mistletoe

mistletoe is a Markdown parser in pure Python, designed to be fast, spec-compliant and fully customizable.

Apart from being the fastest CommonMark-compliant Markdown parser implementation in pure Python, mistletoe also supports easy definitions of custom tokens. Parsing Markdown into an abstract syntax tree also allows us to swap out renderers for different output formats, without touching any of the core components.

Remember to spell mistletoe in lowercase!

Features

Fast: mistletoe is the fastest implementation of CommonMark in Python. See the performance section for details.
Spec-compliant: CommonMark is a useful, high-quality project. mistletoe follows the CommonMark specification to resolve ambiguities during parsing. Outputs are predictable and well-defined.
Extensible: Strikethrough and tables are supported natively, and custom block-level and span-level tokens can easily be added. Writing a new renderer for mistletoe is a relatively trivial task.

You can even write a Lisp in it.

Output formats

Renderers for the following "core" output formats exist within the mistletoe main package:

HTML
LaTeX
AST (Abstract Syntax Tree; handy for debugging the parsing process)
Markdown (Can be used to reflow the text, or make other types of automated changes to Markdown documents)

Renderers for the following output formats can be found in the contrib package:

HTML with MathJax (mathjax.py)
HTML with code highlighting (using Pygments) (pygments_renderer.py)
HTML with TOC (for programmatical use) (toc_renderer.py)
HTML with support for GitHub wiki links (github_wiki.py)
Jira Markdown (jira_renderer.py)
XWiki Syntax (xwiki20_renderer.py)
Scheme (scheme.py)

Installation

mistletoe is tested for Python 3.5 and above. Install mistletoe with pip:

pip3 install mistletoe

Alternatively, clone the repo:

git clone https://github.com/miyuchina/mistletoe.git
cd mistletoe
pip3 install -e .

This installs mistletoe in "editable" mode (because of the -e option). That means that any changes made to the source code will get visible immediately - that's because Python only makes a link to the specified directory (.) instead of copying the files to the standard packages folder.

See the contributing doc for how to contribute to mistletoe.

Usage

Usage from Python

Here's how you can use mistletoe in a Python script:

import mistletoe

with open('foo.md', 'r') as fin:
    rendered = mistletoe.markdown(fin)

mistletoe.markdown() uses mistletoe's default settings: allowing HTML mixins and rendering to HTML. The function also accepts an additional argument renderer. To produce LaTeX output:

import mistletoe
from mistletoe.latex_renderer import LaTeXRenderer

with open('foo.md', 'r') as fin:
    rendered = mistletoe.markdown(fin, LaTeXRenderer)

To reflow the text in a Markdown document with a max line length of 20 characters:

import mistletoe
from mistletoe.markdown_renderer import MarkdownRenderer

with open('dev-guide.md', 'r') as fin:
    with MarkdownRenderer(max_line_length=20) as renderer:
        print(renderer.render(mistletoe.Document(fin)))

Finally, here's how you would manually specify extra tokens via a renderer. In the following example, we use HtmlRenderer to render the AST. The renderer itself adds HtmlBlock and HtmlSpan tokens to the parsing process. The result should be equal to the output obtained from the first example above.

from mistletoe import Document, HtmlRenderer

with open('foo.md', 'r') as fin:
    with HtmlRenderer() as renderer:     # or: `with HtmlRenderer(AnotherToken1, AnotherToken2) as renderer:`
        doc = Document(fin)              # parse the lines into AST
        rendered = renderer.render(doc)  # render the AST
        # internal lists of tokens to be parsed are automatically reset when exiting this `with` block

Important: As can be seen from the example above, the parsing phase is currently tightly connected with initiation and closing of a renderer. Therefore, you should never call Document(...) outside of a with ... as renderer block, unless you know what you are doing.

Usage from command-line

pip installation enables mistletoe's command-line utility. Type the following directly into your shell:

mistletoe foo.md

This will transpile foo.md into HTML, and dump the output to stdout. To save the HTML, direct the output into a file:

mistletoe foo.md > out.html

You can use a different renderer by including the full path to the renderer class after a -r or --renderer flag. For example, to transpile into LaTeX:

mistletoe foo.md --renderer mistletoe.latex_renderer.LaTeXRenderer

and similarly for a renderer in the contrib package:

mistletoe foo.md --renderer mistletoe.contrib.jira_renderer.JiraRenderer

mistletoe interactive mode

Running mistletoe without specifying a file will land you in interactive mode. Like Python's REPL, interactive mode allows you to test how your Markdown will be interpreted by mistletoe:

mistletoe [version 0.7.2] (interactive)
Type Ctrl-D to complete input, or Ctrl-C to exit.
>>> some **bold** text
... and some *italics*
...
<p>some <strong>bold</strong> text
and some <em>italics</em></p>
>>>

The interactive mode also accepts the --renderer flag:

mistletoe [version 0.7.2] (interactive)
Type Ctrl-D to complete input, or Ctrl-C to exit.
Using renderer: LaTeXRenderer
>>> some **bold** text
... and some *italics*
...
\documentclass{article}
\begin{document}

some \textbf{bold} text
and some \textit{italics}
\end{document}
>>>

Who uses mistletoe?

mistletoe is used by projects of various target audience. You can find some concrete projects in the "Used by" section on Libraries.io, but this is definitely not a complete list. Also a list of Dependents is tracked by GitHub directly.

Run mistletoe from CopyQ

One notable example is running mistletoe as a Markdown converter from the advanced clipboard manager called CopyQ. One just needs to install the Convert Markdown to ... custom script command and then run this command on any selected Markdown text.