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_H_ 6 #define MOJO_PUBLIC_CPP_BINDINGS_ARRAY_TRAITS_H_ 7 8 namespace mojo { 9 10 // This must be specialized for any type |T| to be serialized/deserialized as 11 // a mojom array. 12 // 13 // Usually you would like to do a partial specialization for a container (e.g. 14 // vector) template. Imagine you want to specialize it for Container<>, you need 15 // to implement: 16 // 17 // template <typename T> 18 // struct ArrayTraits<Container<T>> { 19 // using Element = T; 20 // // These two statements are optional. Use them if you'd like to serialize 21 // // a container that supports iterators but does not support O(1) random 22 // // access and so GetAt(...) would be expensive. 23 // // using Iterator = T::iterator; 24 // // using ConstIterator = T::const_iterator; 25 // 26 // // These two methods are optional. Please see comments in struct_traits.h 27 // static bool IsNull(const Container<T>& input); 28 // static void SetToNull(Container<T>* output); 29 // 30 // static size_t GetSize(const Container<T>& input); 31 // 32 // // These two methods are optional. They are used to access the 33 // // underlying storage of the array to speed up copy of POD types. 34 // static T* GetData(Container<T>& input); 35 // static const T* GetData(const Container<T>& input); 36 // 37 // // The following six methods are optional if the GetAt(...) methods are 38 // // implemented. These methods specify how to read the elements of 39 // // Container in some sequential order specified by the iterator. 40 // // 41 // // Acquires an iterator positioned at the first element in the container. 42 // static ConstIterator GetBegin(const Container<T>& input); 43 // static Iterator GetBegin(Container<T>& input); 44 // 45 // // Advances |iterator| to the next position within the container. 46 // static void AdvanceIterator(ConstIterator& iterator); 47 // static void AdvanceIterator(Iterator& iterator); 48 // 49 // // Returns a reference to the value at the current position of 50 // // |iterator|. Optionally, the ConstIterator version of GetValue can 51 // // return by value instead of by reference if it makes sense for the 52 // // type. 53 // static const T& GetValue(ConstIterator& iterator); 54 // static T& GetValue(Iterator& iterator); 55 // 56 // // These two methods are optional if the iterator methods are 57 // // implemented. 58 // static T& GetAt(Container<T>& input, size_t index); 59 // static const T& GetAt(const Container<T>& input, size_t index); 60 // 61 // // Returning false results in deserialization failure and causes the 62 // // message pipe receiving it to be disconnected. 63 // static bool Resize(Container<T>& input, size_t size); 64 // }; 65 // 66 template <typename T> 67 struct ArrayTraits; 68 69 } // namespace mojo 70 71 #endif // MOJO_PUBLIC_CPP_BINDINGS_ARRAY_TRAITS_H_ 72
