1 /////////////////////////////////////////////////////////////////////////////// 2 // 3 // Copyright (c) 2015 Microsoft Corporation. All rights reserved. 4 // 5 // This code is licensed under the MIT License (MIT). 6 // 7 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 8 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 9 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 10 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 11 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 12 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 13 // THE SOFTWARE. 14 // 15 /////////////////////////////////////////////////////////////////////////////// 16 17 #ifndef GSL_BYTE_H 18 #define GSL_BYTE_H 19 20 // 21 // make suppress attributes work for some compilers 22 // Hopefully temporary until suppression standardization occurs 23 // 24 #if defined(__clang__) 25 #define GSL_SUPPRESS(x) [[gsl::suppress("x")]] 26 #else 27 #if defined(_MSC_VER) 28 #define GSL_SUPPRESS(x) [[gsl::suppress(x)]] 29 #else 30 #define GSL_SUPPRESS(x) 31 #endif // _MSC_VER 32 #endif // __clang__ 33 34 #include <type_traits> 35 36 #ifdef _MSC_VER 37 38 #pragma warning(push) 39 40 // Turn MSVC /analyze rules that generate too much noise. TODO: fix in the tool. 41 #pragma warning(disable : 26493) // don't use c-style casts // TODO: MSVC suppression in templates does not always work 42 43 #ifndef GSL_USE_STD_BYTE 44 // this tests if we are under MSVC and the standard lib has std::byte and it is enabled 45 #if defined(_HAS_STD_BYTE) && _HAS_STD_BYTE 46 47 #define GSL_USE_STD_BYTE 1 48 49 #else // defined(_HAS_STD_BYTE) && _HAS_STD_BYTE 50 51 #define GSL_USE_STD_BYTE 0 52 53 #endif // defined(_HAS_STD_BYTE) && _HAS_STD_BYTE 54 #endif // GSL_USE_STD_BYTE 55 56 #else // _MSC_VER 57 58 #ifndef GSL_USE_STD_BYTE 59 // this tests if we are under GCC or Clang with enough -std:c++1z power to get us std::byte 60 // also check if libc++ version is sufficient (> 5.0) or libstc++ actually contains std::byte 61 #if defined(__cplusplus) && (__cplusplus >= 201703L) && \ 62 (defined(__cpp_lib_byte) && (__cpp_lib_byte >= 201603) || \ 63 defined(_LIBCPP_VERSION) && (_LIBCPP_VERSION >= 5000)) 64 65 #define GSL_USE_STD_BYTE 1 66 #include <cstddef> 67 68 #else // defined(__cplusplus) && (__cplusplus >= 201703L) && 69 // (defined(__cpp_lib_byte) && (__cpp_lib_byte >= 201603) || 70 // defined(_LIBCPP_VERSION) && (_LIBCPP_VERSION >= 5000)) 71 72 #define GSL_USE_STD_BYTE 0 73 74 #endif //defined(__cplusplus) && (__cplusplus >= 201703L) && 75 // (defined(__cpp_lib_byte) && (__cpp_lib_byte >= 201603) || 76 // defined(_LIBCPP_VERSION) && (_LIBCPP_VERSION >= 5000)) 77 #endif // GSL_USE_STD_BYTE 78 79 #endif // _MSC_VER 80 81 // Use __may_alias__ attribute on gcc and clang 82 #if defined __clang__ || (defined(__GNUC__) && __GNUC__ > 5) 83 #define byte_may_alias __attribute__((__may_alias__)) 84 #else // defined __clang__ || defined __GNUC__ 85 #define byte_may_alias 86 #endif // defined __clang__ || defined __GNUC__ 87 88 namespace gsl 89 { 90 #if GSL_USE_STD_BYTE 91 92 using std::byte; 93 using std::to_integer; 94 95 #else // GSL_USE_STD_BYTE 96 97 // This is a simple definition for now that allows 98 // use of byte within span<> to be standards-compliant 99 enum class byte_may_alias byte : unsigned char 100 { 101 }; 102 103 template <class IntegerType, class = std::enable_if_t<std::is_integral<IntegerType>::value>> 104 constexpr byte& operator<<=(byte& b, IntegerType shift) noexcept 105 { 106 return b = byte(static_cast<unsigned char>(b) << shift); 107 } 108 109 template <class IntegerType, class = std::enable_if_t<std::is_integral<IntegerType>::value>> 110 constexpr byte operator<<(byte b, IntegerType shift) noexcept 111 { 112 return byte(static_cast<unsigned char>(b) << shift); 113 } 114 115 template <class IntegerType, class = std::enable_if_t<std::is_integral<IntegerType>::value>> 116 constexpr byte& operator>>=(byte& b, IntegerType shift) noexcept 117 { 118 return b = byte(static_cast<unsigned char>(b) >> shift); 119 } 120 121 template <class IntegerType, class = std::enable_if_t<std::is_integral<IntegerType>::value>> 122 constexpr byte operator>>(byte b, IntegerType shift) noexcept 123 { 124 return byte(static_cast<unsigned char>(b) >> shift); 125 } 126 127 constexpr byte& operator|=(byte& l, byte r) noexcept 128 { 129 return l = byte(static_cast<unsigned char>(l) | static_cast<unsigned char>(r)); 130 } 131 132 constexpr byte operator|(byte l, byte r) noexcept 133 { 134 return byte(static_cast<unsigned char>(l) | static_cast<unsigned char>(r)); 135 } 136 137 constexpr byte& operator&=(byte& l, byte r) noexcept 138 { 139 return l = byte(static_cast<unsigned char>(l) & static_cast<unsigned char>(r)); 140 } 141 142 constexpr byte operator&(byte l, byte r) noexcept 143 { 144 return byte(static_cast<unsigned char>(l) & static_cast<unsigned char>(r)); 145 } 146 147 constexpr byte& operator^=(byte& l, byte r) noexcept 148 { 149 return l = byte(static_cast<unsigned char>(l) ^ static_cast<unsigned char>(r)); 150 } 151 152 constexpr byte operator^(byte l, byte r) noexcept 153 { 154 return byte(static_cast<unsigned char>(l) ^ static_cast<unsigned char>(r)); 155 } 156 157 constexpr byte operator~(byte b) noexcept { return byte(~static_cast<unsigned char>(b)); } 158 159 template <class IntegerType, class = std::enable_if_t<std::is_integral<IntegerType>::value>> 160 constexpr IntegerType to_integer(byte b) noexcept 161 { 162 return static_cast<IntegerType>(b); 163 } 164 165 #endif // GSL_USE_STD_BYTE 166 167 template <bool E, typename T> 168 constexpr byte to_byte_impl(T t) noexcept 169 { 170 static_assert( 171 E, "gsl::to_byte(t) must be provided an unsigned char, otherwise data loss may occur. " 172 "If you are calling to_byte with an integer contant use: gsl::to_byte<t>() version."); 173 return static_cast<byte>(t); 174 } 175 template <> 176 // NOTE: need suppression since c++14 does not allow "return {t}" 177 // GSL_SUPPRESS(type.4) // NO-FORMAT: attribute // TODO: suppression does not work 178 constexpr byte to_byte_impl<true, unsigned char>(unsigned char t) noexcept 179 { 180 return byte(t); 181 } 182 183 template <typename T> 184 constexpr byte to_byte(T t) noexcept 185 { 186 return to_byte_impl<std::is_same<T, unsigned char>::value, T>(t); 187 } 188 189 template <int I> 190 constexpr byte to_byte() noexcept 191 { 192 static_assert(I >= 0 && I <= 255, 193 "gsl::byte only has 8 bits of storage, values must be in range 0-255"); 194 return static_cast<byte>(I); 195 } 196 197 } // namespace gsl 198 199 #ifdef _MSC_VER 200 #pragma warning(pop) 201 #endif // _MSC_VER 202 203 #endif // GSL_BYTE_H 204
