Import GitHub version of Markdown fenced_code extension

(imported from commit 929de2ba09a5c6dabed20c7f1b3ba319ba42b244)

zephyr/lib/bugdown/fenced_code.py

@@ -0,0 +1,165 @@
+#!/usr/bin/env python
+
+"""
+Fenced Code Extension for Python Markdown
+=========================================
+
+This extension adds Fenced Code Blocks to Python-Markdown.
+
+    >>> import markdown
+    >>> text = '''
+    ... A paragraph before a fenced code block:
+    ...
+    ... ~~~
+    ... Fenced code block
+    ... ~~~
+    ... '''
+    >>> html = markdown.markdown(text, extensions=['fenced_code'])
+    >>> print html
+    <p>A paragraph before a fenced code block:</p>
+    <pre><code>Fenced code block
+    </code></pre>
+
+Works with safe_mode also (we check this because we are using the HtmlStash):
+
+    >>> print markdown.markdown(text, extensions=['fenced_code'], safe_mode='replace')
+    <p>A paragraph before a fenced code block:</p>
+    <pre><code>Fenced code block
+    </code></pre>
+
+Include tilde's in a code block and wrap with blank lines:
+
+    >>> text = '''
+    ... ~~~~~~~~
+    ...
+    ... ~~~~
+    ... ~~~~~~~~'''
+    >>> print markdown.markdown(text, extensions=['fenced_code'])
+    <pre><code>
+    ~~~~
+    </code></pre>
+
+Language tags:
+
+    >>> text = '''
+    ... ~~~~{.python}
+    ... # Some python code
+    ... ~~~~'''
+    >>> print markdown.markdown(text, extensions=['fenced_code'])
+    <pre><code class="python"># Some python code
+    </code></pre>
+
+Optionally backticks instead of tildes as per how github's code block markdown is identified:
+
+    >>> text = '''
+    ... `````
+    ... # Arbitrary code
+    ... ~~~~~ # these tildes will not close the block
+    ... `````'''
+    >>> print markdown.markdown(text, extensions=['fenced_code'])
+    <pre><code># Arbitrary code
+    ~~~~~ # these tildes will not close the block
+    </code></pre>
+
+Copyright 2007-2008 [Waylan Limberg](http://achinghead.com/).
+
+Project website: <http://packages.python.org/Markdown/extensions/fenced_code_blocks.html>
+Contact: markdown@freewisdom.org
+
+License: BSD (see ../docs/LICENSE for details)
+
+Dependencies:
+* [Python 2.4+](http://python.org)
+* [Markdown 2.0+](http://packages.python.org/Markdown/)
+* [Pygments (optional)](http://pygments.org)
+
+"""
+
+import re
+import markdown
+from markdown.extensions.codehilite import CodeHilite, CodeHiliteExtension
+
+# Global vars
+FENCED_BLOCK_RE = re.compile( \
+    r'(?P<fence>^(?:~{3,}|`{3,}))[ ]*(\{?\.?(?P<lang>[a-zA-Z0-9_+-]*)\}?)?[ ]*\n(?P<code>.*?)(?<=\n)(?P=fence)[ ]*$',
+    re.MULTILINE|re.DOTALL
+    )
+CODE_WRAP = '<pre><code%s>%s</code></pre>'
+LANG_TAG = ' class="%s"'
+
+class FencedCodeExtension(markdown.Extension):
+
+    def extendMarkdown(self, md, md_globals):
+        """ Add FencedBlockPreprocessor to the Markdown instance. """
+        md.registerExtension(self)
+
+        md.preprocessors.add('fenced_code_block',
+                                 FencedBlockPreprocessor(md),
+                                 "_begin")
+
+
+class FencedBlockPreprocessor(markdown.preprocessors.Preprocessor):
+
+    def __init__(self, md):
+        markdown.preprocessors.Preprocessor.__init__(self, md)
+
+        self.checked_for_codehilite = False
+        self.codehilite_conf = {}
+
+    def run(self, lines):
+        """ Match and store Fenced Code Blocks in the HtmlStash. """
+
+        # Check for code hilite extension
+        if not self.checked_for_codehilite:
+            for ext in self.markdown.registeredExtensions:
+                if isinstance(ext, CodeHiliteExtension):
+                    self.codehilite_conf = ext.config
+                    break
+
+            self.checked_for_codehilite = True
+
+        text = "\n".join(lines)
+        while 1:
+            m = FENCED_BLOCK_RE.search(text)
+            if m:
+                lang = ''
+                if m.group('lang'):
+                    lang = LANG_TAG % m.group('lang')
+
+                # If config is not empty, then the codehighlite extension
+                # is enabled, so we call it to highlite the code
+                if self.codehilite_conf:
+                    highliter = CodeHilite(m.group('code'),
+                            linenos=self.codehilite_conf['force_linenos'][0],
+                            guess_lang=self.codehilite_conf['guess_lang'][0],
+                            css_class=self.codehilite_conf['css_class'][0],
+                            style=self.codehilite_conf['pygments_style'][0],
+                            lang=(m.group('lang') or None),
+                            noclasses=self.codehilite_conf['noclasses'][0])
+
+                    code = highliter.hilite()
+                else:
+                    code = CODE_WRAP % (lang, self._escape(m.group('code')))
+
+                placeholder = self.markdown.htmlStash.store(code, safe=True)
+                text = '%s\n%s\n%s'% (text[:m.start()], placeholder, text[m.end():])
+            else:
+                break
+        return text.split("\n")
+
+    def _escape(self, txt):
+        """ basic html escaping """
+        txt = txt.replace('&', '&amp;')
+        txt = txt.replace('<', '&lt;')
+        txt = txt.replace('>', '&gt;')
+        txt = txt.replace('"', '&quot;')
+        return txt
+
+
+def makeExtension(configs=None):
+    return FencedCodeExtension(configs=configs)
+
+
+if __name__ == "__main__":
+    import doctest
+    doctest.testmod()