| // Copyright 2016 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. |
| |
| #ifndef MOJO_PUBLIC_CPP_BINDINGS_EQUALS_TRAITS_H_ |
| #define MOJO_PUBLIC_CPP_BINDINGS_EQUALS_TRAITS_H_ |
| |
| #include <type_traits> |
| #include <vector> |
| |
| #include "base/containers/flat_map.h" |
| #include "base/optional.h" |
| #include "mojo/public/cpp/bindings/lib/template_util.h" |
| |
| namespace mojo { |
| |
| // EqualsTraits<> allows you to specify comparison functions for mapped mojo |
| // objects. By default objects can be compared if they implement operator==() |
| // or have a method named Equals(). |
| |
| template <typename T> |
| struct HasEqualsMethod { |
| template <typename U> |
| static char Test(decltype(&U::Equals)); |
| template <typename U> |
| static int Test(...); |
| static const bool value = sizeof(Test<T>(0)) == sizeof(char); |
| |
| private: |
| internal::EnsureTypeIsComplete<T> check_t_; |
| }; |
| |
| template <typename T, bool has_equals_method = HasEqualsMethod<T>::value> |
| struct EqualsTraits; |
| |
| template <typename T> |
| bool Equals(const T& a, const T& b); |
| |
| template <typename T> |
| struct EqualsTraits<T, true> { |
| static bool Equals(const T& a, const T& b) { return a.Equals(b); } |
| }; |
| |
| template <typename T> |
| struct EqualsTraits<T, false> { |
| static bool Equals(const T& a, const T& b) { return a == b; } |
| }; |
| |
| template <typename T> |
| struct EqualsTraits<base::Optional<T>, false> { |
| static bool Equals(const base::Optional<T>& a, const base::Optional<T>& b) { |
| if (!a && !b) |
| return true; |
| if (!a || !b) |
| return false; |
| |
| // NOTE: Not just Equals() because that's EqualsTraits<>::Equals() and we |
| // want mojo::Equals() for things like base::Optional<std::vector<T>>. |
| return mojo::Equals(*a, *b); |
| } |
| }; |
| |
| template <typename T> |
| struct EqualsTraits<std::vector<T>, false> { |
| static bool Equals(const std::vector<T>& a, const std::vector<T>& b) { |
| if (a.size() != b.size()) |
| return false; |
| for (size_t i = 0; i < a.size(); ++i) { |
| if (!mojo::Equals(a[i], b[i])) |
| return false; |
| } |
| return true; |
| } |
| }; |
| |
| template <typename K, typename V> |
| struct EqualsTraits<base::flat_map<K, V>, false> { |
| static bool Equals(const base::flat_map<K, V>& a, |
| const base::flat_map<K, V>& b) { |
| if (a.size() != b.size()) |
| return false; |
| for (const auto& element : a) { |
| auto iter = b.find(element.first); |
| if (iter == b.end() || !mojo::Equals(element.second, iter->second)) |
| return false; |
| } |
| return true; |
| } |
| }; |
| |
| template <typename T> |
| bool Equals(const T& a, const T& b) { |
| return EqualsTraits<T>::Equals(a, b); |
| } |
| |
| } // namespace mojo |
| |
| #endif // MOJO_PUBLIC_CPP_BINDINGS_EQUALS_TRAITS_H_ |