[pypy-commit] pypy virtual-arguments: a special strategy for the especially common case of an empty kwargs dict

[cfbolz]

Author: Carl Friedrich Bolz <cfbolz at gmx.de>
Branch: virtual-arguments
Changeset: r54661:57a4fb6a5b6a
Date: 2012-04-22 20:09 +0200
http://bitbucket.org/pypy/pypy/changeset/57a4fb6a5b6a/

Log:	a special strategy for the especially common case of an empty kwargs
	dict

diff --git a/pypy/objspace/std/dictmultiobject.py b/pypy/objspace/std/dictmultiobject.py
--- a/pypy/objspace/std/dictmultiobject.py
+++ b/pypy/objspace/std/dictmultiobject.py
@@ -48,8 +48,8 @@
 
         elif kwargs:
             assert w_type is None
-            from pypy.objspace.std.kwargsdict import KwargsDictStrategy
-            strategy = space.fromcache(KwargsDictStrategy)
+            from pypy.objspace.std.kwargsdict import EmptyKwargsDictStrategy
+            strategy = space.fromcache(EmptyKwargsDictStrategy)
         else:
             strategy = space.fromcache(EmptyDictStrategy)
         if w_type is None:
diff --git a/pypy/objspace/std/kwargsdict.py b/pypy/objspace/std/kwargsdict.py
--- a/pypy/objspace/std/kwargsdict.py
+++ b/pypy/objspace/std/kwargsdict.py
@@ -3,11 +3,20 @@
 
 from pypy.rlib import rerased, jit
 from pypy.objspace.std.dictmultiobject import (DictStrategy,
+                                               EmptyDictStrategy,
                                                IteratorImplementation,
                                                ObjectDictStrategy,
                                                StringDictStrategy)
 
 
+class EmptyKwargsDictStrategy(EmptyDictStrategy):
+    def switch_to_string_strategy(self, w_dict):
+        strategy = self.space.fromcache(KwargsDictStrategy)
+        storage = strategy.get_empty_storage()
+        w_dict.strategy = strategy
+        w_dict.dstorage = storage
+
+
 class KwargsDictStrategy(DictStrategy):
     erase, unerase = rerased.new_erasing_pair("kwargsdict")
     erase = staticmethod(erase)
diff --git a/pypy/objspace/std/test/test_kwargsdict.py b/pypy/objspace/std/test/test_kwargsdict.py
--- a/pypy/objspace/std/test/test_kwargsdict.py
+++ b/pypy/objspace/std/test/test_kwargsdict.py
@@ -100,6 +100,14 @@
     d = W_DictMultiObject(space, strategy, storage)
     assert (space.view_as_kwargs(d) == [], [])
 
+def test_from_empty_to_kwargs():
+    strategy = EmptyKwargsDictStrategy(space)
+    storage = strategy.get_empty_storage()
+    d = W_DictMultiObject(space, strategy, storage)
+    d.setitem_str("a", 3)
+    assert isinstance(d.strategy, KwargsDictStrategy)
+
+
 from pypy.objspace.std.test.test_dictmultiobject import BaseTestRDictImplementation, BaseTestDevolvedDictImplementation
 def get_impl(self):
     storage = strategy.erase(([], []))
@@ -130,4 +138,6 @@
             return args
         d = f(a=1)
         assert "KwargsDictStrategy" in self.get_strategy(d)
+        d = f()
+        assert "EmptyKwargsDictStrategy" in self.get_strategy(d)