adc7932461
Implemented [[*time.traits.is.clock*]](https://eel.is/c++draft/time.traits.is.clock) from [P0355R7](https://wg21.link/p0355r7). This patch implements the C++20 feature `is_clock` and `is_clock_v` based on the documentation [on cppreference](https://en.cppreference.com/w/cpp/chrono/is_clock.html) Fixes #166049.
73 lines
2.2 KiB
C++
73 lines
2.2 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___CHRONO_IS_CLOCK_H
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#define _LIBCPP___CHRONO_IS_CLOCK_H
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#include <__config>
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#include <__chrono/duration.h>
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#include <__chrono/time_point.h>
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#include <__concepts/same_as.h>
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#include <__type_traits/integral_constant.h>
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#include <__type_traits/is_arithmetic.h>
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#include <__type_traits/is_class.h>
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#include <__type_traits/is_union.h>
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#include <ratio>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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#if _LIBCPP_STD_VER >= 20
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_LIBCPP_BEGIN_NAMESPACE_STD
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namespace chrono {
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// Helper to check that _Tp::time_point has the form time_point<_, typename _Tp::duration>.
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template <class _TimePoint, class _ClockType>
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inline constexpr bool __is_valid_clock_time_point_v = false;
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template <class _TimePointClock, class _ClockType>
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inline constexpr bool
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__is_valid_clock_time_point_v<time_point<_TimePointClock, typename _ClockType::duration>, _ClockType> = true;
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// Check if a clock satisfies the Cpp17Clock requirements as defined in [time.clock.req]
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template <class _Tp>
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_LIBCPP_NO_SPECIALIZATIONS inline constexpr bool is_clock_v = requires {
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typename _Tp::rep;
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requires is_arithmetic_v<typename _Tp::rep> || is_class_v<typename _Tp::rep> || is_union_v<typename _Tp::rep>;
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typename _Tp::period;
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requires __is_ratio_v<typename _Tp::period>;
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typename _Tp::duration;
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requires same_as<typename _Tp::duration, duration<typename _Tp::rep, typename _Tp::period>>;
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typename _Tp::time_point;
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requires __is_valid_clock_time_point_v<typename _Tp::time_point, _Tp>;
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_Tp::is_steady;
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requires same_as<decltype((_Tp::is_steady)), const bool&>;
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_Tp::now();
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requires same_as<decltype(_Tp::now()), typename _Tp::time_point>;
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};
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template <class _Tp>
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struct _LIBCPP_NO_SPECIALIZATIONS is_clock : bool_constant<is_clock_v<_Tp>> {};
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} // namespace chrono
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP_STD_VER
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#endif // _LIBCPP___CHRONO_IS_CLOCK_H
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