Escape all characters with Markdown significance (#118)

* Escape all characters with Markdown significance

There are many punctuation characters that sometimes have significance
in Markdown; more systematically escape them all (based on a new
escape_misc configuration option).

A limited attempt is made to limit the escaping of '.' and ')' to the
context where they might have Markdown significance (after a number,
where they can indicate an ordered list item); no such attempt is made
for the other characters (and even that limiting of '.' and ')' may
not be entirely safe in all cases, as it's possible the HTML could
have the number outside the block being escaped in one go,
e.g. `<span>1</span>.`.

---------

Co-authored-by: AlexVonB <AlexVonB@users.noreply.github.com>

README.rst

@@ -123,6 +123,11 @@ escape_underscores
   If set to ``False``, do not escape ``_`` to ``\_`` in text.
   Defaults to ``True``.
 
+escape_misc
+  If set to ``False``, do not escape miscellaneous punctuation characters
+  that sometimes have Markdown significance in text.
+  Defaults to ``True``.
+
 keep_inline_images_in
   Images are converted to their alt-text when the images are located inside
   headlines or table cells. If some inline images should be converted to

markdownify/__init__.py

@@ -71,6 +71,7 @@ class MarkdownConverter(object):
         default_title = False
         escape_asterisks = True
         escape_underscores = True
+        escape_misc = True
         heading_style = UNDERLINED
         keep_inline_images_in = []
         newline_style = SPACES
@@ -201,6 +202,9 @@ class MarkdownConverter(object):
     def escape(self, text):
         if not text:
             return ''
+        if self.options['escape_misc']:
+            text = re.sub(r'([\\&<`[>~#=+|-])', r'\\\1', text)
+            text = re.sub(r'([0-9])([.)])', r'\1\\\2', text)
         if self.options['escape_asterisks']:
             text = text.replace('*', r'\*')
         if self.options['escape_underscores']:

tests/test_escaping.py

@@ -12,7 +12,7 @@ def test_underscore():
 
 
 def test_xml_entities():
-    assert md('&') == '&'
+    assert md('&') == r'\&'
 
 
 def test_named_entities():
@@ -25,4 +25,23 @@ def test_hexadecimal_entities():
 
 
 def test_single_escaping_entities():
-    assert md('&') == '&'
+    assert md('&') == r'\&'
+
+
+def text_misc():
+    assert md('\\*') == r'\\\*'
+    assert md('<foo>') == r'\<foo\>'
+    assert md('# foo') == r'\# foo'
+    assert md('> foo') == r'\> foo'
+    assert md('~~foo~~') == r'\~\~foo\~\~'
+    assert md('foo\n===\n') == 'foo\n\\=\\=\\=\n'
+    assert md('---\n') == '\\-\\-\\-\n'
+    assert md('+ x\n+ y\n') == '\\+ x\n\\+ y\n'
+    assert md('`x`') == r'\`x\`'
+    assert md('[text](link)') == r'\[text](link)'
+    assert md('1. x') == r'1\. x'
+    assert md('not a number. x') == r'not a number. x'
+    assert md('1) x') == r'1\) x'
+    assert md('not a number) x') == r'not a number) x'
+    assert md('|not table|') == r'\|not table\|'
+    assert md(r'\ <foo> &amp;amp; | ` `', escape_misc=False) == r'\ <foo> &amp; | ` `'