Match markedjs behavior for parsing HTML linebreaks

nbconvert/filters/markdown_mistune.py

@@ -106,6 +106,8 @@ def output_latex_environment(self, m):
 
 class MarkdownWithMath(mistune.Markdown):
     def __init__(self, renderer, **kwargs):
+        kwargs["parse_block_html"] = True
+
         if "inline" not in kwargs:
             kwargs["inline"] = MathInlineLexer
         if "block" not in kwargs:
@@ -115,6 +117,18 @@ def __init__(self, renderer, **kwargs):
     def output_multiline_math(self):
         return self.inline(self.token["text"])
 
+    def output_open_html(self):
+        # This makes mistune behave more like markedjs
+        # (markedjs behing used by Jupyter Notebook and JupyterLab)
+        MathInlineGrammar.linebreak = re.compile(r'^ *\n(?!\s*$)')
+        MathInlineGrammar.text = re.compile(
+            r'^[\s\S]+?(?=[\\<!\[_*`~]|https?://| *\n|$)'
+        )
+        out = super().output_open_html()
+        MathInlineGrammar.linebreak = re.compile(r'^ {2,}\n(?!\s*$)')
+        MathInlineGrammar.text = re.compile(r'^[\s\S]+?(?=[\\<!\[_*`~]|https?://| {2,}\n|$)')
+        return out
+
 
 class IPythonRenderer(mistune.Renderer):
     def block_code(self, code, lang):