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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_STL_CONVERTERS_H_ | |
6 #define MOJO_PUBLIC_CPP_BINDINGS_STL_CONVERTERS_H_ | |
7 | |
8 #include <map> | |
9 #include <string> | |
10 #include <type_traits> | |
11 #include <vector> | |
12 | |
13 #include "mojo/public/cpp/bindings/array.h" | |
14 #include "mojo/public/cpp/bindings/map.h" | |
15 #include "mojo/public/cpp/bindings/string.h" | |
16 | |
17 // Two functions are defined to facilitate conversion between | |
18 // mojo::Array/Map/String and std::vector/map/string: mojo::UnwrapToSTLType() | |
19 // recursively convert mojo types to STL types; mojo::WrapSTLType() does the | |
20 // opposite. For example: | |
21 // mojo::Array<mojo::Map<mojo::String, mojo::Array<int32_t>>> mojo_obj; | |
22 // | |
23 // std::vector<std::map<std::string, std::vector<int32_t>>> stl_obj = | |
24 // mojo::UnwrapToSTLType(std::move(mojo_obj)); | |
25 // | |
26 // mojo_obj = mojo::WrapSTLType(std::move(stl_obj)); | |
27 // | |
28 // Notes: | |
29 // - The conversion moves as much contents as possible. The two functions both | |
30 // take an rvalue ref as input in order to avoid accidental copies. | |
31 // - Because std::vector/map/string cannot express null, UnwrapToSTLType() | |
32 // converts null mojo::Array/Map/String to empty. | |
33 // - The recursive conversion stops at any types that are not the types listed | |
34 // above. For example, unwrapping mojo::Array<StructContainingMojoMap> will | |
35 // result in std::vector<StructContainingMojoMap>. It won't convert | |
36 // mojo::Map inside the struct. | |
37 | |
38 namespace mojo { | |
39 namespace internal { | |
40 | |
41 template <typename T> | |
42 struct UnwrapTraits; | |
43 | |
44 template <typename T> | |
45 struct UnwrapShouldGoDeeper { | |
46 public: | |
47 static const bool value = | |
48 !std::is_same<T, typename UnwrapTraits<T>::Type>::value; | |
49 }; | |
50 | |
51 template <typename T> | |
52 struct UnwrapTraits { | |
53 public: | |
54 using Type = T; | |
55 static Type Unwrap(T input) { return input; } | |
56 }; | |
57 | |
58 template <typename T> | |
59 struct UnwrapTraits<Array<T>> { | |
60 public: | |
61 using Type = std::vector<typename UnwrapTraits<T>::Type>; | |
62 | |
63 static Type Unwrap(Array<T> input) { | |
64 return Helper<T>::Run(std::move(input)); | |
65 } | |
66 | |
67 private: | |
68 template <typename U, bool should_go_deeper = UnwrapShouldGoDeeper<U>::value> | |
69 struct Helper {}; | |
70 | |
71 template <typename U> | |
72 struct Helper<U, true> { | |
73 public: | |
74 static Type Run(Array<T> input) { | |
75 Type output; | |
76 output.reserve(input.size()); | |
77 for (size_t i = 0; i < input.size(); ++i) | |
78 output.push_back(UnwrapTraits<T>::Unwrap(std::move(input[i]))); | |
79 return output; | |
80 } | |
81 }; | |
82 | |
83 template <typename U> | |
84 struct Helper<U, false> { | |
85 public: | |
86 static Type Run(Array<T> input) { return input.PassStorage(); } | |
87 }; | |
88 }; | |
89 | |
90 template <typename K, typename V> | |
91 struct UnwrapTraits<Map<K, V>> { | |
92 public: | |
93 using Type = | |
94 std::map<typename UnwrapTraits<K>::Type, typename UnwrapTraits<V>::Type>; | |
95 | |
96 static Type Unwrap(Map<K, V> input) { | |
97 return Helper<K, V>::Run(std::move(input)); | |
98 } | |
99 | |
100 private: | |
101 template <typename X, | |
102 typename Y, | |
103 bool should_go_deeper = UnwrapShouldGoDeeper<X>::value || | |
104 UnwrapShouldGoDeeper<Y>::value> | |
105 struct Helper {}; | |
106 | |
107 template <typename X, typename Y> | |
108 struct Helper<X, Y, true> { | |
109 public: | |
110 static Type Run(Map<K, V> input) { | |
111 std::map<K, V> input_storage = input.PassStorage(); | |
112 Type output; | |
113 for (auto& pair : input_storage) { | |
114 output.insert( | |
115 std::make_pair(UnwrapTraits<K>::Unwrap(pair.first), | |
116 UnwrapTraits<V>::Unwrap(std::move(pair.second)))); | |
117 } | |
118 return output; | |
119 } | |
120 }; | |
121 | |
122 template <typename X, typename Y> | |
123 struct Helper<X, Y, false> { | |
124 public: | |
125 static Type Run(Map<K, V> input) { return input.PassStorage(); } | |
126 }; | |
127 }; | |
128 | |
129 template <> | |
130 struct UnwrapTraits<String> { | |
131 public: | |
132 using Type = std::string; | |
133 | |
134 static std::string Unwrap(const String& input) { return input; } | |
135 }; | |
136 | |
137 template <typename T> | |
138 struct WrapTraits; | |
139 | |
140 template <typename T> | |
141 struct WrapShouldGoDeeper { | |
142 public: | |
143 static const bool value = | |
144 !std::is_same<T, typename WrapTraits<T>::Type>::value; | |
145 }; | |
146 | |
147 template <typename T> | |
148 struct WrapTraits { | |
149 public: | |
150 using Type = T; | |
151 | |
152 static T Wrap(T input) { return input; } | |
153 }; | |
154 | |
155 template <typename T> | |
156 struct WrapTraits<std::vector<T>> { | |
157 public: | |
158 using Type = Array<typename WrapTraits<T>::Type>; | |
159 | |
160 static Type Wrap(std::vector<T> input) { | |
161 return Helper<T>::Run(std::move(input)); | |
162 } | |
163 | |
164 private: | |
165 template <typename U, bool should_go_deeper = WrapShouldGoDeeper<U>::value> | |
166 struct Helper {}; | |
167 | |
168 template <typename U> | |
169 struct Helper<U, true> { | |
170 public: | |
171 static Type Run(std::vector<T> input) { | |
172 std::vector<typename WrapTraits<T>::Type> output_storage; | |
173 output_storage.reserve(input.size()); | |
174 for (auto& element : input) | |
175 output_storage.push_back(WrapTraits<T>::Wrap(std::move(element))); | |
176 return Type(std::move(output_storage)); | |
177 } | |
178 }; | |
179 | |
180 template <typename U> | |
181 struct Helper<U, false> { | |
182 public: | |
183 static Type Run(std::vector<T> input) { return Type(std::move(input)); } | |
184 }; | |
185 }; | |
186 | |
187 template <typename K, typename V> | |
188 struct WrapTraits<std::map<K, V>> { | |
189 public: | |
190 using Type = Map<typename WrapTraits<K>::Type, typename WrapTraits<V>::Type>; | |
191 | |
192 static Type Wrap(std::map<K, V> input) { | |
193 return Helper<K, V>::Run(std::move(input)); | |
194 } | |
195 | |
196 private: | |
197 template <typename X, | |
198 typename Y, | |
199 bool should_go_deeper = | |
200 WrapShouldGoDeeper<X>::value || WrapShouldGoDeeper<Y>::value> | |
201 struct Helper {}; | |
202 | |
203 template <typename X, typename Y> | |
204 struct Helper<X, Y, true> { | |
205 public: | |
206 static Type Run(std::map<K, V> input) { | |
207 Type output; | |
208 for (auto& pair : input) { | |
209 output.insert(WrapTraits<K>::Wrap(pair.first), | |
210 WrapTraits<V>::Wrap(std::move(pair.second))); | |
211 } | |
212 return output; | |
213 } | |
214 }; | |
215 | |
216 template <typename X, typename Y> | |
217 struct Helper<X, Y, false> { | |
218 public: | |
219 static Type Run(std::map<K, V> input) { return Type(std::move(input)); } | |
220 }; | |
221 }; | |
222 | |
223 template <> | |
224 struct WrapTraits<std::string> { | |
225 public: | |
226 using Type = String; | |
227 | |
228 static String Wrap(const std::string& input) { return input; } | |
229 }; | |
230 | |
231 } // namespace internal | |
232 | |
233 template <typename T> | |
234 typename internal::UnwrapTraits<T>::Type UnwrapToSTLType(T&& input) { | |
235 return internal::UnwrapTraits<T>::Unwrap(std::move(input)); | |
236 } | |
237 | |
238 template <typename T> | |
239 typename internal::WrapTraits<T>::Type WrapSTLType(T&& input) { | |
240 return internal::WrapTraits<T>::Wrap(std::move(input)); | |
241 } | |
242 | |
243 } // namespace mojo | |
244 | |
245 #endif // MOJO_PUBLIC_CPP_BINDINGS_STL_CONVERTERS_H_ | |
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