Add default language retrieval for code fences (#35)

fixes #23

myst_parser/block_tokens.py

@@ -84,7 +84,6 @@ def __init__(self, lines):
             front_matter = FrontMatter(lines)
             self.children.append(front_matter)
             start_line = front_matter.range[1]
-            print(start_line)
             lines = lines[start_line:]
         self.children.extend(tokenize(lines, start_line))
 

myst_parser/docutils_renderer.py

@@ -194,13 +194,24 @@ def render_math(self, token):
     def render_code_fence(self, token):
         if token.language.startswith("{") and token.language.endswith("}"):
             return self.render_directive(token)
-        text = token.children[0].content
-        node = nodes.literal_block(text, text, language=token.language)
-        self.current_node.append(node)
+        self.render_block_code(token, default_language=True)
 
-    def render_block_code(self, token):
+    def render_block_code(self, token, default_language=False):
+        # indented code blocks will always have no language,
+        # but for code fences, if not set, a default_language will be retrieved
         text = token.children[0].content
-        node = nodes.literal_block(text, text, language=token.language)
+        language = token.language
+        if not language and default_language:
+            try:
+                sphinx_env = self.document.settings.env
+                language = sphinx_env.temp_data.get(
+                    "highlight_language", sphinx_env.config.highlight_language
+                )
+            except AttributeError:
+                pass
+        if not language and default_language:
+            language = self.config.get("highlight_language", "")
+        node = nodes.literal_block(text, text, language=language)
         self.current_node.append(node)
 
     def render_inline_code(self, token):

tests/sphinx/sourcedirs/basic/content.md

@@ -58,3 +58,8 @@ this is a second paragraph
 [name][key]
 
 [key]: https://www.google.com "a title"
+
+```
+def func(a, b=1):
+    print(a)
+```

tests/sphinx/test_sphinx_builds/test_basic.html

@@ -157,6 +157,13 @@ <h1>
       name
      </a>
     </p>
+    <div class="highlight-default notranslate">
+     <div class="highlight">
+      <pre><span></span><span class="k">def</span> <span class="nf">func</span><span class="p">(</span><span class="n">a</span><span class="p">,</span> <span class="n">b</span><span class="o">=</span><span class="mi">1</span><span class="p">):</span>
+    <span class="nb">print</span><span class="p">(</span><span class="n">a</span><span class="p">)</span>
+</pre>
+     </div>
+    </div>
    </div>
   </div>
  </div>