1 // Copyright 2016 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_EQUALS_TRAITS_H_ 6 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_EQUALS_TRAITS_H_ 7 8 #include <type_traits> 9 #include <unordered_map> 10 #include <vector> 11 12 #include "base/optional.h" 13 #include "mojo/public/cpp/bindings/lib/template_util.h" 14 15 namespace mojo { 16 namespace internal { 17 18 template <typename T> 19 struct HasEqualsMethod { 20 template <typename U> 21 static char Test(decltype(&U::Equals)); 22 template <typename U> 23 static int Test(...); 24 static const bool value = sizeof(Test<T>(0)) == sizeof(char); 25 26 private: 27 EnsureTypeIsComplete<T> check_t_; 28 }; 29 30 template <typename T, bool has_equals_method = HasEqualsMethod<T>::value> 31 struct EqualsTraits; 32 33 template <typename T> 34 bool Equals(const T& a, const T& b); 35 36 template <typename T> 37 struct EqualsTraits<T, true> { 38 static bool Equals(const T& a, const T& b) { return a.Equals(b); } 39 }; 40 41 template <typename T> 42 struct EqualsTraits<T, false> { 43 static bool Equals(const T& a, const T& b) { return a == b; } 44 }; 45 46 template <typename T> 47 struct EqualsTraits<base::Optional<T>, false> { 48 static bool Equals(const base::Optional<T>& a, const base::Optional<T>& b) { 49 if (!a && !b) 50 return true; 51 if (!a || !b) 52 return false; 53 54 return internal::Equals(*a, *b); 55 } 56 }; 57 58 template <typename T> 59 struct EqualsTraits<std::vector<T>, false> { 60 static bool Equals(const std::vector<T>& a, const std::vector<T>& b) { 61 if (a.size() != b.size()) 62 return false; 63 for (size_t i = 0; i < a.size(); ++i) { 64 if (!internal::Equals(a[i], b[i])) 65 return false; 66 } 67 return true; 68 } 69 }; 70 71 template <typename K, typename V> 72 struct EqualsTraits<std::unordered_map<K, V>, false> { 73 static bool Equals(const std::unordered_map<K, V>& a, 74 const std::unordered_map<K, V>& b) { 75 if (a.size() != b.size()) 76 return false; 77 for (const auto& element : a) { 78 auto iter = b.find(element.first); 79 if (iter == b.end() || !internal::Equals(element.second, iter->second)) 80 return false; 81 } 82 return true; 83 } 84 }; 85 86 template <typename T> 87 bool Equals(const T& a, const T& b) { 88 return EqualsTraits<T>::Equals(a, b); 89 } 90 91 } // namespace internal 92 } // namespace mojo 93 94 #endif // MOJO_PUBLIC_CPP_BINDINGS_LIB_EQUALS_TRAITS_H_ 95
