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The code we use to render README.your_favorite_markup

README.md

GitHub Markup

We use this library on GitHub when rendering your README or any other rich text file.

Markups

The following markups are supported. The dependencies listed are required if you wish to run the library. You can also run script/bootstrap to fetch them all.

HTML sanitization

HTML rendered by the various markup language processors gets passed through an HTML sanitization filter for security reasons. HTML elements not in the whitelist are removed. HTML attributes not in the whitelist are removed from the preserved elements.

The following HTML elements, organized by category, are whitelisted:

  • Headings: h1, h2, h3, h4, h5, h6, h7, h8
  • Prose: p, div, blockquote
  • Preformatted: pre
  • Inline: b, i, strong, em, tt, code, ins, del, sup, sub, kbd, samp, q, var
  • Lists: ol, ul, li, dl, dt, dd
  • Tables: table, thead, tbody, tfoot, tr, td, th
  • Breaks: br, hr
  • Ruby (East Asian): ruby, rt, rp

The following attributes, organized by element, are whitelisted:

  • a: href (http://, https://, mailto://, github-windows:// and github-mac:// URI schemes and relative paths only)
  • img: src (http:// and https::// URI schemes and relative paths only)
  • div: itemscope, itemtype
  • all: abbr, accept, accept-charset, accesskey, action, align, alt, axis, border, cellpadding, cellspacing, char, charoff, charset, checked, cite, clear, cols, colspan, color, compact, coords, datetime, dir, disabled, enctype, for, frame, headers, height, hreflang, hspace, ismap, label, lang, longdesc, maxlength, media, method, multiple, name, nohref, noshade, nowrap, prompt, readonly, rel, rev, rows, rowspan, rules, scope, selected, shape, size, span, start, summary, tabindex, target, title, type, usemap, valign, value, vspace, width, itemprop

Note that the id attribute is not whitelisted.

Contributing

Want to contribute? Great! There are two ways to add markups.

Commands

If your markup is in a language other than Ruby, drop a translator script in lib/github/commands which accepts input on STDIN and returns HTML on STDOUT. See rest2html for an example.

Once your script is in place, edit lib/github/markups.rb and tell GitHub Markup about it. Again we look to rest2html for guidance:

command(:rest2html, /re?st(.txt)?/)

Here we're telling GitHub Markup of the existence of a rest2html command which should be used for any file ending in rest, rst, rest.txt or rst.txt. Any regular expression will do.

Finally add your tests. Create a README.extension in test/markups along with a README.extension.html. As you may imagine, the README.extension should be your known input and the README.extension.html should be the desired output.

Now run the tests: rake

If nothing complains, congratulations!

Classes

If your markup can be translated using a Ruby library, that's great. Check out lib/github/markups.rb for some examples. Let's look at Markdown:

markup(:markdown, /md|mkdn?|markdown/) do |content|
  Markdown.new(content).to_html
end

We give the markup method three bits of information: the name of the file to require, a regular expression for extensions to match, and a block to run with unformatted markup which should return HTML.

If you need to monkeypatch a RubyGem or something, check out the included RDoc example.

Tests should be added in the same manner as described under the Commands section.

Installation

gem install github-markup

Usage

require 'github/markup'
GitHub::Markup.render('README.markdown', "* One\n* Two")

Or, more realistically:

require 'github/markup'
GitHub::Markup.render(file, File.read(file))

Testing

To run the tests:

$ rake

To add tests see the Commands section earlier in this README.

Contributing

  1. Fork it.
  2. Create a branch (git checkout -b my_markup)
  3. Commit your changes (git commit -am "Added Snarkdown")
  4. Push to the branch (git push origin my_markup)
  5. Open a Pull Request
  6. Enjoy a refreshing Diet Coke and wait
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