Patch #1691070 from Roger Upole: Speed up PyArg_ParseTupleAndKeywords() and improve error msg

My tests don't show the promised speed up of 10%. The code is as fast as the old code for simple cases and slightly faster for complex cases with several of args and kwargs. But the patch simplifies the code, too.

Lib/test/test_getargs2.py

@@ -1,5 +1,6 @@
 import unittest
 from test import test_support
+from _testcapi import getargs_keywords
 
 import warnings
 warnings.filterwarnings("ignore",
@@ -248,9 +249,57 @@ class Tuple_TestCase(unittest.TestCase):
                 raise ValueError
         self.assertRaises(TypeError, getargs_tuple, 1, seq())
 
+class Keywords_TestCase(unittest.TestCase):
+    def test_positional_args(self):
+        # using all positional args
+        self.assertEquals(
+            getargs_keywords((1,2), 3, (4,(5,6)), (7,8,9), 10),
+            (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
+            )
+    def test_mixed_args(self):
+        # positional and keyword args
+        self.assertEquals(
+            getargs_keywords((1,2), 3, (4,(5,6)), arg4=(7,8,9), arg5=10),
+            (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
+            )
+    def test_keyword_args(self):
+        # all keywords
+        self.assertEquals(
+            getargs_keywords(arg1=(1,2), arg2=3, arg3=(4,(5,6)), arg4=(7,8,9), arg5=10),
+            (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
+            )
+    def test_optional_args(self):
+        # missing optional keyword args, skipping tuples
+        self.assertEquals(
+            getargs_keywords(arg1=(1,2), arg2=3, arg5=10),
+            (1, 2, 3, -1, -1, -1, -1, -1, -1, 10)
+            )
+    def test_required_args(self):
+        # required arg missing
+        try:
+            getargs_keywords(arg1=(1,2))
+        except TypeError, err:
+            self.assertEquals(str(err), "Required argument 'arg2' (pos 2) not found")
+        else:
+            self.fail('TypeError should have been raised')
+    def test_too_many_args(self):
+        try:
+            getargs_keywords((1,2),3,(4,(5,6)),(7,8,9),10,111)
+        except TypeError, err:
+            self.assertEquals(str(err), "function takes at most 5 arguments (6 given)")
+        else:
+            self.fail('TypeError should have been raised')
+    def test_invalid_keyword(self):
+        # extraneous keyword arg
+        try:
+            getargs_keywords((1,2),3,arg5=10,arg666=666)
+        except TypeError, err:
+            self.assertEquals(str(err), "'arg666' is an invalid keyword argument for this function")
+        else:
+            self.fail('TypeError should have been raised')
 
 def test_main():
-    tests = [Signed_TestCase, Unsigned_TestCase, Tuple_TestCase]
+    tests = [Signed_TestCase, Unsigned_TestCase, Tuple_TestCase, Keywords_TestCase]
     try:
         from _testcapi import getargs_L, getargs_K
     except ImportError: