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CodeHilite Extension for Python-Markdown
Adds code/syntax highlighting to standard Python-Markdown code blocks.
See <>
for documentation.
Original code Copyright 2006-2008 [Waylan Limberg](
All changes Copyright 2008-2014 The Python Markdown Project
License: [BSD](
from . import Extension
from ..treeprocessors import Treeprocessor
from pygments import highlight
from pygments.lexers import get_lexer_by_name, guess_lexer
from pygments.formatters import get_formatter_by_name
pygments = True
except ImportError:
pygments = False
def parse_hl_lines(expr):
"""Support our syntax for emphasizing certain lines of code.
expr should be like '1 2' to emphasize lines 1 and 2 of a code block.
Returns a list of ints, the line numbers to emphasize.
if not expr:
return []
return list(map(int, expr.split()))
except ValueError:
return []
# ------------------ The Main CodeHilite Class ----------------------
class CodeHilite:
Determine language of source code, and pass it into pygments hilighter.
Basic Usage:
>>> code = CodeHilite(src = 'some text')
>>> html = code.hilite()
* src: Source string or any object with a .readline attribute.
* linenums: (Boolean) Set line numbering to 'on' (True),
'off' (False) or 'auto'(None). Set to 'auto' by default.
* guess_lang: (Boolean) Turn language auto-detection
'on' or 'off' (on by default).
* css_class: Set class name of wrapper div ('codehilite' by default).
* hl_lines: (List of integers) Lines to emphasize, 1-indexed.
Low Level Usage:
>>> code = CodeHilite()
>>> code.src = 'some text' # String or anything with a .readline attr.
>>> code.linenos = True # Turns line numbering on or of.
>>> html = code.hilite()
def __init__(self, src=None, linenums=None, guess_lang=True,
css_class="codehilite", lang=None, style='default',
noclasses=False, tab_length=4, hl_lines=None, use_pygments=True):
self.src = src
self.lang = lang
self.linenums = linenums
self.guess_lang = guess_lang
self.css_class = css_class = style
self.noclasses = noclasses
self.tab_length = tab_length
self.hl_lines = hl_lines or []
self.use_pygments = use_pygments
def hilite(self):
Pass code to the [Pygments]( highliter with
optional line numbers. The output should then be styled with css to
your liking. No styles are applied by default - only styling hooks
(i.e.: <span class="k">).
returns : A string of html.
self.src = self.src.strip('\n')
if self.lang is None:
if pygments and self.use_pygments:
lexer = get_lexer_by_name(self.lang)
except ValueError:
if self.guess_lang:
lexer = guess_lexer(self.src)
lexer = get_lexer_by_name('text')
except ValueError:
lexer = get_lexer_by_name('text')
formatter = get_formatter_by_name('html',
return highlight(self.src, lexer, formatter)
# just escape and build markup usable by JS highlighting libs
txt = self.src.replace('&', '&amp;')
txt = txt.replace('<', '&lt;')
txt = txt.replace('>', '&gt;')
txt = txt.replace('"', '&quot;')
classes = []
if self.lang:
classes.append('language-%s' % self.lang)
if self.linenums:
class_str = ''
if classes:
class_str = ' class="%s"' % ' '.join(classes)
return '<pre class="%s"><code%s>%s</code></pre>\n' % \
(self.css_class, class_str, txt)
def _parseHeader(self):
Determines language of a code block from shebang line and whether said
line should be removed or left in place. If the sheband line contains a
path (even a single /) then it is assumed to be a real shebang line and
left alone. However, if no path is given (e.i.: #!python or :::python)
then it is assumed to be a mock shebang for language identifitation of
a code fragment and removed from the code block prior to processing for
code highlighting. When a mock shebang (e.i: #!python) is found, line
numbering is turned on. When colons are found in place of a shebang
(e.i.: :::python), line numbering is left in the current state - off
by default.
Also parses optional list of highlight lines, like:
:::python hl_lines="1 3"
import re
# split text into lines
lines = self.src.split("\n")
# pull first line to examine
fl = lines.pop(0)
c = re.compile(r'''
(?:(?:^::+)|(?P<shebang>^[#]!)) # Shebang or 2 or more colons
(?P<path>(?:/\w+)*[/ ])? # Zero or 1 path
(?P<lang>[\w#.+-]*) # The language
\s* # Arbitrary whitespace
# Optional highlight lines, single- or double-quote-delimited
''', re.VERBOSE)
# search first line for shebang
m =
if m:
# we have a match
self.lang ='lang').lower()
except IndexError:
self.lang = None
# path exists - restore first line
lines.insert(0, fl)
if self.linenums is None and'shebang'):
# Overridable and Shebang exists - use line numbers
self.linenums = True
self.hl_lines = parse_hl_lines('hl_lines'))
# No match
lines.insert(0, fl)
self.src = "\n".join(lines).strip("\n")
# ------------------ The Markdown Extension -------------------------------
class HiliteTreeprocessor(Treeprocessor):
""" Hilight source code in code blocks. """
def code_unescape(self, text):
"""Unescape code."""
text = text.replace("&amp;", "&")
text = text.replace("&lt;", "<")
text = text.replace("&gt;", ">")
return text
def run(self, root):
""" Find code blocks and store in htmlStash. """
blocks = root.iter('pre')
for block in blocks:
if len(block) == 1 and block[0].tag == 'code':
code = CodeHilite(
placeholder =
# Clear codeblock in etree instance
# Change to p element which will later
# be removed when inserting raw html
block.tag = 'p'
block.text = placeholder
class CodeHiliteExtension(Extension):
""" Add source code hilighting to markdown codeblocks. """
def __init__(self, **kwargs):
# define default configs
self.config = {
'linenums': [None,
"Use lines numbers. True=yes, False=no, None=auto"],
'guess_lang': [True,
"Automatic language detection - Default: True"],
'css_class': ["codehilite",
"Set class name for wrapper <div> - "
"Default: codehilite"],
'pygments_style': ['default',
'Pygments HTML Formatter Style '
'(Colorscheme) - Default: default'],
'noclasses': [False,
'Use inline styles instead of CSS classes - '
'Default false'],
'use_pygments': [True,
'Use Pygments to Highlight code blocks. '
'Disable if using a JavaScript library. '
'Default: True']
def extendMarkdown(self, md):
""" Add HilitePostprocessor to Markdown instance. """
hiliter = HiliteTreeprocessor(md)
hiliter.config = self.getConfigs()
md.treeprocessors.register(hiliter, 'hilite', 30)
def makeExtension(**kwargs): # pragma: no cover
return CodeHiliteExtension(**kwargs)
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