined with the `ignore` attribute for examples that should not be tested, but you want to allow the reader to run.
-* `ignore` — Will not be tested and no play button is shown, but it is still highlighted as Rust syntax.
-* `should_panic` — When executed, it should produce a panic.
-* `no_run` — The code is compiled when tested, but it is not run.
+* `ignore` --- Will not be tested and no play button is shown, but it is still highlighted as Rust syntax.
+* `should_panic` --- When executed, it should produce a panic.
+* `no_run` --- The code is compiled when tested, but it is not run.
   The play button is also not shown.
-* `compile_fail` — The code should fail to compile.
-* `edition2015`, `edition2018`, `edition2021` — Forces the use of a specific Rust edition.
+* `compile_fail` --- The code should fail to compile.
+* `edition2015`, `edition2018`, `edition2021` --- Forces the use of a specific Rust edition.
   See [`rust.edition`] to set this globally.
 
 [`mdbook test`]: ../cli/test.md
@@ -274,3 +314,51 @@ contents (sidebar) by including a `\{{#title ...}}` near the top of the page.
 ```hbs
 \{{#title My Title}}
 ```
+
+## HTML classes provided by mdBook
+
+<img class="right" src="images/rust-logo-blk.svg" alt="The Rust logo">
+
+### `class="left"` and `"right"`
+
+These classes are provided by default, for inline HTML to float images.
+
+```html
+<img class="right" src="images/rust-logo-blk.svg" alt="The Rust logo">
+```
+
+### `class="hidden"`
+
+HTML tags with class `hidden` will not be shown.
+
+```html
+<div class="hidden">This will not be seen.</div>
+```
+
+<div class="hidden">This will not be seen.</div>
+
+### `class="warning"`
+
+To make a warning or similar note stand out, wrap it in a warning div.
+
+```html
+<div class="warning">
+
+This is a bad thing that you should pay attention to.
+
+Warning blocks should be used sparingly in documentation, to avoid "warning
+fatigue," where people are trained to ignore them because they usually don't
+matter for what they're doing.
+
+</div>
+```
+
+<div class="warning">
+
+This is a bad thing that you should pay attention to.
+
+Warning blocks should be used sparingly in documentation, to avoid "warning
+fatigue," where people are trained to ignore them because they usually don't
+matter for what they're doing.
+
+</div>

guide/src/format/summary.md

@@ -29,11 +29,12 @@ to be ignored at best, or may cause an error when attempting to build the book.
    - [First Chapter](relative/path/to/markdown2.md)
    ```
 
-1. ***Part Title*** - Headers can be used as a title for the following numbered
-   chapters. This can be used to logically separate different sections
-   of the book. The title is rendered as unclickable text.
-   Titles are optional, and the numbered chapters can be broken into as many
-   parts as desired.
+1. ***Part Title*** -
+   Level 1 headers can be used as a title for the following numbered chapters.
+   This can be used to logically separate different sections of the book.
+   The title is rendered as unclickable text.
+   Titles are optional, and the numbered chapters can be broken into as many parts as desired.
+   Part titles must be h1 headers (one `#`), other heading levels are ignored.
    ```markdown
    # My Part Title
 

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

@@ -18,7 +18,7 @@ handlebars template you can access this information by using
 Here is a list of the properties that are exposed:
 
 - ***language*** Language of the book in the form `en`, as specified in `book.toml` (if not specified, defaults to `en`). To use in <code
-  class="language-html">\<html lang="{{ language }}"></code> for example.
+  class="language-html">\<html lang=\"{{ language }}\"></code> for example.
 - ***title*** Title used for the current page. This is identical to `{{ chapter_title }} - {{ book_title }}` unless `book_title` is not set in which case it just defaults to the `chapter_title`.
 - ***book_title*** Title of the book, as specified in `book.toml`
 - ***chapter_title*** Title of the current chapter, as listed in `SUMMARY.md`
@@ -79,7 +79,7 @@ var chapters = {{chapters}};
 
 ### 2. previous / next
 
-The previous and next helpers expose a `link` and `name` property to the
+The previous and next helpers expose a `link` and `title` property to the
 previous and next chapters.
 
 They are used like this
@@ -87,7 +87,7 @@ They are used like this
 ```handlebars
 {{#previous}}
     <a href="{{link}}" class="nav-chapters previous">
-        <i class="fa fa-angle-left"></i>
+        <i class="fa fa-angle-left"></i> {{title}}
     </a>
 {{/previous}}
 ```

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

@@ -44,6 +44,8 @@ your own `highlight.js` file:
 - makefile
 - markdown
 - nginx
+- nim
+- nix
 - objectivec
 - perl
 - php
@@ -77,38 +79,6 @@ the `theme` folder of your book.
 
 Now your theme will be used instead of the default theme.
 
-## Hiding code lines
-
-There is a feature in mdBook that lets you hide code lines by prepending them
-with a `#`.
-
-
-```bash
-# fn main() {
-    let x = 5;
-    let y = 6;
-
-    println!("{}", x + y);
-# }
-```
-
-Will render as
-
-```rust
-# fn main() {
-    let x = 5;
-    let y = 7;
-
-    println!("{}", x + y);
-# }
-```
-
-**At the moment, this only works for code examples that are annotated with
-`rust`. Because it would collide with semantics of some programming languages.
-In the future, we want to make this configurable through the `book.toml` so that
-everyone can benefit from it.**
-
-
 ## Improve default theme
 
 If you think the default theme doesn't look quite right for a specific language,

guide/src/guide/installation.md

@@ -20,7 +20,7 @@ To make it easier to run, put the path to the binary into your `PATH`.
 
 To build the `mdbook` executable from source, you will first need to install Rust and Cargo.
 Follow the instructions on the [Rust installation page].
-mdBook currently requires at least Rust version 1.65.
+mdBook currently requires at least Rust version 1.74.
 
 Once you have installed Rust, the following command can be used to build and install mdBook:
 

src/book/book.rs

@@ -160,8 +160,20 @@ pub struct Chapter {
     /// Nested items.
     pub sub_items: Vec<BookItem>,
     /// The chapter's location, relative to the `SUMMARY.md` file.
+    ///
+    /// **Note**: After the index preprocessor runs, any README files will be
+    /// modified to be `index.md`. If you need access to the actual filename
+    /// on disk, use [`Chapter::source_path`] instead.
+    ///
+    /// This is `None` for a draft chapter.
     pub path: Option<PathBuf>,
     /// The chapter's source file, relative to the `SUMMARY.md` file.
+    ///
+    /// **Note**: Beware that README files will internally be treated as
+    /// `index.md` via the [`Chapter::path`] field. The `source_path` field
+    /// exists if you need access to the true file path.
+    ///
+    /// This is `None` for a draft chapter.
     pub source_path: Option<PathBuf>,
     /// An ordered list of the names of each chapter above this one in the hierarchy.
     pub parent_names: Vec<String>,
@@ -339,7 +351,6 @@ impl Display for Chapter {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::io::Write;
     use tempfile::{Builder as TempFileBuilder, TempDir};
 
     const DUMMY_SRC: &str = "

src/book/mod.rs

@@ -15,10 +15,10 @@ pub use self::init::BookBuilder;
 pub use self::summary::{parse_summary, Link, SectionNumber, Summary, SummaryItem};
 
 use log::{debug, error, info, log_enabled, trace, warn};
-use std::io::Write;
-use std::path::PathBuf;
+use std::ffi::OsString;
+use std::io::{IsTerminal, Write};
+use std::path::{Path, PathBuf};
 use std::process::Command;
-use std::string::ToString;
 use tempfile::Builder as TempFileBuilder;
 use toml::Value;
 use topological_sort::TopologicalSort;
@@ -71,18 +71,24 @@ impl MDBook {
 
         config.update_from_env();
 
-        if config
-            .html_config()
-            .map_or(false, |html| html.google_analytics.is_some())
-        {
-            warn!(
-                "The output.html.google-analytics field has been deprecated; \
-                 it will be removed in a future release.\n\
-                 Consider placing the appropriate site tag code into the \
-                 theme/head.hbs file instead.\n\
-                 The tracking code may be found in the Google Analytics Admin page.\n\
-               "
-            );
+        if let Some(html_config) = config.html_config() {
+            if html_config.google_analytics.is_some() {
+                warn!(
+                    "The output.html.google-analytics field has been deprecated; \
+                     it will be removed in a future release.\n\
+                     Consider placing the appropriate site tag code into the \
+                     theme/head.hbs file instead.\n\
+                     The tracking code may be found in the Google Analytics Admin page.\n\
+                   "
+                );
+            }
+            if html_config.curly_quotes {
+                warn!(
+                    "The output.html.curly-quotes field has been renamed to \
+                     output.html.smart-punctuation.\n\
+                     Use the new name in book.toml to remove this warning."
+                );
+            }
         }
 
         if log_enabled!(log::Level::Trace) {
@@ -259,10 +265,18 @@ impl MDBook {
     /// Run `rustdoc` tests on a specific chapter of the book, linking against the provided libraries.
     /// If `chapter` is `None`, all tests will be run.
     pub fn test_chapter(&mut self, library_paths: Vec<&str>, chapter: Option<&str>) -> Result<()> {
-        let library_args: Vec<&str> = (0..library_paths.len())
-            .map(|_| "-L")
-            .zip(library_paths.into_iter())
-            .flat_map(|x| vec![x.0, x.1])
+        let cwd = std::env::current_dir()?;
+        let library_args: Vec<OsString> = library_paths
+            .into_iter()
+            .flat_map(|path| {
+                let path = Path::new(path);
+                let path = if path.is_relative() {
+                    cwd.join(path).into_os_string()
+                } else {
+                    path.to_path_buf().into_os_string()
+                };
+                [OsString::from("-L"), path]
+            })
             .collect();
 
         let temp_dir = TempFileBuilder::new().prefix("mdbook-").tempdir()?;
@@ -289,6 +303,7 @@ impl MDBook {
             .collect();
         let (book, _) = self.preprocess_book(&TestRenderer)?;
 
+        let color_output = std::io::stderr().is_terminal();
         let mut failed = false;
         for item in book.iter() {
             if let BookItem::Chapter(ref ch) = *item {
@@ -314,7 +329,10 @@ impl MDBook {
                 tmpf.write_all(ch.content.as_bytes())?;
 
                 let mut cmd = Command::new("rustdoc");
-                cmd.arg(&path).arg("--test").args(&library_args);
+                cmd.current_dir(temp_dir.path())
+                    .arg(chapter_path)
+                    .arg("--test")
+                    .args(&library_args);
 
                 if let Some(edition) = self.config.rust.edition {
                     match edition {
@@ -330,6 +348,10 @@ impl MDBook {
                     }
                 }
 
+                if color_output {
+                    cmd.args(["--color", "always"]);
+                }
+
                 debug!("running {:?}", cmd);
                 let output = cmd.output()?;
 
@@ -605,7 +627,7 @@ fn preprocessor_should_run(
 mod tests {
     use super::*;
     use std::str::FromStr;
-    use toml::value::{Table, Value};
+    use toml::value::Table;
 
     #[test]
     fn config_defaults_to_html_renderer_if_empty() {

src/book/summary.rs

@@ -1,10 +1,9 @@
 use crate::errors::*;
 use log::{debug, trace, warn};
-use memchr::{self, Memchr};
-use pulldown_cmark::{self, Event, HeadingLevel, Tag};
+use memchr::Memchr;
+use pulldown_cmark::{DefaultBrokenLinkCallback, Event, HeadingLevel, Tag, TagEnd};
 use serde::{Deserialize, Serialize};
 use std::fmt::{self, Display, Formatter};
-use std::iter::FromIterator;
 use std::ops::{Deref, DerefMut};
 use std::path::{Path, PathBuf};
 
@@ -163,7 +162,7 @@ impl From<Link> for SummaryItem {
 /// > match the following regex: "[^<>\n[]]+".
 struct SummaryParser<'a> {
     src: &'a str,
-    stream: pulldown_cmark::OffsetIter<'a, 'a>,
+    stream: pulldown_cmark::OffsetIter<'a, DefaultBrokenLinkCallback>,
     offset: usize,
 
     /// We can't actually put an event back into the `OffsetIter` stream, so instead we store it
@@ -210,7 +209,7 @@ macro_rules! collect_events {
 }
 
 impl<'a> SummaryParser<'a> {
-    fn new(text: &str) -> SummaryParser<'_> {
+    fn new(text: &'a str) -> SummaryParser<'a> {
         let pulldown_parser = pulldown_cmark::Parser::new(text).into_offset_iter();
 
         SummaryParser {
@@ -265,7 +264,12 @@ impl<'a> SummaryParser<'a> {
         loop {
             match self.next_event() {
                 Some(ev @ Event::Start(Tag::List(..)))
-                | Some(ev @ Event::Start(Tag::Heading(HeadingLevel::H1, ..))) => {
+                | Some(
+                    ev @ Event::Start(Tag::Heading {
+                        level: HeadingLevel::H1,
+                        ..
+                    }),
+                ) => {
                     if is_prefix {
                         // we've finished prefix chapters and are at the start
                         // of the numbered section.
@@ -275,8 +279,8 @@ impl<'a> SummaryParser<'a> {
                         bail!(self.parse_error("Suffix chapters cannot be followed by a list"));
                     }
                 }
-                Some(Event::Start(Tag::Link(_type, href, _title))) => {
-                    let link = self.parse_link(href.to_string());
+                Some(Event::Start(Tag::Link { dest_url, .. })) => {
+                    let link = self.parse_link(dest_url.to_string());
                     items.push(SummaryItem::Link(link));
                 }
                 Some(Event::Rule) => items.push(SummaryItem::Separator),
@@ -304,10 +308,13 @@ impl<'a> SummaryParser<'a> {
                     break;
                 }
 
-                Some(Event::Start(Tag::Heading(HeadingLevel::H1, ..))) => {
+                Some(Event::Start(Tag::Heading {
+                    level: HeadingLevel::H1,
+                    ..
+                })) => {
                     debug!("Found a h1 in the SUMMARY");
 
-                    let tags = collect_events!(self.stream, end Tag::Heading(HeadingLevel::H1, ..));
+                    let tags = collect_events!(self.stream, end TagEnd::Heading(HeadingLevel::H1));
                     Some(stringify_events(tags))
                 }
 
@@ -336,7 +343,7 @@ impl<'a> SummaryParser<'a> {
     /// Finishes parsing a link once the `Event::Start(Tag::Link(..))` has been opened.
     fn parse_link(&mut self, href: String) -> Link {
         let href = href.replace("%20", " ");
-        let link_content = collect_events!(self.stream, end Tag::Link(..));
+        let link_content = collect_events!(self.stream, end TagEnd::Link);
         let name = stringify_events(link_content);
 
         let path = if href.is_empty() {
@@ -377,7 +384,12 @@ impl<'a> SummaryParser<'a> {
                 }
                 // The expectation is that pulldown cmark will terminate a paragraph before a new
                 // heading, so we can always count on this to return without skipping headings.
-                Some(ev @ Event::Start(Tag::Heading(HeadingLevel::H1, ..))) => {
+                Some(
+                    ev @ Event::Start(Tag::Heading {
+                        level: HeadingLevel::H1,
+                        ..
+                    }),
+                ) => {
                     // we're starting a new part
                     self.back(ev);
                     break;
@@ -398,7 +410,7 @@ impl<'a> SummaryParser<'a> {
 
                     // Skip over the contents of this tag
                     while let Some(event) = self.next_event() {
-                        if event == Event::End(other_tag.clone()) {
+                        if event == Event::End(other_tag.clone().into()) {
                             break;
                         }
                     }
@@ -469,7 +481,7 @@ impl<'a> SummaryParser<'a> {
 
                     last_item.nested_items = sub_items;
                 }
-                Some(Event::End(Tag::List(..))) => break,
+                Some(Event::End(TagEnd::List(..))) => break,
                 Some(_) => {}
                 None => break,
             }
@@ -486,8 +498,8 @@ impl<'a> SummaryParser<'a> {
         loop {
             match self.next_event() {
                 Some(Event::Start(Tag::Paragraph)) => continue,
-                Some(Event::Start(Tag::Link(_type, href, _title))) => {
-                    let mut link = self.parse_link(href.to_string());
+                Some(Event::Start(Tag::Link { dest_url, .. })) => {
+                    let mut link = self.parse_link(dest_url.to_string());
 
                     let mut number = parent.clone();
                     number.0.push(num_existing_items as u32 + 1);
@@ -529,14 +541,18 @@ impl<'a> SummaryParser<'a> {
     fn parse_title(&mut self) -> Option<String> {
         loop {
             match self.next_event() {
-                Some(Event::Start(Tag::Heading(HeadingLevel::H1, ..))) => {
+                Some(Event::Start(Tag::Heading {
+                    level: HeadingLevel::H1,
+                    ..
+                })) => {
                     debug!("Found a h1 in the SUMMARY");
 
-                    let tags = collect_events!(self.stream, end Tag::Heading(HeadingLevel::H1, ..));
+                    let tags = collect_events!(self.stream, end TagEnd::Heading(HeadingLevel::H1));
                     return Some(stringify_events(tags));
                 }
                 // Skip a HTML element such as a comment line.
-                Some(Event::Html(_)) => {}
+                Some(Event::Html(_) | Event::InlineHtml(_))
+                | Some(Event::Start(Tag::HtmlBlock) | Event::End(TagEnd::HtmlBlock)) => {}
                 // Otherwise, no title.
                 Some(ev) => {
                     self.back(ev);
@@ -567,11 +583,13 @@ fn get_last_link(links: &mut [SummaryItem]) -> Result<(usize, &mut Link)> {
         .iter_mut()
         .enumerate()
         .filter_map(|(i, item)| item.maybe_link_mut().map(|l| (i, l)))
-        .rev()
-        .next()
-        .ok_or_else(||
-            anyhow::anyhow!("Unable to get last link because the list of SummaryItems doesn't contain any Links")
+        .next_back()
+        .ok_or_else(|| {
+            anyhow::anyhow!(
+                "Unable to get last link because the list of SummaryItems \
+                 doesn't contain any Links"
             )
+        })
 }
 
 /// Removes the styling from a list of Markdown events and returns just the
@@ -744,7 +762,7 @@ mod tests {
         let _ = parser.stream.next(); // Discard opening paragraph
 
         let href = match parser.stream.next() {
-            Some((Event::Start(Tag::Link(_type, href, _title)), _range)) => href.to_string(),
+            Some((Event::Start(Tag::Link { dest_url, .. }), _range)) => dest_url.to_string(),
             other => panic!("Unreachable, {:?}", other),
         };
 

src/cmd/command_prelude.rs

@@ -36,6 +36,20 @@ pub trait CommandExt: Sized {
     fn arg_open(self) -> Self {
         self._arg(arg!(-o --open "Opens the compiled book in a web browser"))
     }
+
+    #[cfg(any(feature = "watch", feature = "serve"))]
+    fn arg_watcher(self) -> Self {
+        #[cfg(feature = "watch")]
+        return self._arg(
+            Arg::new("watcher")
+                .long("watcher")
+                .value_parser(["poll", "native"])
+                .default_value("poll")
+                .help("The filesystem watching technique"),
+        );
+        #[cfg(not(feature = "watch"))]
+        return self;
+    }
 }
 
 impl CommandExt for Command {

src/cmd/serve.rs

@@ -6,7 +6,6 @@ use clap::builder::NonEmptyStringValueParser;
 use futures_util::sink::SinkExt;
 use futures_util::StreamExt;
 use mdbook::errors::*;
-use mdbook::utils;
 use mdbook::utils::fs::get_404_output_file;
 use mdbook::MDBook;
 use std::net::{SocketAddr, ToSocketAddrs};
@@ -43,12 +42,13 @@ pub fn make_subcommand() -> Command {
                 .help("Port to use for HTTP connections"),
         )
         .arg_open()
+        .arg_watcher()
 }
 
 // Serve command implementation
 pub fn execute(args: &ArgMatches) -> Result<()> {
     let book_dir = get_book_dir(args);
-    let mut book = MDBook::load(book_dir)?;
+    let mut book = MDBook::load(&book_dir)?;
 
     let port = args.get_one::<String>("port").unwrap();
     let hostname = args.get_one::<String>("hostname").unwrap();
@@ -97,23 +97,12 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
     }
 
     #[cfg(feature = "watch")]
-    watch::trigger_on_change(&book, move |paths, book_dir| {
-        info!("Files changed: {:?}", paths);
-        info!("Building book...");
-
-        // FIXME: This area is really ugly because we need to re-set livereload :(
-        let result = MDBook::load(book_dir).and_then(|mut b| {
-            update_config(&mut b);
-            b.build()
-        });
-
-        if let Err(e) = result {
-            error!("Unable to load the book");
-            utils::log_backtrace(&e);
-        } else {
+    {
+        let watcher = watch::WatcherKind::from_str(args.get_one::<String>("watcher").unwrap());
+        watch::rebuild_on_change(watcher, &book_dir, &update_config, &move || {
             let _ = tx.send(Message::text("reload"));
-        }
-    });
+        });
+    }
 
     let _ = thread_handle.join();
 

src/cmd/test.rs

@@ -1,7 +1,7 @@
 use super::command_prelude::*;
 use crate::get_book_dir;
 use clap::builder::NonEmptyStringValueParser;
-use clap::{Arg, ArgAction, ArgMatches, Command};
+use clap::ArgAction;
 use mdbook::errors::Result;
 use mdbook::MDBook;
 use std::path::PathBuf;

src/cmd/watch.rs

@@ -1,13 +1,11 @@
 use super::command_prelude::*;
 use crate::{get_book_dir, open};
-use ignore::gitignore::Gitignore;
 use mdbook::errors::Result;
-use mdbook::utils;
 use mdbook::MDBook;
 use std::path::{Path, PathBuf};
-use std::sync::mpsc::channel;
-use std::thread::sleep;
-use std::time::Duration;
+
+mod native;
+mod poller;
 
 // Create clap subcommand arguments
 pub fn make_subcommand() -> Command {
@@ -16,12 +14,28 @@ pub fn make_subcommand() -> Command {
         .arg_dest_dir()
         .arg_root_dir()
         .arg_open()
+        .arg_watcher()
+}
+
+pub enum WatcherKind {
+    Poll,
+    Native,
+}
+
+impl WatcherKind {
+    pub fn from_str(s: &str) -> WatcherKind {
+        match s {
+            "poll" => WatcherKind::Poll,
+            "native" => WatcherKind::Native,
+            _ => panic!("unsupported watcher {s}"),
+        }
+    }
 }
 
 // Watch command implementation
 pub fn execute(args: &ArgMatches) -> Result<()> {
     let book_dir = get_book_dir(args);
-    let mut book = MDBook::load(book_dir)?;
+    let mut book = MDBook::load(&book_dir)?;
 
     let update_config = |book: &mut MDBook| {
         if let Some(dest_dir) = args.get_one::<PathBuf>("dest-dir") {
@@ -40,42 +54,21 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
         open(path);
     }
 
-    trigger_on_change(&book, |paths, book_dir| {
-        info!("Files changed: {:?}\nBuilding book...\n", paths);
-        let result = MDBook::load(book_dir).and_then(|mut b| {
-            update_config(&mut b);
-            b.build()
-        });
-
-        if let Err(e) = result {
-            error!("Unable to build the book");
-            utils::log_backtrace(&e);
-        }
-    });
+    let watcher = WatcherKind::from_str(args.get_one::<String>("watcher").unwrap());
+    rebuild_on_change(watcher, &book_dir, &update_config, &|| {});
 
     Ok(())
 }
 
-fn remove_ignored_files(book_root: &Path, paths: &[PathBuf]) -> Vec<PathBuf> {
-    if paths.is_empty() {
-        return vec![];
-    }
-
-    match find_gitignore(book_root) {
-        Some(gitignore_path) => {
-            let (ignore, err) = Gitignore::new(&gitignore_path);
-            if let Some(err) = err {
-                warn!(
-                    "error reading gitignore `{}`: {err}",
-                    gitignore_path.display()
-                );
-            }
-            filter_ignored_files(ignore, paths)
-        }
-        None => {
-            // There is no .gitignore file.
-            paths.iter().map(|path| path.to_path_buf()).collect()
-        }
+pub fn rebuild_on_change(
+    kind: WatcherKind,
+    book_dir: &Path,
+    update_config: &dyn Fn(&mut MDBook),
+    post_build: &dyn Fn(),
+) {
+    match kind {
+        WatcherKind::Poll => self::poller::rebuild_on_change(book_dir, update_config, post_build),
+        WatcherKind::Native => self::native::rebuild_on_change(book_dir, update_config, post_build),
     }
 }
 
@@ -85,92 +78,3 @@ fn find_gitignore(book_root: &Path) -> Option<PathBuf> {
         .map(|p| p.join(".gitignore"))
         .find(|p| p.exists())
 }
-
-fn filter_ignored_files(ignore: Gitignore, paths: &[PathBuf]) -> Vec<PathBuf> {
-    paths
-        .iter()
-        .filter(|path| {
-            !ignore
-                .matched_path_or_any_parents(path, path.is_dir())
-                .is_ignore()
-        })
-        .map(|path| path.to_path_buf())
-        .collect()
-}
-
-/// Calls the closure when a book source file is changed, blocking indefinitely.
-pub fn trigger_on_change<F>(book: &MDBook, closure: F)
-where
-    F: Fn(Vec<PathBuf>, &Path),
-{
-    use notify::RecursiveMode::*;
-
-    // Create a channel to receive the events.
-    let (tx, rx) = channel();
-
-    let mut debouncer = match notify_debouncer_mini::new_debouncer(Duration::from_secs(1), None, tx)
-    {
-        Ok(d) => d,
-        Err(e) => {
-            error!("Error while trying to watch the files:\n\n\t{:?}", e);
-            std::process::exit(1)
-        }
-    };
-    let watcher = debouncer.watcher();
-
-    // Add the source directory to the watcher
-    if let Err(e) = watcher.watch(&book.source_dir(), Recursive) {
-        error!("Error while watching {:?}:\n    {:?}", book.source_dir(), e);
-        std::process::exit(1);
-    };
-
-    let _ = watcher.watch(&book.theme_dir(), Recursive);
-
-    // Add the book.toml file to the watcher if it exists
-    let _ = watcher.watch(&book.root.join("book.toml"), NonRecursive);
-
-    for dir in &book.config.build.extra_watch_dirs {
-        let path = dir.canonicalize().unwrap();
-        if let Err(e) = watcher.watch(&path, Recursive) {
-            error!(
-                "Error while watching extra directory {:?}:\n    {:?}",
-                path, e
-            );
-            std::process::exit(1);
-        }
-    }
-
-    info!("Listening for changes...");
-
-    loop {
-        let first_event = rx.recv().unwrap();
-        sleep(Duration::from_millis(50));
-        let other_events = rx.try_iter();
-
-        let all_events = std::iter::once(first_event).chain(other_events);
-
-        let paths: Vec<_> = all_events
-            .filter_map(|event| match event {
-                Ok(events) => Some(events),
-                Err(errors) => {
-                    for error in errors {
-                        log::warn!("error while watching for changes: {error}");
-                    }
-                    None
-                }
-            })
-            .flatten()
-            .map(|event| event.path)
-            .collect();
-
-        // If we are watching files outside the current repository (via extra-watch-dirs), then they are definitionally
-        // ignored by gitignore. So we handle this case by including such files into the watched paths list.
-        let any_external_paths = paths.iter().filter(|p| !p.starts_with(&book.root)).cloned();
-        let mut paths = remove_ignored_files(&book.root, &paths[..]);
-        paths.extend(any_external_paths);
-
-        if !paths.is_empty() {
-            closure(paths, &book.root);
-        }
-    }
-}

src/cmd/watch/native.rs

@@ -0,0 +1,189 @@
+//! A filesystem watcher using native operating system facilities.
+
+use ignore::gitignore::Gitignore;
+use mdbook::MDBook;
+use std::path::{Path, PathBuf};
+use std::sync::mpsc::channel;
+use std::thread::sleep;
+use std::time::Duration;
+
+pub fn rebuild_on_change(
+    book_dir: &Path,
+    update_config: &dyn Fn(&mut MDBook),
+    post_build: &dyn Fn(),
+) {
+    use notify::RecursiveMode::*;
+
+    let mut book = MDBook::load(book_dir).unwrap_or_else(|e| {
+        error!("failed to load book: {e}");
+        std::process::exit(1);
+    });
+
+    // Create a channel to receive the events.
+    let (tx, rx) = channel();
+
+    let mut debouncer = match notify_debouncer_mini::new_debouncer(Duration::from_secs(1), tx) {
+        Ok(d) => d,
+        Err(e) => {
+            error!("Error while trying to watch the files:\n\n\t{:?}", e);
+            std::process::exit(1)
+        }
+    };
+    let watcher = debouncer.watcher();
+
+    // Add the source directory to the watcher
+    if let Err(e) = watcher.watch(&book.source_dir(), Recursive) {
+        error!("Error while watching {:?}:\n    {:?}", book.source_dir(), e);
+        std::process::exit(1);
+    };
+
+    let _ = watcher.watch(&book.theme_dir(), Recursive);
+
+    // Add the book.toml file to the watcher if it exists
+    let _ = watcher.watch(&book.root.join("book.toml"), NonRecursive);
+
+    for dir in &book.config.build.extra_watch_dirs {
+        let path = book.root.join(dir);
+        let canonical_path = path.canonicalize().unwrap_or_else(|e| {
+            error!("Error while watching extra directory {path:?}:\n    {e}");
+            std::process::exit(1);
+        });
+
+        if let Err(e) = watcher.watch(&canonical_path, Recursive) {
+            error!(
+                "Error while watching extra directory {:?}:\n    {:?}",
+                canonical_path, e
+            );
+            std::process::exit(1);
+        }
+    }
+
+    info!("Listening for changes...");
+
+    loop {
+        let first_event = rx.recv().unwrap();
+        sleep(Duration::from_millis(50));
+        let other_events = rx.try_iter();
+
+        let all_events = std::iter::once(first_event).chain(other_events);
+
+        let paths: Vec<_> = all_events
+            .filter_map(|event| match event {
+                Ok(events) => Some(events),
+                Err(error) => {
+                    log::warn!("error while watching for changes: {error}");
+                    None
+                }
+            })
+            .flatten()
+            .map(|event| event.path)
+            .collect();
+
+        // If we are watching files outside the current repository (via extra-watch-dirs), then they are definitionally
+        // ignored by gitignore. So we handle this case by including such files into the watched paths list.
+        let any_external_paths = paths.iter().filter(|p| !p.starts_with(&book.root)).cloned();
+        let mut paths = remove_ignored_files(&book.root, &paths[..]);
+        paths.extend(any_external_paths);
+
+        if !paths.is_empty() {
+            info!("Files changed: {paths:?}");
+            match MDBook::load(book_dir) {
+                Ok(mut b) => {
+                    update_config(&mut b);
+                    if let Err(e) = b.build() {
+                        error!("failed to build the book: {e:?}");
+                    } else {
+                        post_build();
+                    }
+                    book = b;
+                }
+                Err(e) => error!("failed to load book config: {e:?}"),
+            }
+        }
+    }
+}
+
+fn remove_ignored_files(book_root: &Path, paths: &[PathBuf]) -> Vec<PathBuf> {
+    if paths.is_empty() {
+        return vec![];
+    }
+
+    match super::find_gitignore(book_root) {
+        Some(gitignore_path) => {
+            let (ignore, err) = Gitignore::new(&gitignore_path);
+            if let Some(err) = err {
+                warn!(
+                    "error reading gitignore `{}`: {err}",
+                    gitignore_path.display()
+                );
+            }
+            filter_ignored_files(ignore, paths)
+        }
+        None => {
+            // There is no .gitignore file.
+            paths.iter().map(|path| path.to_path_buf()).collect()
+        }
+    }
+}
+
+// Note: The usage of `canonicalize` may encounter occasional failures on the Windows platform, presenting a potential risk.
+// For more details, refer to [Pull Request #2229](https://github.com/rust-lang/mdBook/pull/2229#discussion_r1408665981).
+fn filter_ignored_files(ignore: Gitignore, paths: &[PathBuf]) -> Vec<PathBuf> {
+    let ignore_root = ignore
+        .path()
+        .canonicalize()
+        .expect("ignore root canonicalize error");
+
+    paths
+        .iter()
+        .filter(|path| {
+            let relative_path = pathdiff::diff_paths(&path, &ignore_root)
+                .expect("One of the paths should be an absolute");
+            !ignore
+                .matched_path_or_any_parents(&relative_path, relative_path.is_dir())
+                .is_ignore()
+        })
+        .map(|path| path.to_path_buf())
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ignore::gitignore::GitignoreBuilder;
+    use std::env;
+
+    #[test]
+    fn test_filter_ignored_files() {
+        let current_dir = env::current_dir().unwrap();
+
+        let ignore = GitignoreBuilder::new(&current_dir)
+            .add_line(None, "*.html")
+            .unwrap()
+            .build()
+            .unwrap();
+        let should_remain = current_dir.join("record.text");
+        let should_filter = current_dir.join("index.html");
+
+        let remain = filter_ignored_files(ignore, &[should_remain.clone(), should_filter]);
+        assert_eq!(remain, vec![should_remain])
+    }
+
+    #[test]
+    fn filter_ignored_files_should_handle_parent_dir() {
+        let current_dir = env::current_dir().unwrap();
+
+        let ignore = GitignoreBuilder::new(&current_dir)
+            .add_line(None, "*.html")
+            .unwrap()
+            .build()
+            .unwrap();
+
+        let parent_dir = current_dir.join("..");
+        let should_remain = parent_dir.join("record.text");
+        let should_filter = parent_dir.join("index.html");
+
+        let remain = filter_ignored_files(ignore, &[should_remain.clone(), should_filter]);
+        assert_eq!(remain, vec![should_remain])
+    }
+}

src/cmd/watch/poller.rs

@@ -0,0 +1,386 @@
+//! A simple poll-based filesystem watcher.
+//!
+//! This exists because the native change notifications have historically had
+//! lots of problems. Various operating systems and different filesystems have
+//! had problems correctly reporting changes.
+
+use ignore::gitignore::Gitignore;
+use mdbook::MDBook;
+use pathdiff::diff_paths;
+use std::collections::HashMap;
+use std::fs::FileType;
+use std::path::{Path, PathBuf};
+use std::time::{Duration, Instant, SystemTime};
+use walkdir::WalkDir;
+
+/// Calls the closure when a book source file is changed, blocking indefinitely.
+pub fn rebuild_on_change(
+    book_dir: &Path,
+    update_config: &dyn Fn(&mut MDBook),
+    post_build: &dyn Fn(),
+) {
+    let mut book = MDBook::load(book_dir).unwrap_or_else(|e| {
+        error!("failed to load book: {e}");
+        std::process::exit(1);
+    });
+
+    let mut watcher = Watcher::new(book_dir);
+
+    info!("Watching for changes...");
+    // Scan once to initialize the starting point.
+    watcher.set_roots(&book);
+    watcher.scan();
+
+    // Track average scan time, to help investigate if the poller is taking
+    // undesirably long. This is not a rigorous benchmark, just a rough
+    // estimate.
+    const AVG_SIZE: usize = 60;
+    let mut avgs = vec![0.0; AVG_SIZE];
+    let mut avg_i = 0;
+
+    loop {
+        std::thread::sleep(Duration::new(1, 0));
+        watcher.set_roots(&book);
+        let start = Instant::now();
+        let paths = watcher.scan();
+        let elapsed = start.elapsed().as_secs_f64();
+        avgs[avg_i] = elapsed;
+        avg_i += 1;
+        if avg_i >= AVG_SIZE {
+            avg_i = 0;
+            let avg = avgs.iter().sum::<f64>() / (avgs.len() as f64);
+            trace!(
+                "scan average time: {avg:.2}s, scan size is {}",
+                watcher.path_data.len()
+            );
+        }
+
+        if !paths.is_empty() {
+            info!("Files changed: {paths:?}");
+            match MDBook::load(book_dir) {
+                Ok(mut b) => {
+                    update_config(&mut b);
+                    if let Err(e) = b.build() {
+                        error!("failed to build the book: {e:?}");
+                    } else {
+                        post_build();
+                    }
+                    book = b;
+                }
+                Err(e) => error!("failed to load book config: {e:?}"),
+            }
+        }
+    }
+}
+
+#[derive(PartialEq)]
+struct PathData {
+    file_type: FileType,
+    mtime: SystemTime,
+    size: u64,
+}
+
+/// A very simple poll-watcher that scans for modified files.
+#[derive(Default)]
+struct Watcher {
+    /// The root paths where it will recursively scan for changes.
+    root_paths: Vec<PathBuf>,
+    /// Data about files on disk.
+    path_data: HashMap<PathBuf, PathData>,
+    /// Filters paths that will be watched.
+    ignore: Option<(PathBuf, Gitignore)>,
+}
+
+impl Watcher {
+    fn new(book_root: &Path) -> Watcher {
+        // FIXME: ignore should be reloaded when it changes.
+        let ignore = super::find_gitignore(book_root).map(|gitignore_path| {
+            let (ignore, err) = Gitignore::new(&gitignore_path);
+            if let Some(err) = err {
+                warn!(
+                    "error reading gitignore `{}`: {err}",
+                    gitignore_path.display()
+                );
+            }
+            // Note: The usage of `canonicalize` may encounter occasional
+            // failures on the Windows platform, presenting a potential risk.
+            // For more details, refer to [Pull Request
+            // #2229](https://github.com/rust-lang/mdBook/pull/2229#discussion_r1408665981).
+            let ignore_path = ignore
+                .path()
+                .canonicalize()
+                .expect("ignore root canonicalize error");
+            (ignore_path, ignore)
+        });
+
+        Watcher {
+            ignore,
+            ..Default::default()
+        }
+    }
+
+    /// Sets the root directories where scanning will start.
+    fn set_roots(&mut self, book: &MDBook) {
+        let mut root_paths = vec![
+            book.source_dir(),
+            book.theme_dir(),
+            book.root.join("book.toml"),
+        ];
+        root_paths.extend(
+            book.config
+                .build
+                .extra_watch_dirs
+                .iter()
+                .map(|path| book.root.join(path)),
+        );
+        if let Some(html_config) = book.config.html_config() {
+            root_paths.extend(
+                html_config
+                    .additional_css
+                    .iter()
+                    .chain(html_config.additional_js.iter())
+                    .map(|path| book.root.join(path)),
+            );
+        }
+
+        self.root_paths = root_paths;
+    }
+
+    /// Scans for changes.
+    ///
+    /// Returns the paths that have changed.
+    fn scan(&mut self) -> Vec<PathBuf> {
+        let ignore = &self.ignore;
+        let new_path_data: HashMap<_, _> = self
+            .root_paths
+            .iter()
+            .filter(|root| root.exists())
+            .flat_map(|root| {
+                WalkDir::new(root)
+                    .follow_links(true)
+                    .into_iter()
+                    .filter_entry(|entry| {
+                        if let Some((ignore_path, ignore)) = ignore {
+                            let path = entry.path();
+                            // Canonicalization helps with removing `..` and
+                            // `.` entries, which can cause issues with
+                            // diff_paths.
+                            let path = path.canonicalize().unwrap_or_else(|_| path.to_path_buf());
+                            let relative_path = diff_paths(&path, &ignore_path)
+                                .expect("One of the paths should be an absolute");
+                            if ignore
+                                .matched_path_or_any_parents(&relative_path, relative_path.is_dir())
+                                .is_ignore()
+                            {
+                                trace!("ignoring {path:?}");
+                                return false;
+                            }
+                        }
+                        true
+                    })
+                    .filter_map(move |entry| {
+                        let entry = match entry {
+                            Ok(e) => e,
+                            Err(e) => {
+                                debug!("failed to scan {root:?}: {e}");
+                                return None;
+                            }
+                        };
+                        if entry.file_type().is_dir() {
+                            // Changes to directories themselves aren't
+                            // particularly interesting.
+                            return None;
+                        }
+                        let path = entry.path().to_path_buf();
+
+                        let meta = match entry.metadata() {
+                            Ok(meta) => meta,
+                            Err(e) => {
+                                debug!("failed to scan {path:?}: {e}");
+                                return None;
+                            }
+                        };
+                        let mtime = meta.modified().unwrap_or(SystemTime::UNIX_EPOCH);
+                        let pd = PathData {
+                            file_type: meta.file_type(),
+                            mtime,
+                            size: meta.len(),
+                        };
+                        Some((path, pd))
+                    })
+            })
+            .collect();
+        let mut paths = Vec::new();
+        for (new_path, new_data) in &new_path_data {
+            match self.path_data.get(new_path) {
+                Some(old_data) => {
+                    if new_data != old_data {
+                        paths.push(new_path.to_path_buf());
+                    }
+                }
+                None => {
+                    paths.push(new_path.clone());
+                }
+            }
+        }
+        for old_path in self.path_data.keys() {
+            if !new_path_data.contains_key(old_path) {
+                paths.push(old_path.to_path_buf());
+            }
+        }
+        self.path_data = new_path_data;
+        paths
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Helper for testing the watcher.
+    fn check_watch_behavior(
+        gitignore_path: &str,
+        gitignore: &str,
+        book_root_path: &str,
+        ignored: &[&str],
+        not_ignored: &[&str],
+        extra_setup: &dyn Fn(&Path),
+    ) {
+        // Create the book and initialize things.
+        let temp = tempfile::Builder::new()
+            .prefix("mdbook-")
+            .tempdir()
+            .unwrap();
+        let root = temp.path();
+        let book_root = root.join(book_root_path);
+        // eprintln!("book_root={book_root:?}",);
+        MDBook::init(&book_root).build().unwrap();
+        std::fs::write(root.join(gitignore_path), gitignore).unwrap();
+        let create = |paths: &[&str]| {
+            let mut paths = paths
+                .iter()
+                .map(|path| root.join(path))
+                .inspect(|path| {
+                    std::fs::create_dir_all(path.parent().unwrap()).unwrap();
+                    std::fs::write(path, "initial content").unwrap();
+                })
+                .map(|path| path.canonicalize().unwrap())
+                .collect::<Vec<_>>();
+            paths.sort();
+            paths
+        };
+        let ignored = create(ignored);
+        let not_ignored = create(not_ignored);
+        extra_setup(&book_root);
+        // Create a watcher and check its behavior.
+        let book = MDBook::load(&book_root).unwrap();
+        let mut watcher = Watcher::new(&book_root);
+        watcher.set_roots(&book);
+        // Do an initial scan to initialize its state.
+        watcher.scan();
+        // Verify the steady state is empty.
+        let changed = watcher.scan();
+        assert_eq!(changed, Vec::<PathBuf>::new());
+        // Modify all files, and verify that only not_ignored are detected.
+        for path in ignored.iter().chain(not_ignored.iter()) {
+            std::fs::write(path, "modified").unwrap();
+        }
+        let changed = watcher.scan();
+        let mut changed = changed
+            .into_iter()
+            .map(|p| p.canonicalize().unwrap())
+            .collect::<Vec<_>>();
+        changed.sort();
+        assert_eq!(changed, not_ignored);
+        // Verify again that steady state is empty.
+        let changed = watcher.scan();
+        assert_eq!(changed, Vec::<PathBuf>::new());
+    }
+
+    #[test]
+    fn test_ignore() {
+        // Basic gitignore test.
+        check_watch_behavior(
+            "foo/.gitignore",
+            "*.tmp",
+            "foo",
+            &["foo/src/somefile.tmp"],
+            &["foo/src/chapter.md"],
+            &|_book_root| {},
+        );
+    }
+
+    #[test]
+    fn test_ignore_in_parent() {
+        // gitignore is in the parent of the book
+        check_watch_behavior(
+            ".gitignore",
+            "*.tmp\nsomedir/\n/inroot\n/foo/src/inbook\n",
+            "foo",
+            &[
+                "foo/src/somefile.tmp",
+                "foo/src/somedir/somefile",
+                "inroot/somefile",
+                "foo/src/inbook/somefile",
+            ],
+            &["foo/src/inroot/somefile"],
+            &|_book_root| {},
+        );
+    }
+
+    #[test]
+    fn test_ignore_canonical() {
+        // test with path with ..
+        check_watch_behavior(
+            ".gitignore",
+            "*.tmp\nsomedir/\n/foo/src/inbook\n",
+            "bar/../foo",
+            &[
+                "foo/src/somefile.tmp",
+                "foo/src/somedir/somefile",
+                "foo/src/inbook/somefile",
+            ],
+            &["foo/src/chapter.md"],
+            &|_book_root| {},
+        );
+    }
+
+    #[test]
+    fn test_scan_extra_watch() {
+        // Check behavior with extra-watch-dirs
+        check_watch_behavior(
+            ".gitignore",
+            "*.tmp\n/outside-root/ignoreme\n/foo/examples/ignoreme\n",
+            "foo",
+            &[
+                "foo/src/somefile.tmp",
+                "foo/examples/example.tmp",
+                "outside-root/somefile.tmp",
+                "outside-root/ignoreme",
+                "foo/examples/ignoreme",
+            ],
+            &[
+                "foo/src/chapter.md",
+                "foo/examples/example.rs",
+                "foo/examples/example2.rs",
+                "outside-root/image.png",
+            ],
+            &|book_root| {
+                std::fs::write(
+                    book_root.join("book.toml"),
+                    r#"
+                        [book]
+                        title = "foo"
+
+                        [build]
+                        extra-watch-dirs = [
+                            "examples",
+                            "../outside-root",
+                        ]
+                    "#,
+                )
+                .unwrap();
+            },
+        );
+    }
+}

src/config.rs

@@ -58,7 +58,7 @@ use std::io::Read;
 use std::path::{Path, PathBuf};
 use std::str::FromStr;
 use toml::value::Table;
-use toml::{self, Value};
+use toml::Value;
 
 use crate::errors::*;
 use crate::utils::{self, toml_ext::TomlExt};
@@ -411,6 +411,9 @@ pub struct BookConfig {
     pub multilingual: bool,
     /// The main language of the book.
     pub language: Option<String>,
+    /// The direction of text in the book: Left-to-right (LTR) or Right-to-left (RTL).
+    /// When not specified, the text direction is derived from [`BookConfig::language`].
+    pub text_direction: Option<TextDirection>,
 }
 
 impl Default for BookConfig {
@@ -422,6 +425,43 @@ impl Default for BookConfig {
             src: PathBuf::from("src"),
             multilingual: false,
             language: Some(String::from("en")),
+            text_direction: None,
+        }
+    }
+}
+
+impl BookConfig {
+    /// Gets the realized text direction, either from [`BookConfig::text_direction`]
+    /// or derived from [`BookConfig::language`], to be used by templating engines.
+    pub fn realized_text_direction(&self) -> TextDirection {
+        if let Some(direction) = self.text_direction {
+            direction
+        } else {
+            TextDirection::from_lang_code(self.language.as_deref().unwrap_or_default())
+        }
+    }
+}
+
+/// Text direction to use for HTML output
+#[derive(Debug, Copy, Clone, PartialEq, Serialize, Deserialize)]
+pub enum TextDirection {
+    /// Left to right.
+    #[serde(rename = "ltr")]
+    LeftToRight,
+    /// Right to left
+    #[serde(rename = "rtl")]
+    RightToLeft,
+}
+
+impl TextDirection {
+    /// Gets the text direction from language code
+    pub fn from_lang_code(code: &str) -> Self {
+        match code {
+            // list sourced from here: https://github.com/abarrak/rtl/blob/master/lib/rtl/core.rb#L16
+            "ar" | "ara" | "arc" | "ae" | "ave" | "egy" | "he" | "heb" | "nqo" | "pal" | "phn"
+            | "sam" | "syc" | "syr" | "fa" | "per" | "fas" | "ku" | "kur" | "ur" | "urd"
+            | "pus" | "ps" | "yi" | "yid" => TextDirection::RightToLeft,
+            _ => TextDirection::LeftToRight,
         }
     }
 }
@@ -486,7 +526,9 @@ pub struct HtmlConfig {
     /// The theme to use if the browser requests the dark version of the site.
     /// Defaults to 'navy'.
     pub preferred_dark_theme: Option<String>,
-    /// Use "smart quotes" instead of the usual `"` character.
+    /// Supports smart quotes, apostrophes, ellipsis, en-dash, and em-dash.
+    pub smart_punctuation: bool,
+    /// Deprecated alias for `smart_punctuation`.
     pub curly_quotes: bool,
     /// Should mathjax be enabled?
     pub mathjax_support: bool,
@@ -504,6 +546,8 @@ pub struct HtmlConfig {
     /// Playground settings.
     #[serde(alias = "playpen")]
     pub playground: Playground,
+    /// Code settings.
+    pub code: Code,
     /// Print settings.
     pub print: Print,
     /// Don't render section labels.
@@ -548,6 +592,7 @@ impl Default for HtmlConfig {
             theme: None,
             default_theme: None,
             preferred_dark_theme: None,
+            smart_punctuation: false,
             curly_quotes: false,
             mathjax_support: false,
             copy_fonts: true,
@@ -556,6 +601,7 @@ impl Default for HtmlConfig {
             additional_js: Vec::new(),
             fold: Fold::default(),
             playground: Playground::default(),
+            code: Code::default(),
             print: Print::default(),
             no_section_label: false,
             search: None,
@@ -580,6 +626,11 @@ impl HtmlConfig {
             None => root.join("theme"),
         }
     }
+
+    /// Returns `true` if smart punctuation is enabled.
+    pub fn smart_punctuation(&self) -> bool {
+        self.smart_punctuation || self.curly_quotes
+    }
 }
 
 /// Configuration for how to render the print icon, print.html, and print.css.
@@ -613,7 +664,7 @@ pub struct Fold {
     pub level: u8,
 }
 
-/// Configuration for tweaking how the the HTML renderer handles the playground.
+/// Configuration for tweaking how the HTML renderer handles the playground.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case")]
 pub struct Playground {
@@ -642,6 +693,14 @@ impl Default for Playground {
     }
 }
 
+/// Configuration for tweaking how the HTML renderer handles code blocks.
+#[derive(Debug, Default, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(default, rename_all = "kebab-case")]
+pub struct Code {
+    /// A prefix string to hide lines per language (one or more chars).
+    pub hidelines: HashMap<String, String>,
+}
+
 /// Configuration of the search functionality of the HTML renderer.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case")]
@@ -739,7 +798,7 @@ mod tests {
         [output.html]
         theme = "./themedir"
         default-theme = "rust"
-        curly-quotes = true
+        smart-punctuation = true
         google-analytics = "123456"
         additional-css = ["./foo/bar/baz.css"]
         git-repository-url = "https://foo.com/"
@@ -769,6 +828,7 @@ mod tests {
             multilingual: true,
             src: PathBuf::from("source"),
             language: Some(String::from("ja")),
+            text_direction: None,
         };
         let build_should_be = BuildConfig {
             build_dir: PathBuf::from("outputs"),
@@ -785,7 +845,7 @@ mod tests {
             runnable: true,
         };
         let html_should_be = HtmlConfig {
-            curly_quotes: true,
+            smart_punctuation: true,
             google_analytics: Some(String::from("123456")),
             additional_css: vec![PathBuf::from("./foo/bar/baz.css")],
             theme: Some(PathBuf::from("./themedir")),
@@ -965,7 +1025,7 @@ mod tests {
         [output.html]
         destination = "my-book" # the output files will be generated in `root/my-book` instead of `root/book`
         theme = "my-theme"
-        curly-quotes = true
+        smart-punctuation = true
         google-analytics = "123456"
         additional-css = ["custom.css", "custom2.css"]
         additional-js = ["custom.js"]
@@ -990,7 +1050,7 @@ mod tests {
 
         let html_should_be = HtmlConfig {
             theme: Some(PathBuf::from("my-theme")),
-            curly_quotes: true,
+            smart_punctuation: true,
             google_analytics: Some(String::from("123456")),
             additional_css: vec![PathBuf::from("custom.css"), PathBuf::from("custom2.css")],
             additional_js: vec![PathBuf::from("custom.js")],
@@ -1121,6 +1181,73 @@ mod tests {
         assert_eq!(&get_404_output_file(&html_config.input_404), "missing.html");
     }
 
+    #[test]
+    fn text_direction_ltr() {
+        let src = r#"
+        [book]
+        text-direction = "ltr"
+        "#;
+
+        let got = Config::from_str(src).unwrap();
+        assert_eq!(got.book.text_direction, Some(TextDirection::LeftToRight));
+    }
+
+    #[test]
+    fn text_direction_rtl() {
+        let src = r#"
+        [book]
+        text-direction = "rtl"
+        "#;
+
+        let got = Config::from_str(src).unwrap();
+        assert_eq!(got.book.text_direction, Some(TextDirection::RightToLeft));
+    }
+
+    #[test]
+    fn text_direction_none() {
+        let src = r#"
+        [book]
+        "#;
+
+        let got = Config::from_str(src).unwrap();
+        assert_eq!(got.book.text_direction, None);
+    }
+
+    #[test]
+    fn test_text_direction() {
+        let mut cfg = BookConfig::default();
+
+        // test deriving the text direction from language codes
+        cfg.language = Some("ar".into());
+        assert_eq!(cfg.realized_text_direction(), TextDirection::RightToLeft);
+
+        cfg.language = Some("he".into());
+        assert_eq!(cfg.realized_text_direction(), TextDirection::RightToLeft);
+
+        cfg.language = Some("en".into());
+        assert_eq!(cfg.realized_text_direction(), TextDirection::LeftToRight);
+
+        cfg.language = Some("ja".into());
+        assert_eq!(cfg.realized_text_direction(), TextDirection::LeftToRight);
+
+        // test forced direction
+        cfg.language = Some("ar".into());
+        cfg.text_direction = Some(TextDirection::LeftToRight);
+        assert_eq!(cfg.realized_text_direction(), TextDirection::LeftToRight);
+
+        cfg.language = Some("ar".into());
+        cfg.text_direction = Some(TextDirection::RightToLeft);
+        assert_eq!(cfg.realized_text_direction(), TextDirection::RightToLeft);
+
+        cfg.language = Some("en".into());
+        cfg.text_direction = Some(TextDirection::LeftToRight);
+        assert_eq!(cfg.realized_text_direction(), TextDirection::LeftToRight);
+
+        cfg.language = Some("en".into());
+        cfg.text_direction = Some(TextDirection::RightToLeft);
+        assert_eq!(cfg.realized_text_direction(), TextDirection::RightToLeft);
+    }
+
     #[test]
     #[should_panic(expected = "Invalid configuration file")]
     fn invalid_language_type_error() {
@@ -1193,4 +1320,37 @@ mod tests {
         assert!(html_config.print.enable);
         assert!(!html_config.print.page_break);
     }
+
+    #[test]
+    fn curly_quotes_or_smart_punctuation() {
+        let src = r#"
+        [book]
+        title = "mdBook Documentation"
+
+        [output.html]
+        smart-punctuation = true
+        "#;
+        let config = Config::from_str(src).unwrap();
+        assert_eq!(config.html_config().unwrap().smart_punctuation(), true);
+
+        let src = r#"
+        [book]
+        title = "mdBook Documentation"
+
+        [output.html]
+        curly-quotes = true
+        "#;
+        let config = Config::from_str(src).unwrap();
+        assert_eq!(config.html_config().unwrap().smart_punctuation(), true);
+
+        let src = r#"
+        [book]
+        title = "mdBook Documentation"
+        "#;
+        let config = Config::from_str(src).unwrap();
+        assert_eq!(
+            config.html_config().unwrap_or_default().smart_punctuation(),
+            false
+        );
+    }
 }

src/renderer/html_handlebars/hbs_renderer.rs

@@ -1,5 +1,5 @@
 use crate::book::{Book, BookItem};
-use crate::config::{BookConfig, Config, HtmlConfig, Playground, RustEdition};
+use crate::config::{BookConfig, Code, Config, HtmlConfig, Playground, RustEdition};
 use crate::errors::*;
 use crate::renderer::html_handlebars::helpers;
 use crate::renderer::{RenderContext, Renderer};
@@ -54,11 +54,13 @@ impl HtmlHandlebars {
                 .insert("git_repository_edit_url".to_owned(), json!(edit_url));
         }
 
-        let content = ch.content.clone();
-        let content = utils::render_markdown(&content, ctx.html_config.curly_quotes);
+        let content = utils::render_markdown(&ch.content, ctx.html_config.smart_punctuation());
 
-        let fixed_content =
-            utils::render_markdown_with_path(&ch.content, ctx.html_config.curly_quotes, Some(path));
+        let fixed_content = utils::render_markdown_with_path(
+            &ch.content,
+            ctx.html_config.smart_punctuation(),
+            Some(path),
+        );
         if !ctx.is_index && ctx.html_config.print.page_break {
             // Add page break between chapters
             // See https://developer.mozilla.org/en-US/docs/Web/CSS/break-before and https://developer.mozilla.org/en-US/docs/Web/CSS/page-break-before
@@ -110,7 +112,12 @@ impl HtmlHandlebars {
         debug!("Render template");
         let rendered = ctx.handlebars.render("index", &ctx.data)?;
 
-        let rendered = self.post_process(rendered, &ctx.html_config.playground, ctx.edition);
+        let rendered = self.post_process(
+            rendered,
+            &ctx.html_config.playground,
+            &ctx.html_config.code,
+            ctx.edition,
+        );
 
         // Write to file
         debug!("Creating {}", filepath.display());
@@ -121,8 +128,12 @@ impl HtmlHandlebars {
             ctx.data.insert("path_to_root".to_owned(), json!(""));
             ctx.data.insert("is_index".to_owned(), json!(true));
             let rendered_index = ctx.handlebars.render("index", &ctx.data)?;
-            let rendered_index =
-                self.post_process(rendered_index, &ctx.html_config.playground, ctx.edition);
+            let rendered_index = self.post_process(
+                rendered_index,
+                &ctx.html_config.playground,
+                &ctx.html_config.code,
+                ctx.edition,
+            );
             debug!("Creating index.html from {}", ctx_path);
             utils::fs::write_file(&ctx.destination, "index.html", rendered_index.as_bytes())?;
         }
@@ -156,7 +167,8 @@ impl HtmlHandlebars {
                     .to_string()
             }
         };
-        let html_content_404 = utils::render_markdown(&content_404, html_config.curly_quotes);
+        let html_content_404 =
+            utils::render_markdown(&content_404, html_config.smart_punctuation());
 
         let mut data_404 = data.clone();
         let base_url = if let Some(site_url) = &html_config.site_url {
@@ -182,24 +194,30 @@ impl HtmlHandlebars {
         data_404.insert("title".to_owned(), json!(title));
         let rendered = handlebars.render("index", &data_404)?;
 
-        let rendered =
-            self.post_process(rendered, &html_config.playground, ctx.config.rust.edition);
+        let rendered = self.post_process(
+            rendered,
+            &html_config.playground,
+            &html_config.code,
+            ctx.config.rust.edition,
+        );
         let output_file = get_404_output_file(&html_config.input_404);
         utils::fs::write_file(destination, output_file, rendered.as_bytes())?;
         debug!("Creating 404.html ✓");
         Ok(())
     }
 
-    #[cfg_attr(feature = "cargo-clippy", allow(clippy::let_and_return))]
+    #[allow(clippy::let_and_return)]
     fn post_process(
         &self,
         rendered: String,
         playground_config: &Playground,
+        code_config: &Code,
         edition: Option<RustEdition>,
     ) -> String {
         let rendered = build_header_links(&rendered);
         let rendered = fix_code_blocks(&rendered);
         let rendered = add_playground_pre(&rendered, playground_config, edition);
+        let rendered = hide_lines(&rendered, code_config);
 
         rendered
     }
@@ -463,25 +481,6 @@ impl HtmlHandlebars {
     }
 }
 
-// TODO(mattico): Remove some time after the 0.1.8 release
-fn maybe_wrong_theme_dir(dir: &Path) -> Result<bool> {
-    fn entry_is_maybe_book_file(entry: fs::DirEntry) -> Result<bool> {
-        Ok(entry.file_type()?.is_file()
-            && entry.path().extension().map_or(false, |ext| ext == "md"))
-    }
-
-    if dir.is_dir() {
-        for entry in fs::read_dir(dir)? {
-            if entry_is_maybe_book_file(entry?).unwrap_or(false) {
-                return Ok(false);
-            }
-        }
-        Ok(true)
-    } else {
-        Ok(false)
-    }
-}
-
 impl Renderer for HtmlHandlebars {
     fn name(&self) -> &str {
         "html"
@@ -514,16 +513,6 @@ impl Renderer for HtmlHandlebars {
             None => ctx.root.join("theme"),
         };
 
-        if html_config.theme.is_none()
-            && maybe_wrong_theme_dir(&src_dir.join("theme")).unwrap_or(false)
-        {
-            warn!(
-                "Previous versions of mdBook erroneously accepted `./src/theme` as an automatic \
-                 theme directory"
-            );
-            warn!("Please move your theme files to `./theme` for them to continue being used");
-        }
-
         let theme = theme::Theme::new(theme_dir);
 
         debug!("Register the index handlebars template");
@@ -583,8 +572,12 @@ impl Renderer for HtmlHandlebars {
             debug!("Render template");
             let rendered = handlebars.render("index", &data)?;
 
-            let rendered =
-                self.post_process(rendered, &html_config.playground, ctx.config.rust.edition);
+            let rendered = self.post_process(
+                rendered,
+                &html_config.playground,
+                &html_config.code,
+                ctx.config.rust.edition,
+            );
 
             utils::fs::write_file(destination, "print.html", rendered.as_bytes())?;
             debug!("Creating print.html ✓");
@@ -629,6 +622,10 @@ fn make_data(
         "language".to_owned(),
         json!(config.book.language.clone().unwrap_or_default()),
     );
+    data.insert(
+        "text_direction".to_owned(),
+        json!(config.book.realized_text_direction()),
+    );
     data.insert(
         "book_title".to_owned(),
         json!(config.book.title.clone().unwrap_or_default()),
@@ -789,8 +786,10 @@ fn make_data(
 /// Goes through the rendered HTML, making sure all header tags have
 /// an anchor respectively so people can link to sections directly.
 fn build_header_links(html: &str) -> String {
-    static BUILD_HEADER_LINKS: Lazy<Regex> =
-        Lazy::new(|| Regex::new(r"<h(\d)>(.*?)</h\d>").unwrap());
+    static BUILD_HEADER_LINKS: Lazy<Regex> = Lazy::new(|| {
+        Regex::new(r#"<h(\d)(?: id="([^"]+)")?(?: class="([^"]+)")?>(.*?)</h\d>"#).unwrap()
+    });
+    static IGNORE_CLASS: &[&str] = &["menu-title"];
 
     let mut id_counter = HashMap::new();
 
@@ -800,7 +799,22 @@ fn build_header_links(html: &str) -> String {
                 .parse()
                 .expect("Regex should ensure we only ever get numbers here");
 
-            insert_link_into_header(level, &caps[2], &mut id_counter)
+            // Ignore .menu-title because now it's getting detected by the regex.
+            if let Some(classes) = caps.get(3) {
+                for class in classes.as_str().split(" ") {
+                    if IGNORE_CLASS.contains(&class) {
+                        return caps[0].to_string();
+                    }
+                }
+            }
+
+            insert_link_into_header(
+                level,
+                &caps[4],
+                caps.get(2).map(|x| x.as_str().to_string()),
+                caps.get(3).map(|x| x.as_str().to_string()),
+                &mut id_counter,
+            )
         })
         .into_owned()
 }
@@ -810,15 +824,21 @@ fn build_header_links(html: &str) -> String {
 fn insert_link_into_header(
     level: usize,
     content: &str,
+    id: Option<String>,
+    classes: Option<String>,
     id_counter: &mut HashMap<String, usize>,
 ) -> String {
-    let id = utils::unique_id_from_content(content, id_counter);
+    let id = id.unwrap_or_else(|| utils::unique_id_from_content(content, id_counter));
+    let classes = classes
+        .map(|s| format!(" class=\"{s}\""))
+        .unwrap_or_default();
 
     format!(
-        r##"<h{level} id="{id}"><a class="header" href="#{id}">{text}</a></h{level}>"##,
+        r##"<h{level} id="{id}"{classes}><a class="header" href="#{id}">{text}</a></h{level}>"##,
         level = level,
         id = id,
-        text = content
+        text = content,
+        classes = classes
     )
 }
 
@@ -850,67 +870,64 @@ fn fix_code_blocks(html: &str) -> String {
         .into_owned()
 }
 
+static CODE_BLOCK_RE: Lazy<Regex> =
+    Lazy::new(|| Regex::new(r##"((?s)<code[^>]?class="([^"]+)".*?>(.*?)</code>)"##).unwrap());
+
 fn add_playground_pre(
     html: &str,
     playground_config: &Playground,
     edition: Option<RustEdition>,
 ) -> String {
-    static ADD_PLAYGROUND_PRE: Lazy<Regex> =
-        Lazy::new(|| Regex::new(r##"((?s)<code[^>]?class="([^"]+)".*?>(.*?)</code>)"##).unwrap());
-
-    ADD_PLAYGROUND_PRE
+    CODE_BLOCK_RE
         .replace_all(html, |caps: &Captures<'_>| {
             let text = &caps[1];
             let classes = &caps[2];
             let code = &caps[3];
 
-            if classes.contains("language-rust") {
-                if (!classes.contains("ignore")
+            if classes.contains("language-rust")
+                && ((!classes.contains("ignore")
                     && !classes.contains("noplayground")
                     && !classes.contains("noplaypen")
                     && playground_config.runnable)
-                    || classes.contains("mdbook-runnable")
-                {
-                    let contains_e2015 = classes.contains("edition2015");
-                    let contains_e2018 = classes.contains("edition2018");
-                    let contains_e2021 = classes.contains("edition2021");
-                    let edition_class = if contains_e2015 || contains_e2018 || contains_e2021 {
-                        // the user forced edition, we should not overwrite it
-                        ""
-                    } else {
-                        match edition {
-                            Some(RustEdition::E2015) => " edition2015",
-                            Some(RustEdition::E2018) => " edition2018",
-                            Some(RustEdition::E2021) => " edition2021",
-                            None => "",
-                        }
-                    };
-
-                    // wrap the contents in an external pre block
-                    format!(
-                        "<pre class=\"playground\"><code class=\"{}{}\">{}</code></pre>",
-                        classes,
-                        edition_class,
-                        {
-                            let content: Cow<'_, str> = if playground_config.editable
-                                && classes.contains("editable")
-                                || text.contains("fn main")
-                                || text.contains("quick_main!")
-                            {
-                                code.into()
-                            } else {
-                                // we need to inject our own main
-                                let (attrs, code) = partition_source(code);
-
-                                format!("# #![allow(unused)]\n{}#fn main() {{\n{}#}}", attrs, code)
-                                    .into()
-                            };
-                            hide_lines(&content)
-                        }
-                    )
+                    || classes.contains("mdbook-runnable"))
+            {
+                let contains_e2015 = classes.contains("edition2015");
+                let contains_e2018 = classes.contains("edition2018");
+                let contains_e2021 = classes.contains("edition2021");
+                let edition_class = if contains_e2015 || contains_e2018 || contains_e2021 {
+                    // the user forced edition, we should not overwrite it
+                    ""
                 } else {
-                    format!("<code class=\"{}\">{}</code>", classes, hide_lines(code))
-                }
+                    match edition {
+                        Some(RustEdition::E2015) => " edition2015",
+                        Some(RustEdition::E2018) => " edition2018",
+                        Some(RustEdition::E2021) => " edition2021",
+                        None => "",
+                    }
+                };
+
+                // wrap the contents in an external pre block
+                format!(
+                    "<pre class=\"playground\"><code class=\"{}{}\">{}</code></pre>",
+                    classes,
+                    edition_class,
+                    {
+                        let content: Cow<'_, str> = if playground_config.editable
+                            && classes.contains("editable")
+                            || text.contains("fn main")
+                            || text.contains("quick_main!")
+                        {
+                            code.into()
+                        } else {
+                            // we need to inject our own main
+                            let (attrs, code) = partition_source(code);
+
+                            format!("# #![allow(unused)]\n{}#fn main() {{\n{}#}}", attrs, code)
+                                .into()
+                        };
+                        content
+                    }
+                )
             } else {
                 // not language-rust, so no-op
                 text.to_owned()
@@ -919,7 +936,51 @@ fn add_playground_pre(
         .into_owned()
 }
 
-fn hide_lines(content: &str) -> String {
+/// Modifies all `<code>` blocks to convert "hidden" lines and to wrap them in
+/// a `<span class="boring">`.
+fn hide_lines(html: &str, code_config: &Code) -> String {
+    static LANGUAGE_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"\blanguage-(\w+)\b").unwrap());
+    static HIDELINES_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"\bhidelines=(\S+)").unwrap());
+
+    CODE_BLOCK_RE
+        .replace_all(html, |caps: &Captures<'_>| {
+            let text = &caps[1];
+            let classes = &caps[2];
+            let code = &caps[3];
+
+            if classes.contains("language-rust") {
+                format!(
+                    "<code class=\"{}\">{}</code>",
+                    classes,
+                    hide_lines_rust(code)
+                )
+            } else {
+                // First try to get the prefix from the code block
+                let hidelines_capture = HIDELINES_REGEX.captures(classes);
+                let hidelines_prefix = match &hidelines_capture {
+                    Some(capture) => Some(&capture[1]),
+                    None => {
+                        // Then look up the prefix by language
+                        LANGUAGE_REGEX.captures(classes).and_then(|capture| {
+                            code_config.hidelines.get(&capture[1]).map(|p| p.as_str())
+                        })
+                    }
+                };
+
+                match hidelines_prefix {
+                    Some(prefix) => format!(
+                        "<code class=\"{}\">{}</code>",
+                        classes,
+                        hide_lines_with_prefix(code, prefix)
+                    ),
+                    None => text.to_owned(),
+                }
+            }
+        })
+        .into_owned()
+}
+
+fn hide_lines_rust(content: &str) -> String {
     static BORING_LINES_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"^(\s*)#(.?)(.*)$").unwrap());
 
     let mut result = String::with_capacity(content.len());
@@ -952,6 +1013,26 @@ fn hide_lines(content: &str) -> String {
     result
 }
 
+fn hide_lines_with_prefix(content: &str, prefix: &str) -> String {
+    let mut result = String::with_capacity(content.len());
+    for line in content.lines() {
+        if line.trim_start().starts_with(prefix) {
+            let pos = line.find(prefix).unwrap();
+            let (ws, rest) = (&line[..pos], &line[pos + prefix.len()..]);
+
+            result += "<span class=\"boring\">";
+            result += ws;
+            result += rest;
+            result += "\n";
+            result += "</span>";
+            continue;
+        }
+        result += line;
+        result += "\n";
+    }
+    result
+}
+
 fn partition_source(s: &str) -> (String, String) {
     let mut after_header = false;
     let mut before = String::new();
@@ -986,7 +1067,10 @@ struct RenderItemContext<'a> {
 
 #[cfg(test)]
 mod tests {
+    use crate::config::TextDirection;
+
     use super::*;
+    use pretty_assertions::assert_eq;
 
     #[test]
     fn original_build_header_links() {
@@ -1015,6 +1099,21 @@ mod tests {
                 "<h1>Foo</h1><h3>Foo</h3>",
                 r##"<h1 id="foo"><a class="header" href="#foo">Foo</a></h1><h3 id="foo-1"><a class="header" href="#foo-1">Foo</a></h3>"##,
             ),
+            // id only
+            (
+                r##"<h1 id="foobar">Foo</h1>"##,
+                r##"<h1 id="foobar"><a class="header" href="#foobar">Foo</a></h1>"##,
+            ),
+            // class only
+            (
+                r##"<h1 class="class1 class2">Foo</h1>"##,
+                r##"<h1 id="foo" class="class1 class2"><a class="header" href="#foo">Foo</a></h1>"##,
+            ),
+            // both id and class
+            (
+                r##"<h1 id="foobar" class="class1 class2">Foo</h1>"##,
+                r##"<h1 id="foobar" class="class1 class2"><a class="header" href="#foobar">Foo</a></h1>"##,
+            ),
         ];
 
         for (src, should_be) in inputs {
@@ -1027,17 +1126,17 @@ mod tests {
     fn add_playground() {
         let inputs = [
           ("<code class=\"language-rust\">x()</code>",
-           "<pre class=\"playground\"><code class=\"language-rust\"><span class=\"boring\">#![allow(unused)]\n</span><span class=\"boring\">fn main() {\n</span>x()\n<span class=\"boring\">}</span></code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust\"># #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>"),
           ("<code class=\"language-rust\">fn main() {}</code>",
            "<pre class=\"playground\"><code class=\"language-rust\">fn main() {}</code></pre>"),
           ("<code class=\"language-rust editable\">let s = \"foo\n # bar\n\";</code>",
-           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n<span class=\"boring\"> bar\n</span>\";</code></pre>"),
-          ("<code class=\"language-rust editable\">let s = \"foo\n ## bar\n\";</code>",
            "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n\";</code></pre>"),
+          ("<code class=\"language-rust editable\">let s = \"foo\n ## bar\n\";</code>",
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n ## bar\n\";</code></pre>"),
           ("<code class=\"language-rust editable\">let s = \"foo\n # bar\n#\n\";</code>",
-           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n<span class=\"boring\"> bar\n</span><span class=\"boring\">\n</span>\";</code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n#\n\";</code></pre>"),
           ("<code class=\"language-rust ignore\">let s = \"foo\n # bar\n\";</code>",
-           "<code class=\"language-rust ignore\">let s = \"foo\n<span class=\"boring\"> bar\n</span>\";</code>"),
+           "<code class=\"language-rust ignore\">let s = \"foo\n # bar\n\";</code>"),
           ("<code class=\"language-rust editable\">#![no_std]\nlet s = \"foo\";\n #[some_attr]</code>",
            "<pre class=\"playground\"><code class=\"language-rust editable\">#![no_std]\nlet s = \"foo\";\n #[some_attr]</code></pre>"),
         ];
@@ -1057,7 +1156,7 @@ mod tests {
     fn add_playground_edition2015() {
         let inputs = [
           ("<code class=\"language-rust\">x()</code>",
-           "<pre class=\"playground\"><code class=\"language-rust edition2015\"><span class=\"boring\">#![allow(unused)]\n</span><span class=\"boring\">fn main() {\n</span>x()\n<span class=\"boring\">}</span></code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust edition2015\"># #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>"),
           ("<code class=\"language-rust\">fn main() {}</code>",
            "<pre class=\"playground\"><code class=\"language-rust edition2015\">fn main() {}</code></pre>"),
           ("<code class=\"language-rust edition2015\">fn main() {}</code>",
@@ -1081,7 +1180,7 @@ mod tests {
     fn add_playground_edition2018() {
         let inputs = [
           ("<code class=\"language-rust\">x()</code>",
-           "<pre class=\"playground\"><code class=\"language-rust edition2018\"><span class=\"boring\">#![allow(unused)]\n</span><span class=\"boring\">fn main() {\n</span>x()\n<span class=\"boring\">}</span></code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust edition2018\"># #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>"),
           ("<code class=\"language-rust\">fn main() {}</code>",
            "<pre class=\"playground\"><code class=\"language-rust edition2018\">fn main() {}</code></pre>"),
           ("<code class=\"language-rust edition2015\">fn main() {}</code>",
@@ -1105,7 +1204,7 @@ mod tests {
     fn add_playground_edition2021() {
         let inputs = [
             ("<code class=\"language-rust\">x()</code>",
-             "<pre class=\"playground\"><code class=\"language-rust edition2021\"><span class=\"boring\">#![allow(unused)]\n</span><span class=\"boring\">fn main() {\n</span>x()\n<span class=\"boring\">}</span></code></pre>"),
+             "<pre class=\"playground\"><code class=\"language-rust edition2021\"># #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>"),
             ("<code class=\"language-rust\">fn main() {}</code>",
              "<pre class=\"playground\"><code class=\"language-rust edition2021\">fn main() {}</code></pre>"),
             ("<code class=\"language-rust edition2015\">fn main() {}</code>",
@@ -1125,4 +1224,66 @@ mod tests {
             assert_eq!(&*got, *should_be);
         }
     }
+
+    #[test]
+    fn hide_lines_language_rust() {
+        let inputs = [
+          (
+           "<pre class=\"playground\"><code class=\"language-rust\">\n# #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust\">\n<span class=\"boring\">#![allow(unused)]\n</span><span class=\"boring\">fn main() {\n</span>x()\n<span class=\"boring\">}</span></code></pre>",),
+          (
+           "<pre class=\"playground\"><code class=\"language-rust\">fn main() {}</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust\">fn main() {}</code></pre>",),
+          (
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n\";</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n<span class=\"boring\"> bar\n</span>\";</code></pre>",),
+          (
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n ## bar\n\";</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n\";</code></pre>",),
+          (
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n#\n\";</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n<span class=\"boring\"> bar\n</span><span class=\"boring\">\n</span>\";</code></pre>",),
+          (
+           "<code class=\"language-rust ignore\">let s = \"foo\n # bar\n\";</code>",
+           "<code class=\"language-rust ignore\">let s = \"foo\n<span class=\"boring\"> bar\n</span>\";</code>",),
+          (
+           "<pre class=\"playground\"><code class=\"language-rust editable\">#![no_std]\nlet s = \"foo\";\n #[some_attr]</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust editable\">#![no_std]\nlet s = \"foo\";\n #[some_attr]</code></pre>",),
+        ];
+        for (src, should_be) in &inputs {
+            let got = hide_lines(src, &Code::default());
+            assert_eq!(&*got, *should_be);
+        }
+    }
+
+    #[test]
+    fn hide_lines_language_other() {
+        let inputs = [
+          (
+           "<code class=\"language-python\">~hidden()\nnothidden():\n~    hidden()\n    ~hidden()\n    nothidden()</code>",
+           "<code class=\"language-python\"><span class=\"boring\">hidden()\n</span>nothidden():\n<span class=\"boring\">    hidden()\n</span><span class=\"boring\">    hidden()\n</span>    nothidden()\n</code>",),
+           (
+            "<code class=\"language-python hidelines=!!!\">!!!hidden()\nnothidden():\n!!!    hidden()\n    !!!hidden()\n    nothidden()</code>",
+            "<code class=\"language-python hidelines=!!!\"><span class=\"boring\">hidden()\n</span>nothidden():\n<span class=\"boring\">    hidden()\n</span><span class=\"boring\">    hidden()\n</span>    nothidden()\n</code>",),
+        ];
+        for (src, should_be) in &inputs {
+            let got = hide_lines(
+                src,
+                &Code {
+                    hidelines: {
+                        let mut map = HashMap::new();
+                        map.insert("python".to_string(), "~".to_string());
+                        map
+                    },
+                },
+            );
+            assert_eq!(&*got, *should_be);
+        }
+    }
+
+    #[test]
+    fn test_json_direction() {
+        assert_eq!(json!(TextDirection::RightToLeft), json!("rtl"));
+        assert_eq!(json!(TextDirection::LeftToRight), json!("ltr"));
+    }
 }

src/renderer/html_handlebars/helpers/navigation.rs

@@ -1,7 +1,9 @@
 use std::collections::BTreeMap;
 use std::path::Path;
 
-use handlebars::{Context, Handlebars, Helper, Output, RenderContext, RenderError, Renderable};
+use handlebars::{
+    Context, Handlebars, Helper, Output, RenderContext, RenderError, RenderErrorReason, Renderable,
+};
 
 use crate::utils;
 use log::{debug, trace};
@@ -26,9 +28,9 @@ impl Target {
     ) -> Result<Option<StringMap>, RenderError> {
         match *self {
             Target::Next => {
-                let previous_path = previous_item
-                    .get("path")
-                    .ok_or_else(|| RenderError::new("No path found for chapter in JSON data"))?;
+                let previous_path = previous_item.get("path").ok_or_else(|| {
+                    RenderErrorReason::Other("No path found for chapter in JSON data".to_owned())
+                })?;
 
                 if previous_path == base_path {
                     return Ok(Some(current_item.clone()));
@@ -54,15 +56,18 @@ fn find_chapter(
     debug!("Get data from context");
 
     let chapters = rc.evaluate(ctx, "@root/chapters").and_then(|c| {
-        serde_json::value::from_value::<Vec<StringMap>>(c.as_json().clone())
-            .map_err(|_| RenderError::new("Could not decode the JSON data"))
+        serde_json::value::from_value::<Vec<StringMap>>(c.as_json().clone()).map_err(|_| {
+            RenderErrorReason::Other("Could not decode the JSON data".to_owned()).into()
+        })
     })?;
 
     let base_path = rc
         .evaluate(ctx, "@root/path")?
         .as_json()
         .as_str()
-        .ok_or_else(|| RenderError::new("Type error for `path`, string expected"))?
+        .ok_or_else(|| {
+            RenderErrorReason::Other("Type error for `path`, string expected".to_owned())
+        })?
         .replace('\"', "");
 
     if !rc.evaluate(ctx, "@root/is_index")?.is_missing() {
@@ -98,7 +103,7 @@ fn find_chapter(
                     }
                 }
 
-                previous = Some(item.clone());
+                previous = Some(item);
             }
             _ => continue,
         }
@@ -108,7 +113,7 @@ fn find_chapter(
 }
 
 fn render(
-    _h: &Helper<'_, '_>,
+    _h: &Helper<'_>,
     r: &Handlebars<'_>,
     ctx: &Context,
     rc: &mut RenderContext<'_, '_>,
@@ -122,7 +127,9 @@ fn render(
         .evaluate(ctx, "@root/path")?
         .as_json()
         .as_str()
-        .ok_or_else(|| RenderError::new("Type error for `path`, string expected"))?
+        .ok_or_else(|| {
+            RenderErrorReason::Other("Type error for `path`, string expected".to_owned())
+        })?
         .replace('\"', "");
 
     context.insert(
@@ -132,17 +139,23 @@ fn render(
 
     chapter
         .get("name")
-        .ok_or_else(|| RenderError::new("No title found for chapter in JSON data"))
+        .ok_or_else(|| {
+            RenderErrorReason::Other("No title found for chapter in JSON data".to_owned())
+        })
         .map(|name| context.insert("title".to_owned(), json!(name)))?;
 
     chapter
         .get("path")
-        .ok_or_else(|| RenderError::new("No path found for chapter in JSON data"))
+        .ok_or_else(|| {
+            RenderErrorReason::Other("No path found for chapter in JSON data".to_owned())
+        })
         .and_then(|p| {
             Path::new(p)
                 .with_extension("html")
                 .to_str()
-                .ok_or_else(|| RenderError::new("Link could not be converted to str"))
+                .ok_or_else(|| {
+                    RenderErrorReason::Other("Link could not be converted to str".to_owned())
+                })
                 .map(|p| context.insert("link".to_owned(), json!(p.replace('\\', "/"))))
         })?;
 
@@ -150,14 +163,14 @@ fn render(
 
     let t = _h
         .template()
-        .ok_or_else(|| RenderError::new("Error with the handlebars template"))?;
+        .ok_or_else(|| RenderErrorReason::Other("Error with the handlebars template".to_owned()))?;
     let local_ctx = Context::wraps(&context)?;
     let mut local_rc = rc.clone();
     t.render(r, &local_ctx, &mut local_rc, out)
 }
 
 pub fn previous(
-    _h: &Helper<'_, '_>,
+    _h: &Helper<'_>,
     r: &Handlebars<'_>,
     ctx: &Context,
     rc: &mut RenderContext<'_, '_>,
@@ -173,7 +186,7 @@ pub fn previous(
 }
 
 pub fn next(
-    _h: &Helper<'_, '_>,
+    _h: &Helper<'_>,
     r: &Handlebars<'_>,
     ctx: &Context,
     rc: &mut RenderContext<'_, '_>,

src/renderer/html_handlebars/helpers/theme.rs

@@ -1,8 +1,10 @@
-use handlebars::{Context, Handlebars, Helper, Output, RenderContext, RenderError};
+use handlebars::{
+    Context, Handlebars, Helper, Output, RenderContext, RenderError, RenderErrorReason,
+};
 use log::trace;
 
 pub fn theme_option(
-    h: &Helper<'_, '_>,
+    h: &Helper<'_>,
     _r: &Handlebars<'_>,
     ctx: &Context,
     rc: &mut RenderContext<'_, '_>,
@@ -11,14 +13,21 @@ pub fn theme_option(
     trace!("theme_option (handlebars helper)");
 
     let param = h.param(0).and_then(|v| v.value().as_str()).ok_or_else(|| {
-        RenderError::new("Param 0 with String type is required for theme_option helper.")
+        RenderErrorReason::ParamTypeMismatchForName(
+            "theme_option",
+            "0".to_owned(),
+            "string".to_owned(),
+        )
     })?;
 
     let default_theme = rc.evaluate(ctx, "@root/default_theme")?;
-    let default_theme_name = default_theme
-        .as_json()
-        .as_str()
-        .ok_or_else(|| RenderError::new("Type error for `default_theme`, string expected"))?;
+    let default_theme_name = default_theme.as_json().as_str().ok_or_else(|| {
+        RenderErrorReason::ParamTypeMismatchForName(
+            "theme_option",
+            "default_theme".to_owned(),
+            "string".to_owned(),
+        )
+    })?;
 
     out.write(param)?;
     if param.to_lowercase() == default_theme_name.to_lowercase() {

src/renderer/html_handlebars/helpers/toc.rs

@@ -4,7 +4,9 @@ use std::{cmp::Ordering, collections::BTreeMap};
 use crate::utils;
 use crate::utils::bracket_escape;
 
-use handlebars::{Context, Handlebars, Helper, HelperDef, Output, RenderContext, RenderError};
+use handlebars::{
+    Context, Handlebars, Helper, HelperDef, Output, RenderContext, RenderError, RenderErrorReason,
+};
 
 // Handlebars helper to construct TOC
 #[derive(Clone, Copy)]
@@ -15,7 +17,7 @@ pub struct RenderToc {
 impl HelperDef for RenderToc {
     fn call<'reg: 'rc, 'rc>(
         &self,
-        _h: &Helper<'reg, 'rc>,
+        _h: &Helper<'rc>,
         _r: &'reg Handlebars<'_>,
         ctx: &'rc Context,
         rc: &mut RenderContext<'reg, 'rc>,
@@ -26,13 +28,17 @@ impl HelperDef for RenderToc {
         // param is the key of value you want to display
         let chapters = rc.evaluate(ctx, "@root/chapters").and_then(|c| {
             serde_json::value::from_value::<Vec<BTreeMap<String, String>>>(c.as_json().clone())
-                .map_err(|_| RenderError::new("Could not decode the JSON data"))
+                .map_err(|_| {
+                    RenderErrorReason::Other("Could not decode the JSON data".to_owned()).into()
+                })
         })?;
         let current_path = rc
             .evaluate(ctx, "@root/path")?
             .as_json()
             .as_str()
-            .ok_or_else(|| RenderError::new("Type error for `path`, string expected"))?
+            .ok_or_else(|| {
+                RenderErrorReason::Other("Type error for `path`, string expected".to_owned())
+            })?
             .replace('\"', "");
 
         let current_section = rc
@@ -46,13 +52,17 @@ impl HelperDef for RenderToc {
             .evaluate(ctx, "@root/fold_enable")?
             .as_json()
             .as_bool()
-            .ok_or_else(|| RenderError::new("Type error for `fold_enable`, bool expected"))?;
+            .ok_or_else(|| {
+                RenderErrorReason::Other("Type error for `fold_enable`, bool expected".to_owned())
+            })?;
 
         let fold_level = rc
             .evaluate(ctx, "@root/fold_level")?
             .as_json()
             .as_u64()
-            .ok_or_else(|| RenderError::new("Type error for `fold_level`, u64 expected"))?;
+            .ok_or_else(|| {
+                RenderErrorReason::Other("Type error for `fold_level`, u64 expected".to_owned())
+            })?;
 
         out.write("<ol class=\"chapter\">")?;
 
@@ -64,12 +74,6 @@ impl HelperDef for RenderToc {
         let mut is_first_chapter = ctx.data().get("is_index").is_some();
 
         for item in chapters {
-            // Spacer
-            if item.get("spacer").is_some() {
-                out.write("<li class=\"spacer\"></li>")?;
-                continue;
-            }
-
             let (section, level) = if let Some(s) = item.get("section") {
                 (s.as_str(), s.matches('.').count())
             } else {
@@ -104,10 +108,16 @@ impl HelperDef for RenderToc {
                     write_li_open_tag(out, is_expanded, false)?;
                 }
                 Ordering::Equal => {
-                    write_li_open_tag(out, is_expanded, item.get("section").is_none())?;
+                    write_li_open_tag(out, is_expanded, !item.contains_key("section"))?;
                 }
             }
 
+            // Spacer
+            if item.contains_key("spacer") {
+                out.write("<li class=\"spacer\"></li>")?;
+                continue;
+            }
+
             // Part title
             if let Some(title) = item.get("part") {
                 out.write("<li class=\"part-title\">")?;

src/renderer/html_handlebars/search.rs

@@ -66,10 +66,23 @@ fn add_doc(
     index: &mut Index,
     doc_urls: &mut Vec<String>,
     anchor_base: &str,
-    section_id: &Option<String>,
+    heading: &str,
+    id_counter: &mut HashMap<String, usize>,
+    section_id: &Option<CowStr<'_>>,
     items: &[&str],
 ) {
-    let url = if let Some(ref id) = *section_id {
+    // Either use the explicit section id the user specified, or generate one
+    // from the heading content.
+    let section_id = section_id.as_ref().map(|id| id.to_string()).or_else(|| {
+        if heading.is_empty() {
+            // In the case where a chapter has no heading, don't set a section id.
+            None
+        } else {
+            Some(utils::unique_id_from_content(heading, id_counter))
+        }
+    });
+
+    let url = if let Some(id) = section_id {
         Cow::Owned(format!("{}#{}", anchor_base, id))
     } else {
         Cow::Borrowed(anchor_base)
@@ -119,7 +132,7 @@ fn render_item(
     let mut id_counter = HashMap::new();
     while let Some(event) = p.next() {
         match event {
-            Event::Start(Tag::Heading(i, ..)) if i as u32 <= max_section_depth => {
+            Event::Start(Tag::Heading { level, id, .. }) if level as u32 <= max_section_depth => {
                 if !heading.is_empty() {
                     // Section finished, the next heading is following now
                     // Write the data to the index, and clear it for the next section
@@ -127,20 +140,21 @@ fn render_item(
                         index,
                         doc_urls,
                         &anchor_base,
+                        &heading,
+                        &mut id_counter,
                         &section_id,
                         &[&heading, &body, &breadcrumbs.join(" » ")],
                     );
-                    section_id = None;
                     heading.clear();
                     body.clear();
                     breadcrumbs.pop();
                 }
 
+                section_id = id;
                 in_heading = true;
             }
-            Event::End(Tag::Heading(i, ..)) if i as u32 <= max_section_depth => {
+            Event::End(TagEnd::Heading(level)) if level as u32 <= max_section_depth => {
                 in_heading = false;
-                section_id = Some(utils::unique_id_from_content(&heading, &mut id_counter));
                 breadcrumbs.push(heading.clone());
             }
             Event::Start(Tag::FootnoteDefinition(name)) => {
@@ -157,9 +171,19 @@ fn render_item(
                     html_block.push_str(html);
                     p.next();
                 }
-
                 body.push_str(&clean_html(&html_block));
             }
+            Event::InlineHtml(html) => {
+                // This is not capable of cleaning inline tags like
+                // `foo <script>…</script>`. The `<script>` tags show up as
+                // individual InlineHtml events, and the content inside is
+                // just a regular Text event. There isn't a very good way to
+                // know how to collect all the content in-between. I'm not
+                // sure if this is easily fixable. It should be extremely
+                // rare, since script and style tags should almost always be
+                // blocks, and worse case you have some noise in the index.
+                body.push_str(&clean_html(&html));
+            }
             Event::Start(_) | Event::End(_) | Event::Rule | Event::SoftBreak | Event::HardBreak => {
                 // Insert spaces where HTML output would usually separate text
                 // to ensure words don't get merged together
@@ -186,18 +210,24 @@ fn render_item(
     }
 
     if !body.is_empty() || !heading.is_empty() {
-        if heading.is_empty() {
+        let title = if heading.is_empty() {
             if let Some(chapter) = breadcrumbs.first() {
-                heading = chapter.clone();
+                chapter
+            } else {
+                ""
             }
-        }
+        } else {
+            &heading
+        };
         // Make sure the last section is added to the index
         add_doc(
             index,
             doc_urls,
             &anchor_base,
+            &heading,
+            &mut id_counter,
             &section_id,
-            &[&heading, &body, &breadcrumbs.join(" » ")],
+            &[title, &body, &breadcrumbs.join(" » ")],
         );
     }
 

src/theme/book.js

@@ -179,7 +179,7 @@ function playground_text(playground, hidden = true) {
     // even if highlighting doesn't apply
     code_nodes.forEach(function (block) { block.classList.add('hljs'); });
 
-    Array.from(document.querySelectorAll("code.language-rust")).forEach(function (block) {
+    Array.from(document.querySelectorAll("code.hljs")).forEach(function (block) {
 
         var lines = Array.from(block.querySelectorAll('.boring'));
         // If no lines were hidden, return
@@ -346,7 +346,7 @@ function playground_text(playground, hidden = true) {
         }
 
         setTimeout(function () {
-            themeColorMetaTag.content = getComputedStyle(document.body).backgroundColor;
+            themeColorMetaTag.content = getComputedStyle(document.documentElement).backgroundColor;
         }, 1);
 
         if (window.ace && window.editors) {
@@ -441,7 +441,7 @@ function playground_text(playground, hidden = true) {
 })();
 
 (function sidebar() {
-    var html = document.querySelector("html");
+    var body = document.querySelector("body");
     var sidebar = document.getElementById("sidebar");
     var sidebarLinks = document.querySelectorAll('#sidebar a');
     var sidebarToggleButton = document.getElementById("sidebar-toggle");
@@ -449,8 +449,8 @@ function playground_text(playground, hidden = true) {
     var firstContact = null;
 
     function showSidebar() {
-        html.classList.remove('sidebar-hidden')
-        html.classList.add('sidebar-visible');
+        body.classList.remove('sidebar-hidden')
+        body.classList.add('sidebar-visible');
         Array.from(sidebarLinks).forEach(function (link) {
             link.setAttribute('tabIndex', 0);
         });
@@ -471,8 +471,8 @@ function playground_text(playground, hidden = true) {
     });
 
     function hideSidebar() {
-        html.classList.remove('sidebar-visible')
-        html.classList.add('sidebar-hidden');
+        body.classList.remove('sidebar-visible')
+        body.classList.add('sidebar-hidden');
         Array.from(sidebarLinks).forEach(function (link) {
             link.setAttribute('tabIndex', -1);
         });
@@ -483,14 +483,14 @@ function playground_text(playground, hidden = true) {
 
     // Toggle sidebar
     sidebarToggleButton.addEventListener('click', function sidebarToggle() {
-        if (html.classList.contains("sidebar-hidden")) {
+        if (body.classList.contains("sidebar-hidden")) {
             var current_width = parseInt(
                 document.documentElement.style.getPropertyValue('--sidebar-width'), 10);
             if (current_width < 150) {
                 document.documentElement.style.setProperty('--sidebar-width', '150px');
             }
             showSidebar();
-        } else if (html.classList.contains("sidebar-visible")) {
+        } else if (body.classList.contains("sidebar-visible")) {
             hideSidebar();
         } else {
             if (getComputedStyle(sidebar)['transform'] === 'none') {
@@ -506,14 +506,14 @@ function playground_text(playground, hidden = true) {
     function initResize(e) {
         window.addEventListener('mousemove', resize, false);
         window.addEventListener('mouseup', stopResize, false);
-        html.classList.add('sidebar-resizing');
+        body.classList.add('sidebar-resizing');
     }
     function resize(e) {
         var pos = (e.clientX - sidebar.offsetLeft);
         if (pos < 20) {
             hideSidebar();
         } else {
-            if (html.classList.contains("sidebar-hidden")) {
+            if (body.classList.contains("sidebar-hidden")) {
                 showSidebar();
             }
             pos = Math.min(pos, window.innerWidth - 100);
@@ -522,7 +522,7 @@ function playground_text(playground, hidden = true) {
     }
     //on mouseup remove windows functions mousemove & mouseup
     function stopResize(e) {
-        html.classList.remove('sidebar-resizing');
+        body.classList.remove('sidebar-resizing');
         window.removeEventListener('mousemove', resize, false);
         window.removeEventListener('mouseup', stopResize, false);
     }
@@ -551,33 +551,41 @@ function playground_text(playground, hidden = true) {
             firstContact = null;
         }
     }, { passive: true });
-
-    // Scroll sidebar to current active section
-    var activeSection = document.getElementById("sidebar").querySelector(".active");
-    if (activeSection) {
-        // https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollIntoView
-        activeSection.scrollIntoView({ block: 'center' });
-    }
 })();
 
 (function chapterNavigation() {
     document.addEventListener('keydown', function (e) {
         if (e.altKey || e.ctrlKey || e.metaKey || e.shiftKey) { return; }
         if (window.search && window.search.hasFocus()) { return; }
+        var html = document.querySelector('html');
 
+        function next() {
+            var nextButton = document.querySelector('.nav-chapters.next');
+            if (nextButton) {
+                window.location.href = nextButton.href;
+            }
+        }
+        function prev() {
+            var previousButton = document.querySelector('.nav-chapters.previous');
+            if (previousButton) {
+                window.location.href = previousButton.href;
+            }
+        }
         switch (e.key) {
             case 'ArrowRight':
                 e.preventDefault();
-                var nextButton = document.querySelector('.nav-chapters.next');
-                if (nextButton) {
-                    window.location.href = nextButton.href;
+                if (html.dir == 'rtl') {
+                    prev();
+                } else {
+                    next();
                 }
                 break;
             case 'ArrowLeft':
                 e.preventDefault();
-                var previousButton = document.querySelector('.nav-chapters.previous');
-                if (previousButton) {
-                    window.location.href = previousButton.href;
+                if (html.dir == 'rtl') {
+                    next();
+                } else {
+                    prev();
                 }
                 break;
         }
@@ -676,13 +684,14 @@ function playground_text(playground, hidden = true) {
         }, { passive: true });
     })();
     (function controllBorder() {
-        menu.classList.remove('bordered');
-        document.addEventListener('scroll', function () {
+        function updateBorder() {
             if (menu.offsetTop === 0) {
                 menu.classList.remove('bordered');
             } else {
                 menu.classList.add('bordered');
             }
-        }, { passive: true });
+        }
+        updateBorder();
+        document.addEventListener('scroll', updateBorder, { passive: true });
     })();
 })();

src/theme/css/chrome.css

@@ -1,7 +1,5 @@
 /* CSS for UI elements (a.k.a. chrome) */
 
-@import 'variables.css';
-
 html {
     scrollbar-color: var(--scrollbar) var(--bg);
 }
@@ -37,9 +35,9 @@ a > .hljs {
     display: flex;
     flex-wrap: wrap;
     background-color: var(--bg);
-    border-bottom-color: var(--bg);
-    border-bottom-width: 1px;
-    border-bottom-style: solid;
+    border-block-end-color: var(--bg);
+    border-block-end-width: 1px;
+    border-block-end-style: solid;
 }
 #menu-bar.sticky,
 .js #menu-bar-hover-placeholder:hover + #menu-bar,
@@ -56,7 +54,7 @@ a > .hljs {
     height: var(--menu-bar-height);
 }
 #menu-bar.bordered {
-    border-bottom-color: var(--table-border-color);
+    border-block-end-color: var(--table-border-color);
 }
 #menu-bar i, #menu-bar .icon-button {
     position: relative;
@@ -93,7 +91,7 @@ a > .hljs {
     display: flex;
     margin: 0 5px;
 }
-.no-js .left-buttons {
+.no-js .left-buttons button {
     display: none;
 }
 
@@ -160,7 +158,7 @@ a > .hljs {
 }
 
 .nav-wrapper {
-    margin-top: 50px;
+    margin-block-start: 50px;
     display: none;
 }
 
@@ -173,23 +171,34 @@ a > .hljs {
     background-color: var(--sidebar-bg);
 }
 
-.previous {
-    float: left;
-}
+/* Only Firefox supports flow-relative values */
+.previous { float: left; }
+[dir=rtl] .previous { float: right; }
 
+/* Only Firefox supports flow-relative values */
 .next {
     float: right;
     right: var(--page-padding);
 }
+[dir=rtl] .next {
+    float: left;
+    right: unset;
+    left: var(--page-padding);
+}
+
+/* Use the correct buttons for RTL layouts*/
+[dir=rtl] .previous i.fa-angle-left:before {content:"\f105";}
+[dir=rtl] .next i.fa-angle-right:before { content:"\f104"; }
 
 @media only screen and (max-width: 1080px) {
     .nav-wide-wrapper { display: none; }
     .nav-wrapper { display: block; }
 }
 
+/* sidebar-visible */
 @media only screen and (max-width: 1380px) {
-    .sidebar-visible .nav-wide-wrapper { display: none; }
-    .sidebar-visible .nav-wrapper { display: block; }
+    #sidebar-toggle-anchor:checked ~ .page-wrapper .nav-wide-wrapper { display: none; }
+    #sidebar-toggle-anchor:checked ~ .page-wrapper .nav-wrapper { display: block; }
 }
 
 /* Inline code */
@@ -236,7 +245,7 @@ pre > .buttons :hover {
     background-color: var(--theme-hover);
 }
 pre > .buttons i {
-    margin-left: 8px;
+    margin-inline-start: 8px;
 }
 pre > .buttons button {
     cursor: inherit;
@@ -258,8 +267,14 @@ pre > .buttons button {
         /* On mobile, make it easier to tap buttons. */
         padding: 0.3rem 1rem;
     }
+
+    .sidebar-resize-indicator {
+        /* Hide resize indicator on devices with limited accuracy */
+        display: none;
+    }
 }
 pre > code {
+    display: block;
     padding: 1rem;
 }
 
@@ -273,7 +288,7 @@ pre > code {
 }
 
 pre > .result {
-    margin-top: 10px;
+    margin-block-start: 10px;
 }
 
 /* Search */
@@ -284,8 +299,14 @@ pre > .result {
 
 mark {
     border-radius: 2px;
-    padding: 0 3px 1px 3px;
-    margin: 0 -3px -1px -3px;
+    padding-block-start: 0;
+    padding-block-end: 1px;
+    padding-inline-start: 3px;
+    padding-inline-end: 3px;
+    margin-block-start: 0;
+    margin-block-end: -1px;
+    margin-inline-start: -3px;
+    margin-inline-end: -3px;
     background-color: var(--search-mark-bg);
     transition: background-color 300ms linear;
     cursor: pointer;
@@ -297,14 +318,17 @@ mark.fade-out {
 }
 
 .searchbar-outer {
-    margin-left: auto;
-    margin-right: auto;
+    margin-inline-start: auto;
+    margin-inline-end: auto;
     max-width: var(--content-max-width);
 }
 
 #searchbar {
     width: 100%;
-    margin: 5px auto 0px auto;
+    margin-block-start: 5px;
+    margin-block-end: 0;
+    margin-inline-start: auto;
+    margin-inline-end: auto;
     padding: 10px 16px;
     transition: box-shadow 300ms ease-in-out;
     border: 1px solid var(--searchbar-border-color);
@@ -320,20 +344,23 @@ mark.fade-out {
 .searchresults-header {
     font-weight: bold;
     font-size: 1em;
-    padding: 18px 0 0 5px;
+    padding-block-start: 18px;
+    padding-block-end: 0;
+    padding-inline-start: 5px;
+    padding-inline-end: 0;
     color: var(--searchresults-header-fg);
 }
 
 .searchresults-outer {
-    margin-left: auto;
-    margin-right: auto;
+    margin-inline-start: auto;
+    margin-inline-end: auto;
     max-width: var(--content-max-width);
-    border-bottom: 1px dashed var(--searchresults-border-color);
+    border-block-end: 1px dashed var(--searchresults-border-color);
 }
 
 ul#searchresults {
     list-style: none;
-    padding-left: 20px;
+    padding-inline-start: 20px;
 }
 ul#searchresults li {
     margin: 10px 0px;
@@ -346,7 +373,10 @@ ul#searchresults li.focus {
 ul#searchresults span.teaser {
     display: block;
     clear: both;
-    margin: 5px 0 0 20px;
+    margin-block-start: 5px;
+    margin-block-end: 0;
+    margin-inline-start: 20px;
+    margin-inline-end: 0;
     font-size: 0.8em;
 }
 ul#searchresults span.teaser em {
@@ -369,12 +399,14 @@ ul#searchresults span.teaser em {
     background-color: var(--sidebar-bg);
     color: var(--sidebar-fg);
 }
+[dir=rtl] .sidebar { left: unset; right: 0; }
 .sidebar-resizing {
     -moz-user-select: none;
     -webkit-user-select: none;
     -ms-user-select: none;
     user-select: none;
 }
+.no-js .sidebar,
 .js:not(.sidebar-resizing) .sidebar {
     transition: transform 0.3s; /* Animation: slide away */
 }
@@ -394,16 +426,35 @@ ul#searchresults span.teaser em {
     position: absolute;
     cursor: col-resize;
     width: 0;
-    right: 0;
+    right: calc(var(--sidebar-resize-indicator-width) * -1);
     top: 0;
     bottom: 0;
+    display: flex;
+    align-items: center;
+}
+
+.sidebar-resize-handle .sidebar-resize-indicator {
+    width: 100%;
+    height: 12px;
+    background-color: var(--icons);
+    margin-inline-start: var(--sidebar-resize-indicator-space);
+}
+
+[dir=rtl] .sidebar .sidebar-resize-handle {
+    left: calc(var(--sidebar-resize-indicator-width) * -1);
+    right: unset;
 }
 .js .sidebar .sidebar-resize-handle {
     cursor: col-resize;
-    width: 5px;
+    width: calc(var(--sidebar-resize-indicator-width) - var(--sidebar-resize-indicator-space));
 }
-.sidebar-hidden .sidebar {
-    transform: translateX(calc(0px - var(--sidebar-width)));
+/* sidebar-hidden */
+#sidebar-toggle-anchor:not(:checked) ~ .sidebar {
+    transform: translateX(calc(0px - var(--sidebar-width) - var(--sidebar-resize-indicator-width)));
+    z-index: -1;
+}
+[dir=rtl] #sidebar-toggle-anchor:not(:checked) ~ .sidebar {
+    transform: translateX(calc(var(--sidebar-width) + var(--sidebar-resize-indicator-width)));
 }
 .sidebar::-webkit-scrollbar {
     background: var(--sidebar-bg);
@@ -412,19 +463,26 @@ ul#searchresults span.teaser em {
     background: var(--scrollbar);
 }
 
-.sidebar-visible .page-wrapper {
-    transform: translateX(var(--sidebar-width));
+/* sidebar-visible */
+#sidebar-toggle-anchor:checked ~ .page-wrapper {
+    transform: translateX(calc(var(--sidebar-width) + var(--sidebar-resize-indicator-width)));
+}
+[dir=rtl] #sidebar-toggle-anchor:checked ~ .page-wrapper {
+    transform: translateX(calc(0px - var(--sidebar-width) - var(--sidebar-resize-indicator-width)));
 }
 @media only screen and (min-width: 620px) {
-    .sidebar-visible .page-wrapper {
+    #sidebar-toggle-anchor:checked ~ .page-wrapper {
+        transform: none;
+        margin-inline-start: calc(var(--sidebar-width) + var(--sidebar-resize-indicator-width));
+    }
+    [dir=rtl] #sidebar-toggle-anchor:checked ~ .page-wrapper {
         transform: none;
-        margin-left: var(--sidebar-width);
     }
 }
 
 .chapter {
     list-style: none outside none;
-    padding-left: 0;
+    padding-inline-start: 0;
     line-height: 2.2em;
 }
 
@@ -454,7 +512,7 @@ ul#searchresults span.teaser em {
 .chapter li > a.toggle {
     cursor: pointer;
     display: block;
-    margin-left: auto;
+    margin-inline-start: auto;
     padding: 0 10px;
     user-select: none;
     opacity: 0.68;
@@ -471,7 +529,7 @@ ul#searchresults span.teaser em {
 
 .chapter li.chapter-item {
     line-height: 1.5em;
-    margin-top: 0.6em;
+    margin-block-start: 0.6em;
 }
 
 .chapter li.expanded > a.toggle div {
@@ -494,7 +552,7 @@ ul#searchresults span.teaser em {
 
 .section {
     list-style: none outside none;
-    padding-left: 20px;
+    padding-inline-start: 20px;
     line-height: 1.9em;
 }
 
@@ -517,6 +575,7 @@ ul#searchresults span.teaser em {
     /* Don't let the children's background extend past the rounded corners. */
     overflow: hidden;
 }
+[dir=rtl] .theme-popup { left: unset;  right: 10px; }
 .theme-popup .default {
     color: var(--icons);
 }
@@ -527,7 +586,7 @@ ul#searchresults span.teaser em {
     padding: 2px 20px;
     line-height: 25px;
     white-space: nowrap;
-    text-align: left;
+    text-align: start;
     cursor: pointer;
     color: inherit;
     background: inherit;
@@ -540,6 +599,6 @@ ul#searchresults span.teaser em {
 .theme-selected::before {
     display: inline-block;
     content: "✓";
-    margin-left: -14px;
+    margin-inline-start: -14px;
     width: 14px;
 }

src/theme/css/general.css

@@ -1,10 +1,9 @@
 /* Base styles and content styles */
 
-@import 'variables.css';
-
 :root {
     /* Browser default font-size is 16px, this way 1 rem = 10px */
     font-size: 62.5%;
+    color-scheme: var(--color-scheme);
 }
 
 html {
@@ -24,6 +23,7 @@ body {
 code {
     font-family: var(--mono-font) !important;
     font-size: var(--code-font-size);
+    direction: ltr !important;
 }
 
 /* make long words/inline code not x overflow */
@@ -47,13 +47,13 @@ h1 code, h2 code, h3 code, h4 code, h5 code, h6 code {
 .hide-boring .boring { display: none; }
 .hidden { display: none !important; }
 
-h2, h3 { margin-top: 2.5em; }
-h4, h5 { margin-top: 2em; }
+h2, h3 { margin-block-start: 2.5em; }
+h4, h5 { margin-block-start: 2em; }
 
 .header + .header h3,
 .header + .header h4,
 .header + .header h5 {
-    margin-top: 1em;
+    margin-block-start: 1em;
 }
 
 h1:target::before,
@@ -64,7 +64,7 @@ h5:target::before,
 h6:target::before {
     display: inline-block;
     content: "»";
-    margin-left: -30px;
+    margin-inline-start: -30px;
     width: 30px;
 }
 
@@ -73,28 +73,34 @@ h6:target::before {
    https://bugs.webkit.org/show_bug.cgi?id=218076
 */
 :target {
+    /* Safari does not support logical properties */
     scroll-margin-top: calc(var(--menu-bar-height) + 0.5em);
 }
 
 .page {
     outline: 0;
     padding: 0 var(--page-padding);
-    margin-top: calc(0px - var(--menu-bar-height)); /* Compensate for the #menu-bar-hover-placeholder */
+    margin-block-start: calc(0px - var(--menu-bar-height)); /* Compensate for the #menu-bar-hover-placeholder */
 }
 .page-wrapper {
     box-sizing: border-box;
+    background-color: var(--bg);
 }
+.no-js .page-wrapper,
 .js:not(.sidebar-resizing) .page-wrapper {
     transition: margin-left 0.3s ease, transform 0.3s ease; /* Animation: slide away */
 }
+[dir=rtl] .js:not(.sidebar-resizing) .page-wrapper {
+    transition: margin-right 0.3s ease, transform 0.3s ease; /* Animation: slide away */
+}
 
 .content {
     overflow-y: auto;
     padding: 0 5px 50px 5px;
 }
 .content main {
-    margin-left: auto;
-    margin-right: auto;
+    margin-inline-start: auto;
+    margin-inline-end: auto;
     max-width: var(--content-max-width);
 }
 .content p { line-height: 1.45em; }
@@ -144,8 +150,31 @@ blockquote {
     padding: 0 20px;
     color: var(--fg);
     background-color: var(--quote-bg);
-    border-top: .1em solid var(--quote-border);
-    border-bottom: .1em solid var(--quote-border);
+    border-block-start: .1em solid var(--quote-border);
+    border-block-end: .1em solid var(--quote-border);
+}
+
+.warning {
+    margin: 20px;
+    padding: 0 20px;
+    border-inline-start: 2px solid var(--warning-border);
+}
+
+.warning:before {
+    position: absolute;
+    width: 3rem;
+    height: 3rem;
+    margin-inline-start: calc(-1.5rem - 21px);
+    content: "ⓘ";
+    text-align: center;
+    background-color: var(--bg);
+    color: var(--warning-border);
+    font-weight: bold;
+    font-size: 2rem;
+}
+
+blockquote .warning:before {
+    background-color: var(--quote-bg);
 }
 
 kbd {
@@ -163,7 +192,7 @@ kbd {
 
 :not(.footnote-definition) + .footnote-definition,
 .footnote-definition + :not(.footnote-definition) {
-    margin-top: 2em;
+    margin-block-start: 2em;
 }
 .footnote-definition {
     font-size: 0.9em;

src/theme/css/print.css

@@ -7,8 +7,8 @@
 }
 
 #page-wrapper.page-wrapper {
-    transform: none;
-    margin-left: 0px;
+    transform: none !important;
+    margin-inline-start: 0px;
     overflow-y: initial;
 }
 
@@ -23,11 +23,7 @@
 }
 
 code {
-    background-color: #666666;
-    border-radius: 5px;
-
-    /* Force background to be printed in Chrome */
-    -webkit-print-color-adjust: exact;
+    direction: ltr !important;
 }
 
 pre > .buttons {

src/theme/css/variables.css

@@ -3,6 +3,8 @@
 
 :root {
     --sidebar-width: 300px;
+    --sidebar-resize-indicator-width: 8px;
+    --sidebar-resize-indicator-space: 2px;
     --page-padding: 15px;
     --content-max-width: 750px;
     --menu-bar-height: 50px;
@@ -38,6 +40,8 @@
     --quote-bg: hsl(226, 15%, 17%);
     --quote-border: hsl(226, 15%, 22%);
 
+    --warning-border: #ff8e00;
+
     --table-border-color: hsl(210, 25%, 13%);
     --table-header-bg: hsl(210, 25%, 28%);
     --table-alternate-bg: hsl(210, 25%, 11%);
@@ -50,6 +54,8 @@
     --searchresults-border-color: #888;
     --searchresults-li-bg: #252932;
     --search-mark-bg: #e3b171;
+
+    --color-scheme: dark;
 }
 
 .coal {
@@ -78,6 +84,8 @@
     --quote-bg: hsl(234, 21%, 18%);
     --quote-border: hsl(234, 21%, 23%);
 
+    --warning-border: #ff8e00;
+
     --table-border-color: hsl(200, 7%, 13%);
     --table-header-bg: hsl(200, 7%, 28%);
     --table-alternate-bg: hsl(200, 7%, 11%);
@@ -90,6 +98,8 @@
     --searchresults-border-color: #98a3ad;
     --searchresults-li-bg: #2b2b2f;
     --search-mark-bg: #355c7d;
+
+    --color-scheme: dark;
 }
 
 .light {
@@ -118,6 +128,8 @@
     --quote-bg: hsl(197, 37%, 96%);
     --quote-border: hsl(197, 37%, 91%);
 
+    --warning-border: #ff8e00;
+
     --table-border-color: hsl(0, 0%, 95%);
     --table-header-bg: hsl(0, 0%, 80%);
     --table-alternate-bg: hsl(0, 0%, 97%);
@@ -130,6 +142,8 @@
     --searchresults-border-color: #888;
     --searchresults-li-bg: #e4f2fe;
     --search-mark-bg: #a2cff5;
+
+    --color-scheme: light;
 }
 
 .navy {
@@ -158,6 +172,8 @@
     --quote-bg: hsl(226, 15%, 17%);
     --quote-border: hsl(226, 15%, 22%);
 
+    --warning-border: #ff8e00;
+
     --table-border-color: hsl(226, 23%, 16%);
     --table-header-bg: hsl(226, 23%, 31%);
     --table-alternate-bg: hsl(226, 23%, 14%);
@@ -170,6 +186,8 @@
     --searchresults-border-color: #5c5c68;
     --searchresults-li-bg: #242430;
     --search-mark-bg: #a2cff5;
+
+    --color-scheme: dark;
 }
 
 .rust {
@@ -198,6 +216,8 @@
     --quote-bg: hsl(60, 5%, 75%);
     --quote-border: hsl(60, 5%, 70%);
 
+    --warning-border: #ff8e00;
+
     --table-border-color: hsl(60, 9%, 82%);
     --table-header-bg: #b3a497;
     --table-alternate-bg: hsl(60, 9%, 84%);
@@ -210,6 +230,8 @@
     --searchresults-border-color: #888;
     --searchresults-li-bg: #dec2a2;
     --search-mark-bg: #e69f67;
+
+    --color-scheme: light;
 }
 
 @media (prefers-color-scheme: dark) {
@@ -239,6 +261,8 @@
         --quote-bg: hsl(234, 21%, 18%);
         --quote-border: hsl(234, 21%, 23%);
 
+        --warning-border: #ff8e00;
+
         --table-border-color: hsl(200, 7%, 13%);
         --table-header-bg: hsl(200, 7%, 28%);
         --table-alternate-bg: hsl(200, 7%, 11%);

src/theme/index.hbs

@@ -1,11 +1,11 @@
 <!DOCTYPE HTML>
-<html lang="{{ language }}" class="sidebar-visible no-js {{ default_theme }}">
+<html lang="{{ language }}" class="{{ default_theme }}" dir="{{ text_direction }}">
     <head>
         <!-- Book generated using mdBook -->
         <meta charset="UTF-8">
         <title>{{ title }}</title>
         {{#if is_print }}
-        <meta name="robots" content="noindex" />
+        <meta name="robots" content="noindex">
         {{/if}}
         {{#if base_url}}
         <base href="{{ base_url }}">
@@ -17,7 +17,7 @@
 
         <meta name="description" content="{{ description }}">
         <meta name="viewport" content="width=device-width, initial-scale=1">
-        <meta name="theme-color" content="#ffffff" />
+        <meta name="theme-color" content="#ffffff">
 
         {{#if favicon_svg}}
         <link rel="icon" href="{{ path_to_root }}favicon.svg">
@@ -53,7 +53,7 @@
         <script async src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
         {{/if}}
     </head>
-    <body>
+    <body class="sidebar-visible no-js">
     <div id="body-container">
         <!-- Provide site root to javascript -->
         <script>
@@ -83,43 +83,72 @@
             try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
             if (theme === null || theme === undefined) { theme = default_theme; }
             var html = document.querySelector('html');
-            html.classList.remove('no-js')
             html.classList.remove('{{ default_theme }}')
             html.classList.add(theme);
-            html.classList.add('js');
+            var body = document.querySelector('body');
+            body.classList.remove('no-js')
+            body.classList.add('js');
         </script>
 
+        <input type="checkbox" id="sidebar-toggle-anchor" class="hidden">
+
         <!-- Hide / unhide sidebar before it is displayed -->
         <script>
-            var html = document.querySelector('html');
+            var body = document.querySelector('body');
             var sidebar = null;
+            var sidebar_toggle = document.getElementById("sidebar-toggle-anchor");
             if (document.body.clientWidth >= 1080) {
                 try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
                 sidebar = sidebar || 'visible';
             } else {
                 sidebar = 'hidden';
             }
-            html.classList.remove('sidebar-visible');
-            html.classList.add("sidebar-" + sidebar);
+            sidebar_toggle.checked = sidebar === 'visible';
+            body.classList.remove('sidebar-visible');
+            body.classList.add("sidebar-" + sidebar);
         </script>
 
         <nav id="sidebar" class="sidebar" aria-label="Table of contents">
             <div class="sidebar-scrollbox">
                 {{#toc}}{{/toc}}
             </div>
-            <div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
+            <div id="sidebar-resize-handle" class="sidebar-resize-handle">
+                <div class="sidebar-resize-indicator"></div>
+            </div>
         </nav>
 
+        <!-- Track and set sidebar scroll position -->
+        <script>
+            var sidebarScrollbox = document.querySelector('#sidebar .sidebar-scrollbox');
+            sidebarScrollbox.addEventListener('click', function(e) {
+                if (e.target.tagName === 'A') {
+                    sessionStorage.setItem('sidebar-scroll', sidebarScrollbox.scrollTop);
+                }
+            }, { passive: true });
+            var sidebarScrollTop = sessionStorage.getItem('sidebar-scroll');
+            sessionStorage.removeItem('sidebar-scroll');
+            if (sidebarScrollTop) {
+                // preserve sidebar scroll position when navigating via links within sidebar
+                sidebarScrollbox.scrollTop = sidebarScrollTop;
+            } else {
+                // scroll sidebar to current active section when navigating via "next/previous chapter" buttons
+                var activeSection = document.querySelector('#sidebar .active');
+                if (activeSection) {
+                    activeSection.scrollIntoView({ block: 'center' });
+                }
+            }
+        </script>
+
         <div id="page-wrapper" class="page-wrapper">
 
             <div class="page">
                 {{> header}}
                 <div id="menu-bar-hover-placeholder"></div>
-                <div id="menu-bar" class="menu-bar sticky bordered">
+                <div id="menu-bar" class="menu-bar sticky">
                     <div class="left-buttons">
-                        <button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
+                        <label id="sidebar-toggle" class="icon-button" for="sidebar-toggle-anchor" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
                             <i class="fa fa-bars"></i>
-                        </button>
+                        </label>
                         <button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
                             <i class="fa fa-paint-brush"></i>
                         </button>
@@ -195,7 +224,7 @@
                         {{/previous}}
 
                         {{#next}}
-                            <a rel="next" href="{{ path_to_root }}{{link}}" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
+                            <a rel="next prefetch" href="{{ path_to_root }}{{link}}" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
                                 <i class="fa fa-angle-right"></i>
                             </a>
                         {{/next}}
@@ -213,7 +242,7 @@
                 {{/previous}}
 
                 {{#next}}
-                    <a rel="next" href="{{ path_to_root }}{{link}}" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
+                    <a rel="next prefetch" href="{{ path_to_root }}{{link}}" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
                         <i class="fa fa-angle-right"></i>
                     </a>
                 {{/next}}

src/theme/mod.rs

@@ -212,7 +212,6 @@ fn load_file_contents<P: AsRef<Path>>(filename: P, dest: &mut Vec<u8>) -> Result
 mod tests {
     use super::*;
     use std::fs;
-    use std::path::PathBuf;
     use tempfile::Builder as TempFileBuilder;
 
     #[test]

src/theme/searcher/searcher.js

@@ -316,7 +316,7 @@ window.search = window.search || {};
     
     // Eventhandler for keyevents on `document`
     function globalKeyHandler(e) {
-        if (e.altKey || e.ctrlKey || e.metaKey || e.shiftKey || e.target.type === 'textarea' || e.target.type === 'text') { return; }
+        if (e.altKey || e.ctrlKey || e.metaKey || e.shiftKey || e.target.type === 'textarea' || e.target.type === 'text' || !hasFocus() && /^(?:input|select|textarea)$/i.test(e.target.nodeName)) { return; }
 
         if (e.keyCode === ESCAPE_KEYCODE) {
             e.preventDefault();

src/utils/fs.rs

@@ -1,6 +1,5 @@
 use crate::errors::*;
 use log::{debug, trace};
-use std::convert::Into;
 use std::fs::{self, File};
 use std::io::Write;
 use std::path::{Component, Path, PathBuf};
@@ -73,14 +72,12 @@ pub fn create_file(path: &Path) -> Result<File> {
 
 /// Removes all the content of a directory but not the directory itself
 pub fn remove_dir_content(dir: &Path) -> Result<()> {
-    for item in fs::read_dir(dir)? {
-        if let Ok(item) = item {
-            let item = item.path();
-            if item.is_dir() {
-                fs::remove_dir_all(item)?;
-            } else {
-                fs::remove_file(item)?;
-            }
+    for item in fs::read_dir(dir)?.flatten() {
+        let item = item.path();
+        if item.is_dir() {
+            fs::remove_dir_all(item)?;
+        } else {
+            fs::remove_file(item)?;
         }
     }
     Ok(())
@@ -109,77 +106,102 @@ pub fn copy_files_except_ext(
     }
 
     for entry in fs::read_dir(from)? {
-        let entry = entry?;
+        let entry = entry?.path();
         let metadata = entry
-            .path()
             .metadata()
-            .with_context(|| format!("Failed to read {:?}", entry.path()))?;
+            .with_context(|| format!("Failed to read {entry:?}"))?;
+
+        let entry_file_name = entry.file_name().unwrap();
+        let target_file_path = to.join(entry_file_name);
 
         // If the entry is a dir and the recursive option is enabled, call itself
         if metadata.is_dir() && recursive {
-            if entry.path() == to.to_path_buf() {
+            if entry == to.as_os_str() {
                 continue;
             }
 
             if let Some(avoid) = avoid_dir {
-                if entry.path() == *avoid {
+                if entry == *avoid {
                     continue;
                 }
             }
 
             // check if output dir already exists
-            if !to.join(entry.file_name()).exists() {
-                fs::create_dir(&to.join(entry.file_name()))?;
+            if !target_file_path.exists() {
+                fs::create_dir(&target_file_path)?;
             }
 
-            copy_files_except_ext(
-                &from.join(entry.file_name()),
-                &to.join(entry.file_name()),
-                true,
-                avoid_dir,
-                ext_blacklist,
-            )?;
+            copy_files_except_ext(&entry, &target_file_path, true, avoid_dir, ext_blacklist)?;
         } else if metadata.is_file() {
             // Check if it is in the blacklist
-            if let Some(ext) = entry.path().extension() {
+            if let Some(ext) = entry.extension() {
                 if ext_blacklist.contains(&ext.to_str().unwrap()) {
                     continue;
                 }
             }
-            debug!(
-                "creating path for file: {:?}",
-                &to.join(
-                    entry
-                        .path()
-                        .file_name()
-                        .expect("a file should have a file name...")
-                )
-            );
-
-            debug!(
-                "Copying {:?} to {:?}",
-                entry.path(),
-                &to.join(
-                    entry
-                        .path()
-                        .file_name()
-                        .expect("a file should have a file name...")
-                )
-            );
-            fs::copy(
-                entry.path(),
-                &to.join(
-                    entry
-                        .path()
-                        .file_name()
-                        .expect("a file should have a file name..."),
-                ),
-            )?;
+            debug!("Copying {entry:?} to {target_file_path:?}");
+            copy(&entry, &target_file_path)?;
         }
     }
     Ok(())
 }
 
+/// Copies a file.
+fn copy<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> Result<()> {
+    let from = from.as_ref();
+    let to = to.as_ref();
+    return copy_inner(from, to)
+        .with_context(|| format!("failed to copy `{}` to `{}`", from.display(), to.display()));
+
+    // This is a workaround for an issue with the macOS file watcher.
+    // Rust's `std::fs::copy` function uses `fclonefileat`, which creates
+    // clones on APFS. Unfortunately fs events seem to trigger on both
+    // sides of the clone, and there doesn't seem to be a way to differentiate
+    // which side it is.
+    // https://github.com/notify-rs/notify/issues/465#issuecomment-1657261035
+    // contains more information.
+    //
+    // This is essentially a copy of the simple copy code path in Rust's
+    // standard library.
+    #[cfg(target_os = "macos")]
+    fn copy_inner(from: &Path, to: &Path) -> Result<()> {
+        use std::fs::OpenOptions;
+        use std::os::unix::fs::{OpenOptionsExt, PermissionsExt};
+
+        let mut reader = File::open(from)?;
+        let metadata = reader.metadata()?;
+        if !metadata.is_file() {
+            anyhow::bail!(
+                "expected a file, `{}` appears to be {:?}",
+                from.display(),
+                metadata.file_type()
+            );
+        }
+        let perm = metadata.permissions();
+        let mut writer = OpenOptions::new()
+            .mode(perm.mode())
+            .write(true)
+            .create(true)
+            .truncate(true)
+            .open(to)?;
+        let writer_metadata = writer.metadata()?;
+        if writer_metadata.is_file() {
+            // Set the correct file permissions, in case the file already existed.
+            // Don't set the permissions on already existing non-files like
+            // pipes/FIFOs or device nodes.
+            writer.set_permissions(perm)?;
+        }
+        std::io::copy(&mut reader, &mut writer)?;
+        Ok(())
+    }
+
+    #[cfg(not(target_os = "macos"))]
+    fn copy_inner(from: &Path, to: &Path) -> Result<()> {
+        fs::copy(from, to)?;
+        Ok(())
+    }
+}
+
 pub fn get_404_output_file(input_404: &Option<String>) -> String {
     input_404
         .as_ref()

src/utils/mod.rs

@@ -6,7 +6,7 @@ pub(crate) mod toml_ext;
 use crate::errors::Error;
 use log::error;
 use once_cell::sync::Lazy;
-use pulldown_cmark::{html, CodeBlockKind, CowStr, Event, Options, Parser, Tag};
+use pulldown_cmark::{html, CodeBlockKind, CowStr, Event, Options, Parser, Tag, TagEnd};
 use regex::Regex;
 
 use std::borrow::Cow;
@@ -161,37 +161,59 @@ fn adjust_links<'a>(event: Event<'a>, path: Option<&Path>) -> Event<'a> {
     }
 
     match event {
-        Event::Start(Tag::Link(link_type, dest, title)) => {
-            Event::Start(Tag::Link(link_type, fix(dest, path), title))
-        }
-        Event::Start(Tag::Image(link_type, dest, title)) => {
-            Event::Start(Tag::Image(link_type, fix(dest, path), title))
-        }
+        Event::Start(Tag::Link {
+            link_type,
+            dest_url,
+            title,
+            id,
+        }) => Event::Start(Tag::Link {
+            link_type,
+            dest_url: fix(dest_url, path),
+            title,
+            id,
+        }),
+        Event::Start(Tag::Image {
+            link_type,
+            dest_url,
+            title,
+            id,
+        }) => Event::Start(Tag::Image {
+            link_type,
+            dest_url: fix(dest_url, path),
+            title,
+            id,
+        }),
         Event::Html(html) => Event::Html(fix_html(html, path)),
+        Event::InlineHtml(html) => Event::InlineHtml(fix_html(html, path)),
         _ => 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_path(text, curly_quotes, None)
+pub fn render_markdown(text: &str, smart_punctuation: bool) -> String {
+    render_markdown_with_path(text, smart_punctuation, None)
 }
 
-pub fn new_cmark_parser(text: &str, curly_quotes: bool) -> Parser<'_, '_> {
+pub fn new_cmark_parser(text: &str, smart_punctuation: bool) -> Parser<'_> {
     let mut opts = Options::empty();
     opts.insert(Options::ENABLE_TABLES);
     opts.insert(Options::ENABLE_FOOTNOTES);
     opts.insert(Options::ENABLE_STRIKETHROUGH);
     opts.insert(Options::ENABLE_TASKLISTS);
-    if curly_quotes {
+    opts.insert(Options::ENABLE_HEADING_ATTRIBUTES);
+    if smart_punctuation {
         opts.insert(Options::ENABLE_SMART_PUNCTUATION);
     }
     Parser::new_ext(text, opts)
 }
 
-pub fn render_markdown_with_path(text: &str, curly_quotes: bool, path: Option<&Path>) -> String {
+pub fn render_markdown_with_path(
+    text: &str,
+    smart_punctuation: bool,
+    path: Option<&Path>,
+) -> String {
     let mut s = String::with_capacity(text.len() * 3 / 2);
-    let p = new_cmark_parser(text, curly_quotes);
+    let p = new_cmark_parser(text, smart_punctuation);
     let events = p
         .map(clean_codeblock_headers)
         .map(|event| adjust_links(event, path))
@@ -211,7 +233,7 @@ fn wrap_tables(event: Event<'_>) -> (Option<Event<'_>>, Option<Event<'_>>) {
             Some(Event::Html(r#"<div class="table-wrapper">"#.into())),
             Some(event),
         ),
-        Event::End(Tag::Table(_)) => (Some(event), Some(Event::Html(r#"</div>"#.into()))),
+        Event::End(TagEnd::Table) => (Some(event), Some(Event::Html(r#"</div>"#.into()))),
         _ => (Some(event), None),
     }
 }

test_book/src/SUMMARY.md

@@ -22,6 +22,7 @@
   - [Tables](individual/table.md)
   - [Tasks](individual/task.md)
   - [Strikethrough](individual/strikethrough.md)
+  - [MathJax](individual/mathjax.md)
   - [Mixed](individual/mixed.md)
 - [Languages](languages/README.md)
   - [Syntax Highlight](languages/highlight.md)

test_book/src/individual/code.md

@@ -10,7 +10,9 @@ This is a codeblock
 
 ---
 
-This line contains `inline code`
+This line contains `inline code` mixed with some other stuff. (LTR)
+
+ושורה זו מכילה `inline code` אבל עם טקסט בשפה שנכתבת מימין לשמאל. (RTL)
 
 ---
 

test_book/src/individual/heading.md

@@ -13,3 +13,9 @@
 ##### Really Small Heading
 
 ###### Is it even a heading anymore - heading
+
+## Custom id {#example-id}
+
+## Custom class {.class1 .class2}
+
+## Both id and class {#example-id2 .class1 .class2}

test_book/src/individual/mathjax.md

@@ -0,0 +1,42 @@
+# MathJax
+
+Fourier Transform
+
+\\[
+\begin{aligned}
+f(x) &= \int_{-\infty}^{\infty}F(s)(-1)^{ 2xs}ds \\\\
+F(s) &= \int_{-\infty}^{\infty}f(x)(-1)^{-2xs}dx
+\end{aligned}
+\\]
+
+The kernel can also be written as \\(e^{2i\pi xs}\\) which is more frequently used in literature.
+
+> Proof that \\(e^{ix} = \cos x + i\sin x\\) a.k.a Euler's Formula:
+>
+> \\(
+\begin{aligned}
+  e^x &= \sum_{n=0}^\infty \frac{x^n}{n!} \implies e^{ix} = \sum_{n=0}^\infty \frac{(ix)^n}{n!} \\\\
+  \cos x &= \sum_{m=0}^\infty \frac{(-1)^m x^{2m}}{(2m)!} = \sum_{m=0}^\infty \frac{(ix)^{2m}}{(2m)!} \\\\
+  \sin x &= \sum_{s=0}^\infty \frac{(-1)^s x^{2s+1}}{(2s+1)!} = \sum_{s=0}^\infty \frac{(ix)^{2s+1}}{i(2s+1)!} \\\\
+  \cos x + i\sin x &= \sum_{l=0}^\infty \frac{(ix)^{2l}}{(2l)!} + \sum_{s=0}^\infty \frac{(ix)^{2s+1}}{(2s+1)!} = \sum_{n=0}^\infty \frac{(ix)^{n}}{n!} \\\\
+         &= e^{ix}
+\end{aligned}
+\\)
+>
+
+
+Pauli Matrices
+
+\\[
+\begin{aligned}
+  \sigma_x &= \begin{pmatrix}
+  1 & 0 \\\\ 0 & 1
+  \end{pmatrix} \\\\
+  \sigma_y &= \begin{pmatrix}
+  0 & -i \\\\ i & 0
+  \end{pmatrix} \\\\
+  \sigma_z &= \begin{pmatrix}
+  1 & 0 \\\\ 0 & -1
+  \end{pmatrix}
+\end{aligned}
+\\]

test_book/src/individual/strikethrough.md

@@ -1,5 +1,7 @@
 # Strikethrough
 
+~Single strike~
+
 ~~This is Striked~~
 
 ~~This is **strong**, _italic_ , **_both_** and striked~~

test_book/src/languages/README.md

@@ -27,6 +27,8 @@ This Currently contains following languages
 - makefile
 - markdown
 - nginx
+- nim
+- nix
 - objectivec
 - perl
 - php

test_book/src/languages/highlight.md

@@ -57,7 +57,7 @@ _start:
 
 ## bash
 
-```
+```bash
 #!/bin/bash
 
 ###### CONFIG
@@ -529,6 +529,26 @@ http {
 var doors {.compileTime.}: array[1..numDoors, bool]
 
 proc calcDoors(): string =
+  for pass in 1..numDoors:
+    for door in countup(pass, numDoors, pass):
+      doors[door] = not doors[door]
+  for door in 1..numDoors:
+    result.add("Door $1 is $2.\n" % [$door, if doors[door]: "open" else: "closed"])
+
+const outputString: string = calcDoors()
+
+echo outputString
+```
+
+## objectivec
+
+```objectivec
+#import <Foundation/Foundation.h>
+
+int main(int argc, const char * argv[]) {
+    @mylak {
+        NSLog(@"Hello World!");
+    }
     return 0;
 }
 
@@ -543,6 +563,15 @@ int main(int argc, const char * argv[]) {
 "Hello " + world
 ```
 
+## perl
+
+```perl
+print "Hello World!\n";
+```
+
+## php
+
+```php
 <?php
 echo "Hello World!";
 ?>

tests/alternative_backends.rs

@@ -39,29 +39,27 @@ fn alternate_backend_with_arguments() {
     md.build().unwrap();
 }
 
-/// Get a command which will pipe `stdin` to the provided file.
-#[cfg(not(windows))]
-fn tee_command<P: AsRef<Path>>(out_file: P) -> String {
-    let out_file = out_file.as_ref();
-
-    if cfg!(windows) {
-        format!("cmd.exe /c \"type > {}\"", out_file.display())
-    } else {
-        format!("tee {}", out_file.display())
-    }
-}
-
 #[test]
-#[cfg(not(windows))]
 fn backends_receive_render_context_via_stdin() {
     use mdbook::renderer::RenderContext;
     use std::fs::File;
 
-    let temp = TempFileBuilder::new().prefix("output").tempdir().unwrap();
-    let out_file = temp.path().join("out.txt");
-    let cmd = tee_command(&out_file);
+    let (md, temp) = dummy_book_with_backend("cat-to-file", "renderers/myrenderer", false);
 
-    let (md, _temp) = dummy_book_with_backend("cat-to-file", &cmd, false);
+    let renderers = temp.path().join("renderers");
+    fs::create_dir(&renderers).unwrap();
+    rust_exe(
+        &renderers,
+        "myrenderer",
+        r#"fn main() {
+            use std::io::Read;
+            let mut s = String::new();
+            std::io::stdin().read_to_string(&mut s).unwrap();
+            std::fs::write("out.txt", s).unwrap();
+        }"#,
+    );
+
+    let out_file = temp.path().join("book/out.txt");
 
     assert!(!out_file.exists());
     md.build().unwrap();

tests/dummy_book/src/SUMMARY.md

@@ -14,6 +14,7 @@
     - [Unicode](first/unicode.md)
     - [No Headers](first/no-headers.md)
     - [Duplicate Headers](first/duplicate-headers.md)
+    - [Heading Attributes](first/heading-attributes.md)
 - [Second Chapter](second.md)
     - [Nested Chapter](second/nested.md)
 

tests/dummy_book/src/conclusion.md

@@ -18,3 +18,7 @@ css looks, like this {
 }
 */
 </style>
+
+Sneaky inline event <script>alert("inline");</script>.
+
+But regular <b>inline</b> is indexed.

tests/dummy_book/src/first/heading-attributes.md

@@ -0,0 +1,5 @@
+# Heading Attributes {#attrs}
+
+## Heading with classes {.class1 .class2}
+
+## Heading with id and classes {#both .class1 .class2}

tests/rendered_output.rs

@@ -35,6 +35,7 @@ const TOC_SECOND_LEVEL: &[&str] = &[
     "1.5. Unicode",
     "1.6. No Headers",
     "1.7. Duplicate Headers",
+    "1.8. Heading Attributes",
     "2.1. Nested Chapter",
 ];
 
@@ -374,10 +375,7 @@ fn able_to_include_playground_files_in_chapters() {
 
     let second = temp.path().join("book/second.html");
 
-    let playground_strings = &[
-        r#"class="playground""#,
-        r#"println!("Hello World!");"#,
-    ];
+    let playground_strings = &[r#"class="playground""#, r#"println!("Hello World!");"#];
 
     assert_contains_strings(&second, playground_strings);
     assert_doesnt_contain_strings(&second, &["{{#playground example.rs}}"]);
@@ -744,6 +742,7 @@ mod search {
         let index = read_book_index(temp.path());
 
         let doc_urls = index["doc_urls"].as_array().unwrap();
+        eprintln!("doc_urls={doc_urls:#?}",);
         let get_doc_ref =
             |url: &str| -> String { doc_urls.iter().position(|s| s == url).unwrap().to_string() };
 
@@ -754,6 +753,7 @@ mod search {
         let no_headers = get_doc_ref("first/no-headers.html");
         let duplicate_headers_1 = get_doc_ref("first/duplicate-headers.html#header-text-1");
         let conclusion = get_doc_ref("conclusion.html#conclusion");
+        let heading_attrs = get_doc_ref("first/heading-attributes.html#both");
 
         let bodyidx = &index["index"]["index"]["body"]["root"];
         let textidx = &bodyidx["t"]["e"]["x"]["t"];
@@ -766,13 +766,16 @@ mod search {
         assert_eq!(docs[&some_section]["body"], "");
         assert_eq!(
             docs[&summary]["body"],
-            "Dummy Book Introduction First Chapter Nested Chapter Includes Recursive Markdown Unicode No Headers Duplicate Headers Second Chapter Nested Chapter Conclusion"
+            "Dummy Book Introduction First Chapter Nested Chapter Includes Recursive Markdown Unicode No Headers Duplicate Headers Heading Attributes Second Chapter Nested Chapter Conclusion"
         );
         assert_eq!(
             docs[&summary]["breadcrumbs"],
             "First Chapter » Includes » Summary"
         );
-        assert_eq!(docs[&conclusion]["body"], "I put <HTML> in here!");
+        // See note about InlineHtml in search.rs. Ideally the `alert()` part
+        // should not be in the index, but we don't have a way to scrub inline
+        // html.
+        assert_eq!(docs[&conclusion]["body"], "I put <HTML> in here! Sneaky inline event alert(\"inline\");. But regular inline is indexed.");
         assert_eq!(
             docs[&no_headers]["breadcrumbs"],
             "First Chapter » No Headers"
@@ -785,6 +788,10 @@ mod search {
             docs[&no_headers]["body"],
             "Capybara capybara capybara. Capybara capybara capybara. ThisLongWordIsIncludedSoWeCanCheckThatSufficientlyLongWordsAreOmittedFromTheSearchIndex."
         );
+        assert_eq!(
+            docs[&heading_attrs]["breadcrumbs"],
+            "First Chapter » Heading Attributes » Heading with id and classes"
+        );
     }
 
     // Setting this to `true` may cause issues with `cargo watch`,
@@ -946,3 +953,19 @@ fn custom_fonts() {
         &["fonts.css", "myfont.woff"]
     );
 }
+
+#[test]
+fn custom_header_attributes() {
+    let temp = DummyBook::new().build().unwrap();
+    let md = MDBook::load(temp.path()).unwrap();
+    md.build().unwrap();
+
+    let contents = temp.path().join("book/first/heading-attributes.html");
+
+    let summary_strings = &[
+        r##"<h1 id="attrs"><a class="header" href="#attrs">Heading Attributes</a></h1>"##,
+        r##"<h2 id="heading-with-classes" class="class1 class2"><a class="header" href="#heading-with-classes">Heading with classes</a></h2>"##,
+        r##"<h2 id="both" class="class1 class2"><a class="header" href="#both">Heading with id and classes</a></h2>"##,
+    ];
+    assert_contains_strings(&contents, summary_strings);
+}