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Diffstat (limited to 'gsl/gsl_util.h')
-rw-r--r-- | gsl/gsl_util.h | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/gsl/gsl_util.h b/gsl/gsl_util.h new file mode 100644 index 0000000..92a795b --- /dev/null +++ b/gsl/gsl_util.h @@ -0,0 +1,177 @@ +/////////////////////////////////////////////////////////////////////////////// +// +// 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_assert.h" // Ensures/Expects +#include <array> +#include <exception> +#include <type_traits> +#include <utility> + +#ifdef _MSC_VER + +// No MSVC does constexpr fully yet +#pragma push_macro("constexpr") +#define constexpr + +#pragma warning(push) +#pragma warning(disable : 4127) // conditional expression is constant + +// MSVC 2013 workarounds +#if _MSC_VER <= 1800 +// noexcept is not understood +#pragma push_macro("noexcept") +#define noexcept + +// turn off some misguided warnings +#pragma warning(push) +#pragma warning(disable : 4351) // warns about newly introduced aggregate initializer behavior + +#endif // _MSC_VER <= 1800 + +#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 +template <class T, class U> +inline constexpr T narrow_cast(U u) noexcept +{ + return static_cast<T>(u); +} + +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> +constexpr T& at(T (&arr)[N], size_t index) +{ + Expects(index < N); + return arr[index]; +} + +template <class T, size_t N> +constexpr T& at(std::array<T, N>& arr, size_t index) +{ + Expects(index < N); + return arr[index]; +} + +template <class Cont> +constexpr typename Cont::value_type& at(Cont& cont, size_t index) +{ + Expects(index < cont.size()); + return cont[index]; +} + +template <class T> +constexpr const T& at(std::initializer_list<T> cont, size_t index) +{ + Expects(index < cont.size()); + return *(cont.begin() + index); +} + +} // namespace gsl + +#ifdef _MSC_VER + +#pragma warning(pop) + +#undef constexpr +#pragma pop_macro("constexpr") + +#if _MSC_VER <= 1800 + +#undef noexcept +#pragma pop_macro("noexcept") + +#pragma warning(pop) + +#endif // _MSC_VER <= 1800 + +#endif // _MSC_VER + +#endif // GSL_UTIL_H |