Support ast.Constant

gast/gast.py

@@ -144,6 +144,7 @@ def create_node(self, *args, **kwargs):
     'FormattedValue': (('value', 'conversion', 'format_spec',),
                        ('lineno', 'col_offset',), (expr,)),
     'JoinedStr': (('values',), ('lineno', 'col_offset',), (expr,)),
+    'Constant': (('value',), ('lineno', 'col_offset',), (expr,)),
     'Bytes': (('s',), ('lineno', 'col_offset',),
               (expr,)),
     'NameConstant': (('value',), ('lineno', 'col_offset',),
@@ -256,11 +257,14 @@ def literal_eval(node_or_string):
 
 
 def get_docstring(node, clean=True):
+    import sys
     if not isinstance(node, (FunctionDef, ClassDef, Module)):
         raise TypeError("%r can't have docstrings" % node.__class__.__name__)
+    DocStringTy = Str if sys.version_info[:2] < (3, 8) else Constant
     if node.body and isinstance(node.body[0], Expr) and \
-       isinstance(node.body[0].value, Str):
+       isinstance(node.body[0].value, DocStringTy):
         if clean:
             import inspect
-            return inspect.cleandoc(node.body[0].value.s)
+            holder = node.body[0].value
+            return inspect.cleandoc(getattr(holder, holder._fields[0]))
         return node.body[0].value.s

tests/test_api.py

@@ -40,8 +40,12 @@ def test_walk(self):
         code = 'x + 1'
         tree = gast.parse(code, mode='eval')
         dump = gast.dump(tree)
-        norm = ("Expression(body=BinOp(left=Name(id='x', ctx=Load(), "
-                "annotation=None), op=Add(), right=Num(n=1)))")
+        if sys.version_info[:2] < (3, 8):
+            norm = ("Expression(body=BinOp(left=Name(id='x', ctx=Load(), "
+                    "annotation=None), op=Add(), right=Num(n=1)))")
+        else:
+            norm = ("Expression(body=BinOp(left=Name(id='x', ctx=Load(), "
+                    "annotation=None), op=Add(), right=Constant(value=1)))")
         self.assertEqual(dump, norm)
         self.assertEqual(len(list(gast.walk(tree))), 6)