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 88namespace gsl 89{ 90#if GSL_USE_STD_BYTE 91 92using std::byte; 93using 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 99enum class byte_may_alias byte : unsigned char 100{ 101}; 102 103template <class IntegerType, class = std::enable_if_t<std::is_integral<IntegerType>::value>> 104constexpr byte& operator<<=(byte& b, IntegerType shift) noexcept 105{ 106 return b = byte(static_cast<unsigned char>(b) << shift); 107} 108 109template <class IntegerType, class = std::enable_if_t<std::is_integral<IntegerType>::value>> 110constexpr byte operator<<(byte b, IntegerType shift) noexcept 111{ 112 return byte(static_cast<unsigned char>(b) << shift); 113} 114 115template <class IntegerType, class = std::enable_if_t<std::is_integral<IntegerType>::value>> 116constexpr byte& operator>>=(byte& b, IntegerType shift) noexcept 117{ 118 return b = byte(static_cast<unsigned char>(b) >> shift); 119} 120 121template <class IntegerType, class = std::enable_if_t<std::is_integral<IntegerType>::value>> 122constexpr byte operator>>(byte b, IntegerType shift) noexcept 123{ 124 return byte(static_cast<unsigned char>(b) >> shift); 125} 126 127constexpr byte& operator|=(byte& l, byte r) noexcept 128{ 129 return l = byte(static_cast<unsigned char>(l) | static_cast<unsigned char>(r)); 130} 131 132constexpr byte operator|(byte l, byte r) noexcept 133{ 134 return byte(static_cast<unsigned char>(l) | static_cast<unsigned char>(r)); 135} 136 137constexpr byte& operator&=(byte& l, byte r) noexcept 138{ 139 return l = byte(static_cast<unsigned char>(l) & static_cast<unsigned char>(r)); 140} 141 142constexpr byte operator&(byte l, byte r) noexcept 143{ 144 return byte(static_cast<unsigned char>(l) & static_cast<unsigned char>(r)); 145} 146 147constexpr byte& operator^=(byte& l, byte r) noexcept 148{ 149 return l = byte(static_cast<unsigned char>(l) ^ static_cast<unsigned char>(r)); 150} 151 152constexpr byte operator^(byte l, byte r) noexcept 153{ 154 return byte(static_cast<unsigned char>(l) ^ static_cast<unsigned char>(r)); 155} 156 157constexpr byte operator~(byte b) noexcept { return byte(~static_cast<unsigned char>(b)); } 158 159template <class IntegerType, class = std::enable_if_t<std::is_integral<IntegerType>::value>> 160constexpr IntegerType to_integer(byte b) noexcept 161{ 162 return static_cast<IntegerType>(b); 163} 164 165#endif // GSL_USE_STD_BYTE 166 167template <bool E, typename T> 168constexpr 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} 175template <> 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 178constexpr byte to_byte_impl<true, unsigned char>(unsigned char t) noexcept 179{ 180 return byte(t); 181} 182 183template <typename T> 184constexpr byte to_byte(T t) noexcept 185{ 186 return to_byte_impl<std::is_same<T, unsigned char>::value, T>(t); 187} 188 189template <int I> 190constexpr 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