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_ARRAY_TRAITS_STL_H_ 6 #define MOJO_PUBLIC_CPP_BINDINGS_ARRAY_TRAITS_STL_H_ 7 8 #include <map> 9 #include <set> 10 #include <vector> 11 12 #include "mojo/public/cpp/bindings/array_traits.h" 13 14 namespace mojo { 15 16 template <typename T> 17 struct ArrayTraits<std::vector<T>> { 18 using Element = T; 19 20 static bool IsNull(const std::vector<T>& input) { 21 // std::vector<> is always converted to non-null mojom array. 22 return false; 23 } 24 25 static void SetToNull(std::vector<T>* output) { 26 // std::vector<> doesn't support null state. Set it to empty instead. 27 output->clear(); 28 } 29 30 static size_t GetSize(const std::vector<T>& input) { return input.size(); } 31 32 static T* GetData(std::vector<T>& input) { return input.data(); } 33 34 static const T* GetData(const std::vector<T>& input) { return input.data(); } 35 36 static typename std::vector<T>::reference GetAt(std::vector<T>& input, 37 size_t index) { 38 return input[index]; 39 } 40 41 static typename std::vector<T>::const_reference GetAt( 42 const std::vector<T>& input, 43 size_t index) { 44 return input[index]; 45 } 46 47 static inline bool Resize(std::vector<T>& input, size_t size) { 48 // Instead of calling std::vector<T>::resize() directly, this is a hack to 49 // make compilers happy. Some compilers (e.g., Mac, Android, Linux MSan) 50 // currently don't allow resizing types like 51 // std::vector<std::vector<MoveOnlyType>>. 52 // Because the deserialization code doesn't care about the original contents 53 // of |input|, we discard them directly. 54 // 55 // The "inline" keyword of this method matters. Without it, we have observed 56 // significant perf regression with some tests on Mac. crbug.com/631415 57 if (input.size() != size) { 58 std::vector<T> temp(size); 59 input.swap(temp); 60 } 61 62 return true; 63 } 64 }; 65 66 // This ArrayTraits specialization is used only for serialization. 67 template <typename T> 68 struct ArrayTraits<std::set<T>> { 69 using Element = T; 70 using ConstIterator = typename std::set<T>::const_iterator; 71 72 static bool IsNull(const std::set<T>& input) { 73 // std::set<> is always converted to non-null mojom array. 74 return false; 75 } 76 77 static size_t GetSize(const std::set<T>& input) { return input.size(); } 78 79 static ConstIterator GetBegin(const std::set<T>& input) { 80 return input.begin(); 81 } 82 static void AdvanceIterator(ConstIterator& iterator) { 83 ++iterator; 84 } 85 static const T& GetValue(ConstIterator& iterator) { 86 return *iterator; 87 } 88 }; 89 90 template <typename K, typename V> 91 struct MapValuesArrayView { 92 explicit MapValuesArrayView(const std::map<K, V>& map) : map(map) {} 93 const std::map<K, V>& map; 94 }; 95 96 // Convenience function to create a MapValuesArrayView<> that infers the 97 // template arguments from its argument type. 98 template <typename K, typename V> 99 MapValuesArrayView<K, V> MapValuesToArray(const std::map<K, V>& map) { 100 return MapValuesArrayView<K, V>(map); 101 } 102 103 // This ArrayTraits specialization is used only for serialization and converts 104 // a map<K, V> into an array<V>, discarding the keys. 105 template <typename K, typename V> 106 struct ArrayTraits<MapValuesArrayView<K, V>> { 107 using Element = V; 108 using ConstIterator = typename std::map<K, V>::const_iterator; 109 110 static bool IsNull(const MapValuesArrayView<K, V>& input) { 111 // std::map<> is always converted to non-null mojom array. 112 return false; 113 } 114 115 static size_t GetSize(const MapValuesArrayView<K, V>& input) { 116 return input.map.size(); 117 } 118 static ConstIterator GetBegin(const MapValuesArrayView<K, V>& input) { 119 return input.map.begin(); 120 } 121 static void AdvanceIterator(ConstIterator& iterator) { ++iterator; } 122 static const V& GetValue(ConstIterator& iterator) { return iterator->second; } 123 }; 124 125 } // namespace mojo 126 127 #endif // MOJO_PUBLIC_CPP_BINDINGS_ARRAY_TRAITS_STL_H_ 128