forked from OSchip/llvm-project
74 lines
3.0 KiB
C++
74 lines
3.0 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___RANGES_RANGE_ADAPTOR_H
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#define _LIBCPP___RANGES_RANGE_ADAPTOR_H
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#include <__config>
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#include <__functional/compose.h>
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#include <__functional/invoke.h>
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#include <__ranges/concepts.h>
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#include <__utility/forward.h>
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#include <__utility/move.h>
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#include <concepts>
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#include <type_traits>
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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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_LIBCPP_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
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// CRTP base that one can derive from in order to be considered a range adaptor closure
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// by the library. When deriving from this class, a pipe operator will be provided to
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// make the following hold:
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// - `x | f` is equivalent to `f(x)`
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// - `f1 | f2` is an adaptor closure `g` such that `g(x)` is equivalent to `f2(f1(x))`
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template <class _Tp>
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struct __range_adaptor_closure;
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// Type that wraps an arbitrary function object and makes it into a range adaptor closure,
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// i.e. something that can be called via the `x | f` notation.
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template <class _Fn>
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struct __range_adaptor_closure_t : _Fn, __range_adaptor_closure<__range_adaptor_closure_t<_Fn>> {
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constexpr explicit __range_adaptor_closure_t(_Fn&& __f) : _Fn(std::move(__f)) { }
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};
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template <class _Tp>
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concept _RangeAdaptorClosure = derived_from<remove_cvref_t<_Tp>, __range_adaptor_closure<remove_cvref_t<_Tp>>>;
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template <class _Tp>
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struct __range_adaptor_closure {
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template <ranges::viewable_range _View, _RangeAdaptorClosure _Closure>
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requires same_as<_Tp, remove_cvref_t<_Closure>> &&
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invocable<_Closure, _View>
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI
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friend constexpr decltype(auto) operator|(_View&& __view, _Closure&& __closure)
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noexcept(is_nothrow_invocable_v<_Closure, _View>)
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{ return std::invoke(std::forward<_Closure>(__closure), std::forward<_View>(__view)); }
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template <_RangeAdaptorClosure _Closure, _RangeAdaptorClosure _OtherClosure>
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requires same_as<_Tp, remove_cvref_t<_Closure>> &&
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constructible_from<decay_t<_Closure>, _Closure> &&
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constructible_from<decay_t<_OtherClosure>, _OtherClosure>
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI
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friend constexpr auto operator|(_Closure&& __c1, _OtherClosure&& __c2)
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noexcept(is_nothrow_constructible_v<decay_t<_Closure>, _Closure> &&
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is_nothrow_constructible_v<decay_t<_OtherClosure>, _OtherClosure>)
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{ return __range_adaptor_closure_t(std::__compose(std::forward<_OtherClosure>(__c2), std::forward<_Closure>(__c1))); }
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};
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#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___RANGES_RANGE_ADAPTOR_H
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