1 files changed, 158 insertions, 0 deletions
diff --git a/plugins/render_math/pelican_mathjax_markdown_extension.py b/plugins/render_math/pelican_mathjax_markdown_extension.py
new file mode 100755
index 0000000..e739363
--- /dev/null
+++ b/plugins/render_math/pelican_mathjax_markdown_extension.py
@@ -0,0 +1,158 @@
+# -*- coding: utf-8 -*-
+"""
+Pelican Mathjax Markdown Extension
+==================================
+An extension for the Python Markdown module that enables
+the Pelican python blog to process mathjax. This extension
+gives Pelican the ability to use Mathjax as a "first class
+citizen" of the blog
+"""
+
+import markdown
+
+from markdown.util import etree
+from markdown.util import AtomicString
+
+class PelicanMathJaxPattern(markdown.inlinepatterns.Pattern):
+    """Inline markdown processing that matches mathjax"""
+
+    def __init__(self, pelican_mathjax_extension, tag, pattern):
+        super(PelicanMathJaxPattern,self).__init__(pattern)
+        self.math_tag_class = pelican_mathjax_extension.getConfig('math_tag_class')
+        self.pelican_mathjax_extension = pelican_mathjax_extension
+        self.tag = tag
+
+    def handleMatch(self, m):
+        node = markdown.util.etree.Element(self.tag)
+        node.set('class', self.math_tag_class)
+
+        prefix = '\\(' if m.group('prefix') == '$' else m.group('prefix')
+        suffix = '\\)' if m.group('suffix') == '$' else m.group('suffix')
+        node.text = markdown.util.AtomicString(prefix + m.group('math') + suffix)
+
+        # If mathjax was successfully matched, then JavaScript needs to be added
+        # for rendering. The boolean below indicates this
+        self.pelican_mathjax_extension.mathjax_needed = True
+        return node
+
+class PelicanMathJaxCorrectDisplayMath(markdown.treeprocessors.Treeprocessor):
+    """Corrects invalid html that results from a <div> being put inside
+    a <p> for displayed math"""
+
+    def __init__(self, pelican_mathjax_extension):
+        self.pelican_mathjax_extension = pelican_mathjax_extension
+
+    def correct_html(self, root, children, div_math, insert_idx, text):
+        """Separates out <div class="math"> from the parent tag <p>. Anything
+        in between is put into its own parent tag of <p>"""
+
+        current_idx = 0
+
+        for idx in div_math:
+            el = markdown.util.etree.Element('p')
+            el.text = text
+            el.extend(children[current_idx:idx])
+
+            # Test to ensure that empty <p> is not inserted  
+            if len(el) != 0 or (el.text and not el.text.isspace()):
+               root.insert(insert_idx, el)
+               insert_idx += 1
+
+            text = children[idx].tail
+            children[idx].tail = None
+            root.insert(insert_idx, children[idx])
+            insert_idx += 1
+            current_idx = idx+1
+
+        el = markdown.util.etree.Element('p')
+        el.text = text
+        el.extend(children[current_idx:])
+
+        if len(el) != 0 or (el.text and not el.text.isspace()):
+            root.insert(insert_idx, el)
+
+    def run(self, root):
+        """Searches for <div class="math"> that are children in <p> tags and corrects
+        the invalid HTML that results"""
+
+        math_tag_class = self.pelican_mathjax_extension.getConfig('math_tag_class')
+
+        for parent in root:
+            div_math = []
+            children = list(parent)
+
+            for div in parent.findall('div'):
+                if div.get('class') == math_tag_class:
+                    div_math.append(children.index(div))
+
+            # Do not process further if no displayed math has been found
+            if not div_math:
+                continue
+
+            insert_idx = list(root).index(parent)
+            self.correct_html(root, children, div_math, insert_idx, parent.text) 
+            root.remove(parent)  # Parent must be removed last for correct insertion index
+
+        return root
+
+class PelicanMathJaxAddJavaScript(markdown.treeprocessors.Treeprocessor):
+    """Tree Processor for adding Mathjax JavaScript to the blog"""
+
+    def __init__(self, pelican_mathjax_extension):
+        self.pelican_mathjax_extension = pelican_mathjax_extension
+
+    def run(self, root):
+        # If no mathjax was present, then exit
+        if (not self.pelican_mathjax_extension.mathjax_needed):
+            return root
+
+        # Add the mathjax script to the html document
+        mathjax_script = etree.Element('script')
+        mathjax_script.set('type','text/javascript')
+        mathjax_script.text = AtomicString(self.pelican_mathjax_extension.getConfig('mathjax_script'))
+        root.append(mathjax_script)
+
+        # Reset the boolean switch to false so that script is only added
+        # to other pages if needed
+        self.pelican_mathjax_extension.mathjax_needed = False
+        return root
+
+class PelicanMathJaxExtension(markdown.Extension):
+    """A markdown extension enabling mathjax processing in Markdown for Pelican"""
+    def __init__(self, config):
+
+        try:
+            # Needed for markdown versions >= 2.5
+            self.config['mathjax_script'] = ['', 'Mathjax JavaScript script']
+            self.config['math_tag_class'] = ['math', 'The class of the tag in which mathematics is wrapped']
+            self.config['auto_insert'] = [True, 'Determines if mathjax script is automatically inserted into content']
+            super(PelicanMathJaxExtension,self).__init__(**config)
+        except AttributeError:
+            # Markdown versions < 2.5
+            config['mathjax_script'] = [config['mathjax_script'], 'Mathjax JavaScript script']
+            config['math_tag_class'] = [config['math_tag_class'], 'The class of the tag in which mathematic is wrapped']
+            config['auto_insert'] = [config['auto_insert'], 'Determines if mathjax script is automatically inserted into content']
+            super(PelicanMathJaxExtension,self).__init__(config)
+
+        # Used as a flag to determine if javascript
+        # needs to be injected into a document
+        self.mathjax_needed = False
+
+    def extendMarkdown(self, md):
+        # Regex to detect mathjax
+        mathjax_inline_regex = r'(?P<prefix>\$)(?P<math>.+?)(?P<suffix>(?<!\s)\2)'
+        mathjax_display_regex = r'(?P<prefix>\$\$|\\begin\{(.+?)\})(?P<math>.+?)(?P<suffix>\2|\\end\{\3\})'
+
+        # Process mathjax before escapes are processed since escape processing will
+        # intefer with mathjax. The order in which the displayed and inlined math
+        # is registered below matters: we should have higher priority than 'escape' which has 180
+        md.inlinePatterns.register(PelicanMathJaxPattern(self, 'div', mathjax_display_regex), 'mathjax_displayed', 186)
+        md.inlinePatterns.register(PelicanMathJaxPattern(self, 'span', mathjax_inline_regex), 'mathjax_inlined', 185)
+
+        # Correct the invalid HTML that results from teh displayed math (<div> tag within a <p> tag) 
+        md.treeprocessors.register(PelicanMathJaxCorrectDisplayMath(self), 'mathjax_correctdisplayedmath', 15)
+
+        # If necessary, add the JavaScript Mathjax library to the document. This must
+        # be last in the ordered dict (hence it is given the position '_end')
+        if self.getConfig('auto_insert'):
+            md.treeprocessors.register(PelicanMathJaxAddJavaScript(self), 'mathjax_addjavascript', 0)