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1 // Copyright 2014 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_LIB_TEMPLATE_UTIL_H_ | |
6 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_TEMPLATE_UTIL_H_ | |
7 | |
8 #include <type_traits> | |
9 | |
10 namespace mojo { | |
11 namespace internal { | |
12 | |
13 // Types YesType and NoType are guaranteed such that sizeof(YesType) < | |
14 // sizeof(NoType). | |
15 typedef char YesType; | |
16 | |
17 struct NoType { | |
18 YesType dummy[2]; | |
19 }; | |
20 | |
21 // A helper template to determine if given type is non-const move-only-type, | |
22 // i.e. if a value of the given type should be passed via .Pass() in a | |
23 // destructive way. | |
24 template <typename T> | |
25 struct IsMoveOnlyType { | |
26 template <typename U> | |
27 static YesType Test(const typename U::MoveOnlyTypeForCPP03*); | |
28 | |
29 template <typename U> | |
30 static NoType Test(...); | |
31 | |
32 static const bool value = | |
33 sizeof(Test<T>(0)) == sizeof(YesType) && !std::is_const<T>::value; | |
34 }; | |
35 | |
36 // Returns a reference to |t| when T is not a move-only type. | |
37 template <typename T> | |
38 typename std::enable_if<!IsMoveOnlyType<T>::value, T>::type& Forward(T& t) { | |
39 return t; | |
40 } | |
41 | |
42 // Returns the result of t.Pass() when T is a move-only type. | |
43 template <typename T> | |
44 typename std::enable_if<IsMoveOnlyType<T>::value, T>::type Forward(T& t) { | |
45 return t.Pass(); | |
46 } | |
47 | |
48 template <template <typename...> class Template, typename T> | |
49 struct IsSpecializationOf : std::false_type {}; | |
50 | |
51 template <template <typename...> class Template, typename... Args> | |
52 struct IsSpecializationOf<Template, Template<Args...>> : std::true_type {}; | |
53 | |
54 } // namespace internal | |
55 } // namespace mojo | |
56 | |
57 #endif // MOJO_PUBLIC_CPP_BINDINGS_LIB_TEMPLATE_UTIL_H_ | |
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