# Comrak
[](https://github.com/kivikakk/comrak/actions/workflows/rust.yml)  [](https://opencollective.com/comrak)
[](https://crates.io/crates/comrak)
[](https://docs.rs/comrak)
Rust port of [github's `cmark-gfm`](https://github.com/github/cmark).
- [Installation](#installation)
- [Usage](#usage)
- [Security](#security)
- [Extensions](#extensions)
- [Related projects](#related-projects)
- [Contributing](#contributing)
- [Legal](#legal)
## Installation
Specify it as a requirement in `Cargo.toml`:
``` toml
[dependencies]
comrak = "0.18"
```
Comrak supports Rust stable.
### Mac & Linux Binaries
``` bash
### Windows 10 Binaries
``` powershell
## Usage
``` 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>
Path to config file containing command-line arguments, or 'none'
[default: /Users/kivikakk/.config/comrak/config]
--hardbreaks
Treat newlines as hard line breaks
--smart
Use smart punctuation
--github-pre-lang
Use GitHub-style <pre lang> 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
--relaxed-tasklist-character
Enable relaxing which character is allowed in a tasklists
--default-info-string <INFO>
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
-e, --extension <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]
-t, --to <FORMAT>
Specify output format
[default: html]
[possible values: html, xml, commonmark]
-o, --output <FILE>
Write output to FILE instead of stdout
--width <WIDTH>
Specify wrap width (0 = nowrap)
[default: 0]
--header-ids <PREFIX>
Use the Comrak header IDs extension, with the given ID prefix
--front-matter-delimiter <DELIMITER>
Ignore front-matter that starts and ends with the given string
--syntax-highlighting <THEME>
Syntax highlighting for codefence blocks. Choose a theme or 'none' for disabling
[default: base16-ocean.dark]
--list-style <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
-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, 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::{parse_document, format_html, 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 iter_nodes<'a, F>(node: &'a AstNode<'a>, f: &F)
where F : Fn(&'a AstNode<'a>) {
f(node);
for c in node.children() {
iter_nodes(c, f);
}
}
iter_nodes(root, &|node| {
match &mut node.data.borrow_mut().value {
&mut NodeValue::Text(ref mut text) => {
let orig = std::mem::replace(text, vec![]);
*text = String::from_utf8(orig).unwrap().replace("my", "your").as_bytes().to_vec();
}
_ => (),
}
});
let mut html = vec![];
format_html(root, &ComrakOptions::default(), &mut html).unwrap();
assert_eq!(
String::from_utf8(html).unwrap(),
"<p>This is your input.</p>\n\
<ol>\n\
<li>Also your input.</li>\n\
<li>Certainly your input.</li>\n\
</ol>\n");
```
## 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.
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
- Shortcodes
By default none are enabled; they are individually enabled with each parse by setting the appropriate values in the
[`ComrakOptions` struct](https://docs.rs/comrak/newest/comrak/struct.ComrakOptions.html).
## Plugins
### Codefence syntax highlighter
At the moment syntax highlighting of codefence blocks is the only feature that can be enhanced with plugins.
Create an implementation of the `SyntaxHighlighterAdapter` trait, and then provide an instance of such adapter to
`ComrakPlugins.render.codefence_syntax_highlighter`. For formatting a markdown document with plugins, use the
`markdown_to_html_with_plugins` function, which accepts your plugin 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 as your
`ComrakPlugins` 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 is not what I'd call idiomatic Rust (*so many `RefCell`s*), 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](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. It appears semi-maintained as of March 2023.
- [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) 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](http://hintjens.com/blog:106) as
described by Peter Hintjens. Please keep the [code of conduct](CODE_OF_CONDUCT.md) in mind when interacting with this
project.
Thank you to comrak's many contributors for PRs and issues opened\!
### Code Contributors
<a href="https://github.com/kivikakk/comrak/graphs/contributors"><img src="https://opencollective.com/comrak/contributors.svg?width=890&button=false" /></a>
### 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)
- [Open Collective](https://opencollective.com/comrak/contribute)
#### Individuals
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## Contact
Asherah Connor \<ashe kivikakk ee\>
## Legal
Copyright (c) 2017–2023, Asherah Connor. 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.