Add ListContainer::swap

cc/base/list_container_unittest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/base/list_container.h"
 
 #include <vector>
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 863 matching lines @@
   list_1.AppendByMoving(list_2.back());
   EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementOne,
             list_1.front()->get_value());
   EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementThree,
             list_1.back()->get_value());
   EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementTwo,
             list_2.back()->get_value());
 
   // AppendByMoving replaces the source element with a new derived element so
   // we do not expect sizes to shrink after AppendByMoving is called.
-  EXPECT_EQ(2u,
-            list_1.size());  // One direct allocation and one AppendByMoving.
+  EXPECT_EQ(2u, list_1.size());  // One direct allocation, one AppendByMoving.

[danakj, 2015/06/24 17:53:11]

teehee

   EXPECT_EQ(1u, list_2.size());  // One AppendByMoving.
 }
 
 const size_t kLongCountForLongSimpleDerivedElement = 5;
 
 class LongSimpleDerivedElement : public SimpleDerivedElement {
  public:
   ~LongSimpleDerivedElement() override {}
   void SetAllValues(unsigned long value) {
     for (size_t i = 0; i < kLongCountForLongSimpleDerivedElement; i++)
@@ skipping 51 matching lines @@
 
   LongSimpleDerivedElement* long_element =
       static_cast<LongSimpleDerivedElement*>(list.back());
   list.AppendByMoving(simple_element);
   EXPECT_TRUE(long_element->AreAllValuesEqualTo(
       kMagicNumberToUseForLongSimpleDerivedElement));
   EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementOne,
             list.back()->get_value());
 }
 
+TEST(ListContainerTest, Swap) {
+  ListContainer<SimpleDerivedElement> list_1(kCurrentLargestDerivedElementSize);
+  list_1.AllocateAndConstruct<SimpleDerivedElementConstructMagicNumberOne>();
+  ListContainer<SimpleDerivedElement> list_2(kCurrentLargestDerivedElementSize);
+  list_2.AllocateAndConstruct<SimpleDerivedElementConstructMagicNumberTwo>();
+  list_2.AllocateAndConstruct<SimpleDerivedElementConstructMagicNumberTwo>();
+
+  SimpleDerivedElement* pre_swap_list_1_front = list_1.front();
+
+  EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementOne,
+            list_1.front()->get_value());

[chrishtr, 2015/06/24 17:52:52]

Why not check back() also?

+  EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementTwo,
+            list_2.front()->get_value());
+  EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementTwo,
+            list_2.back()->get_value());
+  EXPECT_EQ(1u, list_1.size());
+  EXPECT_EQ(2u, list_2.size());
+
+  list_2.swap(list_1);
+
+  EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementTwo,
+            list_1.front()->get_value());
+  EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementTwo,
+            list_1.back()->get_value());
+  EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementOne,
+            list_2.front()->get_value());
+  EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementOne,
+            list_2.back()->get_value());

[danakj, 2015/06/24 17:53:11]

no need to check back here, since the size is 1 (verified below)

+  EXPECT_EQ(2u, list_1.size());
+  EXPECT_EQ(1u, list_2.size());
+
+  // Ensure pointers are still valid after swapping.
+  EXPECT_EQ(pre_swap_list_1_front, list_2.front());
+}
+
 }  // namespace
 }  // namespace cc