Check in a simple pure-python based Markdown previewer.

third_party/Python-Markdown/markdown/extensions/extra.py

+"""
+Python-Markdown Extra Extension
+===============================
+
+A compilation of various Python-Markdown extensions that imitates
+[PHP Markdown Extra](http://michelf.com/projects/php-markdown/extra/).
+
+Note that each of the individual extensions still need to be available
+on your PYTHONPATH. This extension simply wraps them all up as a
+convenience so that only one extension needs to be listed when
+initiating Markdown. See the documentation for each individual
+extension for specifics about that extension.
+
+There may be additional extensions that are distributed with
+Python-Markdown that are not included here in Extra. Those extensions
+are not part of PHP Markdown Extra, and therefore, not part of
+Python-Markdown Extra. If you really would like Extra to include
+additional extensions, we suggest creating your own clone of Extra
+under a differant name. You could also edit the `extensions` global
+variable defined below, but be aware that such changes may be lost
+when you upgrade to any future version of Python-Markdown.
+
+See <https://pythonhosted.org/Markdown/extensions/extra.html>
+for documentation.
+
+Copyright The Python Markdown Project
+
+License: [BSD](http://www.opensource.org/licenses/bsd-license.php)
+
+"""
+
+from __future__ import absolute_import
+from __future__ import unicode_literals
+from . import Extension
+from ..blockprocessors import BlockProcessor
+from .. import util
+import re
+
+extensions = [
+    'markdown.extensions.smart_strong',
+    'markdown.extensions.fenced_code',
+    'markdown.extensions.footnotes',
+    'markdown.extensions.attr_list',
+    'markdown.extensions.def_list',
+    'markdown.extensions.tables',
+    'markdown.extensions.abbr'
+]
+
+
+class ExtraExtension(Extension):
+    """ Add various extensions to Markdown class."""
+
+    def __init__(self, *args, **kwargs):
+        """ config is a dumb holder which gets passed to actual ext later. """
+        self.config = kwargs.pop('configs', {})
+        self.config.update(kwargs)
+
+    def extendMarkdown(self, md, md_globals):
+        """ Register extension instances. """
+        md.registerExtensions(extensions, self.config)
+        if not md.safeMode:
+            # Turn on processing of markdown text within raw html
+            md.preprocessors['html_block'].markdown_in_raw = True
+            md.parser.blockprocessors.add('markdown_block',
+                                          MarkdownInHtmlProcessor(md.parser),
+                                          '_begin')
+            md.parser.blockprocessors.tag_counter = -1
+            md.parser.blockprocessors.contain_span_tags = re.compile(
+                r'^(p|h[1-6]|li|dd|dt|td|th|legend|address)$', re.IGNORECASE)
+
+
+def makeExtension(*args, **kwargs):
+    return ExtraExtension(*args, **kwargs)
+
+
+class MarkdownInHtmlProcessor(BlockProcessor):
+    """Process Markdown Inside HTML Blocks."""
+    def test(self, parent, block):
+        return block == util.TAG_PLACEHOLDER % \
+            str(self.parser.blockprocessors.tag_counter + 1)
+
+    def _process_nests(self, element, block):
+        """Process the element's child elements in self.run."""
+        # Build list of indexes of each nest within the parent element.
+        nest_index = []  # a list of tuples: (left index, right index)
+        i = self.parser.blockprocessors.tag_counter + 1
+        while len(self._tag_data) > i and self._tag_data[i]['left_index']:
+            left_child_index = self._tag_data[i]['left_index']
+            right_child_index = self._tag_data[i]['right_index']
+            nest_index.append((left_child_index - 1, right_child_index))
+            i += 1
+
+        # Create each nest subelement.
+        for i, (left_index, right_index) in enumerate(nest_index[:-1]):
+            self.run(element, block[left_index:right_index],
+                     block[right_index:nest_index[i + 1][0]], True)
+        self.run(element, block[nest_index[-1][0]:nest_index[-1][1]],  # last
+                 block[nest_index[-1][1]:], True)                      # nest
+
+    def run(self, parent, blocks, tail=None, nest=False):
+        self._tag_data = self.parser.markdown.htmlStash.tag_data
+
+        self.parser.blockprocessors.tag_counter += 1
+        tag = self._tag_data[self.parser.blockprocessors.tag_counter]
+
+        # Create Element
+        markdown_value = tag['attrs'].pop('markdown')
+        element = util.etree.SubElement(parent, tag['tag'], tag['attrs'])
+
+        # Slice Off Block
+        if nest:
+            self.parser.parseBlocks(parent, tail)  # Process Tail
+            block = blocks[1:]
+        else:  # includes nests since a third level of nesting isn't supported
+            block = blocks[tag['left_index'] + 1: tag['right_index']]
+            del blocks[:tag['right_index']]
+
+        # Process Text
+        if (self.parser.blockprocessors.contain_span_tags.match(  # Span Mode
+                tag['tag']) and markdown_value != 'block') or \
+                markdown_value == 'span':
+            element.text = '\n'.join(block)
+        else:                                                     # Block Mode
+            i = self.parser.blockprocessors.tag_counter + 1
+            if len(self._tag_data) > i and self._tag_data[i]['left_index']:
+                first_subelement_index = self._tag_data[i]['left_index'] - 1
+                self.parser.parseBlocks(
+                    element, block[:first_subelement_index])
+                if not nest:
+                    block = self._process_nests(element, block)
+            else:
+                self.parser.parseBlocks(element, block)