1 // Copyright 2017 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_CLONE_TRAITS_H_ 6 #define MOJO_PUBLIC_CPP_BINDINGS_CLONE_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 17 template <typename T> 18 struct HasCloneMethod { 19 template <typename U> 20 static char Test(decltype(&U::Clone)); 21 template <typename U> 22 static int Test(...); 23 static const bool value = sizeof(Test<T>(0)) == sizeof(char); 24 25 private: 26 internal::EnsureTypeIsComplete<T> check_t_; 27 }; 28 29 template <typename T, bool has_clone_method = HasCloneMethod<T>::value> 30 struct CloneTraits; 31 32 template <typename T> 33 T Clone(const T& input); 34 35 template <typename T> 36 struct CloneTraits<T, true> { 37 static T Clone(const T& input) { return input.Clone(); } 38 }; 39 40 template <typename T> 41 struct CloneTraits<T, false> { 42 static T Clone(const T& input) { return input; } 43 }; 44 45 template <typename T> 46 struct CloneTraits<base::Optional<T>, false> { 47 static base::Optional<T> Clone(const base::Optional<T>& input) { 48 if (!input) 49 return base::nullopt; 50 51 return base::Optional<T>(mojo::Clone(*input)); 52 } 53 }; 54 55 template <typename T> 56 struct CloneTraits<std::vector<T>, false> { 57 static std::vector<T> Clone(const std::vector<T>& input) { 58 std::vector<T> result; 59 result.reserve(input.size()); 60 for (const auto& element : input) 61 result.push_back(mojo::Clone(element)); 62 63 return result; 64 } 65 }; 66 67 template <typename K, typename V> 68 struct CloneTraits<std::unordered_map<K, V>, false> { 69 static std::unordered_map<K, V> Clone(const std::unordered_map<K, V>& input) { 70 std::unordered_map<K, V> result; 71 for (const auto& element : input) { 72 result.insert(std::make_pair(mojo::Clone(element.first), 73 mojo::Clone(element.second))); 74 } 75 return result; 76 } 77 }; 78 79 template <typename T> 80 T Clone(const T& input) { 81 return CloneTraits<T>::Clone(input); 82 }; 83 84 } // namespace mojo 85 86 #endif // MOJO_PUBLIC_CPP_BINDINGS_CLONE_TRAITS_H_ 87
