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