Markdown CodeHilite Extension achinghead.com

Summary

The Markdown CodeHilite Extension adds code/syntax highlighting to standard Python-Markdown code blocks using Pygments.

NOTE: This document is out-of-date. A more recent version of this document is available at the official Python-Markdown site. All future improvements and additions will be tracked there.

Get the Code

You can view the latest code or download version 0.2.

Previous Versions

(https://code.achinghead.com/browser/mdx/codehilite/tags/mdx_codehilite-0.1/)

Dependencies

Python 2.3+
Markdown 1.7+
[Pygments] (http://pygments.org/)

License

The Markdown CodeHilite Extension is licensed under the BSD License.

Installation

After downloading, copy the file mdx_codehilite.py to a location on your PYTHONPATH.

You will also need to download and install the Pygments package on your PYTHONPATH. You will need to determine the appropriate CSS classes and create appropriate rules for them, which are either defined in or linked from the header of your HTML templates. See the excellent documentation for more details. If no language is defined, Pygments will attempt to guess the language. When that fails, the code block will display as un-highlighted code.

Note: The css and/or javascript is not included as part of this extension but shall always be provided by the end user.

Syntax

Mdx_codehilite follows the same syntax as regular Markdown code blocks, with one exception. The hiliter needs to know what language to use for the code block. There are three ways to tell the hiliter what language the code block contains and each one has a different result.

SheBang (with path)

If the first line of the codeblock contains a shebang, the language is derived from that and line numbers are used.

    #!/usr/bin/python
    # Code goes here ...

Will result in:

1 2	#!/usr/bin/python # Code goes here ...

SheBang (no path)

If the first line contains a shebang, but the shebang line does not contain a path (a single / or even a space), then that line is removed from the code block before processing. Line numbers are used.

    #!python
    # Code goes here ...

Will result in:

1	# Code goes here ...

Colons

If the first line begins with three or more colons, the text following the colons identifies the language. The first line is removed from the code block before processing and line numbers are not used.

    :::python
    # Code goes here ...

Will result in:

# Code goes here ...

When No Language is Defined

CodeHilite is completely backward compatible so that if a code block is encountered that does not define a language, the block is simple wrapped in <pre> tags and output. Note: one exception would be that the Pygments highlighting engine will try to guess the language. Upon failure, the same behavior will happen as described here.

    # Code goes here ...

Will result in:

# Code goes here ...

Lets see the source for that:

<div class="codehilite" ><pre># Code goes here ...
</pre></div>

Usage

From the Python interpreter:

>>> import markdown
>>> md = markdown.markdown(text, ['codehilite'])
>>> html = str(md)

To use with other extensions, just add them to the list, like this:

>>> md = markdown.markdown(text, ['codehilite', 'wikilink', 'footnotes'])

CodeHilite can also be called from the command line using Markdown's -x parameter, like so:

python markdown.py -x codehilite source.txt > output.html

Forcing Line Numbers

If you want every code block to have line numbers, even when using colons (:::) for language identification, the setting force_linenos is available to do so.

>>> md = markdown.markdown(text, 
...     ['codehilite(force_linenos=True)']
... )

Misc

For more info you may want to read my blog posts related to markdown. The Python Markdown mailing list should be of assistance should you need help getting things to work. Bug reports and improvements are welcome (waylan [AT] gmail [DOT] com).

achinghead.com