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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_MEMORY_VALUES_EQUIVALENT_H_
#define BASE_MEMORY_VALUES_EQUIVALENT_H_
#include <memory>
#include "base/memory/scoped_refptr.h"
namespace base {
// Compares two pointers for equality, returns the dereferenced value comparison
// if both are non-null.
// Behaves like std::optional<T>::operator==(const std::optional<T>&) but for
// pointers.
template <typename T>
bool ValuesEquivalent(const T* a, const T* b) {
if (a == b)
return true;
if (!a || !b)
return false;
return *a == *b;
}
// Specialize for smart pointers like std::unique_ptr and base::scoped_refptr
// that provide a T* get() method.
// Example usage:
// struct Example {
// std::unique_ptr<Child> child;
// bool operator==(const Example& other) const {
// return base::ValuesEquivalent(child, other.child);
// }
// };
template <typename T,
std::enable_if_t<
std::is_pointer_v<decltype(std::declval<T>().get())>>* = nullptr>
bool ValuesEquivalent(const T& x, const T& y) {
return ValuesEquivalent(x.get(), y.get());
}
// Specialize for smart pointers like blink::Persistent and blink::Member that
// provide a T* Get() method.
// Example usage:
// namespace blink {
// struct Example : public GarbageCollected<Example> {
// Member<Child> child;
// bool operator==(const Example& other) const {
// return base::ValuesEquivalent(child, other.child);
// }
// void Trace(Visitor*) const;
// };
// } // namespace blink
template <typename T,
std::enable_if_t<
std::is_pointer_v<decltype(std::declval<T>().Get())>>* = nullptr>
bool ValuesEquivalent(const T& x, const T& y) {
return ValuesEquivalent(x.Get(), y.Get());
}
} // namespace base
#endif // BASE_MEMORY_VALUES_EQUIVALENT_H_
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