Default to a basic DFHack-specific pygments lexer (supporting comments and prompts)

conf.py

@@ -195,6 +195,7 @@ needs_sphinx = '1.8'
 extensions = [
     'sphinx.ext.extlinks',
     'dfhack.changelog',
+    'dfhack.lexer',
 ]
 
 # This config value must be a dictionary of external sites, mapping unique
@@ -283,7 +284,7 @@ default_role = 'ref'
 pygments_style = 'sphinx'
 
 # The default language to highlight source code in.
-highlight_language = 'none'
+highlight_language = 'dfhack'
 
 # If true, `todo` and `todoList` produce output, else they produce nothing.
 todo_include_todos = False

docs/sphinx_extensions/dfhack/lexer.py

@@ -0,0 +1,34 @@
+# adapted from:
+#   https://stackoverflow.com/a/16470058
+#   https://pygments.org/docs/lexerdevelopment/
+
+import re
+
+from pygments.lexer import RegexLexer
+from pygments.token import Comment, Generic, Text
+from sphinx.highlighting import lexers
+
+class DFHackLexer(RegexLexer):
+    name = 'DFHack'
+    aliases = ['dfhack']
+    flags = re.IGNORECASE | re.MULTILINE
+
+    tokens = {
+        'root': [
+            (r'\#.+$', Comment.Single),
+            (r'^\[[a-z]+\]\# ', Generic.Prompt),
+            (r'.+?', Text),
+        ]
+    }
+
+def register_lexer(app):
+    lexers['dfhack'] = DFHackLexer()
+
+def setup(app):
+    app.connect('builder-inited', register_lexer)
+
+    return {
+        'version': '0.1',
+        'parallel_read_safe': True,
+        'parallel_write_safe': True,
+    }