# MDEx
<!-- MDOC -->
<p align="center">
<img src="https://raw.githubusercontent.com/leandrocp/mdex/main/assets/images/mdex_logo.png" width="512" alt="MDEx logo">
</p>
<p align="center">
A CommonMark-compliant fast and extensible Markdown parser and formatter for Elixir.
</p>
<p align="center">
<a href="https://hex.pm/packages/mdex">
<img alt="Hex Version" src="https://img.shields.io/hexpm/v/mdex">
</a>
<a href="https://hexdocs.pm/mdex">
<img alt="Hex Docs" src="http://img.shields.io/badge/hex.pm-docs-green.svg?style=flat">
</a>
<a href="https://opensource.org/licenses/MIT">
<img alt="MIT" src="https://img.shields.io/hexpm/l/mdex">
</a>
</p>
## Features
Compliant with [CommonMark](https://spec.commonmark.org) and [GitHub Flavored Markdown](https://github.github.com/gfm) specifications with extra [extensions](https://docs.rs/comrak/latest/comrak/struct.ExtensionOptions.html)
as Wiki Links, Discord Markdown tags, and emoji. Also supports syntax highlighting out-of-the-box using the [Autumn](https://github.com/leandrocp/autumn) library.
Under the hood it's calling the [comrak](https://crates.io/crates/comrak) APIs to process Markdown,
a fast Rust crate that ports the cmark fork maintained by GitHub, a widely and well adopted Markdown implementation.
The AST structure is based on [Floki](https://hex.pm/packages/floki) so a similar API to manipulate HTML can be used to manipulate Markdown documents.
Check out some examples at [mdex/examples/](https://github.com/leandrocp/mdex/tree/main/examples)
And some samples are available at https://mdex-c31.pages.dev
## Installation
Add `:mdex` dependency:
```elixir
def deps do
[
{:mdex, "~> 0.2"}
]
end
```
## Usage
```elixir
Mix.install([{:mdex, "~> 0.2"}])
```
```elixir
iex> MDEx.to_html!("# Hello")
"<h1>Hello</h1>"
```
```elixir
iex> MDEx.to_html!("# Hello :smile:", extension: [shortcodes: true])
"<h1>Hello 😄</h1>"
```
## Sigils
Convert and generate AST, Markdown (CommonMark), HTML, and XML formats.
First, import the sigils:
```elixir
iex> import MDEx.Sigil
```
```elixir
iex> import MDEx.Sigil
iex> ~M|# Hello from `~M` sigil|
%MDEx.Document{
nodes: [
%MDEx.Heading{
nodes: [
%MDEx.Text{literal: "Hello from "},
%MDEx.Code{num_backticks: 1, literal: "~M"},
%MDEx.Text{literal: " sigil"}
],
level: 1,
setext: false
}
]
}
```
```elixir
iex> import MDEx.Sigil
iex> ~M|`~M` also converts to HTML format|HTML
"<p><code>~M</code> also converts to HTML format</p>"
```
```elixir
iex> import MDEx.Sigil
iex> ~M|and to XML as well|XML
"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<!DOCTYPE document SYSTEM \"CommonMark.dtd\">\n<document xmlns=\"http://commonmark.org/xml/1.0\">\n <paragraph>\n <text xml:space=\"preserve\">and to XML as well</text>\n </paragraph>\n</document>\n"
```
Use [~m](https://hexdocs.pm/mdex/MDEx.Sigil.html#sigil_m/2) to interpolate variables:
```elixir
iex> import MDEx.Sigil
iex> lang = :elixir
iex> ~m|`lang = #{inspect(lang)}`|
%MDEx.Document{nodes: [%MDEx.Paragraph{nodes: [%MDEx.Code{num_backticks: 1, literal: "lang = :elixir"}]}]}
```
See more info at https://hexdocs.pm/mdex/MDEx.Sigil.html
## Safety
For security reasons, every piece of raw HTML is omitted from the output by default:
```elixir
iex> MDEx.to_html!("<h1>Hello</h1>")
"<!-- raw HTML omitted -->"
```
That's not very useful for most cases, but you can render raw HTML and escape it instead:
```elixir
iex> MDEx.to_html!("<h1>Hello</h1>", render: [escape: true])
"<h1>Hello</h1>"
```
If the input is provided by external sources, it might be a good idea to sanitize it instead for extra security:
```elixir
iex> MDEx.to_html!("<a href=https://elixir-lang.org/>Elixir</a>", render: [unsafe_: true], features: [sanitize: true])
"<p><a href=\"https://elixir-lang.org/\" rel=\"noopener noreferrer\">Elixir</a></p>"
```
Note that you must pass the `unsafe_: true` option to first generate the raw HTML in order to sanitize it.
All sanitization rules are defined in the [ammonia docs](https://docs.rs/ammonia/latest/ammonia/fn.clean.html).
For example, the link in the example below was marked as `noopener noreferrer` to prevent attacks.
If those rules are too strict and you really trust the input, or you really need to render raw HTML,
then you can just render it directly without escaping nor sanitizing:
```elixir
iex> MDEx.to_html!("<script>alert('hello')</script>", render: [unsafe_: true])
"<script>alert('hello')</script>"
```
## Parsing
Converts Markdown to an AST data structure that can be inspected and manipulated to change the content of the document programmatically.
The data structure format is inspired on [Floki](https://github.com/philss/floki) (with `:attributes_as_maps = true`) so we can keep similar APIs and keep the same mental model when
working with these documents, either Markdown or HTML, where each node is represented as a struct holding the node name as the struct name and its attributes and children, for eg:
```elixir
%MDEx.Heading{
level: 1
nodes: [...],
}
```
The parent node that represents the root of the document is the [MDEx.Document](https://hexdocs.pm/mdex/MDEx.Document.html) struct,
where you can find more more information about the AST and what operations are available.
The complete list of nodes is listed in the [documentation](https://hexdocs.pm/mdex/), section `Document Nodes`.
## Formatting
Formatting is the process of converting from one format to another, for example from AST or Markdown to HTML.
Formatting to XML and to Markdown is also supported.
You can use [MDEx.parse_document/2](https://hexdocs.pm/mdex/MDEx.html#parse_document/2) to generate an AST or any of the `to_*` functions
to convert to Markdown (CommonMark), HTML, or XML.
## Options
Use options to change the behavior and the generated output.
All the [comrak Options](https://docs.rs/comrak/latest/comrak/struct.Options.html) are available as keyword lists,
and an additional `:features` option to extend it further.
_The full documentation and list of all options with description and examples can be found on the links below:_
* `:extension` - https://docs.rs/comrak/latest/comrak/struct.ExtensionOptions.html
* `:parse` - https://docs.rs/comrak/latest/comrak/struct.ParseOptions.html
* `:render` - https://docs.rs/comrak/latest/comrak/struct.RenderOptions.html
* `:features` - see the available options below
### Features Options
* `:sanitize` (defaults to `false`) - sanitize output using [ammonia](https://crates.io/crates/ammonia). See the [Safety](#module-safety) section for more info.
* `:syntax_highlight_theme` (defaults to `"onedark"`) - syntax highlight code fences using [autumn themes](https://github.com/leandrocp/autumn/tree/main/priv/themes),
you should pass the filename without special chars and without extension, for example you should pass `syntax_highlight_theme: "adwaita_dark"` to use the [Adwaita Dark](https://github.com/leandrocp/autumn/blob/main/priv/themes/adwaita-dark.toml) theme
* `:syntax_highlight_inline_style` (defaults to `true`) - embed styles in the output for each generated token. You'll need to [serve CSS themes](https://github.com/leandrocp/autumn?tab=readme-ov-file#linked) if inline styles are disabled to properly highlight code
See some examples below on how to use the provided options:
### GitHub Flavored Markdown with [emojis](https://www.webfx.com/tools/emoji-cheat-sheet/)
```elixir
MDEx.to_html!(~S"""
# GitHub Flavored Markdown :rocket:
- [x] Task A
- [x] Task B
- [ ] Task C
| Feature | Status |
| ------- | ------ |
| Fast | :white_check_mark: |
| GFM | :white_check_mark: |
Check out the spec at https://github.github.com/gfm/
""",
extension: [
strikethrough: true,
tagfilter: true,
table: true,
autolink: true,
tasklist: true,
footnotes: true,
shortcodes: true,
],
parse: [
smart: true,
relaxed_tasklist_matching: true,
relaxed_autolinks: true
],
render: [
github_pre_lang: true,
unsafe_: true,
],
features: [
sanitize: true
]) |> IO.puts()
"""
<p>GitHub Flavored Markdown 🚀</p>
<ul>
<li><input type="checkbox" checked="" disabled="" /> Task A</li>
<li><input type="checkbox" checked="" disabled="" /> Task B</li>
<li><input type="checkbox" disabled="" /> Task C</li>
</ul>
<table>
<thead>
<tr>
<th>Feature</th>
<th>Status</th>
</tr>
</thead>
<tbody>
<tr>
<td>Fast</td>
<td>✅</td>
</tr>
<tr>
<td>GFM</td>
<td>✅</td>
</tr>
</tbody>
</table>
<p>Check out the spec at <a href="https://github.github.com/gfm/">https://github.github.com/gfm/</a></p>
"""
```
### Code Syntax Highlighting
````elixir
MDEx.to_html!(~S"""
```elixir
String.upcase("elixir")
```
""",
features: [syntax_highlight_theme: "catppuccin_latte"]
) |> IO.puts()
"""
<pre class=\"autumn highlight\" style=\"background-color: #282C34; color: #ABB2BF;\">
<code class=\"language-elixir\" translate=\"no\">
<span class=\"namespace\" style=\"color: #61AFEF;\">String</span><span class=\"operator\" style=\"color: #C678DD;\">.</span><span class=\"function\" style=\"color: #61AFEF;\">upcase</span><span class=\"\" style=\"color: #ABB2BF;\">(</span><span class=\"string\" style=\"color: #98C379;\">"elixir"</span><span class=\"\" style=\"color: #ABB2BF;\">)</span>
</code>
</pre>
"""
````
## Demo and Samples
A [livebook](https://github.com/leandrocp/mdex/blob/main/playground.livemd) and a [script](https://github.com/leandrocp/mdex/blob/main/playground.exs) are available to play with and experiment with this library, or you can check out all [available samples](https://github.com/leandrocp/mdex/tree/main/priv/generated/samples) at https://mdex-c31.pages.dev
## Used By
- [BeaconCMS](https://github.com/BeaconCMS/beacon)
- [Tableau](https://github.com/elixir-tools/tableau)
- [Bonfire](https://github.com/bonfire-networks/bonfire-app)
- [00](https://github.com/technomancy-dev/00)
- [Plural Console](https://github.com/pluralsh/console)
- And [more...](https://github.com/search?q=lang%3Aelixir+%3Amdex&type=code)
_Are you using MDEx and want to list your project here? Please send a PR!_
## Benchmark
A [simple script](benchmark.exs) is available to compare existing libs:
```
Name ips average deviation median 99th %
cmark 22.82 K 0.0438 ms ±16.24% 0.0429 ms 0.0598 ms
mdex 3.57 K 0.28 ms ±9.79% 0.28 ms 0.33 ms
md 0.34 K 2.95 ms ±10.56% 2.90 ms 3.62 ms
earmark 0.25 K 4.04 ms ±4.50% 4.00 ms 4.44 ms
Comparison:
cmark 22.82 K
mdex 3.57 K - 6.39x slower +0.24 ms
md 0.34 K - 67.25x slower +2.90 ms
earmark 0.25 K - 92.19x slower +4.00 ms
```
## Motivation
MDEx was born out of the necessity of parsing CommonMark files, to parse hundreds of files quickly, and to be easily extensible by consumers of the library.
* [earmark](https://hex.pm/packages/earmark) is extensible but [can't parse](https://github.com/RobertDober/earmark_parser/issues/126) all kinds of documents and is slow to convert hundreds of markdowns.
* [md](https://hex.pm/packages/md) is very extensible but the doc says "If one needs to perfectly parse the common markdown, Md is probably not the correct choice" and CommonMark was a requirement to parse many existing files.
* [markdown](https://hex.pm/packages/markdown) is not precompiled and has not received updates in a while.
* [cmark](https://hex.pm/packages/cmark) is a fast CommonMark parser but it requires compiling the C library, is hard to extend, and was archived on Apr 2024
_Note that MDEx is the only one that syntax highlights out-of-the-box which contributes to make it slower than cmark._
To finish, a friendly reminder that all libs have their own strengths and trade-offs so use the one that better suit your needs.
## Looking for help with your Elixir project?
<img src="https://raw.githubusercontent.com/leandrocp/mdex/main/assets/images/dockyard_logo.png" width="256" alt="DockYard logo">
At DockYard we are [ready to help you build your next Elixir project](https://dockyard.com/phoenix-consulting).
We have a unique expertise in Elixir and Phoenix development that is unmatched and we love to [write about Elixir](https://dockyard.com/blog/categories/elixir).
Have a project in mind? [Get in touch](https://dockyard.com/contact/hire-us)!
## Acknowledgements
* [comrak](https://crates.io/crates/comrak) crate for all the heavy work on parsing Markdown and rendering HTML
* [Floki](https://hex.pm/packages/floki) for the AST manipulation
* [Logo](https://www.flaticon.com/free-icons/rpg) created by Freepik - Flaticon
* [Logo font](https://github.com/quoteunquoteapps/CourierPrime) designed by [Alan Greene](https://github.com/a-dg)
