kramdown GFM parser

This is a parser for kramdown that converts Markdown documents in the GitHub Flavored Markdown (GFM) dialect to HTML.

Note: Until kramdown version 2.0.0 this parser was part of the kramdown distribution.

gem install kramdown-parser-gfm

require 'kramdown'
require 'kramdown-parser-gfm'

Kramdown::Document.new(text, input: 'GFM').to_html

At the moment this parser is based on the kramdown parser, with the following changes:

• Support for fenced code blocks using three or more backticks has been added.
• Hard line breaks in paragraphs are enforced by default (see option hard_wrap).
• ATX headers need a whitespace character after the hash signs.
• Strikethroughs can be created using two tildes surrounding a piece of text.
• Blank lines between paragraphs and other block elements are not needed by default (see option gfm_quirks).
• Render emojis used at GitHub .

Please note that the GFM parser tries to mimic the parser used at GitHub which means that for some special cases broken behaviour is the expected behaviour.

Here is an example:

This ~~is a complex strike through *test ~~with nesting~~ involved* here~~.

In this case the correct GFM result is:

<p>This <del>is a complex strike through *test ~~with nesting</del> involved* here~~.</p>

The GFM parser provides the following options:

• hard_wrap: Interprets line breaks literally (default: true)

  Insert HTML <br /> tags inside paragraphs where the original Markdown document had newlines (by default, Markdown ignores these newlines).

• gfm_quirks: Enables a set of GFM specific quirks (default: paragraph_end)

  The way how GFM is transformed on GitHub often differs from the way kramdown does things. Many of these differences are negligible but others are not.

  This option allows one to enable/disable certain GFM quirks, i.e. ways in which GFM parsing differs from kramdown parsing.

  The value has to be a list of quirk names that should be enabled, separated by commas. Possible names are:

  • paragraph_end

    Disables the kramdown restriction that at least one blank line has to be used after a paragraph before a new block element can be started.

    Note that if this quirk is used, lazy line wrapping does not fully work anymore!

  • no_auto_typographic

    Disables automatic conversion of some characters into their corresponding typographic symbols (like -- to em-dash etc). This helps to achieve results closer to what GitHub Flavored Markdown produces.

• gfm_emojis: Enables rendering emoji amidst GFM (default: false)

  Usage requires gem "gemoji", "~> 3.0" that will have to be installed and managed separately either directly or via your Gemfile.

• gfm_emoji_opts: Configuration for rendering emoji amidst GFM (default: {})

  The value has to be mapping of key-value pairs.

  Valid option(s):

  • asset_path

    The remote location of emoji assets that will be prefixed to emoji file path. Gemoji 3 has the file path set to unicode/[emoji-filename].

    Defaults to https://github.githubassets.com/images/icons/emoji.

    Therefore the absolute path to an emoji file would be: https://github.githubassets.com/images/icons/emoji/unicode/[emoji-filename]

Clone the git repository and you are good to go. You'll probably want to install rake to use the provided rake tasks.

Run rake --tasks to view a list of available tasks.

MIT - see the COPYING file.