cc: Add RandomAccessListContainer, which has more restricted API.
This patch adds RandomAccessListContainer, which is similar to ListContainer with two important differences: - It supports random access via operator[] - This is important for DisplayItemList use-case where an access into an rtree returns indices of elements to be rasterized. With this, we can access those elements directly. - It doesn't support middle-of-list operations (inserts/deletes) - This is done in order to simplify maintaining random access capabilities BUG=527245 R=weiliangc, danakj CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel Review URL: https://codereview.chromium.org/1340703002 Cr-Commit-Position: refs/heads/master@{#349564}
This commit is contained in:
@@ -725,6 +725,7 @@ test("cc_unittests") {
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"base/histograms_unittest.cc",
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"base/list_container_unittest.cc",
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"base/math_util_unittest.cc",
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"base/random_access_list_container_unittest.cc",
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"base/region_unittest.cc",
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"base/rolling_time_delta_history_unittest.cc",
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"base/scoped_ptr_vector_unittest.cc",
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@@ -18,6 +18,7 @@ source_set("base") {
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"list_container_helper.h",
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"math_util.cc",
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"math_util.h",
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"random_access_list_container.h",
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"region.cc",
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"region.h",
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"resource_id.h",
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@@ -18,6 +18,9 @@ class CC_EXPORT ListContainerHelper final {
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template <typename T>
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friend class ListContainer;
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template <typename T>
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friend class RandomAccessListContainer;
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explicit ListContainerHelper(size_t max_size_for_derived_class);
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ListContainerHelper(size_t max_size_for_derived_class,
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size_t num_of_elements_to_reserve_for);
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94
cc/base/random_access_list_container.h
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94
cc/base/random_access_list_container.h
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@@ -0,0 +1,94 @@
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// Copyright 2015 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef CC_BASE_RANDOM_ACCESS_LIST_CONTAINER_H_
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#define CC_BASE_RANDOM_ACCESS_LIST_CONTAINER_H_
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#include <vector>
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#include "base/logging.h"
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#include "cc/base/list_container_helper.h"
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namespace cc {
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// RandomAccessListContainer is a container similar to ListContainer (see
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// list_container.h), but it allows random access into its elements via
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// operator[]. In order to have efficient support for random access, some
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// functionality is not available for RandomAccessListContainers, such as
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// insert/deletes in the middle of the list.
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template <class BaseElementType>
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class RandomAccessListContainer {
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public:
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// BaseElementType is the type of raw pointers this class hands out; however,
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// its derived classes might require different memory sizes.
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// max_size_for_derived_class the largest memory size required for all the
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// derived classes to use for allocation.
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explicit RandomAccessListContainer(size_t max_size_for_derived_class)
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: helper_(max_size_for_derived_class) {}
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// This constructor reserves the requested memory up front so only a single
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// allocation is needed. When num_of_elements_to_reserve_for is zero, use the
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// default size.
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RandomAccessListContainer(size_t max_size_for_derived_class,
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size_t num_of_elements_to_reserve_for)
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: helper_(max_size_for_derived_class, num_of_elements_to_reserve_for) {
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items_.reserve(num_of_elements_to_reserve_for);
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}
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~RandomAccessListContainer() {
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for (BaseElementType* item : items_)
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item->~BaseElementType();
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}
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void clear() {
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for (BaseElementType* item : items_)
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item->~BaseElementType();
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helper_.clear();
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items_.clear();
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}
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bool empty() const { return helper_.empty(); }
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size_t size() const { return helper_.size(); }
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size_t GetCapacityInBytes() const { return helper_.GetCapacityInBytes(); }
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template <typename DerivedElementType>
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DerivedElementType* AllocateAndConstruct() {
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auto* value =
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new (helper_.Allocate(sizeof(DerivedElementType))) DerivedElementType;
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items_.push_back(value);
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return value;
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}
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void RemoveLast() {
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items_.back()->~BaseElementType();
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items_.pop_back();
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helper_.RemoveLast();
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}
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const BaseElementType* operator[](size_t index) const {
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DCHECK_GE(index, 0u);
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DCHECK_LT(index, items_.size());
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return items_[index];
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}
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BaseElementType* operator[](size_t index) {
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DCHECK_GE(index, 0u);
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DCHECK_LT(index, items_.size());
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return items_[index];
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}
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// Note that although BaseElementType objects can change, the pointer itself
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// (in the vector) cannot. So this class only supports a const iterator.
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using ConstIterator = typename std::vector<BaseElementType*>::const_iterator;
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ConstIterator begin() const { return items_.begin(); }
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ConstIterator end() const { return items_.end(); }
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private:
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ListContainerHelper helper_;
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std::vector<BaseElementType*> items_;
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};
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} // namespace cc
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#endif // CC_BASE_RANDOM_ACCESS_LIST_CONTAINER_H_
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107
cc/base/random_access_list_container_unittest.cc
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107
cc/base/random_access_list_container_unittest.cc
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@@ -0,0 +1,107 @@
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// Copyright 2015 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "cc/base/random_access_list_container.h"
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#include <algorithm>
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#include <vector>
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#include "testing/gmock/include/gmock/gmock.h"
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#include "testing/gtest/include/gtest/gtest.h"
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namespace cc {
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namespace {
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class Base {
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public:
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virtual ~Base() {}
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int get_value() const { return value_; }
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protected:
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explicit Base(int value) : value_(value) {}
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int value_;
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};
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const int kMagicNumberOne = 1;
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const int kMagicNumberTwo = 2;
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const int kMagicNumberThree = 3;
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class Derived1 : public Base {
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public:
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Derived1() : Base(kMagicNumberOne) {}
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};
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class Derived2 : public Base {
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public:
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Derived2() : Base(kMagicNumberTwo) {}
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};
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class Derived3 : public Base {
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public:
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Derived3() : Base(kMagicNumberThree) {}
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};
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size_t LargestDerivedElementSize() {
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static_assert(sizeof(Derived1) >= sizeof(Derived2),
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"Derived2 is larger than Derived1");
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static_assert(sizeof(Derived1) >= sizeof(Derived3),
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"Derived3 is larger than Derived1");
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return sizeof(Derived1);
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}
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TEST(RandomAccessListContainerTest, RandomAccess) {
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RandomAccessListContainer<Base> list(LargestDerivedElementSize(), 1);
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list.AllocateAndConstruct<Derived1>();
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list.AllocateAndConstruct<Derived2>();
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list.AllocateAndConstruct<Derived3>();
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list.AllocateAndConstruct<Derived1>();
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list.AllocateAndConstruct<Derived2>();
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list.AllocateAndConstruct<Derived3>();
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EXPECT_EQ(kMagicNumberOne, list[0]->get_value());
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EXPECT_EQ(kMagicNumberTwo, list[1]->get_value());
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EXPECT_EQ(kMagicNumberThree, list[2]->get_value());
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EXPECT_EQ(kMagicNumberOne, list[3]->get_value());
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EXPECT_EQ(kMagicNumberTwo, list[4]->get_value());
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EXPECT_EQ(kMagicNumberThree, list[5]->get_value());
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list.RemoveLast();
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list.RemoveLast();
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list.RemoveLast();
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EXPECT_EQ(kMagicNumberOne, list[0]->get_value());
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EXPECT_EQ(kMagicNumberTwo, list[1]->get_value());
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EXPECT_EQ(kMagicNumberThree, list[2]->get_value());
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list.AllocateAndConstruct<Derived3>();
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list.AllocateAndConstruct<Derived2>();
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list.AllocateAndConstruct<Derived1>();
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EXPECT_EQ(kMagicNumberOne, list[0]->get_value());
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EXPECT_EQ(kMagicNumberTwo, list[1]->get_value());
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EXPECT_EQ(kMagicNumberThree, list[2]->get_value());
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EXPECT_EQ(kMagicNumberThree, list[3]->get_value());
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EXPECT_EQ(kMagicNumberTwo, list[4]->get_value());
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EXPECT_EQ(kMagicNumberOne, list[5]->get_value());
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}
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TEST(RandomAccessListContainerTest, Clear) {
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RandomAccessListContainer<Base> list(LargestDerivedElementSize(), 1);
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list.AllocateAndConstruct<Derived1>();
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list.AllocateAndConstruct<Derived2>();
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EXPECT_EQ(kMagicNumberOne, list[0]->get_value());
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EXPECT_EQ(kMagicNumberTwo, list[1]->get_value());
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list.clear();
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list.AllocateAndConstruct<Derived3>();
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EXPECT_EQ(kMagicNumberThree, list[0]->get_value());
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}
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} // namespace
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} // namespace cc
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@@ -85,6 +85,7 @@
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'base/list_container_helper.h',
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'base/math_util.cc',
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'base/math_util.h',
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'base/random_access_list_container.h',
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'base/region.cc',
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'base/region.h',
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'base/resource_id.h',
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@@ -22,6 +22,7 @@
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'base/histograms_unittest.cc',
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'base/list_container_unittest.cc',
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'base/math_util_unittest.cc',
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'base/random_access_list_container_unittest.cc',
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'base/region_unittest.cc',
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'base/rolling_time_delta_history_unittest.cc',
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'base/scoped_ptr_vector_unittest.cc',
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