Merge pull request #573 from navanchauhan/latex-extra

Add new LaTeX Extra

Author: nicholasserra

lib/markdown2.py

@@ -2764,6 +2764,55 @@ def sub(self, match):
     def run(self, text):
         return self.fenced_code_block_re.sub(self.sub, text)
 
+class Latex(Extra):
+    '''
+    Convert $ and $$ to <math> and </math> tags for inline and block math.
+    '''
+    name = 'latex'
+    order = (Stage.CODE_BLOCKS, FencedCodeBlocks), ()
+
+    _single_dollar_re = re.compile(r'(?<!\$)\$(?!\$)(.*?)\$')
+    _double_dollar_re = re.compile(r'\$\$(.*?)\$\$', re.DOTALL)
+    
+    # Ways to escape
+    _pre_code_block_re = re.compile(r"<pre>(.*?)</pre>", re.DOTALL) # Wraped in <pre>
+    _triple_re = re.compile(r'```(.*?)```', re.DOTALL) # Wrapped in a code block ```
+    _single_re = re.compile(r'(?<!`)(`)(.*?)(?<!`)\1(?!`)') # Wrapped in a single `
+
+    converter = None
+    code_blocks = {}
+
+    def _convert_single_match(self, match):
+        return self.converter.convert(match.group(1))
+
+    def _convert_double_match(self, match):
+        return self.converter.convert(match.group(1).replace(r"\n", ''), display="block")
+
+    def code_placeholder(self, match):
+        placeholder = f"<!--CODE_BLOCK_{len(self.code_blocks)}-->"
+        self.code_blocks[placeholder] = match.group(0)
+        return placeholder
+
+    def run(self, text):
+        try:
+            import latex2mathml.converter
+            self.converter = latex2mathml.converter
+        except ImportError:
+            raise ImportError('The "latex" extra requires the "latex2mathml" package to be installed.')
+
+        # Escape by replacing with a code block
+        text = self._pre_code_block_re.sub(self.code_placeholder, text)
+        text = self._single_re.sub(self.code_placeholder, text)
+        text = self._triple_re.sub(self.code_placeholder, text)
+
+        text = self._single_dollar_re.sub(self._convert_single_match, text)
+        text = self._double_dollar_re.sub(self._convert_double_match, text)
+
+        # Convert placeholder tag back to original code
+        for placeholder, code_block in self.code_blocks.items():
+            text = text.replace(placeholder, code_block)
+
+        return text
 
 class LinkPatterns(Extra):
     '''
@@ -3328,6 +3377,7 @@ def test(self, text):
 Breaks.register()
 CodeFriendly.register()
 FencedCodeBlocks.register()
+Latex.register()
 LinkPatterns.register()
 MarkdownInHTML.register()
 MiddleWordEm.register()

setup.py

@@ -33,7 +33,8 @@
 
 extras_require = {
     "code_syntax_highlighting": ["pygments>=2.7.3"],
-    "wavedrom": ["wavedrom; python_version>='3.7'"]
+    "wavedrom": ["wavedrom; python_version>='3.7'"],
+    "latex": ['latex2mathml; python_version>="3.8.1"'],
 }
 # nested listcomp to combine all optional extras into convenient "all" option
 extras_require["all"] = [i for v in tuple(extras_require.values()) for i in v]

test/test.py

@@ -38,7 +38,7 @@ def setup():
     setup()
     default_tags = []
     warnings = []
-    for extra_lib in ('pygments', 'wavedrom'):
+    for extra_lib in ('pygments', 'wavedrom', 'latex2mathml'):
         try:
             mod = importlib.import_module(extra_lib)
         except ImportError:

test/tm-cases/latex.html

@@ -0,0 +1,18 @@
+<h2>Simple Test</h2>
+
+<p>Inline Equations can be written as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>y</mi><mo>&#x0003D;</mo><mi>m</mi><mi>x</mi><mo>&#x0002B;</mo><mi>b</mi></mrow></math>.
+Block equations are wrapped using</p>
+
+<math xmlns="http://www.w3.org/1998/Math/MathML" display="block"><mrow><mi>x</mi><mo>&#x0003D;</mo><mfrac><mrow><mo>&#x02212;</mo><mi>b</mi><mi>&#x000B1;</mi><msqrt><mrow><msup><mi>b</mi><mn>2</mn></msup><mo>&#x02212;</mo><mn>4</mn><mi>a</mi><mi>c</mi></mrow></msqrt></mrow><mrow><mn>2</mn><mi>a</mi></mrow></mfrac></mrow></math>
+
+<p>This code block will not have the math rendered.
+<code>
+some random code, describing $a and $b will not be rendered, $y=mx$ 
+</code>
+This will not work either <code>$\sqrt{2}</code> or</p>
+
+<p><code>
+$$
+f = 12
+$$
+</code></p>

test/tm-cases/latex.opts

@@ -0,0 +1 @@
+{"extras": ["latex","latex2mathml"]}

test/tm-cases/latex.tags

@@ -0,0 +1 @@
+extra latex latex2mathml

test/tm-cases/latex.text

@@ -0,0 +1,17 @@
+## Simple Test
+Inline Equations can be written as $y=mx+b$.
+Block equations are wrapped using
+$$
+x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}
+$$
+This code block will not have the math rendered.
+```
+some random code, describing $a and $b will not be rendered, $y=mx$ 
+```
+This will not work either `$\sqrt{2}` or
+
+```
+$$
+f = 12
+$$
+```