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comparison: gfx/skia/trunk/src/utils/SkTLogic.h
gfx/skia/trunk/src/utils/SkTLogic.h
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
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| -1:000000000000 | 0:cbc8d94053b8 |
|---|---|
| 1 /* | |
| 2 * Copyright 2013 Google Inc. | |
| 3 * | |
| 4 * Use of this source code is governed by a BSD-style license that can be | |
| 5 * found in the LICENSE file. | |
| 6 * | |
| 7 * | |
| 8 * This header provides some of the helpers (std::integral_constant) and | |
| 9 * type transformations (std::conditional) which will become available with | |
| 10 * C++11 in the type_traits header. | |
| 11 * | |
| 12 * Because we lack constexpr, we cannot mimic | |
| 13 * std::integral_constant::'constexpr operator T()'. | |
| 14 * As a result we introduce SkTBool and SkTIf similar to Boost in order to | |
| 15 * minimize the visual noise of many uses of '::value'. | |
| 16 */ | |
| 17 | |
| 18 #ifndef SkTLogic_DEFINED | |
| 19 #define SkTLogic_DEFINED | |
| 20 | |
| 21 /** Represents a templated integer constant. | |
| 22 * Pre-C++11 version of std::integral_constant. | |
| 23 */ | |
| 24 template <typename T, T v> struct SkTIntegralConstant { | |
| 25 static const T value = v; | |
| 26 typedef T value_type; | |
| 27 typedef SkTIntegralConstant<T, v> type; | |
| 28 }; | |
| 29 | |
| 30 /** Convenience specialization of SkTIntegralConstant. */ | |
| 31 template <bool b> struct SkTBool : SkTIntegralConstant<bool, b> { }; | |
| 32 | |
| 33 /** Pre-C++11 version of std::true_type. */ | |
| 34 typedef SkTBool<true> SkTrue; | |
| 35 | |
| 36 /** Pre-C++11 version of std::false_type. */ | |
| 37 typedef SkTBool<false> SkFalse; | |
| 38 | |
| 39 /** SkTIf_c::type = (condition) ? T : F; | |
| 40 * Pre-C++11 version of std::conditional. | |
| 41 */ | |
| 42 template <bool condition, typename T, typename F> struct SkTIf_c { | |
| 43 typedef F type; | |
| 44 }; | |
| 45 template <typename T, typename F> struct SkTIf_c<true, T, F> { | |
| 46 typedef T type; | |
| 47 }; | |
| 48 | |
| 49 /** SkTIf::type = (Condition::value) ? T : F; */ | |
| 50 template <typename Condition, typename T, typename F> struct SkTIf { | |
| 51 typedef typename SkTIf_c<static_cast<bool>(Condition::value), T, F>::type type; | |
| 52 }; | |
| 53 | |
| 54 /** SkTMux::type = (a && b) ? Both : (a) ? A : (b) ? B : Neither; */ | |
| 55 template <typename a, typename b, typename Both, typename A, typename B, typename Neither> | |
| 56 struct SkTMux { | |
| 57 typedef typename SkTIf<a, typename SkTIf<b, Both, A>::type, | |
| 58 typename SkTIf<b, B, Neither>::type>::type type; | |
| 59 }; | |
| 60 | |
| 61 #endif |
