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Diffstat (limited to 'include/gsl/gsl_util')
-rw-r--r-- | include/gsl/gsl_util | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/include/gsl/gsl_util b/include/gsl/gsl_util new file mode 100644 index 0000000..164bf58 --- /dev/null +++ b/include/gsl/gsl_util @@ -0,0 +1,175 @@ +/////////////////////////////////////////////////////////////////////////////// +// +// Copyright (c) 2015 Microsoft Corporation. All rights reserved. +// +// This code is licensed under the MIT License (MIT). +// +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN +// THE SOFTWARE. +// +/////////////////////////////////////////////////////////////////////////////// + +#pragma once + +#ifndef GSL_UTIL_H +#define GSL_UTIL_H + +#include <gsl/gsl_assert> // Ensures/Expects +#include <array> +#include <exception> +#include <type_traits> +#include <utility> + +#if defined(_MSC_VER) + #pragma warning(push) + #pragma warning(disable : 4127) // conditional expression is constant + + #if _MSC_VER < 1910 + #pragma push_macro("constexpr") + #define constexpr /*constexpr*/ + // MSVC 2013 workarounds + #if _MSC_VER <= 1800 + // noexcept is not understood + #pragma push_macro("noexcept") + #define noexcept /*noexcept*/ + // turn off some misguided warnings + #pragma warning(disable : 4351) // warns about newly introduced aggregate initializer behavior + #endif // _MSC_VER <= 1800 + #endif // _MSC_VER < 1910 +#endif // _MSC_VER + +namespace gsl +{ +// +// GSL.util: utilities +// + +// final_act allows you to ensure something gets run at the end of a scope +template <class F> +class final_act +{ +public: + explicit final_act(F f) noexcept : f_(std::move(f)), invoke_(true) {} + + final_act(final_act&& other) noexcept : f_(std::move(other.f_)), invoke_(other.invoke_) + { + other.invoke_ = false; + } + + final_act(const final_act&) = delete; + final_act& operator=(const final_act&) = delete; + + ~final_act() noexcept + { + if (invoke_) f_(); + } + +private: + F f_; + bool invoke_; +}; + +// finally() - convenience function to generate a final_act +template <class F> +inline final_act<F> finally(const F& f) noexcept +{ + return final_act<F>(f); +} + +template <class F> +inline final_act<F> finally(F&& f) noexcept +{ + return final_act<F>(std::forward<F>(f)); +} + +// narrow_cast(): a searchable way to do narrowing casts of values +#if defined(_MSC_VER) && _MSC_VER <= 1800 +template <class T, class U> +inline constexpr T narrow_cast(U u) noexcept +{ + return static_cast<T>(u); +} +#else +template <class T, class U> +inline constexpr T narrow_cast(U&& u) noexcept +{ + return static_cast<T>(std::forward<U>(u)); +} +#endif + +struct narrowing_error : public std::exception +{ +}; + +namespace details +{ + template <class T, class U> + struct is_same_signedness + : public std::integral_constant<bool, std::is_signed<T>::value == std::is_signed<U>::value> + { + }; +} + +// narrow() : a checked version of narrow_cast() that throws if the cast changed the value +template <class T, class U> +inline T narrow(U u) +{ + T t = narrow_cast<T>(u); + if (static_cast<U>(t) != u) throw narrowing_error(); + if (!details::is_same_signedness<T, U>::value && ((t < T{}) != (u < U{}))) + throw narrowing_error(); + return t; +} + +// +// at() - Bounds-checked way of accessing static arrays, std::array, std::vector +// +template <class T, size_t N> +inline constexpr T& at(T (&arr)[N], std::ptrdiff_t index) +{ + Expects(index >= 0 && index < narrow_cast<std::ptrdiff_t>(N)); + return arr[static_cast<size_t>(index)]; +} + +template <class T, size_t N> +inline constexpr T& at(std::array<T, N>& arr, std::ptrdiff_t index) +{ + Expects(index >= 0 && index < narrow_cast<std::ptrdiff_t>(N)); + return arr[static_cast<size_t>(index)]; +} + +template <class Cont> +inline constexpr typename Cont::value_type& at(Cont& cont, std::ptrdiff_t index) +{ + Expects(index >= 0 && index < narrow_cast<std::ptrdiff_t>(cont.size())); + return cont[static_cast<typename Cont::size_type>(index)]; +} + +template <class T> +inline constexpr const T& at(std::initializer_list<T> cont, std::ptrdiff_t index) +{ + Expects(index >= 0 && index < narrow_cast<std::ptrdiff_t>(cont.size())); + return *(cont.begin() + index); +} + +} // namespace gsl + +#if defined(_MSC_VER) + #if _MSC_VER < 1910 + #undef constexpr + #pragma pop_macro("constexpr") + + #if _MSC_VER <= 1800 + #undef noexcept + #pragma pop_macro("noexcept") + #endif // _MSC_VER <= 1800 + #endif // _MSC_VER < 1910 + #pragma warning(pop) +#endif // _MSC_VER + +#endif // GSL_UTIL_H |