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

third_party/markdown/preprocessors.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.
+
+
+"""
+PRE-PROCESSORS
+=============================================================================
+
+Preprocessors work on source text before we start doing anything too
+complicated. 
+"""
+
+from __future__ import absolute_import
+from __future__ import unicode_literals
+from . import util
+from . import odict
+import re
+
+
+def build_preprocessors(md_instance, **kwargs):
+    """ Build the default set of preprocessors used by Markdown. """
+    preprocessors = odict.OrderedDict()
+    preprocessors['normalize_whitespace'] = NormalizeWhitespace(md_instance)
+    if md_instance.safeMode != 'escape':
+        preprocessors["html_block"] = HtmlBlockPreprocessor(md_instance)
+    preprocessors["reference"] = ReferencePreprocessor(md_instance)
+    return preprocessors
+
+
+class Preprocessor(util.Processor):
+    """
+    Preprocessors are run after the text is broken into lines.
+
+    Each preprocessor implements a "run" method that takes a pointer to a
+    list of lines of the document, modifies it as necessary and returns
+    either the same pointer or a pointer to a new list.
+
+    Preprocessors must extend markdown.Preprocessor.
+
+    """
+    def run(self, lines):
+        """
+        Each subclass of Preprocessor should override the `run` method, which
+        takes the document as a list of strings split by newlines and returns
+        the (possibly modified) list of lines.
+
+        """
+        pass
+
+
+class NormalizeWhitespace(Preprocessor):
+    """ Normalize whitespace for consistant parsing. """
+
+    def run(self, lines):
+        source = '\n'.join(lines)
+        source = source.replace(util.STX, "").replace(util.ETX, "")
+        source = source.replace("\r\n", "\n").replace("\r", "\n") + "\n\n"
+        source = source.expandtabs(self.markdown.tab_length)
+        source = re.sub(r'(?<=\n) +\n', '\n', source)
+        return source.split('\n')
+
+
+class HtmlBlockPreprocessor(Preprocessor):
+    """Remove html blocks from the text and store them for later retrieval."""
+
+    right_tag_patterns = ["</%s>", "%s>"]
+    attrs_pattern = r"""
+        \s+(?P<attr>[^>"'/= ]+)=(?P<q>['"])(?P<value>.*?)(?P=q)   # attr="value"
+        |                                                         # OR 
+        \s+(?P<attr1>[^>"'/= ]+)=(?P<value1>[^> ]+)               # attr=value
+        |                                                         # OR
+        \s+(?P<attr2>[^>"'/= ]+)                                  # attr
+        """
+    left_tag_pattern = r'^\<(?P<tag>[^> ]+)(?P<attrs>(%s)*)\s*\/?\>?' % attrs_pattern
+    attrs_re = re.compile(attrs_pattern, re.VERBOSE)
+    left_tag_re = re.compile(left_tag_pattern, re.VERBOSE)
+    markdown_in_raw = False
+
+    def _get_left_tag(self, block):
+        m = self.left_tag_re.match(block)
+        if m:
+            tag = m.group('tag')
+            raw_attrs = m.group('attrs')
+            attrs = {}
+            if raw_attrs:
+                for ma in self.attrs_re.finditer(raw_attrs):
+                    if ma.group('attr'):
+                        if ma.group('value'):
+                            attrs[ma.group('attr').strip()] = ma.group('value')
+                        else:
+                            attrs[ma.group('attr').strip()] = ""
+                    elif ma.group('attr1'):
+                        if ma.group('value1'):
+                            attrs[ma.group('attr1').strip()] = ma.group('value1')
+                        else:
+                            attrs[ma.group('attr1').strip()] = ""
+                    elif ma.group('attr2'):
+                        attrs[ma.group('attr2').strip()] = ""
+            return tag, len(m.group(0)), attrs
+        else:
+            tag = block[1:].split(">", 1)[0].lower()
+            return tag, len(tag)+2, {}
+
+    def _recursive_tagfind(self, ltag, rtag, start_index, block):
+        while 1:
+            i = block.find(rtag, start_index)
+            if i == -1:
+                return -1
+            j = block.find(ltag, start_index) 
+            # if no ltag, or rtag found before another ltag, return index
+            if (j > i or j == -1):
+                return i + len(rtag)
+            # another ltag found before rtag, use end of ltag as starting
+            # point and search again
+            j = block.find('>', j)
+            start_index = self._recursive_tagfind(ltag, rtag, j + 1, block)
+            if start_index == -1:
+                # HTML potentially malformed- ltag has no corresponding 
+                # rtag
+                return -1
+
+    def _get_right_tag(self, left_tag, left_index, block):
+        for p in self.right_tag_patterns:
+            tag = p % left_tag
+            i = self._recursive_tagfind("<%s" % left_tag, tag, left_index, block)
+            if i > 2:
+                return tag.lstrip("<").rstrip(">"), i
+        return block.rstrip()[-left_index:-1].lower(), len(block)
+    
+    def _equal_tags(self, left_tag, right_tag):
+        if left_tag[0] in ['?', '@', '%']: # handle PHP, etc.
+            return True
+        if ("/" + left_tag) == right_tag:
+            return True
+        if (right_tag == "--" and left_tag == "--"):
+            return True
+        elif left_tag == right_tag[1:] \
+            and right_tag[0] == "/":
+            return True
+        else:
+            return False
+
+    def _is_oneliner(self, tag):
+        return (tag in ['hr', 'hr/'])
+
+    def run(self, lines):
+        text = "\n".join(lines)
+        new_blocks = []
+        text = text.rsplit("\n\n")
+        items = []
+        left_tag = ''
+        right_tag = ''
+        in_tag = False # flag
+
+        while text:
+            block = text[0]
+            if block.startswith("\n"):
+                block = block[1:]
+            text = text[1:]
+
+            if block.startswith("\n"):
+                block = block[1:]
+
+            if not in_tag:
+                if block.startswith("<") and len(block.strip()) > 1:
+
+                    if block[1] == "!":
+                        # is a comment block
+                        left_tag, left_index, attrs  = "--", 2, {}
+                    else:
+                        left_tag, left_index, attrs = self._get_left_tag(block)
+                    right_tag, data_index = self._get_right_tag(left_tag, 
+                                                                left_index,
+                                                                block)
+                    # keep checking conditions below and maybe just append
+                    
+                    if data_index < len(block) \
+                        and (util.isBlockLevel(left_tag)
+                        or left_tag == '--'): 
+                        text.insert(0, block[data_index:])
+                        block = block[:data_index]
+
+                    if not (util.isBlockLevel(left_tag) \
+                        or block[1] in ["!", "?", "@", "%"]):
+                        new_blocks.append(block)
+                        continue
+
+                    if self._is_oneliner(left_tag):
+                        new_blocks.append(block.strip())
+                        continue
+
+                    if block.rstrip().endswith(">") \
+                        and self._equal_tags(left_tag, right_tag):
+                        if self.markdown_in_raw and 'markdown' in attrs.keys():
+                            start = re.sub(r'\smarkdown(=[\'"]?[^> ]*[\'"]?)?', 
+                                           '', block[:left_index])
+                            end = block[-len(right_tag)-2:]
+                            block = block[left_index:-len(right_tag)-2]
+                            new_blocks.append(
+                                self.markdown.htmlStash.store(start))
+                            new_blocks.append(block)
+                            new_blocks.append(
+                                self.markdown.htmlStash.store(end))
+                        else:
+                            new_blocks.append(
+                                self.markdown.htmlStash.store(block.strip()))
+                        continue
+                    else: 
+                        # if is block level tag and is not complete
+
+                        if util.isBlockLevel(left_tag) or left_tag == "--" \
+                            and not block.rstrip().endswith(">"):
+                            items.append(block.strip())
+                            in_tag = True
+                        else:
+                            new_blocks.append(
+                            self.markdown.htmlStash.store(block.strip()))
+
+                        continue
+
+                new_blocks.append(block)
+
+            else:
+                items.append(block)
+
+                right_tag, data_index = self._get_right_tag(left_tag, 0, block)
+
+                if self._equal_tags(left_tag, right_tag):
+                    # if find closing tag
+                    
+                    if data_index < len(block):
+                        # we have more text after right_tag
+                        items[-1] = block[:data_index]
+                        text.insert(0, block[data_index:])
+
+                    in_tag = False
+                    if self.markdown_in_raw and 'markdown' in attrs.keys():
+                        start = re.sub(r'\smarkdown(=[\'"]?[^> ]*[\'"]?)?', 
+                                       '', items[0][:left_index])
+                        items[0] = items[0][left_index:]
+                        end = items[-1][-len(right_tag)-2:]
+                        items[-1] = items[-1][:-len(right_tag)-2]
+                        new_blocks.append(
+                            self.markdown.htmlStash.store(start))
+                        new_blocks.extend(items)
+                        new_blocks.append(
+                            self.markdown.htmlStash.store(end))
+                    else:
+                        new_blocks.append(
+                            self.markdown.htmlStash.store('\n\n'.join(items)))
+                    items = []
+
+        if items:
+            if self.markdown_in_raw and 'markdown' in attrs.keys():
+                start = re.sub(r'\smarkdown(=[\'"]?[^> ]*[\'"]?)?', 
+                               '', items[0][:left_index])
+                items[0] = items[0][left_index:]
+                end = items[-1][-len(right_tag)-2:]
+                items[-1] = items[-1][:-len(right_tag)-2]
+                new_blocks.append(
+                    self.markdown.htmlStash.store(start))
+                new_blocks.extend(items)
+                if end.strip():
+                    new_blocks.append(
+                        self.markdown.htmlStash.store(end))
+            else:
+                new_blocks.append(
+                    self.markdown.htmlStash.store('\n\n'.join(items)))
+            #new_blocks.append(self.markdown.htmlStash.store('\n\n'.join(items)))
+            new_blocks.append('\n')
+
+        new_text = "\n\n".join(new_blocks)
+        return new_text.split("\n")
+
+
+class ReferencePreprocessor(Preprocessor):
+    """ Remove reference definitions from text and store for later use. """
+
+    TITLE = r'[ ]*(\"(.*)\"|\'(.*)\'|\((.*)\))[ ]*'
+    RE = re.compile(r'^[ ]{0,3}\[([^\]]*)\]:\s*([^ ]*)[ ]*(%s)?$' % TITLE, re.DOTALL)
+    TITLE_RE = re.compile(r'^%s$' % TITLE)
+
+    def run (self, lines):
+        new_text = [];
+        while lines:
+            line = lines.pop(0)
+            m = self.RE.match(line)
+            if m:
+                id = m.group(1).strip().lower()
+                link = m.group(2).lstrip('<').rstrip('>')
+                t = m.group(5) or m.group(6) or m.group(7)
+                if not t:
+                    # Check next line for title
+                    tm = self.TITLE_RE.match(lines[0])
+                    if tm:
+                        lines.pop(0)
+                        t = tm.group(2) or tm.group(3) or tm.group(4)
+                self.markdown.references[id] = (link, t)
+            else:
+                new_text.append(line)
+
+        return new_text #+ "\n"