| /* |
| * 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 (like std::enable_if_t) which will |
| * become available with C++14 in the type_traits header (in the skstd |
| * namespace). This header also provides several Skia specific additions such |
| * as SK_WHEN and the sknonstd namespace. |
| */ |
| |
| #ifndef SkTLogic_DEFINED |
| #define SkTLogic_DEFINED |
| |
| #include "SkTypes.h" |
| |
| #include <stddef.h> |
| #include <stdint.h> |
| #include <type_traits> |
| #include <utility> |
| |
| namespace skstd { |
| |
| template <bool B> using bool_constant = std::integral_constant<bool, B>; |
| |
| template <bool B, typename T, typename F> using conditional_t = typename std::conditional<B, T, F>::type; |
| template <bool B, typename T = void> using enable_if_t = typename std::enable_if<B, T>::type; |
| |
| template <typename T> using remove_const_t = typename std::remove_const<T>::type; |
| template <typename T> using remove_volatile_t = typename std::remove_volatile<T>::type; |
| template <typename T> using remove_cv_t = typename std::remove_cv<T>::type; |
| template <typename T> using remove_reference_t = typename std::remove_reference<T>::type; |
| template <typename T> using remove_extent_t = typename std::remove_extent<T>::type; |
| |
| template <typename T, typename U> struct is_same : std::false_type {}; |
| template <typename T> struct is_same<T, T> : std::true_type {}; |
| |
| template <typename T> struct is_void : is_same<void, remove_cv_t<T>> {}; |
| |
| template <typename T> struct is_const : std::false_type {}; |
| template <typename T> struct is_const<const T> : std::true_type {}; |
| |
| template <typename T> struct is_volatile : std::false_type {}; |
| template <typename T> struct is_volatile<volatile T> : std::true_type {}; |
| |
| template <typename T> struct is_pointer_detector : std::false_type {}; |
| template <typename T> struct is_pointer_detector<T*> : std::true_type {}; |
| template <typename T> struct is_pointer : is_pointer_detector<remove_cv_t<T>> {}; |
| |
| template <typename T> struct is_reference : std::false_type {}; |
| template <typename T> struct is_reference<T&> : std::true_type {}; |
| template <typename T> struct is_reference<T&&> : std::true_type {}; |
| |
| template <typename T> struct is_lvalue_reference : std::false_type {}; |
| template <typename T> struct is_lvalue_reference<T&> : std::true_type {}; |
| |
| template <typename T> struct is_rvalue_reference : std::false_type {}; |
| template <typename T> struct is_rvalue_reference<T&&> : std::true_type {}; |
| |
| template <typename T> struct is_class_detector { |
| using yes_type = uint8_t; |
| using no_type = uint16_t; |
| template <typename U> static yes_type clazz(int U::*); |
| template <typename U> static no_type clazz(...); |
| static const/*expr*/ bool value = sizeof(clazz<T>(0)) == sizeof(yes_type) /*&& !is_union<T>::value*/; |
| }; |
| template <typename T> struct is_class : bool_constant<is_class_detector<T>::value> {}; |
| |
| template <typename T, bool = is_class<T>::value> struct is_empty_detector { |
| struct Derived : public T { char unused; }; |
| static const/*expr*/ bool value = sizeof(Derived) == sizeof(char); |
| }; |
| template <typename T> struct is_empty_detector<T, false> { |
| static const/*expr*/ bool value = false; |
| }; |
| template <typename T> struct is_empty : bool_constant<is_empty_detector<T>::value> {}; |
| |
| template <typename T> struct is_array : std::false_type {}; |
| template <typename T> struct is_array<T[]> : std::true_type {}; |
| template <typename T, size_t N> struct is_array<T[N]> : std::true_type {}; |
| |
| // template<typename R, typename... Args> struct is_function< |
| // R [calling-convention] (Args...[, ...]) [const] [volatile] [&|&&]> : std::true_type {}; |
| // The cv and ref-qualified versions are strange types we're currently avoiding, so not supported. |
| // On all platforms, variadic functions only exist in the c calling convention. |
| template <typename> struct is_function : std::false_type {}; |
| #if !defined(SK_BUILD_FOR_WIN) |
| template <typename R, typename... Args> struct is_function<R(Args...)> : std::true_type {}; |
| #else |
| #if defined(_M_IX86) |
| template <typename R, typename... Args> struct is_function<R __cdecl (Args...)> : std::true_type {}; |
| template <typename R, typename... Args> struct is_function<R __stdcall (Args...)> : std::true_type {}; |
| template <typename R, typename... Args> struct is_function<R __fastcall (Args...)> : std::true_type {}; |
| #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2 |
| template <typename R, typename... Args> struct is_function<R __vectorcall (Args...)> : std::true_type {}; |
| #endif |
| #else |
| template <typename R, typename... Args> struct is_function<R __cdecl (Args...)> : std::true_type {}; |
| template <typename R, typename... Args> struct is_function<R __vectorcall (Args...)> : std::true_type {}; |
| #endif |
| #endif |
| template <typename R, typename... Args> struct is_function<R(Args..., ...)> : std::true_type {}; |
| |
| template <typename T> using add_const_t = typename std::add_const<T>::type; |
| template <typename T> using add_volatile_t = typename std::add_volatile<T>::type; |
| template <typename T> using add_cv_t = typename std::add_cv<T>::type; |
| template <typename T> using add_pointer_t = typename std::add_pointer<T>::type; |
| |
| template <typename T, bool=is_void<T>::value> struct add_lvalue_reference_init { using type = T; }; |
| template <typename T> struct add_lvalue_reference_init<T, false> { using type = T&; }; |
| template <typename T> struct add_lvalue_reference : add_lvalue_reference_init<T> {}; |
| template <typename T> using add_lvalue_reference_t = typename add_lvalue_reference<T>::type; |
| |
| template <typename T, bool=is_void<T>::value> struct add_rvalue_reference_init { using type = T; }; |
| template <typename T> struct add_rvalue_reference_init<T, false> { using type = T&&; }; |
| template <typename T> struct add_rvalue_reference : add_rvalue_reference_init<T> {}; |
| template <typename T> using add_rvalue_reference_t = typename add_rvalue_reference<T>::type; |
| |
| template <typename S, typename D, bool=is_void<S>::value||is_function<D>::value||is_array<D>::value> |
| struct is_convertible_detector { |
| static const/*expr*/ bool value = is_void<D>::value; |
| }; |
| template <typename S, typename D> struct is_convertible_detector<S, D, false> { |
| using yes_type = uint8_t; |
| using no_type = uint16_t; |
| |
| template <typename To> static void param_convertable_to(To); |
| |
| template <typename From, typename To> |
| static decltype(param_convertable_to<To>(std::declval<From>()), yes_type()) convertible(int); |
| |
| template <typename, typename> static no_type convertible(...); |
| |
| static const/*expr*/ bool value = sizeof(convertible<S, D>(0)) == sizeof(yes_type); |
| }; |
| template<typename S, typename D> struct is_convertible |
| : bool_constant<is_convertible_detector<S, D>::value> {}; |
| |
| template <typename T> struct decay { |
| using U = remove_reference_t<T>; |
| using type = conditional_t<is_array<U>::value, |
| remove_extent_t<U>*, |
| conditional_t<is_function<U>::value, add_pointer_t<U>, remove_cv_t<U>>>; |
| }; |
| template <typename T> using decay_t = typename decay<T>::type; |
| |
| } // namespace skstd |
| |
| // The sknonstd namespace contains things we would like to be proposed and feel std-ish. |
| namespace sknonstd { |
| |
| // The name 'copy' here is fraught with peril. In this case it means 'append', not 'overwrite'. |
| // Alternate proposed names are 'propagate', 'augment', or 'append' (and 'add', but already taken). |
| // std::experimental::propagate_const already exists for other purposes in TSv2. |
| // These also follow the <dest, source> pattern used by boost. |
| template <typename D, typename S> struct copy_const { |
| using type = skstd::conditional_t<skstd::is_const<S>::value, skstd::add_const_t<D>, D>; |
| }; |
| template <typename D, typename S> using copy_const_t = typename copy_const<D, S>::type; |
| |
| template <typename D, typename S> struct copy_volatile { |
| using type = skstd::conditional_t<skstd::is_volatile<S>::value, skstd::add_volatile_t<D>, D>; |
| }; |
| template <typename D, typename S> using copy_volatile_t = typename copy_volatile<D, S>::type; |
| |
| template <typename D, typename S> struct copy_cv { |
| using type = copy_volatile_t<copy_const_t<D, S>, S>; |
| }; |
| template <typename D, typename S> using copy_cv_t = typename copy_cv<D, S>::type; |
| |
| // The name 'same' here means 'overwrite'. |
| // Alternate proposed names are 'replace', 'transfer', or 'qualify_from'. |
| // same_xxx<D, S> can be written as copy_xxx<remove_xxx_t<D>, S> |
| template <typename D, typename S> using same_const = copy_const<skstd::remove_const_t<D>, S>; |
| template <typename D, typename S> using same_const_t = typename same_const<D, S>::type; |
| template <typename D, typename S> using same_volatile =copy_volatile<skstd::remove_volatile_t<D>,S>; |
| template <typename D, typename S> using same_volatile_t = typename same_volatile<D, S>::type; |
| template <typename D, typename S> using same_cv = copy_cv<skstd::remove_cv_t<D>, S>; |
| template <typename D, typename S> using same_cv_t = typename same_cv<D, S>::type; |
| |
| } // namespace sknonstd |
| |
| // Just a pithier wrapper for enable_if_t. |
| #define SK_WHEN(condition, T) skstd::enable_if_t<!!(condition), T> |
| |
| #endif |