# [Comrak](https://github.com/kivikakk/comrak) [![Build status](https://github.com/kivikakk/comrak/actions/workflows/rust.yml/badge.svg)](https://github.com/kivikakk/comrak/actions/workflows/rust.yml) [![CommonMark: 652/652](https://img.shields.io/badge/commonmark-652%2F652-brightgreen.svg)](https://github.com/commonmark/commonmark-spec/blob/9103e341a973013013bb1a80e13567007c5cef6f/spec.txt) [![GFM: 670/670](https://img.shields.io/badge/gfm-670%2F670-brightgreen.svg)](https://github.com/kivikakk/cmark-gfm/blob/2f13eeedfe9906c72a1843b03552550af7bee29a/test/spec.txt) [![crates.io version](https://img.shields.io/crates/v/comrak.svg)](https://crates.io/crates/comrak) [![docs.rs](https://docs.rs/comrak/badge.svg)](https://docs.rs/comrak) Rust port of [github's `cmark-gfm`](https://github.com/github/cmark-gfm). Compliant with [CommonMark 0.31.2](https://spec.commonmark.org/0.31.2/) in default mode. GFM support synced with release `0.29.0.gfm.13`. ## Installation Specify it as a requirement in `Cargo.toml`: ``` toml [dependencies] comrak = "0.29" ``` Comrak's library supports Rust 1.62.1+. ### CLI - Anywhere with a Rust toolchain: - `cargo install comrak` - Many Unix distributions: - `pacman -S comrak` - `brew install comrak` - `dnf install comrak` - `nix run nixpkgs#comrak` You can also find builds I've published in [GitHub Releases](https://github.com/kivikakk/comrak/releases), but they're limited to machines I have access to at the time of making them\! [webinstall.dev](https://webinstall.dev/comrak/) offers `curl | shell`-style installation of the latest of these for your OS. ## Usage
Click to expand the CLI --help output. ``` console $ comrak --help ``` ``` A 100% CommonMark-compatible GitHub Flavored Markdown parser and formatter Usage: comrak [OPTIONS] [FILE]... Arguments: [FILE]... CommonMark file(s) to parse; or standard input if none passed Options: -c, --config-file Path to config file containing command-line arguments, or 'none' [default: /home/runner/.config/comrak/config] -i, --inplace To perform an in-place formatting --hardbreaks Treat newlines as hard line breaks --smart Use smart punctuation --github-pre-lang Use GitHub-style
 for code blocks

      --full-info-string
          Enable full info strings for code blocks

      --gfm
          Enable GitHub-flavored markdown extensions: strikethrough, tagfilter, table, autolink, and
          tasklist. Also enables --github-pre-lang and --gfm-quirks

      --gfm-quirks
          Enables GFM-style quirks in output HTML, such as not nesting  tags, which
          otherwise breaks CommonMark compatibility

      --relaxed-tasklist-character
          Enable relaxing which character is allowed in a tasklists

      --relaxed-autolinks
          Enable relaxing of autolink parsing, allow links to be recognized when in brackets and
          allow all url schemes

      --default-info-string 
          Default value for fenced code block's info strings if none is given

      --unsafe
          Allow raw HTML and dangerous URLs

      --gemojis
          Translate gemojis into UTF-8 characters

      --escape
          Escape raw HTML instead of clobbering it

      --escaped-char-spans
          Wrap escaped characters in span tags

  -e, --extension 
          Specify extension name(s) to use
          
          Multiple extensions can be delimited with ",", e.g. --extension strikethrough,table
          
          [possible values: strikethrough, tagfilter, table, autolink, tasklist, superscript,
          footnotes, description-lists, multiline-block-quotes, math-dollars, math-code,
          wikilinks-title-after-pipe, wikilinks-title-before-pipe, underline, spoiler, greentext]

  -t, --to 
          Specify output format
          
          [default: html]
          [possible values: html, xml, commonmark]

  -o, --output 
          Write output to FILE instead of stdout

      --width 
          Specify wrap width (0 = nowrap)
          
          [default: 0]

      --header-ids 
          Use the Comrak header IDs extension, with the given ID prefix

      --front-matter-delimiter 
          Ignore front-matter that starts and ends with the given string

      --syntax-highlighting 
          Syntax highlighting for codefence blocks. Choose a theme or 'none' for disabling
          
          [default: base16-ocean.dark]

      --list-style 
          Specify bullet character for lists (-, +, *) in CommonMark output
          
          [default: dash]
          [possible values: dash, plus, star]

      --sourcepos
          Include source position attribute in HTML and XML output

      --experimental-inline-sourcepos
          Include inline sourcepos in HTML output, which is known to have issues

      --ignore-setext
          Ignore setext headers

      --ignore-empty-links
          Ignore empty links

  -h, --help
          Print help information (use `-h` for a summary)

  -V, --version
          Print version information

By default, Comrak will attempt to read command-line options from a config file specified by
--config-file. This behaviour can be disabled by passing --config-file none. It is not an error if
the file does not exist.
```

And there's a Rust interface. You can use `comrak::markdown_to_html` directly: ``` rust use comrak::{markdown_to_html, Options}; assert_eq!(markdown_to_html("Hello, **世界**!", &Options::default()), "

Hello, 世界!

\n"); ``` Or you can parse the input into an AST yourself, manipulate it, and then use your desired formatter: ``` rust use comrak::nodes::NodeValue; use comrak::{format_html, parse_document, Arena, Options}; fn replace_text(document: &str, orig_string: &str, replacement: &str) -> String { // The returned nodes are created in the supplied Arena, and are bound by its lifetime. let arena = Arena::new(); // Parse the document into a root `AstNode` let root = parse_document(&arena, document, &Options::default()); // Iterate over all the descendants of root. for node in root.descendants() { if let NodeValue::Text(ref mut text) = node.data.borrow_mut().value { // If the node is a text node, perform the string replacement. *text = text.replace(orig_string, replacement); } } let mut html = vec![]; format_html(root, &Options::default(), &mut html).unwrap(); String::from_utf8(html).unwrap() } fn main() { let doc = "This is my input.\n\n1. Also [my](#) input.\n2. Certainly *my* input.\n"; let orig = "my"; let repl = "your"; let html = replace_text(&doc, &orig, &repl); println!("{}", html); // Output: // //

This is your input.

//
    //
  1. Also your input.
  2. //
  3. Certainly your input.
  4. //
} ``` For a slightly more real-world example, see how I [generate my GitHub user README](https://github.com/kivikakk/kivikakk) from a base document with embedded YAML, which itself has embedded Markdown, or [check out some of Comrak's dependents on crates.io](https://crates.io/crates/comrak/reverse_dependencies) or [on GitHub](https://github.com/kivikakk/comrak/network/dependents). ## Security As with [`cmark`](https://github.com/commonmark/cmark) and [`cmark-gfm`](https://github.com/github/cmark-gfm#security), Comrak will scrub raw HTML and potentially dangerous links. This change was introduced in Comrak 0.4.0 in support of a safe-by-default posture, and later adopted by our contemporaries. :) To allow these, use the `unsafe_` option (or `--unsafe` with the command line program). If doing so, we recommend the use of a sanitisation library like [`ammonia`](https://github.com/notriddle/ammonia) configured specific to your needs. ## Extensions Comrak supports the five extensions to CommonMark defined in the [GitHub Flavored Markdown Spec](https://github.github.com/gfm/): - [Tables](https://github.github.com/gfm/#tables-extension-) - [Task list items](https://github.github.com/gfm/#task-list-items-extension-) - [Strikethrough](https://github.github.com/gfm/#strikethrough-extension-) - [Autolinks](https://github.github.com/gfm/#autolinks-extension-) - [Disallowed Raw HTML](https://github.github.com/gfm/#disallowed-raw-html-extension-) Comrak additionally supports its own extensions, which are yet to be specced out (PRs welcome\!): - Superscript - Header IDs - Footnotes - Description lists - Front matter - Multi-line blockquotes - Math - Emoji shortcodes - Wikilinks - Underline - Spoiler text - "Greentext" By default none are enabled; they are individually enabled with each parse by setting the appropriate values in the [`ExtensionOptions` struct](https://docs.rs/comrak/latest/comrak/struct.ExtensionOptions.html). ## Plugins ### Fenced code block syntax highlighting You can provide your own syntax highlighting engine. Create an implementation of the `SyntaxHighlighterAdapter` trait, and then provide an instance of such adapter to `Plugins.render.codefence_syntax_highlighter`. For formatting a Markdown document with plugins, use the `markdown_to_html_with_plugins` function, which accepts your plugins object as a parameter. See the `syntax_highlighter.rs` and `syntect.rs` examples for more details. #### Syntect [`syntect`](https://github.com/trishume/syntect) is a syntax highlighting library for Rust. By default, `comrak` offers a plugin for it. In order to utilize it, create an instance of `plugins::syntect::SyntectAdapter` and use it in your `Plugins` option. ## Related projects Comrak's design goal is to model the upstream [`cmark-gfm`](https://github.com/github/cmark-gfm) as closely as possible in terms of code structure. The upside of this is that a change in `cmark-gfm` has a very predictable change in Comrak. Likewise, any bug in `cmark-gfm` is likely to be reproduced in Comrak. This could be considered a pro or a con, depending on your use case. The downside, of course, is that the code often diverges from idiomatic Rust, especially in the AST's extensive use of `RefCell`, and while contributors have made it as fast as possible, it simply won't be as fast as some other CommonMark parsers depending on your use-case. Here are some other projects to consider: - [Raph Levien](https://github.com/raphlinus)'s [`pulldown-cmark`](https://github.com/google/pulldown-cmark). It's very fast, uses a novel parsing algorithm, and doesn't construct an AST (but you can use it to make one if you want). `cargo doc` uses this, as do many other projects in the ecosystem. - [markdown-rs](https://github.com/wooorm/markdown-rs) (1.x) looks worth watching. - Know of another library? Please open a PR to add it\! As far as I know, Comrak is the only library to implement all of the [GitHub Flavored Markdown extensions](https://github.github.com/gfm) rigorously. ## Benchmarking You'll need to [install hyperfine](https://github.com/sharkdp/hyperfine#installation), and CMake if you want to compare against `cmark-gfm`. If you want to just run the benchmark for the `comrak` binary itself, run: ``` bash make bench-comrak ``` This will build Comrak in release mode, and run benchmark on it. You will see the time measurements as reported by hyperfine in the console. The `Makefile` also provides a way to run benchmarks for `comrak` current state (with your changes), `comrak` main branch, [`cmark-gfm`](https://github.com/github/cmark-gfm), [`pulldown-cmark`](https://github.com/raphlinus/pulldown-cmark) and [`markdown-it.rs`](https://github.com/rlidwka/markdown-it.rs). You'll need CMake, and ensure [submodules are prepared](https://stackoverflow.com/a/10168693/499609). ``` bash make bench-all ``` This will build and run benchmarks across all, and report the time taken by each as well as relative time. ## Contributing Contributions are **highly encouraged**; if you'd like to assist, consider checking out the [`good first issue` label](https://github.com/kivikakk/comrak/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22)\! I'm happy to help provide direction and guidance throughout, even if (especially if\!) you're new to Rust or open source. Where possible I practice [Optimistic Merging](http://hintjens.com/blog:106) as described by Peter Hintjens. Please keep the [code of conduct](CODE_OF_CONDUCT.md) in mind too. Thank you to Comrak's many contributors for PRs and issues opened\! ### Code Contributors [![Small chart showing Comrak contributors.](https://opencollective.com/comrak/contributors.svg?width=890&button=false)](https://github.com/kivikakk/comrak/graphs/contributors) ### Financial Contributors Become a financial contributor and help sustain Comrak's development. I'm self-employed --- open-source software relies on the collective. - [GitHub Sponsors](https://github.com/sponsors/kivikakk) ## Contact Asherah Connor \ ## Legal Copyright (c) 2017–2024, Asherah Connor and Comrak contributors. Licensed under the [2-Clause BSD License](https://opensource.org/licenses/BSD-2-Clause). `cmark` itself is is copyright (c) 2014, John MacFarlane. See [COPYING](COPYING) for all the details.