Fixed partials (Issue #398)

lark/utils.py

@@ -160,7 +160,7 @@ def smart_decorator(f, create_decorator):
 
     elif isinstance(f, partial):
         # wraps does not work for partials in 2.7: https://bugs.python.org/issue3445
-        return wraps(f.func)(create_decorator(f.func, True))
+        return wraps(f.func)(create_decorator(lambda *args, **kw: f(*args[1:], **kw), True))
 
     else:
         return create_decorator(f.__func__.__call__, True)

tests/test_trees.py

@@ -151,16 +151,16 @@ class TestTrees(TestCase):
 
         tree = Tree("start", [Tree("a", ["test1"]), Tree("b", ["test2"])])
 
-        def test(t, s):
-            return s.upper()
+        def test(prefix, s, postfix):
+            return prefix + s.upper() + postfix
 
         @v_args(inline=True)
         class T(Transformer):
-            a = functools.partial(test)
-            b = functools.partial(lambda t, s: s + "!")
+            a = functools.partial(test, "@", postfix="!")
+            b = functools.partial(lambda s: s + "!")
 
         res = T().transform(tree)
-        assert res.children == ["TEST1", "test2!"]
+        assert res.children == ["@TEST1!", "test2!"]
 
 
     def test_discard(self):