158 lines
4.6 KiB
C++
158 lines
4.6 KiB
C++
///////////////////////////////////////////////////////////////////////////////
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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 "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 <limits> // for numeric_limits
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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 exchange, forward
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#if defined(__has_include) && __has_include(<version>)
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#include <version>
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#if defined(__cpp_lib_span) && __cpp_lib_span >= 202002L
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#include <span>
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#endif // __cpp_lib_span >= 202002L
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#endif //__has_include(<version>)
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#if defined(_MSC_VER) && !defined(__clang__)
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#pragma warning(push)
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#pragma warning(disable : 4127) // conditional expression is constant
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#endif // _MSC_VER
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#if defined(__cplusplus) && (__cplusplus >= 201703L)
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#define GSL_NODISCARD [[nodiscard]]
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#else
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#define GSL_NODISCARD
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#endif // defined(__cplusplus) && (__cplusplus >= 201703L)
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#if defined(__cpp_inline_variables)
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#define GSL_INLINE inline
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#else
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#define GSL_INLINE
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#endif
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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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// index type for all container indexes/subscripts/sizes
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using index = std::ptrdiff_t;
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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(const F& ff) noexcept : f{ff} { }
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explicit final_action(F&& ff) noexcept : f{std::move(ff)} { }
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~final_action() noexcept { if (invoke) f(); }
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final_action(final_action&& other) noexcept
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: f(std::move(other.f)), invoke(std::exchange(other.invoke, false))
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{ }
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final_action(const final_action&) = delete;
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void operator=(const final_action&) = delete;
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void operator=(final_action&&) = delete;
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private:
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F f;
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bool invoke = true;
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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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GSL_NODISCARD auto finally(F&& f) noexcept
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{
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return final_action<std::decay_t<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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// clang-format off
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GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
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// clang-format on
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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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//
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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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// clang-format off
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GSL_SUPPRESS(bounds.4) // NO-FORMAT: attribute
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GSL_SUPPRESS(bounds.2) // NO-FORMAT: attribute
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// clang-format on
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constexpr T& at(T (&arr)[N], const index i)
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{
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static_assert(N <= static_cast<std::size_t>((std::numeric_limits<std::ptrdiff_t>::max)()), "We only support arrays up to PTRDIFF_MAX bytes.");
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Expects(i >= 0 && i < narrow_cast<index>(N));
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return arr[narrow_cast<std::size_t>(i)];
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}
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template <class Cont>
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// clang-format off
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GSL_SUPPRESS(bounds.4) // NO-FORMAT: attribute
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GSL_SUPPRESS(bounds.2) // NO-FORMAT: attribute
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// clang-format on
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constexpr auto at(Cont& cont, const index i) -> decltype(cont[cont.size()])
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{
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Expects(i >= 0 && i < narrow_cast<index>(cont.size()));
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using size_type = decltype(cont.size());
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return cont[narrow_cast<size_type>(i)];
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}
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template <class T>
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// clang-format off
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GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
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// clang-format on
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constexpr T at(const std::initializer_list<T> cont, const index i)
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{
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Expects(i >= 0 && i < narrow_cast<index>(cont.size()));
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return *(cont.begin() + i);
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}
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#if defined(__cpp_lib_span) && __cpp_lib_span >= 202002L
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template <class T, std::size_t extent = std::dynamic_extent>
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constexpr auto at(std::span<T, extent> sp, const index i) -> decltype(sp[sp.size()])
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{
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Expects(i >= 0 && i < narrow_cast<index>(sp.size()));
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return sp[gsl::narrow_cast<std::size_t>(i)];
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}
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#endif // __cpp_lib_span >= 202002L
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} // namespace gsl
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#if defined(_MSC_VER) && !defined(__clang__)
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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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