Using pygments for syntax highlighting

Oct 18, 2009 - 06 p.m.

In a previous post I talked a bit about trying to get syntax highlighting working properly in blog posts. I said something or other about it being more difficult than all the implementations available would imply, but it turns out its (as suspected) just as simple as I thought it might be. The real issue was that it didn't work the way I wanted it to. So I slapped together two other implementations with features I liked. I've lost the links to those (sorry anonymous other programmers).

My version requires Beautiful Soup and Pygments and combines two features that I liked in other versions - automatically including the relevant stylesheets (cause I don't want to write my own) and understanding the code language based on the class of the page element (because using the lexer to automatically figure out the code is a crappy method).

Anywho, here is the code:

from django import template
from BeautifulSoup import BeautifulSoup
import pygments
import pygments.lexers as lexers
import pygments.formatters as formatters

register = template.Library()

@register.filter(name='pygmentize')
def pygmentize(value):
    try:
        formatter = formatters.HtmlFormatter(style='trac')
        tree = BeautifulSoup(value)
        for code in tree.findAll('code'):
            if not code['class']: code['class'] = 'text'
            lexer = lexers.get_lexer_by_name(code['class'])
            new_content = pygments.highlight(code.decodeContents(), lexer, formatter)
            new_content += u"%s" % formatter.get_style_defs('.highlight')
            code.replaceWith ( "%s\n" % new_content )
        content = str(tree)
        return content
    except KeyError:
      return value

Used like so in a template:

{{ value|pygmentize }}

If you need some instructions for putting that in place, the django book has some pointers

Anywho, back to trying to solve the rubik's cube.