pagespeed/kernel/base/ref_counted_ptr_test.cc

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */


// Unit-test RefCountedPtr.

#include "pagespeed/kernel/base/basictypes.h"
#include "pagespeed/kernel/base/gtest.h"
#include "pagespeed/kernel/base/ref_counted_ptr.h"

namespace net_instaweb {

namespace {

int counter = 0;

class SimpleClass {
 public:
  SimpleClass() : index_(counter++) {}
  int index() const { return index_; }

 private:
  int index_;
  DISALLOW_COPY_AND_ASSIGN(SimpleClass);
};

class BaseClass : public RefCounted<BaseClass> {
 public:
  BaseClass() {}
  int index() const { return simple_.index(); }

 protected:
  virtual ~BaseClass() {}
  REFCOUNT_FRIEND_DECLARATION(BaseClass);

 private:
  SimpleClass simple_;
  DISALLOW_COPY_AND_ASSIGN(BaseClass);
};

struct DerivedA : public BaseClass {};
struct DerivedB : public BaseClass {};

}  // namespace

typedef RefCountedObj<SimpleClass> SimplePtr;
typedef RefCountedPtr<BaseClass> PolymorphicPtr;

class RefCountedPtrTest : public testing::Test {
 protected:
};

TEST_F(RefCountedPtrTest, Simple) {
  SimplePtr simple1;
  EXPECT_TRUE(simple1.unique());
  int index = simple1->index();
  SimplePtr simple2 = simple1;
  EXPECT_FALSE(simple1.unique());
  EXPECT_FALSE(simple2.unique());
  EXPECT_EQ(index, simple2->index());
  SimplePtr simple3(simple1);
  EXPECT_FALSE(simple3.unique());
  EXPECT_EQ(index, simple3->index());
  SimplePtr simple4;
  EXPECT_TRUE(simple4.unique());
  EXPECT_NE(index, simple4->index());
}

TEST_F(RefCountedPtrTest, Polymorphic) {
  PolymorphicPtr poly1(new DerivedA);
  int index = poly1->index();
  EXPECT_TRUE(poly1.unique());
  PolymorphicPtr poly2(poly1);
  EXPECT_FALSE(poly1.unique());
  EXPECT_FALSE(poly2.unique());
  EXPECT_EQ(index, poly2->index());
  PolymorphicPtr poly3 = poly1;
  EXPECT_FALSE(poly3.unique());
  EXPECT_EQ(index, poly3->index());
  PolymorphicPtr poly4(new DerivedB);
  EXPECT_TRUE(poly4.unique());
  EXPECT_NE(index, poly4->index());
  PolymorphicPtr poly5;
  EXPECT_TRUE(poly5.get() == NULL);
  EXPECT_TRUE(poly5.unique());
  poly5.clear();
  EXPECT_TRUE(poly5.get() == NULL);
  poly1.reset(new DerivedA);
  EXPECT_TRUE(poly1.unique());
}

TEST_F(RefCountedPtrTest, Upcast) {
  RefCountedPtr<DerivedA> derived(new DerivedA);
  PolymorphicPtr base(derived);
  EXPECT_FALSE(derived.unique());
  EXPECT_FALSE(base.unique());
  EXPECT_EQ(base->index(), derived->index());
}

TEST_F(RefCountedPtrTest, AssignUpcast) {
  RefCountedPtr<DerivedA> derived(new DerivedA);
  PolymorphicPtr base;
  base = derived;
  EXPECT_FALSE(derived.unique());
  EXPECT_FALSE(base.unique());
  EXPECT_EQ(base->index(), derived->index());
}

TEST_F(RefCountedPtrTest, ExplicitDowncast) {
  PolymorphicPtr base(new DerivedB);
  RefCountedPtr<DerivedB> derived = base.StaticCast<DerivedB>();
  EXPECT_FALSE(derived.unique());
  EXPECT_FALSE(base.unique());
  EXPECT_EQ(base->index(), derived->index());
}

// It is not possible to use RefCountedUpcast to perform a downcast.
// To prove that to yourself, uncomment this and compile:
//
// TEST_F(RefCountedPtrTest, DownCast) {
//   PolymorphicPtr base(new DerivedB);
//   RefCountedPtr<DerivedA> derived(base);
//   EXPECT_FALSE(derived.unique());
//   EXPECT_FALSE(base.unique());
//   EXPECT_EQ(base->index(), derived->index());
// }

// It is not possible to use RefCountedUpcast to perform a cast between two
// unrelated pointers.  To prove that to yourself, uncomment this:
//
// TEST_F(RefCountedPtrTest, CrossCast) {
//   RefCountedPtr<DerivedA> derived_a(new DerivedA);
//   RefCountedPtr<DerivedB> derived_b(derived_a);
//   EXPECT_FALSE(derived_a.unique());
//   EXPECT_FALSE(derived_b.unique());
// }

}  // namespace net_instaweb