Implement weak pointers

core/fxcrt/cfx_weak_ptr_unittest.cpp

+// Copyright 2016 PDFium 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 "core/fxcrt/include/cfx_weak_ptr.h"
+
+#include <memory>
+#include <utility>
+
+#include "core/fxcrt/include/fx_memory.h"
+#include "testing/fx_string_testhelpers.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+class PseudoDeletable;
+using WeakPtr = CFX_WeakPtr<PseudoDeletable, ReleaseDeleter<PseudoDeletable>>;
+using UniquePtr =
+    std::unique_ptr<PseudoDeletable, ReleaseDeleter<PseudoDeletable>>;
+
+class PseudoDeletable {
+ public:
+  PseudoDeletable() : delete_count_(0) {}
+  void Release() {
+    ++delete_count_;
+    next_.Reset();
+  }
+  void SetNext(const WeakPtr& next) { next_ = next; }
+  int delete_count() const { return delete_count_; }
+
+ private:
+  int delete_count_;
+  WeakPtr next_;
+};
+
+}  // namespace
+
+TEST(fxcrt, WeakPtrNull) {
+  WeakPtr ptr1;
+  EXPECT_FALSE(ptr1);
+
+  WeakPtr ptr2;
+  EXPECT_TRUE(ptr1 == ptr2);
+  EXPECT_FALSE(ptr1 != ptr2);
+
+  WeakPtr ptr3(ptr1);
+  EXPECT_TRUE(ptr1 == ptr3);
+  EXPECT_FALSE(ptr1 != ptr3);
+
+  WeakPtr ptr4 = ptr1;
+  EXPECT_TRUE(ptr1 == ptr4);
+  EXPECT_FALSE(ptr1 != ptr4);
+}
+
+TEST(fxcrt, WeakPtrNonNull) {
+  PseudoDeletable thing;
+  EXPECT_EQ(0, thing.delete_count());
+  {
+    UniquePtr unique(&thing);
+    WeakPtr ptr1(std::move(unique));
+    EXPECT_TRUE(ptr1);
+    EXPECT_EQ(&thing, ptr1.Get());
+
+    WeakPtr ptr2;
+    EXPECT_FALSE(ptr1 == ptr2);
+    EXPECT_TRUE(ptr1 != ptr2);
+    {
+      WeakPtr ptr3(ptr1);
+      EXPECT_TRUE(ptr1 == ptr3);
+      EXPECT_FALSE(ptr1 != ptr3);
+      EXPECT_EQ(&thing, ptr3.Get());
+      {
+        WeakPtr ptr4 = ptr1;
+        EXPECT_TRUE(ptr1 == ptr4);
+        EXPECT_FALSE(ptr1 != ptr4);
+        EXPECT_EQ(&thing, ptr4.Get());
+      }
+    }
+    EXPECT_EQ(0, thing.delete_count());
+  }
+  EXPECT_EQ(1, thing.delete_count());
+}
+
+TEST(fxcrt, WeakPtrResetNull) {
+  PseudoDeletable thing;
+  {
+    UniquePtr unique(&thing);
+    WeakPtr ptr1(std::move(unique));
+    WeakPtr ptr2 = ptr1;
+    ptr1.Reset();
+    EXPECT_FALSE(ptr1);
+    EXPECT_EQ(nullptr, ptr1.Get());
+    EXPECT_TRUE(ptr2);
+    EXPECT_EQ(&thing, ptr2.Get());
+    EXPECT_FALSE(ptr1 == ptr2);
+    EXPECT_TRUE(ptr1 != ptr2);
+    EXPECT_EQ(0, thing.delete_count());
+  }
+  EXPECT_EQ(1, thing.delete_count());
+}
+
+TEST(fxcrt, WeakPtrResetNonNull) {
+  PseudoDeletable thing1;
+  PseudoDeletable thing2;
+  {
+    UniquePtr unique1(&thing1);
+    WeakPtr ptr1(std::move(unique1));
+    WeakPtr ptr2 = ptr1;
+    UniquePtr unique2(&thing2);
+    ptr2.Reset(std::move(unique2));
+    EXPECT_TRUE(ptr1);
+    EXPECT_EQ(&thing1, ptr1.Get());
+    EXPECT_TRUE(ptr2);
+    EXPECT_EQ(&thing2, ptr2.Get());
+    EXPECT_FALSE(ptr1 == ptr2);
+    EXPECT_TRUE(ptr1 != ptr2);
+    EXPECT_EQ(0, thing1.delete_count());
+    EXPECT_EQ(0, thing2.delete_count());
+  }
+  EXPECT_EQ(1, thing1.delete_count());
+  EXPECT_EQ(1, thing2.delete_count());
+}
+
+TEST(fxcrt, WeakPtrClear) {
+  PseudoDeletable thing;
+  {
+    UniquePtr unique(&thing);
+    WeakPtr ptr1(std::move(unique));
+    WeakPtr ptr2 = ptr1;
+    ptr1.Clear();
+    EXPECT_FALSE(ptr1);
+    EXPECT_EQ(nullptr, ptr1.Get());
+    EXPECT_FALSE(ptr2);
+    EXPECT_EQ(nullptr, ptr2.Get());
+    EXPECT_FALSE(ptr1 == ptr2);
+    EXPECT_TRUE(ptr1 != ptr2);
+    EXPECT_EQ(1, thing.delete_count());
+  }
+  EXPECT_EQ(1, thing.delete_count());
+}
+
+TEST(fxcrt, WeakPtrCyclic) {
+  PseudoDeletable thing1;
+  PseudoDeletable thing2;
+  {
+    UniquePtr unique1(&thing1);
+    UniquePtr unique2(&thing2);
+    WeakPtr ptr1(std::move(unique1));
+    WeakPtr ptr2(std::move(unique2));
+    ptr1->SetNext(ptr2);
+    ptr2->SetNext(ptr1);
+  }
+  // Leaks without explicit clear.
+  EXPECT_EQ(0, thing1.delete_count());
+  EXPECT_EQ(0, thing2.delete_count());
+}
+
+TEST(fxcrt, WeakPtrCyclicClear) {
+  PseudoDeletable thing1;
+  PseudoDeletable thing2;
+  {
+    UniquePtr unique1(&thing1);
+    UniquePtr unique2(&thing2);
+    WeakPtr ptr1(std::move(unique1));
+    WeakPtr ptr2(std::move(unique2));
+    ptr1->SetNext(ptr2);
+    ptr2->SetNext(ptr1);
+    ptr1.Clear();
+    EXPECT_EQ(1, thing1.delete_count());
+    EXPECT_EQ(0, thing2.delete_count());
+  }
+  EXPECT_EQ(1, thing1.delete_count());
+  EXPECT_EQ(1, thing2.delete_count());
+}