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comparison: security/sandbox/chromium/base/template_util.h
security/sandbox/chromium/base/template_util.h
- branch
- TOR_BUG_9701
- changeset 14
- 925c144e1f1f
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| -1:000000000000 | 0:1653581c0124 |
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| 1 // Copyright (c) 2011 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 BASE_TEMPLATE_UTIL_H_ | |
| 6 #define BASE_TEMPLATE_UTIL_H_ | |
| 7 | |
| 8 #include <cstddef> // For size_t. | |
| 9 | |
| 10 #include "build/build_config.h" | |
| 11 | |
| 12 namespace base { | |
| 13 | |
| 14 // template definitions from tr1 | |
| 15 | |
| 16 template<class T, T v> | |
| 17 struct integral_constant { | |
| 18 static const T value = v; | |
| 19 typedef T value_type; | |
| 20 typedef integral_constant<T, v> type; | |
| 21 }; | |
| 22 | |
| 23 template <class T, T v> const T integral_constant<T, v>::value; | |
| 24 | |
| 25 typedef integral_constant<bool, true> true_type; | |
| 26 typedef integral_constant<bool, false> false_type; | |
| 27 | |
| 28 template <class T> struct is_pointer : false_type {}; | |
| 29 template <class T> struct is_pointer<T*> : true_type {}; | |
| 30 | |
| 31 template <class T, class U> struct is_same : public false_type {}; | |
| 32 template <class T> struct is_same<T,T> : true_type {}; | |
| 33 | |
| 34 template<class> struct is_array : public false_type {}; | |
| 35 template<class T, size_t n> struct is_array<T[n]> : public true_type {}; | |
| 36 template<class T> struct is_array<T[]> : public true_type {}; | |
| 37 | |
| 38 template <class T> struct is_non_const_reference : false_type {}; | |
| 39 template <class T> struct is_non_const_reference<T&> : true_type {}; | |
| 40 template <class T> struct is_non_const_reference<const T&> : false_type {}; | |
| 41 | |
| 42 template <class T> struct is_void : false_type {}; | |
| 43 template <> struct is_void<void> : true_type {}; | |
| 44 | |
| 45 namespace internal { | |
| 46 | |
| 47 // Types YesType and NoType are guaranteed such that sizeof(YesType) < | |
| 48 // sizeof(NoType). | |
| 49 typedef char YesType; | |
| 50 | |
| 51 struct NoType { | |
| 52 YesType dummy[2]; | |
| 53 }; | |
| 54 | |
| 55 // This class is an implementation detail for is_convertible, and you | |
| 56 // don't need to know how it works to use is_convertible. For those | |
| 57 // who care: we declare two different functions, one whose argument is | |
| 58 // of type To and one with a variadic argument list. We give them | |
| 59 // return types of different size, so we can use sizeof to trick the | |
| 60 // compiler into telling us which function it would have chosen if we | |
| 61 // had called it with an argument of type From. See Alexandrescu's | |
| 62 // _Modern C++ Design_ for more details on this sort of trick. | |
| 63 | |
| 64 struct ConvertHelper { | |
| 65 template <typename To> | |
| 66 static YesType Test(To); | |
| 67 | |
| 68 template <typename To> | |
| 69 static NoType Test(...); | |
| 70 | |
| 71 template <typename From> | |
| 72 static From& Create(); | |
| 73 }; | |
| 74 | |
| 75 // Used to determine if a type is a struct/union/class. Inspired by Boost's | |
| 76 // is_class type_trait implementation. | |
| 77 struct IsClassHelper { | |
| 78 template <typename C> | |
| 79 static YesType Test(void(C::*)(void)); | |
| 80 | |
| 81 template <typename C> | |
| 82 static NoType Test(...); | |
| 83 }; | |
| 84 | |
| 85 } // namespace internal | |
| 86 | |
| 87 // Inherits from true_type if From is convertible to To, false_type otherwise. | |
| 88 // | |
| 89 // Note that if the type is convertible, this will be a true_type REGARDLESS | |
| 90 // of whether or not the conversion would emit a warning. | |
| 91 template <typename From, typename To> | |
| 92 struct is_convertible | |
| 93 : integral_constant<bool, | |
| 94 sizeof(internal::ConvertHelper::Test<To>( | |
| 95 internal::ConvertHelper::Create<From>())) == | |
| 96 sizeof(internal::YesType)> { | |
| 97 }; | |
| 98 | |
| 99 template <typename T> | |
| 100 struct is_class | |
| 101 : integral_constant<bool, | |
| 102 sizeof(internal::IsClassHelper::Test<T>(0)) == | |
| 103 sizeof(internal::YesType)> { | |
| 104 }; | |
| 105 | |
| 106 } // namespace base | |
| 107 | |
| 108 #endif // BASE_TEMPLATE_UTIL_H_ |
