Comrak

Build Status

Rust port of github's cmark-gfm.

Installation
Usage
Security
Extensions
Related projects
Contributing
Legal

Installation

Specify it as a requirement in Cargo.toml:

toml [dependencies] comrak = "0.9"

Comrak supports Rust stable.

Mac & Linux Binaries

bash curl https://webinstall.dev/comrak | bash

Windows 10 Binaries

powershell curl.exe -A "MS" https://webinstall.dev/comrak | powershell

Usage

``` console $ comrak --help comrak 0.9.1 Ashe Connor ashe@kivikakk.ee A 100% CommonMark-compatible GitHub Flavored Markdown parser and formatter

USAGE: comrak [FLAGS] [OPTIONS] [--] [FILE]...

FLAGS: --escape Escape raw HTML instead of clobbering it --gfm Enable GitHub-flavored markdown extensions strikethrough, tagfilter, table, autolink, and tasklist. It also enables --github-pre-lang. --github-pre-lang Use GitHub-style

for code blocks --hardbreaks Treat newlines as hard line breaks -h, --help Prints help information --smart Use smart punctuation --unsafe Allow raw HTML and dangerous URLs -V, --version Prints version information

OPTIONS: -c, --config-file Path to config file containing command-line arguments, or `none' [default: /Users/kameliya/.config/comrak/config] --default-info-string Default value for fenced code block's info strings if none is given -e, --extension ... Specify an extension name to use [possible values: strikethrough, tagfilter, table, autolink, tasklist, superscript, footnotes, description-lists] -t, --to Specify output format [default: html] [possible values: html, commonmark] --front-matter-delimiter Ignore front-matter that starts and ends with the given string --header-ids Use the Comrak header IDs extension, with the given ID prefix --width Specify wrap width (0 = nowrap) [default: 0]

ARGS: ... The CommonMark file to parse; or standard input if none passed

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, ComrakOptions}; assert_eq!(markdown_to_html("Hello, **世界**!", &ComrakOptions::default()), "<p>Hello, <strong>世界</strong>!</p>\n");

Or you can parse the input into an AST yourself, manipulate it, and then use your desired formatter:

``` rust extern crate comrak; use comrak::{parsedocument, formathtml, Arena, ComrakOptions}; use comrak::nodes::{AstNode, NodeValue};

// The returned nodes are created in the supplied Arena, and are bound by its lifetime. let arena = Arena::new();

let root = parse_document( &arena, "This is my input.\n\n1. Also my input.\n2. Certainly my input.\n", &ComrakOptions::default());

fn iternodes<'a, F>(node: &'a AstNode<'a>, f: &F) where F : Fn(&'a AstNode<'a>) { f(node); for c in node.children() { iternodes(c, f); } }

iternodes(root, &|node| { match &mut node.data.borrowmut().value { &mut NodeValue::Text(ref mut text) => { let orig = std::mem::replace(text, vec![]); *text = String::fromutf8(orig).unwrap().replace("my", "your").asbytes().to_vec(); } _ => (), } });

let mut html = vec![]; format_html(root, &ComrakOptions::default(), &mut html).unwrap();

asserteq!( String::fromutf8(html).unwrap(), "

This is your input.

\n\

Also your input.
Certainly your input.

\n"); ```

Security

As with cmark and cmark-gfm, 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.

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 configured specific to your needs.

Extensions

Comrak supports the five extensions to CommonMark defined in the GitHub Flavored Markdown Spec:

Comrak additionally supports its own extensions, which are yet to be specced out (PRs welcome!):

Superscript
Header IDs
Footnotes
Description lists

By default none are enabled; they are individually enabled with each parse by setting the appropriate values in the ComrakOptions struct.

Related projects

Comrak's design goal is to model the upstream 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 is not what I'd call idiomatic Rust (so many RefCells), and while contributors and I 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's 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). Recent cargo doc uses this, as do many other projects in the ecosystem. It's not quite at 100% spec compatibility yet.
Ben Navetta's rcmark is a set of bindings to libcmark. It hasn't been updated in a while, though there's an open pull request.
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 to the spec, but this tends to only be important if you want to reproduce GitHub's Markdown rendering exactly, e.g. in a GitHub client app.

Contributing

Contributions are highly encouraged; where possible I practice Optimistic Merging as described by Peter Hintjens. Please keep the code of conduct in mind when interacting with this project.

Thank you to comrak's many contributors for PRs and issues opened!