Format files with dprint (google#711)

The dprint formatter is a flexible system which will use sandboxed
WebAssembly formatters to format our code (mostly: it calls out to
`rustfmt` for Rust code).

A particularly interesting feature is that dprint can format Rust code
blocks in the Markdown files. However, before we turn that on, we need
to have a way to normalize the Markdown text as it is extracted[1].
That is so that the word put into the translations is kept after the
reformatting.

[1]: google/mdbook-i18n-helpers#19

.github/workflows/build.yml

@@ -21,8 +21,8 @@ jobs:
           rustup default nightly
           rustup component add rustfmt
 
-      - name: Check Rust formatting
-        run: cargo fmt --all -- --check
+      - name: Check formatting
+        uses: dprint/check@v2.2
 
   cargo:
     runs-on: ubuntu-latest

CONTRIBUTING.md

@@ -24,5 +24,5 @@ information on using pull requests.
 
 ## Community Guidelines
 
-This project follows [Google's Open Source Community
-Guidelines](https://opensource.google/conduct/).
+This project follows
+[Google's Open Source Community Guidelines](https://opensource.google/conduct/).

README.md

@@ -31,6 +31,7 @@ trigger when going through the code samples. We hope to improve on this via
 ## Building
 
 The course is built using a few tools:
+
 - [mdbook](https://github.com/rust-lang/mdBook)
 - [mdbook-svgbob](https://github.com/boozook/mdbook-svgbob)
 - [mdbook-i18n-helpers](https://github.com/google/mdbook-i18n-helpers)
@@ -64,9 +65,10 @@ and zip exercises and add them to `book/html`. To build any of the translated
 versions of the course, run `MDBOOK_BOOK__LANGUAGE=xx mdbook build -d book/xx`
 where `xx` is the ISO 639 language code (e.g. `da` for the Danish translation).
 [TRANSLATIONS.md](TRANSLATIONS.md) contains further instructions.
+
 ## Contact
 
-For questions or comments, please contact [Martin
-Geisler](mailto:[email protected]) or start a [discussion on
-GitHub](https://github.com/google/comprehensive-rust/discussions). We would love
-to hear from you.
+For questions or comments, please contact
+[Martin Geisler](mailto:[email protected]) or start a
+[discussion on GitHub](https://github.com/google/comprehensive-rust/discussions).
+We would love to hear from you.

STYLE.md

@@ -37,11 +37,17 @@ When showing Rust code, please use the same spacing as `rustfmt`: `3 * x`
 instead of `3*x`. However, feel free to remove newlines when it can make the
 code more compact and easier to understand, e.g., you can use
 
+<!-- dprint-ignore-start -->
+
 ```rust
 struct Person { name: String }
 ```
 
-if you like.
+<!-- dprint-ignore-end -->
+
+if the `Person` struct is not important for your example. Please use this
+sparingly: enclose the code block in `<!-- dprint-ignore-start -->` and
+`<!-- dprint-ignore-start -->` to suppress warnings about the formatting.
 
 ## Speaker Notes
 
@@ -61,27 +67,27 @@ collapsed or removed entirely from the slide.
 
 ## Translations
 
-This section is about what you write in the translation. We describe [how to
-create or update translations elsewhere](TRANSLATIONS.md).
+This section is about what you write in the translation. We describe
+[how to create or update translations elsewhere](TRANSLATIONS.md).
 
 When translating the course, please take the following into account:
 
 - Do not translate the course name ("Comprehensive Rust 🦀"). If the name is not
   easily understood in your language, please add the translated version after
   the original name.
 
-- If the Rust Book has been [translated into your
-  language](https://doc.rust-lang.org/book/appendix-06-translation.html), please
-  use the same vocabulary.
+- If the Rust Book has been
+  [translated into your language](https://doc.rust-lang.org/book/appendix-06-translation.html),
+  please use the same vocabulary.
 
 - Be careful to preserve the Markdown syntax of the original text. Pay special
   attention to reference links in all their variations: `[foo][bar]`, `[foo][]`
   (which means `[foo][foo]`), and `[foo]` (which also means `[foo][foo]`).
 
   As an example, if you translate `[foo]`, to `[FOO]`, you must also update the
-  corresponding link definition from `[foo]: https://example.net` to `[FOO]:
-  https://example.net`. If you forget to do this, you end up with a broken link
-  in the translation.
+  corresponding link definition from `[foo]: https://example.net` to
+  `[FOO]: https://example.net`. If you forget to do this, you end up with a
+  broken link in the translation.
 
 - If you find mistakes or things that sound awkward in the original English
   text, please submit PRs to fix them! Fixing typos in the translation is great,

TRANSLATIONS.md

@@ -5,9 +5,9 @@ languages! We use the [Gettext] system for translations. This means that you
 don't modify the Markdown files directly: instead you modify `.po` files in a
 `po/` directory. The `.po` files are small text-based translation databases.
 
-> **Tip:** You should not edit the `.po` files by hand. Instead use a PO
-> editor, such as [Poedit](https://poedit.net/). There are also several online
-> editors available. This will ensure that the file is encoded correctly.
+> **Tip:** You should not edit the `.po` files by hand. Instead use a PO editor,
+> such as [Poedit](https://poedit.net/). There are also several online editors
+> available. This will ensure that the file is encoded correctly.
 
 There is a `.po` file for each language. They are named after the [ISO 639]
 language codes: Danish would go into `po/da.po`, Korean would go into
@@ -25,9 +25,9 @@ GNU Gettext utilities below.
 
 We use two helpers for the translations:
 
-* `mdbook-xgettext`: This program extracts the English text. It is an mdbook
+- `mdbook-xgettext`: This program extracts the English text. It is an mdbook
   renderer.
-* `mdbook-gettext`: This program translates the book into a target language. It
+- `mdbook-gettext`: This program translates the book into a target language. It
   is an mdbook preprocessor.
 
 Install both helpers with:

dprint.json

@@ -0,0 +1,30 @@
+{
+  "lineWidth": 80,
+  "json": {},
+  "markdown": {
+    "textWrap": "always"
+  },
+  "toml": {},
+  "exec": {
+    "associations": "**/*.rs",
+    "rustfmt": "rustfmt --edition 2021",
+    "rustfmt.associations": "**/*.rs"
+  },
+  "includes": [
+    "**/*.json",
+    "**/*.md",
+    "**/*.rs",
+    "**/*.toml"
+  ],
+  "excludes": [
+    "/src/",
+    "/third_party/",
+    "target/"
+  ],
+  "plugins": [
+    "https://plugins.dprint.dev/exec-0.3.5.json@d687dda57be0fe9a0088ccdaefa5147649ff24127d8b3ea227536c68ee7abeab",
+    "https://plugins.dprint.dev/json-0.17.2.wasm",
+    "https://plugins.dprint.dev/markdown-0.15.2.wasm",
+    "https://plugins.dprint.dev/toml-0.5.4.wasm"
+  ]
+}

mdbook-exerciser/Cargo.toml

@@ -1,11 +1,11 @@
 [package]
 name = "mdbook-exerciser"
 version = "0.1.0"
+authors = ["Andrew Walbran <[email protected]>"]
 edition = "2021"
 license = "Apache-2.0"
-authors = ["Andrew Walbran <[email protected]>"]
-description = "A tool for extracting starter code for exercises from Markdown files."
 repository = "https://github.com/google/comprehensive-rust"
+description = "A tool for extracting starter code for exercises from Markdown files."
 
 [dependencies]
 anyhow = "1.0.68"

mdbook-exerciser/README.md

@@ -1,7 +1,7 @@
 # exerciser
 
-This is an mdBook renderer to generate templates for exercises from the Markdown source. Given a
-Markdown file `example.md` with one or more sections like:
+This is an mdBook renderer to generate templates for exercises from the Markdown
+source. Given a Markdown file `example.md` with one or more sections like:
 
 ````markdown
 <!-- File src/main.rs -->
@@ -22,5 +22,6 @@ and mdbook configuration in `book.toml` like:
 output-directory = "comprehensive-rust-exercises"
 ```
 
-It will create a file `book/exerciser/comprehensive-rust-exercises/example/src/main.rs` with the
+It will create a file
+`book/exerciser/comprehensive-rust-exercises/example/src/main.rs` with the
 appropriate contents.

rustfmt.toml

@@ -1,2 +1,2 @@
-imports_granularity = "module"  # Please use nightly for this setting.
+imports_granularity = "module" # Please use nightly for this setting.
 max_width = 90