1/* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17#ifndef STAGEFRIGHT_FOUNDATION_TYPE_TRAITS_H_ 18#define STAGEFRIGHT_FOUNDATION_TYPE_TRAITS_H_ 19 20#include <type_traits> 21 22#undef HIDE 23#define HIDE __attribute__((visibility("hidden"))) 24 25namespace android { 26 27/** 28 * std::is_signed, is_unsigned and is_integral does not consider enums even though the standard 29 * considers them integral. Create modified versions of these here. Also create a wrapper around 30 * std::underlying_type that does not require checking if the type is an enum. 31 */ 32 33/** 34 * Type support utility class to check if a type is an integral type or an enum. 35 */ 36template<typename T> 37struct HIDE is_integral_or_enum 38 : std::integral_constant<bool, std::is_integral<T>::value || std::is_enum<T>::value> { }; 39 40/** 41 * Type support utility class to get the underlying std::is_integral supported type for a type. 42 * This returns the underlying type for enums, and the same type for types covered by 43 * std::is_integral. 44 * 45 * This is also used as a conditional to return an alternate type if the template param is not 46 * an integral or enum type (as in underlying_integral_type<T, TypeIfNotEnumOrIntegral>::type). 47 */ 48template<typename T, 49 typename U=typename std::enable_if<is_integral_or_enum<T>::value>::type, 50 bool=std::is_enum<T>::value, 51 bool=std::is_integral<T>::value> 52struct HIDE underlying_integral_type { 53 static_assert(!std::is_enum<T>::value, "T should not be enum here"); 54 static_assert(!std::is_integral<T>::value, "T should not be integral here"); 55 typedef U type; 56}; 57 58/** Specialization for enums. */ 59template<typename T, typename U> 60struct HIDE underlying_integral_type<T, U, true, false> { 61 static_assert(std::is_enum<T>::value, "T should be enum here"); 62 static_assert(!std::is_integral<T>::value, "T should not be integral here"); 63 typedef typename std::underlying_type<T>::type type; 64}; 65 66/** Specialization for non-enum std-integral types. */ 67template<typename T, typename U> 68struct HIDE underlying_integral_type<T, U, false, true> { 69 static_assert(!std::is_enum<T>::value, "T should not be enum here"); 70 static_assert(std::is_integral<T>::value, "T should be integral here"); 71 typedef T type; 72}; 73 74/** 75 * Type support utility class to check if the underlying integral type is signed. 76 */ 77template<typename T> 78struct HIDE is_signed_integral 79 : std::integral_constant<bool, std::is_signed< 80 typename underlying_integral_type<T, unsigned>::type>::value> { }; 81 82/** 83 * Type support utility class to check if the underlying integral type is unsigned. 84 */ 85template<typename T> 86struct HIDE is_unsigned_integral 87 : std::integral_constant<bool, std::is_unsigned< 88 typename underlying_integral_type<T, signed>::type>::value> { 89}; 90 91/** 92 * Type support relationship query template. 93 * 94 * If T occurs as one of the types in Us with the same const-volatile qualifications, provides the 95 * member constant |value| equal to true. Otherwise value is false. 96 */ 97template<typename T, typename ...Us> 98struct HIDE is_one_of; 99 100/// \if 0 101/** 102 * Template specialization when first type matches the searched type. 103 */ 104template<typename T, typename ...Us> 105struct HIDE is_one_of<T, T, Us...> : std::true_type {}; 106 107/** 108 * Template specialization when first type does not match the searched type. 109 */ 110template<typename T, typename U, typename ...Us> 111struct HIDE is_one_of<T, U, Us...> : is_one_of<T, Us...> {}; 112 113/** 114 * Template specialization when there are no types to search. 115 */ 116template<typename T> 117struct HIDE is_one_of<T> : std::false_type {}; 118/// \endif 119 120/** 121 * Type support relationship query template. 122 * 123 * If all types in Us are unique, provides the member constant |value| equal to true. 124 * Otherwise value is false. 125 */ 126template<typename ...Us> 127struct HIDE are_unique; 128 129/// \if 0 130/** 131 * Template specialization when there are no types. 132 */ 133template<> 134struct HIDE are_unique<> : std::true_type {}; 135 136/** 137 * Template specialization when there is at least one type to check. 138 */ 139template<typename T, typename ...Us> 140struct HIDE are_unique<T, Us...> 141 : std::integral_constant<bool, are_unique<Us...>::value && !is_one_of<T, Us...>::value> {}; 142/// \endif 143 144/// \if 0 145template<size_t Base, typename T, typename ...Us> 146struct HIDE _find_first_impl; 147 148/** 149 * Template specialization when there are no types to search. 150 */ 151template<size_t Base, typename T> 152struct HIDE _find_first_impl<Base, T> : std::integral_constant<size_t, 0> {}; 153 154/** 155 * Template specialization when T is the first type in Us. 156 */ 157template<size_t Base, typename T, typename ...Us> 158struct HIDE _find_first_impl<Base, T, T, Us...> : std::integral_constant<size_t, Base> {}; 159 160/** 161 * Template specialization when T is not the first type in Us. 162 */ 163template<size_t Base, typename T, typename U, typename ...Us> 164struct HIDE _find_first_impl<Base, T, U, Us...> 165 : std::integral_constant<size_t, _find_first_impl<Base + 1, T, Us...>::value> {}; 166 167/// \endif 168 169/** 170 * Type support relationship query template. 171 * 172 * If T occurs in Us, index is the 1-based left-most index of T in Us. Otherwise, index is 0. 173 */ 174template<typename T, typename ...Us> 175struct HIDE find_first { 176 static constexpr size_t index = _find_first_impl<1, T, Us...>::value; 177}; 178 179/// \if 0 180/** 181 * Helper class for find_first_convertible_to template. 182 * 183 * Adds a base index. 184 */ 185template<size_t Base, typename T, typename ...Us> 186struct HIDE _find_first_convertible_to_helper; 187 188/** 189 * Template specialization for when there are more types to consider 190 */ 191template<size_t Base, typename T, typename U, typename ...Us> 192struct HIDE _find_first_convertible_to_helper<Base, T, U, Us...> { 193 static constexpr size_t index = 194 std::is_convertible<T, U>::value ? Base : 195 _find_first_convertible_to_helper<Base + 1, T, Us...>::index; 196 typedef typename std::conditional< 197 std::is_convertible<T, U>::value, U, 198 typename _find_first_convertible_to_helper<Base + 1, T, Us...>::type>::type type; 199}; 200 201/** 202 * Template specialization for when there are no more types to consider 203 */ 204template<size_t Base, typename T> 205struct HIDE _find_first_convertible_to_helper<Base, T> { 206 static constexpr size_t index = 0; 207 typedef void type; 208}; 209 210/// \endif 211 212/** 213 * Type support template that returns the type that T can be implicitly converted into, and its 214 * index, from a list of other types (Us). 215 * 216 * Returns index of 0 and type of void if there are no convertible types. 217 * 218 * \param T type that is converted 219 * \param Us types into which the conversion is considered 220 */ 221template<typename T, typename ...Us> 222struct HIDE find_first_convertible_to : public _find_first_convertible_to_helper<1, T, Us...> { }; 223 224} // namespace android 225 226#endif // STAGEFRIGHT_FOUNDATION_TYPE_TRAITS_H_ 227 228