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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_MAP_TRAITS_H_
6 #define MOJO_PUBLIC_CPP_BINDINGS_MAP_TRAITS_H_
7 
8 namespace mojo {
9 
10 // This must be specialized for any type |T| to be serialized/deserialized as
11 // a mojom map.
12 //
13 // Usually you would like to do a partial specialization for a map template.
14 // Imagine you want to specialize it for CustomMap<>, you need to implement:
15 //
16 //   template <typename K, typename V>
17 //   struct MapTraits<CustomMap<K, V>> {
18 //     using Key = K;
19 //     using Value = V;
20 //
21 //     // These two methods are optional. Please see comments in struct_traits.h
22 //     static bool IsNull(const CustomMap<K, V>& input);
23 //     static void SetToNull(CustomMap<K, V>* output);
24 //
25 //     static size_t GetSize(const CustomMap<K, V>& input);
26 //
27 //     static CustomConstIterator GetBegin(const CustomMap<K, V>& input);
28 //     static CustomIterator GetBegin(CustomMap<K, V>& input);
29 //
30 //     static void AdvanceIterator(CustomConstIterator& iterator);
31 //     static void AdvanceIterator(CustomIterator& iterator);
32 //
33 //     static const K& GetKey(CustomIterator& iterator);
34 //     static const K& GetKey(CustomConstIterator& iterator);
35 //
36 //     static V& GetValue(CustomIterator& iterator);
37 //     static const V& GetValue(CustomConstIterator& iterator);
38 //
39 //     // Returning false results in deserialization failure and causes the
40 //     // message pipe receiving it to be disconnected. |IK| and |IV| are
41 //     // separate input key/value template parameters that allows for the
42 //     // the key/value types to be forwarded.
43 //     template <typename IK, typename IV>
44 //     static bool Insert(CustomMap<K, V>& input,
45 //                        IK&& key,
46 //                        IV&& value);
47 //
48 //     static void SetToEmpty(CustomMap<K, V>* output);
49 //   };
50 //
51 template <typename T>
52 struct MapTraits;
53 
54 }  // namespace mojo
55 
56 #endif  // MOJO_PUBLIC_CPP_BINDINGS_MAP_TRAITS_H_
57