Re-land "Check in a simple pure-python based Markdown previewer."

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

+"""
+Definition List Extension for Python-Markdown
+=============================================
+
+Adds parsing of Definition Lists to Python-Markdown.
+
+See <https://pythonhosted.org/Markdown/extensions/definition_lists.html>
+for documentation.
+
+Original code Copyright 2008 [Waylan Limberg](http://achinghead.com)
+
+All changes Copyright 2008-2014 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, ListIndentProcessor
+from ..util import etree
+import re
+
+
+class DefListProcessor(BlockProcessor):
+    """ Process Definition Lists. """
+
+    RE = re.compile(r'(^|\n)[ ]{0,3}:[ ]{1,3}(.*?)(\n|$)')
+    NO_INDENT_RE = re.compile(r'^[ ]{0,3}[^ :]')
+
+    def test(self, parent, block):
+        return bool(self.RE.search(block))
+
+    def run(self, parent, blocks):
+
+        raw_block = blocks.pop(0)
+        m = self.RE.search(raw_block)
+        terms = [l.strip() for l in
+                 raw_block[:m.start()].split('\n') if l.strip()]
+        block = raw_block[m.end():]
+        no_indent = self.NO_INDENT_RE.match(block)
+        if no_indent:
+            d, theRest = (block, None)
+        else:
+            d, theRest = self.detab(block)
+        if d:
+            d = '%s\n%s' % (m.group(2), d)
+        else:
+            d = m.group(2)
+        sibling = self.lastChild(parent)
+        if not terms and sibling is None:
+            # This is not a definition item. Most likely a paragraph that
+            # starts with a colon at the begining of a document or list.
+            blocks.insert(0, raw_block)
+            return False
+        if not terms and sibling.tag == 'p':
+            # The previous paragraph contains the terms
+            state = 'looselist'
+            terms = sibling.text.split('\n')
+            parent.remove(sibling)
+            # Aquire new sibling
+            sibling = self.lastChild(parent)
+        else:
+            state = 'list'
+
+        if sibling is not None and sibling.tag == 'dl':
+            # This is another item on an existing list
+            dl = sibling
+            if not terms and len(dl) and dl[-1].tag == 'dd' and len(dl[-1]):
+                state = 'looselist'
+        else:
+            # This is a new list
+            dl = etree.SubElement(parent, 'dl')
+        # Add terms
+        for term in terms:
+            dt = etree.SubElement(dl, 'dt')
+            dt.text = term
+        # Add definition
+        self.parser.state.set(state)
+        dd = etree.SubElement(dl, 'dd')
+        self.parser.parseBlocks(dd, [d])
+        self.parser.state.reset()
+
+        if theRest:
+            blocks.insert(0, theRest)
+
+
+class DefListIndentProcessor(ListIndentProcessor):
+    """ Process indented children of definition list items. """
+
+    ITEM_TYPES = ['dd']
+    LIST_TYPES = ['dl']
+
+    def create_item(self, parent, block):
+        """ Create a new dd and parse the block with it as the parent. """
+        dd = etree.SubElement(parent, 'dd')
+        self.parser.parseBlocks(dd, [block])
+
+
+class DefListExtension(Extension):
+    """ Add definition lists to Markdown. """
+
+    def extendMarkdown(self, md, md_globals):
+        """ Add an instance of DefListProcessor to BlockParser. """
+        md.parser.blockprocessors.add('defindent',
+                                      DefListIndentProcessor(md.parser),
+                                      '>indent')
+        md.parser.blockprocessors.add('deflist',
+                                      DefListProcessor(md.parser),
+                                      '>ulist')
+
+
+def makeExtension(*args, **kwargs):
+    return DefListExtension(*args, **kwargs)