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154 lines
4.1 KiB
Plaintext
154 lines
4.1 KiB
Plaintext
///////////////////////////////////////////////////////////////////////////////
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//
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// Copyright (c) 2015 Microsoft Corporation. All rights reserved.
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//
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// This code is licensed under the MIT License (MIT).
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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//
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///////////////////////////////////////////////////////////////////////////////
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#ifndef GSL_UTIL_H
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#define GSL_UTIL_H
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#include <gsl/gsl_assert> // for Expects
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#include <array>
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#include <cstddef> // for ptrdiff_t, size_t
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#include <exception> // for exception
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#include <initializer_list> // for initializer_list
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#include <type_traits> // for is_signed, integral_constant
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#include <utility> // for forward
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#if defined(_MSC_VER)
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#pragma warning(push)
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#pragma warning(disable : 4127) // conditional expression is constant
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#if _MSC_VER < 1910
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#pragma push_macro("constexpr")
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#define constexpr /*constexpr*/
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#endif // _MSC_VER < 1910
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#endif // _MSC_VER
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namespace gsl
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{
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//
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// GSL.util: utilities
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//
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// final_action allows you to ensure something gets run at the end of a scope
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template <class F>
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class final_action
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{
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public:
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explicit final_action(F f) noexcept : f_(std::move(f)), invoke_(true) {}
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final_action(final_action&& other) noexcept : f_(std::move(other.f_)), invoke_(other.invoke_)
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{
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other.invoke_ = false;
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}
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final_action(const final_action&) = delete;
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final_action& operator=(const final_action&) = delete;
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~final_action() noexcept
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{
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if (invoke_) f_();
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}
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private:
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F f_;
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bool invoke_;
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};
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// finally() - convenience function to generate a final_action
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template <class F>
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inline final_action<F> finally(const F& f) noexcept
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{
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return final_action<F>(f);
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}
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template <class F>
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inline final_action<F> finally(F&& f) noexcept
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{
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return final_action<F>(std::forward<F>(f));
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}
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// narrow_cast(): a searchable way to do narrowing casts of values
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template <class T, class U>
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inline constexpr T narrow_cast(U&& u) noexcept
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{
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return static_cast<T>(std::forward<U>(u));
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}
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struct narrowing_error : public std::exception
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{
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};
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namespace details
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{
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template <class T, class U>
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struct is_same_signedness
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: public std::integral_constant<bool, std::is_signed<T>::value == std::is_signed<U>::value>
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{
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};
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}
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// narrow() : a checked version of narrow_cast() that throws if the cast changed the value
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template <class T, class U>
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inline T narrow(U u)
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{
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T t = narrow_cast<T>(u);
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if (static_cast<U>(t) != u) throw narrowing_error();
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if (!details::is_same_signedness<T, U>::value && ((t < T{}) != (u < U{})))
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throw narrowing_error();
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return t;
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}
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//
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// at() - Bounds-checked way of accessing builtin arrays, std::array, std::vector
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//
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template <class T, std::size_t N>
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inline constexpr T& at(T (&arr)[N], const std::ptrdiff_t index)
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{
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Expects(index >= 0 && index < narrow_cast<std::ptrdiff_t>(N));
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return arr[static_cast<std::size_t>(index)];
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}
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template <class Cont>
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inline constexpr auto at(Cont& cont, const std::ptrdiff_t index) -> decltype(cont[cont.size()])
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{
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Expects(index >= 0 && index < narrow_cast<std::ptrdiff_t>(cont.size()));
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using size_type = decltype(cont.size());
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return cont[static_cast<size_type>(index)];
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}
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template <class T>
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inline constexpr T at(const std::initializer_list<T> cont, const std::ptrdiff_t index)
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{
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Expects(index >= 0 && index < narrow_cast<std::ptrdiff_t>(cont.size()));
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return *(cont.begin() + index);
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}
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} // namespace gsl
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#if defined(_MSC_VER)
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#if _MSC_VER < 1910
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#undef constexpr
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#pragma pop_macro("constexpr")
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#endif // _MSC_VER < 1910
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#pragma warning(pop)
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#endif // _MSC_VER
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#endif // GSL_UTIL_H
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