Docserver: Support markdown for HTML content. Request thirdparty submission review.

third_party/markdown/blockparser.py

+# markdown is released under the BSD license
+# Copyright 2007, 2008 The Python Markdown Project (v. 1.7 and later)
+# Copyright 2004, 2005, 2006 Yuri Takhteyev (v. 0.2-1.6b)
+# Copyright 2004 Manfred Stienstra (the original version)
+# 
+# All rights reserved.
+# 
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+# 
+# *   Redistributions of source code must retain the above copyright
+#     notice, this list of conditions and the following disclaimer.
+# *   Redistributions in binary form must reproduce the above copyright
+#     notice, this list of conditions and the following disclaimer in the
+#     documentation and/or other materials provided with the distribution.
+# *   Neither the name of the <organization> nor the
+#     names of its contributors may be used to endorse or promote products
+#     derived from this software without specific prior written permission.
+# 
+# THIS SOFTWARE IS PROVIDED BY THE PYTHON MARKDOWN PROJECT ''AS IS'' AND ANY
+# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL ANY CONTRIBUTORS TO THE PYTHON MARKDOWN PROJECT
+# BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+
+
+from __future__ import unicode_literals
+from __future__ import absolute_import
+from . import util
+from . import odict
+
+class State(list):
+    """ Track the current and nested state of the parser. 
+    
+    This utility class is used to track the state of the BlockParser and 
+    support multiple levels if nesting. It's just a simple API wrapped around
+    a list. Each time a state is set, that state is appended to the end of the
+    list. Each time a state is reset, that state is removed from the end of
+    the list.
+
+    Therefore, each time a state is set for a nested block, that state must be 
+    reset when we back out of that level of nesting or the state could be
+    corrupted.
+
+    While all the methods of a list object are available, only the three
+    defined below need be used.
+
+    """
+
+    def set(self, state):
+        """ Set a new state. """
+        self.append(state)
+
+    def reset(self):
+        """ Step back one step in nested state. """
+        self.pop()
+
+    def isstate(self, state):
+        """ Test that top (current) level is of given state. """
+        if len(self):
+            return self[-1] == state
+        else:
+            return False
+
+class BlockParser:
+    """ Parse Markdown blocks into an ElementTree object. 
+    
+    A wrapper class that stitches the various BlockProcessors together,
+    looping through them and creating an ElementTree object.
+    """
+
+    def __init__(self, markdown):
+        self.blockprocessors = odict.OrderedDict()
+        self.state = State()
+        self.markdown = markdown
+
+    def parseDocument(self, lines):
+        """ Parse a markdown document into an ElementTree. 
+        
+        Given a list of lines, an ElementTree object (not just a parent Element)
+        is created and the root element is passed to the parser as the parent.
+        The ElementTree object is returned.
+        
+        This should only be called on an entire document, not pieces.
+
+        """
+        # Create a ElementTree from the lines
+        self.root = util.etree.Element(self.markdown.doc_tag)
+        self.parseChunk(self.root, '\n'.join(lines))
+        return util.etree.ElementTree(self.root)
+
+    def parseChunk(self, parent, text):
+        """ Parse a chunk of markdown text and attach to given etree node. 
+        
+        While the ``text`` argument is generally assumed to contain multiple
+        blocks which will be split on blank lines, it could contain only one
+        block. Generally, this method would be called by extensions when
+        block parsing is required. 
+        
+        The ``parent`` etree Element passed in is altered in place. 
+        Nothing is returned.
+
+        """
+        self.parseBlocks(parent, text.split('\n\n'))
+
+    def parseBlocks(self, parent, blocks):
+        """ Process blocks of markdown text and attach to given etree node. 
+        
+        Given a list of ``blocks``, each blockprocessor is stepped through
+        until there are no blocks left. While an extension could potentially
+        call this method directly, it's generally expected to be used internally.
+
+        This is a public method as an extension may need to add/alter additional
+        BlockProcessors which call this method to recursively parse a nested
+        block.
+
+        """
+        while blocks:
+            for processor in self.blockprocessors.values():
+                if processor.test(parent, blocks[0]):
+                    if processor.run(parent, blocks) is not False:
+                        # run returns True or None
+                        break
+
+