security/sandbox/chromium/base/template_util.h@141e0f1194b1 (annotated)
security/sandbox/chromium/base/template_util.h
Wed, 31 Dec 2014 07:16:47 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 07:16:47 +0100
- branch
- TOR_BUG_9701
- changeset 3
- 141e0f1194b1
- permissions
- -rw-r--r--
Revert simplistic fix pending revisit of Mozilla integration attempt.
| michael@0 | 1 | // Copyright (c) 2011 The Chromium Authors. All rights reserved. |
| michael@0 | 2 | // Use of this source code is governed by a BSD-style license that can be |
| michael@0 | 3 | // found in the LICENSE file. |
| michael@0 | 4 | |
| michael@0 | 5 | #ifndef BASE_TEMPLATE_UTIL_H_ |
| michael@0 | 6 | #define BASE_TEMPLATE_UTIL_H_ |
| michael@0 | 7 | |
| michael@0 | 8 | #include <cstddef> // For size_t. |
| michael@0 | 9 | |
| michael@0 | 10 | #include "build/build_config.h" |
| michael@0 | 11 | |
| michael@0 | 12 | namespace base { |
| michael@0 | 13 | |
| michael@0 | 14 | // template definitions from tr1 |
| michael@0 | 15 | |
| michael@0 | 16 | template<class T, T v> |
| michael@0 | 17 | struct integral_constant { |
| michael@0 | 18 | static const T value = v; |
| michael@0 | 19 | typedef T value_type; |
| michael@0 | 20 | typedef integral_constant<T, v> type; |
| michael@0 | 21 | }; |
| michael@0 | 22 | |
| michael@0 | 23 | template <class T, T v> const T integral_constant<T, v>::value; |
| michael@0 | 24 | |
| michael@0 | 25 | typedef integral_constant<bool, true> true_type; |
| michael@0 | 26 | typedef integral_constant<bool, false> false_type; |
| michael@0 | 27 | |
| michael@0 | 28 | template <class T> struct is_pointer : false_type {}; |
| michael@0 | 29 | template <class T> struct is_pointer<T*> : true_type {}; |
| michael@0 | 30 | |
| michael@0 | 31 | template <class T, class U> struct is_same : public false_type {}; |
| michael@0 | 32 | template <class T> struct is_same<T,T> : true_type {}; |
| michael@0 | 33 | |
| michael@0 | 34 | template<class> struct is_array : public false_type {}; |
| michael@0 | 35 | template<class T, size_t n> struct is_array<T[n]> : public true_type {}; |
| michael@0 | 36 | template<class T> struct is_array<T[]> : public true_type {}; |
| michael@0 | 37 | |
| michael@0 | 38 | template <class T> struct is_non_const_reference : false_type {}; |
| michael@0 | 39 | template <class T> struct is_non_const_reference<T&> : true_type {}; |
| michael@0 | 40 | template <class T> struct is_non_const_reference<const T&> : false_type {}; |
| michael@0 | 41 | |
| michael@0 | 42 | template <class T> struct is_void : false_type {}; |
| michael@0 | 43 | template <> struct is_void<void> : true_type {}; |
| michael@0 | 44 | |
| michael@0 | 45 | namespace internal { |
| michael@0 | 46 | |
| michael@0 | 47 | // Types YesType and NoType are guaranteed such that sizeof(YesType) < |
| michael@0 | 48 | // sizeof(NoType). |
| michael@0 | 49 | typedef char YesType; |
| michael@0 | 50 | |
| michael@0 | 51 | struct NoType { |
| michael@0 | 52 | YesType dummy[2]; |
| michael@0 | 53 | }; |
| michael@0 | 54 | |
| michael@0 | 55 | // This class is an implementation detail for is_convertible, and you |
| michael@0 | 56 | // don't need to know how it works to use is_convertible. For those |
| michael@0 | 57 | // who care: we declare two different functions, one whose argument is |
| michael@0 | 58 | // of type To and one with a variadic argument list. We give them |
| michael@0 | 59 | // return types of different size, so we can use sizeof to trick the |
| michael@0 | 60 | // compiler into telling us which function it would have chosen if we |
| michael@0 | 61 | // had called it with an argument of type From. See Alexandrescu's |
| michael@0 | 62 | // _Modern C++ Design_ for more details on this sort of trick. |
| michael@0 | 63 | |
| michael@0 | 64 | struct ConvertHelper { |
| michael@0 | 65 | template <typename To> |
| michael@0 | 66 | static YesType Test(To); |
| michael@0 | 67 | |
| michael@0 | 68 | template <typename To> |
| michael@0 | 69 | static NoType Test(...); |
| michael@0 | 70 | |
| michael@0 | 71 | template <typename From> |
| michael@0 | 72 | static From& Create(); |
| michael@0 | 73 | }; |
| michael@0 | 74 | |
| michael@0 | 75 | // Used to determine if a type is a struct/union/class. Inspired by Boost's |
| michael@0 | 76 | // is_class type_trait implementation. |
| michael@0 | 77 | struct IsClassHelper { |
| michael@0 | 78 | template <typename C> |
| michael@0 | 79 | static YesType Test(void(C::*)(void)); |
| michael@0 | 80 | |
| michael@0 | 81 | template <typename C> |
| michael@0 | 82 | static NoType Test(...); |
| michael@0 | 83 | }; |
| michael@0 | 84 | |
| michael@0 | 85 | } // namespace internal |
| michael@0 | 86 | |
| michael@0 | 87 | // Inherits from true_type if From is convertible to To, false_type otherwise. |
| michael@0 | 88 | // |
| michael@0 | 89 | // Note that if the type is convertible, this will be a true_type REGARDLESS |
| michael@0 | 90 | // of whether or not the conversion would emit a warning. |
| michael@0 | 91 | template <typename From, typename To> |
| michael@0 | 92 | struct is_convertible |
| michael@0 | 93 | : integral_constant<bool, |
| michael@0 | 94 | sizeof(internal::ConvertHelper::Test<To>( |
| michael@0 | 95 | internal::ConvertHelper::Create<From>())) == |
| michael@0 | 96 | sizeof(internal::YesType)> { |
| michael@0 | 97 | }; |
| michael@0 | 98 | |
| michael@0 | 99 | template <typename T> |
| michael@0 | 100 | struct is_class |
| michael@0 | 101 | : integral_constant<bool, |
| michael@0 | 102 | sizeof(internal::IsClassHelper::Test<T>(0)) == |
| michael@0 | 103 | sizeof(internal::YesType)> { |
| michael@0 | 104 | }; |
| michael@0 | 105 | |
| michael@0 | 106 | } // namespace base |
| michael@0 | 107 | |
| michael@0 | 108 | #endif // BASE_TEMPLATE_UTIL_H_ |
