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_UTIL_H 18#define GSL_UTIL_H 19 20#include <gsl/gsl_assert> // for Expects 21 22#include <array> 23#include <cstddef> // for ptrdiff_t, size_t 24#include <exception> // for exception 25#include <initializer_list> // for initializer_list 26#include <type_traits> // for is_signed, integral_constant 27#include <utility> // for forward 28 29#if defined(_MSC_VER) && !defined(__clang__) 30 31#pragma warning(push) 32#pragma warning(disable : 4127) // conditional expression is constant 33 34#if _MSC_VER < 1910 35#pragma push_macro("constexpr") 36#define constexpr /*constexpr*/ 37#endif // _MSC_VER < 1910 38#endif // _MSC_VER 39 40#if (defined(_MSC_VER) && _MSC_VER < 1910) || (!defined(__clang__) && defined(__GNUC__) && __GUNC__ < 6) 41#define GSL_CONSTEXPR_NARROW 0 42#else 43#define GSL_CONSTEXPR_NARROW 1 44#endif 45 46namespace gsl 47{ 48// 49// GSL.util: utilities 50// 51 52// index type for all container indexes/subscripts/sizes 53using index = std::ptrdiff_t; 54 55// final_action allows you to ensure something gets run at the end of a scope 56template <class F> 57class final_action 58{ 59public: 60 explicit final_action(F f) noexcept : f_(std::move(f)) {} 61 62 final_action(final_action&& other) noexcept : f_(std::move(other.f_)), invoke_(other.invoke_) 63 { 64 other.invoke_ = false; 65 } 66 67 final_action(const final_action&) = delete; 68 final_action& operator=(const final_action&) = delete; 69 final_action& operator=(final_action&&) = delete; 70 71 GSL_SUPPRESS(f.6) // NO-FORMAT: attribute // terminate if throws 72 ~final_action() noexcept 73 { 74 if (invoke_) f_(); 75 } 76 77private: 78 F f_; 79 bool invoke_{true}; 80}; 81 82// finally() - convenience function to generate a final_action 83template <class F> 84final_action<F> finally(const F& f) noexcept 85{ 86 return final_action<F>(f); 87} 88 89template <class F> 90final_action<F> finally(F&& f) noexcept 91{ 92 return final_action<F>(std::forward<F>(f)); 93} 94 95// narrow_cast(): a searchable way to do narrowing casts of values 96template <class T, class U> 97GSL_SUPPRESS(type.1) // NO-FORMAT: attribute 98constexpr T narrow_cast(U&& u) noexcept 99{ 100 return static_cast<T>(std::forward<U>(u)); 101} 102 103struct narrowing_error : public std::exception 104{ 105}; 106 107namespace details 108{ 109 template <class T, class U> 110 struct is_same_signedness 111 : public std::integral_constant<bool, std::is_signed<T>::value == std::is_signed<U>::value> 112 { 113 }; 114} // namespace details 115 116// narrow() : a checked version of narrow_cast() that throws if the cast changed the value 117template <class T, class U> 118GSL_SUPPRESS(type.1) // NO-FORMAT: attribute 119GSL_SUPPRESS(f.6) // NO-FORMAT: attribute // TODO: MSVC /analyze does not recognise noexcept(false) 120#if GSL_CONSTEXPR_NARROW 121constexpr 122#endif 123T narrow(U u) noexcept(false) 124{ 125 T t = narrow_cast<T>(u); 126 if (static_cast<U>(t) != u) gsl::details::throw_exception(narrowing_error()); 127 if (!details::is_same_signedness<T, U>::value && ((t < T{}) != (u < U{}))) 128 gsl::details::throw_exception(narrowing_error()); 129 return t; 130} 131 132// 133// at() - Bounds-checked way of accessing builtin arrays, std::array, std::vector 134// 135template <class T, std::size_t N> 136GSL_SUPPRESS(bounds.4) // NO-FORMAT: attribute 137GSL_SUPPRESS(bounds.2) // NO-FORMAT: attribute 138constexpr T& at(T (&arr)[N], const index i) 139{ 140 Expects(i >= 0 && i < narrow_cast<index>(N)); 141 return arr[narrow_cast<std::size_t>(i)]; 142} 143 144template <class Cont> 145GSL_SUPPRESS(bounds.4) // NO-FORMAT: attribute 146GSL_SUPPRESS(bounds.2) // NO-FORMAT: attribute 147constexpr auto at(Cont& cont, const index i) -> decltype(cont[cont.size()]) 148{ 149 Expects(i >= 0 && i < narrow_cast<index>(cont.size())); 150 using size_type = decltype(cont.size()); 151 return cont[narrow_cast<size_type>(i)]; 152} 153 154template <class T> 155GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute 156constexpr T at(const std::initializer_list<T> cont, const index i) 157{ 158 Expects(i >= 0 && i < narrow_cast<index>(cont.size())); 159 return *(cont.begin() + i); 160} 161 162} // namespace gsl 163 164#if defined(_MSC_VER) && !defined(__clang__) 165#if _MSC_VER < 1910 166#undef constexpr 167#pragma pop_macro("constexpr") 168 169#endif // _MSC_VER < 1910 170 171#pragma warning(pop) 172 173#endif // _MSC_VER 174 175#endif // GSL_UTIL_H 176