Add support for parsing function type comments

This commit exposes two new attributes to the FunctionDef nodes, type_comment_args
respectively type_comment_annotations. These two attributes hold the type annotations
provided via type comments.

1 files changed, 17 insertions, 0 deletions

diff --git a/astroid/_ast.py b/astroid/_ast.py
index 8220e108..58a58c77 100644
--- a/astroid/_ast.py
+++ b/astroid/_ast.py
@@ -1,4 +1,6 @@
 import ast
+from collections import namedtuple
+from typing import Optional
 
 _ast_py2 = _ast_py3 = None
 try:
@@ -8,6 +10,9 @@ except ImportError:
     pass
 
 
+FunctionType = namedtuple('FunctionType', ['argtypes', 'returns'])
+
+
 def _get_parser_module(parse_python_two: bool = False):
     if parse_python_two:
         parser_module = _ast_py2
@@ -19,3 +24,15 @@ def _get_parser_module(parse_python_two: bool = False):
 def _parse(string: str,
            parse_python_two: bool = False):
     return _get_parser_module(parse_python_two=parse_python_two).parse(string)
+
+
+def parse_function_type_comment(type_comment: str) -> Optional[FunctionType]:
+    """Given a correct type comment, obtain a FunctionType object"""
+    if _ast_py3 is None:
+        return None
+
+    func_type = _ast_py3.parse(type_comment, "<type_comment>", "func_type")
+    return FunctionType(
+        argtypes=func_type.argtypes,
+        returns=func_type.returns,
+    )