Move SkTHash.h to include/private.

src/utils/SkTLogic.h

-/*
- * Copyright 2013 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- *
- *
- * This header provides some of the helpers (std::integral_constant) and
- * type transformations (std::conditional) which will become available with
- * C++11 in the type_traits header.
- *
- * Because we lack constexpr, we cannot mimic
- * std::integral_constant::'constexpr operator T()'.
- * As a result we introduce SkTBool and SkTIf similar to Boost in order to
- * minimize the visual noise of many uses of '::value'.
- */
-
-#ifndef SkTLogic_DEFINED
-#define SkTLogic_DEFINED
-
-/** Represents a templated integer constant.
- *  Pre-C++11 version of std::integral_constant.
- */
-template <typename T, T v> struct SkTIntegralConstant {
-    static const T value = v;
-    typedef T value_type;
-    typedef SkTIntegralConstant<T, v> type;
-};
-
-/** Convenience specialization of SkTIntegralConstant. */
-template <bool b> struct SkTBool : SkTIntegralConstant<bool, b> { };
-
-/** Pre-C++11 version of std::is_empty<T>. */
-template <typename T>
-class SkTIsEmpty {
-    struct Derived : public T { char unused; };
-public:
-    static const bool value = sizeof(Derived) == sizeof(char);
-};
-
-/** Pre-C++11 version of std::true_type. */
-typedef SkTBool<true> SkTrue;
-
-/** Pre-C++11 version of std::false_type. */
-typedef SkTBool<false> SkFalse;
-
-/** SkTIf_c::type = (condition) ? T : F;
- *  Pre-C++11 version of std::conditional.
- */
-template <bool condition, typename T, typename F> struct SkTIf_c {
-    typedef F type;
-};
-template <typename T, typename F> struct SkTIf_c<true, T, F> {
-    typedef T type;
-};
-
-/** SkTIf::type = (Condition::value) ? T : F; */
-template <typename Condition, typename T, typename F> struct SkTIf {
-    typedef typename SkTIf_c<static_cast<bool>(Condition::value), T, F>::type type;
-};
-
-/** SkTMux::type = (a && b) ? Both : (a) ? A : (b) ? B : Neither; */
-template <typename a, typename b, typename Both, typename A, typename B, typename Neither>
-struct SkTMux {
-    typedef typename SkTIf<a, typename SkTIf<b, Both, A>::type,
-                              typename SkTIf<b, B, Neither>::type>::type type;
-};
-
-/** SkTEnableIf_c::type = (condition) ? T : [does not exist]; */
-template <bool condition, class T = void> struct SkTEnableIf_c { };
-template <class T> struct SkTEnableIf_c<true, T> {
-    typedef T type;
-};
-
-/** SkTEnableIf::type = (Condition::value) ? T : [does not exist]; */
-template <class Condition, class T = void> struct SkTEnableIf
-    : public SkTEnableIf_c<static_cast<bool>(Condition::value), T> { };
-
-/** Use as a return type to enable a function only when cond_type::value is true,
- *  like C++14's std::enable_if_t.  E.g.  (N.B. this is a dumb example.)
- *  SK_WHEN(SkTrue, int) f(void* ptr) { return 1; }
- *  SK_WHEN(!SkTrue, int) f(void* ptr) { return 2; }
- */
-#define SK_WHEN(cond_prefix, T) typename SkTEnableIf_c<cond_prefix::value, T>::type
-#define SK_WHEN_C(cond, T) typename SkTEnableIf_c<cond, T>::type
-
-// See http://en.wikibooks.org/wiki/More_C++_Idioms/Member_Detector
-#define SK_CREATE_MEMBER_DETECTOR(member)                                           \
-template <typename T>                                                               \
-class HasMember_##member {                                                          \
-    struct Fallback { int member; };                                                \
-    struct Derived : T, Fallback {};                                                \
-    template <typename U, U> struct Check;                                          \
-    template <typename U> static uint8_t func(Check<int Fallback::*, &U::member>*); \
-    template <typename U> static uint16_t func(...);                                \
-public:                                                                             \
-    typedef HasMember_##member type;                                                \
-    static const bool value = sizeof(func<Derived>(NULL)) == sizeof(uint16_t);      \
-}
-
-// Same sort of thing as SK_CREATE_MEMBER_DETECTOR, but checks for the existence of a nested type.
-#define SK_CREATE_TYPE_DETECTOR(type)                                   \
-template <typename T>                                                   \
-class HasType_##type {                                                  \
-    template <typename U> static uint8_t func(typename U::type*);       \
-    template <typename U> static uint16_t func(...);                    \
-public:                                                                 \
-    static const bool value = sizeof(func<T>(NULL)) == sizeof(uint8_t); \
-}
-
-#endif