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Diffstat (limited to 'markdown/extensions/footnotes.py')
-rw-r--r-- | markdown/extensions/footnotes.py | 293 |
1 files changed, 293 insertions, 0 deletions
diff --git a/markdown/extensions/footnotes.py b/markdown/extensions/footnotes.py new file mode 100644 index 0000000..f65a79d --- /dev/null +++ b/markdown/extensions/footnotes.py @@ -0,0 +1,293 @@ +""" +========================= FOOTNOTES ================================= + +This section adds footnote handling to markdown. It can be used as +an example for extending python-markdown with relatively complex +functionality. While in this case the extension is included inside +the module itself, it could just as easily be added from outside the +module. Not that all markdown classes above are ignorant about +footnotes. All footnote functionality is provided separately and +then added to the markdown instance at the run time. + +Footnote functionality is attached by calling extendMarkdown() +method of FootnoteExtension. The method also registers the +extension to allow it's state to be reset by a call to reset() +method. + +Example: + Footnotes[^1] have a label[^label] and a definition[^!DEF]. + + [^1]: This is a footnote + [^label]: A footnote on "label" + [^!DEF]: The footnote for definition + +""" + +import re, markdown +from markdown import etree + +FN_BACKLINK_TEXT = "zz1337820767766393qq" +NBSP_PLACEHOLDER = "qq3936677670287331zz" +DEF_RE = re.compile(r'(\ ?\ ?\ ?)\[\^([^\]]*)\]:\s*(.*)') +TABBED_RE = re.compile(r'((\t)|( ))(.*)') + +class FootnoteExtension(markdown.Extension): + """ Footnote Extension. """ + + def __init__ (self, configs): + """ Setup configs. """ + self.config = {'PLACE_MARKER': + ["///Footnotes Go Here///", + "The text string that marks where the footnotes go"]} + + for key, value in configs: + self.config[key][0] = value + + self.reset() + + def extendMarkdown(self, md, md_globals): + """ Add pieces to Markdown. """ + md.registerExtension(self) + self.parser = md.parser + # Insert a preprocessor before ReferencePreprocessor + md.preprocessors.add("footnote", FootnotePreprocessor(self), + "<reference") + # Insert an inline pattern before ImageReferencePattern + FOOTNOTE_RE = r'\[\^([^\]]*)\]' # blah blah [^1] blah + md.inlinePatterns.add("footnote", FootnotePattern(FOOTNOTE_RE, self), + "<reference") + # Insert a tree-processor that would actually add the footnote div + # This must be before the inline treeprocessor so inline patterns + # run on the contents of the div. + md.treeprocessors.add("footnote", FootnoteTreeprocessor(self), + "<inline") + # Insert a postprocessor after amp_substitute oricessor + md.postprocessors.add("footnote", FootnotePostprocessor(self), + ">amp_substitute") + + def reset(self): + """ Clear the footnotes on reset. """ + self.footnotes = markdown.OrderedDict() + + def findFootnotesPlaceholder(self, root): + """ Return ElementTree Element that contains Footnote placeholder. """ + def finder(element): + for child in element: + if child.text: + if child.text.find(self.getConfig("PLACE_MARKER")) > -1: + return child, True + if child.tail: + if child.tail.find(self.getConfig("PLACE_MARKER")) > -1: + return (child, element), False + finder(child) + return None + + res = finder(root) + return res + + def setFootnote(self, id, text): + """ Store a footnote for later retrieval. """ + self.footnotes[id] = text + + def makeFootnoteId(self, id): + """ Return footnote link id. """ + return 'fn:%s' % id + + def makeFootnoteRefId(self, id): + """ Return footnote back-link id. """ + return 'fnref:%s' % id + + def makeFootnotesDiv(self, root): + """ Return div of footnotes as et Element. """ + + if not self.footnotes.keys(): + return None + + div = etree.Element("div") + div.set('class', 'footnote') + hr = etree.SubElement(div, "hr") + ol = etree.SubElement(div, "ol") + + for id in self.footnotes.keys(): + li = etree.SubElement(ol, "li") + li.set("id", self.makeFootnoteId(id)) + self.parser.parseChunk(li, self.footnotes[id]) + backlink = etree.Element("a") + backlink.set("href", "#" + self.makeFootnoteRefId(id)) + backlink.set("rev", "footnote") + backlink.set("title", "Jump back to footnote %d in the text" % \ + (self.footnotes.index(id)+1)) + backlink.text = FN_BACKLINK_TEXT + + if li.getchildren(): + node = li[-1] + if node.tag == "p": + node.text = node.text + NBSP_PLACEHOLDER + node.append(backlink) + else: + p = etree.SubElement(li, "p") + p.append(backlink) + return div + + +class FootnotePreprocessor(markdown.Preprocessor): + """ Find all footnote references and store for later use. """ + + def __init__ (self, footnotes): + self.footnotes = footnotes + + def run(self, lines): + lines = self._handleFootnoteDefinitions(lines) + text = "\n".join(lines) + return text.split("\n") + + def _handleFootnoteDefinitions(self, lines): + """ + Recursively find all footnote definitions in lines. + + Keywords: + + * lines: A list of lines of text + + Return: A list of lines with footnote definitions removed. + + """ + i, id, footnote = self._findFootnoteDefinition(lines) + + if id : + plain = lines[:i] + detabbed, theRest = self.detectTabbed(lines[i+1:]) + self.footnotes.setFootnote(id, + footnote + "\n" + + "\n".join(detabbed)) + more_plain = self._handleFootnoteDefinitions(theRest) + return plain + [""] + more_plain + else : + return lines + + def _findFootnoteDefinition(self, lines): + """ + Find the parts of a footnote definition. + + Keywords: + + * lines: A list of lines of text. + + Return: A three item tuple containing the index of the first line of a + footnote definition, the id of the definition and the body of the + definition. + + """ + counter = 0 + for line in lines: + m = DEF_RE.match(line) + if m: + return counter, m.group(2), m.group(3) + counter += 1 + return counter, None, None + + def detectTabbed(self, lines): + """ Find indented text and remove indent before further proccesing. + + Keyword arguments: + + * lines: an array of strings + + Returns: a list of post processed items and the unused + remainder of the original list + + """ + items = [] + item = -1 + i = 0 # to keep track of where we are + + def detab(line): + match = TABBED_RE.match(line) + if match: + return match.group(4) + + for line in lines: + if line.strip(): # Non-blank line + line = detab(line) + if line: + items.append(line) + i += 1 + continue + else: + return items, lines[i:] + + else: # Blank line: _maybe_ we are done. + i += 1 # advance + + # Find the next non-blank line + for j in range(i, len(lines)): + if lines[j].strip(): + next_line = lines[j]; break + else: + break # There is no more text; we are done. + + # Check if the next non-blank line is tabbed + if detab(next_line): # Yes, more work to do. + items.append("") + continue + else: + break # No, we are done. + else: + i += 1 + + return items, lines[i:] + + +class FootnotePattern(markdown.Pattern): + """ InlinePattern for footnote markers in a document's body text. """ + + def __init__(self, pattern, footnotes): + markdown.Pattern.__init__(self, pattern) + self.footnotes = footnotes + + def handleMatch(self, m): + sup = etree.Element("sup") + a = etree.SubElement(sup, "a") + id = m.group(2) + sup.set('id', self.footnotes.makeFootnoteRefId(id)) + a.set('href', '#' + self.footnotes.makeFootnoteId(id)) + a.set('rel', 'footnote') + a.text = str(self.footnotes.footnotes.index(id) + 1) + return sup + + +class FootnoteTreeprocessor(markdown.Treeprocessor): + """ Build and append footnote div to end of document. """ + + def __init__ (self, footnotes): + self.footnotes = footnotes + + def run(self, root): + footnotesDiv = self.footnotes.makeFootnotesDiv(root) + if footnotesDiv: + result = self.footnotes.findFootnotesPlaceholder(root) + if result: + node, isText = result + if isText: + node.text = None + node.getchildren().insert(0, footnotesDiv) + else: + child, element = node + ind = element.getchildren().find(child) + element.getchildren().insert(ind + 1, footnotesDiv) + child.tail = None + fnPlaceholder.parent.replaceChild(fnPlaceholder, footnotesDiv) + else: + root.append(footnotesDiv) + +class FootnotePostprocessor(markdown.Postprocessor): + """ Replace placeholders with html entities. """ + + def run(self, text): + text = text.replace(FN_BACKLINK_TEXT, "↩") + return text.replace(NBSP_PLACEHOLDER, " ") + +def makeExtension(configs=[]): + """ Return an instance of the FootnoteExtension """ + return FootnoteExtension(configs=configs) + |