331 lines
13 KiB
Python
331 lines
13 KiB
Python
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"""
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CodeHilite Extension for Python-Markdown
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========================================
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Adds code/syntax highlighting to standard Python-Markdown code blocks.
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See <https://Python-Markdown.github.io/extensions/code_hilite>
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for documentation.
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Original code Copyright 2006-2008 [Waylan Limberg](http://achinghead.com/).
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All changes Copyright 2008-2014 The Python Markdown Project
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License: [BSD](https://opensource.org/licenses/bsd-license.php)
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"""
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from . import Extension
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from ..treeprocessors import Treeprocessor
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from ..util import parseBoolValue
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try: # pragma: no cover
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from pygments import highlight
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from pygments.lexers import get_lexer_by_name, guess_lexer
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from pygments.formatters import get_formatter_by_name
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from pygments.util import ClassNotFound
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pygments = True
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except ImportError: # pragma: no cover
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pygments = False
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def parse_hl_lines(expr):
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"""Support our syntax for emphasizing certain lines of code.
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expr should be like '1 2' to emphasize lines 1 and 2 of a code block.
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Returns a list of ints, the line numbers to emphasize.
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"""
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if not expr:
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return []
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try:
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return list(map(int, expr.split()))
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except ValueError: # pragma: no cover
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return []
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# ------------------ The Main CodeHilite Class ----------------------
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class CodeHilite:
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"""
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Determine language of source code, and pass it on to the Pygments highlighter.
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Usage:
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code = CodeHilite(src=some_code, lang='python')
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html = code.hilite()
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Arguments:
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* `src`: Source string or any object with a `.readline` attribute.
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* `lang`: String name of Pygments lexer to use for highlighting. Default: `None`.
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* `guess_lang`: Auto-detect which lexer to use. Ignored if `lang` is set to a valid
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value. Default: `True`.
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* `use_pygments`: Pass code to Pygments for code highlighting. If `False`, the code is
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instead wrapped for highlighting by a JavaScript library. Default: `True`.
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* `pygments_formatter`: The name of a Pygments formatter or a formatter class used for
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highlighting the code blocks. Default: `html`.
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* `linenums`: An alias to Pygments `linenos` formatter option. Default: `None`.
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* `css_class`: An alias to Pygments `cssclass` formatter option. Default: 'codehilite'.
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* `lang_prefix`: Prefix prepended to the language. Default: "language-".
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Other Options:
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Any other options are accepted and passed on to the lexer and formatter. Therefore,
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valid options include any options which are accepted by the `html` formatter or
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whichever lexer the code's language uses. Note that most lexers do not have any
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options. However, a few have very useful options, such as PHP's `startinline` option.
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Any invalid options are ignored without error.
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Formatter options: https://pygments.org/docs/formatters/#HtmlFormatter
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Lexer Options: https://pygments.org/docs/lexers/
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Additionally, when Pygments is enabled, the code's language is passed to the
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formatter as an extra option `lang_str`, whose value being `{lang_prefix}{lang}`.
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This option has no effect to the Pygments' builtin formatters.
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Advanced Usage:
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code = CodeHilite(
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src = some_code,
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lang = 'php',
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startinline = True, # Lexer option. Snippet does not start with `<?php`.
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linenostart = 42, # Formatter option. Snippet starts on line 42.
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hl_lines = [45, 49, 50], # Formatter option. Highlight lines 45, 49, and 50.
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linenos = 'inline' # Formatter option. Avoid alignment problems.
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)
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html = code.hilite()
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"""
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def __init__(self, src, **options):
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self.src = src
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self.lang = options.pop('lang', None)
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self.guess_lang = options.pop('guess_lang', True)
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self.use_pygments = options.pop('use_pygments', True)
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self.lang_prefix = options.pop('lang_prefix', 'language-')
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self.pygments_formatter = options.pop('pygments_formatter', 'html')
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if 'linenos' not in options:
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options['linenos'] = options.pop('linenums', None)
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if 'cssclass' not in options:
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options['cssclass'] = options.pop('css_class', 'codehilite')
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if 'wrapcode' not in options:
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# Override Pygments default
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options['wrapcode'] = True
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# Disallow use of `full` option
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options['full'] = False
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self.options = options
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def hilite(self, shebang=True):
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"""
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Pass code to the [Pygments](https://pygments.org/) highlighter with
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optional line numbers. The output should then be styled with CSS to
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your liking. No styles are applied by default - only styling hooks
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(i.e.: `<span class="k">`).
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returns : A string of html.
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"""
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self.src = self.src.strip('\n')
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if self.lang is None and shebang:
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self._parseHeader()
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if pygments and self.use_pygments:
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try:
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lexer = get_lexer_by_name(self.lang, **self.options)
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except ValueError:
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try:
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if self.guess_lang:
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lexer = guess_lexer(self.src, **self.options)
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else:
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lexer = get_lexer_by_name('text', **self.options)
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except ValueError: # pragma: no cover
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lexer = get_lexer_by_name('text', **self.options)
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if not self.lang:
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# Use the guessed lexer's language instead
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self.lang = lexer.aliases[0]
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lang_str = f'{self.lang_prefix}{self.lang}'
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if isinstance(self.pygments_formatter, str):
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try:
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formatter = get_formatter_by_name(self.pygments_formatter, **self.options)
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except ClassNotFound:
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formatter = get_formatter_by_name('html', **self.options)
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else:
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formatter = self.pygments_formatter(lang_str=lang_str, **self.options)
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return highlight(self.src, lexer, formatter)
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else:
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# just escape and build markup usable by JavaScript highlighting libraries
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txt = self.src.replace('&', '&')
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txt = txt.replace('<', '<')
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txt = txt.replace('>', '>')
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txt = txt.replace('"', '"')
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classes = []
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if self.lang:
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classes.append('{}{}'.format(self.lang_prefix, self.lang))
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if self.options['linenos']:
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classes.append('linenums')
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class_str = ''
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if classes:
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class_str = ' class="{}"'.format(' '.join(classes))
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return '<pre class="{}"><code{}>{}\n</code></pre>\n'.format(
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self.options['cssclass'],
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class_str,
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txt
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)
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def _parseHeader(self):
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"""
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Determines language of a code block from shebang line and whether the
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said line should be removed or left in place. If the shebang line
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contains a path (even a single /) then it is assumed to be a real
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shebang line and left alone. However, if no path is given
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(e.i.: `#!python` or `:::python`) then it is assumed to be a mock shebang
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for language identification of a code fragment and removed from the
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code block prior to processing for code highlighting. When a mock
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shebang (e.i: `#!python`) is found, line numbering is turned on. When
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colons are found in place of a shebang (e.i.: `:::python`), line
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numbering is left in the current state - off by default.
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Also parses optional list of highlight lines, like:
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:::python hl_lines="1 3"
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"""
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import re
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# split text into lines
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lines = self.src.split("\n")
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# pull first line to examine
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fl = lines.pop(0)
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c = re.compile(r'''
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(?:(?:^::+)|(?P<shebang>^[#]!)) # Shebang or 2 or more colons
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(?P<path>(?:/\w+)*[/ ])? # Zero or 1 path
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(?P<lang>[\w#.+-]*) # The language
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\s* # Arbitrary whitespace
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# Optional highlight lines, single- or double-quote-delimited
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(hl_lines=(?P<quot>"|')(?P<hl_lines>.*?)(?P=quot))?
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''', re.VERBOSE)
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# search first line for shebang
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m = c.search(fl)
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if m:
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# we have a match
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try:
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self.lang = m.group('lang').lower()
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except IndexError: # pragma: no cover
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self.lang = None
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if m.group('path'):
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# path exists - restore first line
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lines.insert(0, fl)
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if self.options['linenos'] is None and m.group('shebang'):
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# Overridable and Shebang exists - use line numbers
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self.options['linenos'] = True
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self.options['hl_lines'] = parse_hl_lines(m.group('hl_lines'))
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else:
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# No match
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lines.insert(0, fl)
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self.src = "\n".join(lines).strip("\n")
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# ------------------ The Markdown Extension -------------------------------
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class HiliteTreeprocessor(Treeprocessor):
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""" Highlight source code in code blocks. """
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def code_unescape(self, text):
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"""Unescape code."""
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text = text.replace("<", "<")
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text = text.replace(">", ">")
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# Escaped '&' should be replaced at the end to avoid
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# conflicting with < and >.
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text = text.replace("&", "&")
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return text
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def run(self, root):
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""" Find code blocks and store in `htmlStash`. """
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blocks = root.iter('pre')
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for block in blocks:
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if len(block) == 1 and block[0].tag == 'code':
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local_config = self.config.copy()
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code = CodeHilite(
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self.code_unescape(block[0].text),
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tab_length=self.md.tab_length,
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style=local_config.pop('pygments_style', 'default'),
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**local_config
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)
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placeholder = self.md.htmlStash.store(code.hilite())
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# Clear code block in `etree` instance
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block.clear()
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# Change to `p` element which will later
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# be removed when inserting raw html
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block.tag = 'p'
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block.text = placeholder
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class CodeHiliteExtension(Extension):
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""" Add source code highlighting to markdown code blocks. """
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def __init__(self, **kwargs):
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# define default configs
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self.config = {
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'linenums': [None,
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"Use lines numbers. True|table|inline=yes, False=no, None=auto"],
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'guess_lang': [True,
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"Automatic language detection - Default: True"],
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'css_class': ["codehilite",
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"Set class name for wrapper <div> - "
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"Default: codehilite"],
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'pygments_style': ['default',
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'Pygments HTML Formatter Style '
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'(Colorscheme) - Default: default'],
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'noclasses': [False,
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'Use inline styles instead of CSS classes - '
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'Default false'],
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'use_pygments': [True,
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'Use Pygments to Highlight code blocks. '
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'Disable if using a JavaScript library. '
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'Default: True'],
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'lang_prefix': [
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'language-',
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'Prefix prepended to the language when use_pygments is false. Default: "language-"'
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],
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'pygments_formatter': ['html',
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'Use a specific formatter for Pygments highlighting.'
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'Default: "html"',
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],
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}
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for key, value in kwargs.items():
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if key in self.config:
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self.setConfig(key, value)
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else:
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# manually set unknown keywords.
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if isinstance(value, str):
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try:
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# Attempt to parse `str` as a boolean value
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value = parseBoolValue(value, preserve_none=True)
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except ValueError:
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pass # Assume it's not a boolean value. Use as-is.
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self.config[key] = [value, '']
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def extendMarkdown(self, md):
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""" Add `HilitePostprocessor` to Markdown instance. """
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hiliter = HiliteTreeprocessor(md)
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hiliter.config = self.getConfigs()
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md.treeprocessors.register(hiliter, 'hilite', 30)
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md.registerExtension(self)
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def makeExtension(**kwargs): # pragma: no cover
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return CodeHiliteExtension(**kwargs)
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