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128 lines
4.8 KiB
C++
128 lines
4.8 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___ALGORITHM_FOLD_H
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#define _LIBCPP___ALGORITHM_FOLD_H
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#include <__concepts/assignable.h>
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#include <__concepts/convertible_to.h>
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#include <__concepts/invocable.h>
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#include <__concepts/movable.h>
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#include <__config>
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#include <__functional/invoke.h>
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#include <__functional/reference_wrapper.h>
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#include <__iterator/concepts.h>
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#include <__iterator/iterator_traits.h>
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#include <__iterator/next.h>
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#include <__ranges/access.h>
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#include <__ranges/concepts.h>
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#include <__ranges/dangling.h>
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#include <__type_traits/decay.h>
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#include <__type_traits/invoke.h>
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#include <__utility/forward.h>
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#include <__utility/move.h>
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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_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER >= 23
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namespace ranges {
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template <class _Ip, class _Tp>
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struct in_value_result {
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_LIBCPP_NO_UNIQUE_ADDRESS _Ip in;
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_LIBCPP_NO_UNIQUE_ADDRESS _Tp value;
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template <class _I2, class _T2>
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requires convertible_to<const _Ip&, _I2> && convertible_to<const _Tp&, _T2>
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_LIBCPP_HIDE_FROM_ABI constexpr operator in_value_result<_I2, _T2>() const& {
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return {in, value};
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}
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template <class _I2, class _T2>
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requires convertible_to<_Ip, _I2> && convertible_to<_Tp, _T2>
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_LIBCPP_HIDE_FROM_ABI constexpr operator in_value_result<_I2, _T2>() && {
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return {std::move(in), std::move(value)};
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}
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};
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template <class _Ip, class _Tp>
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using fold_left_with_iter_result = in_value_result<_Ip, _Tp>;
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template <class _Fp, class _Tp, class _Ip, class _Rp, class _Up = decay_t<_Rp>>
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concept __indirectly_binary_left_foldable_impl =
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convertible_to<_Rp, _Up> && //
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movable<_Tp> && //
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movable<_Up> && //
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convertible_to<_Tp, _Up> && //
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invocable<_Fp&, _Up, iter_reference_t<_Ip>> && //
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assignable_from<_Up&, invoke_result_t<_Fp&, _Up, iter_reference_t<_Ip>>>;
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template <class _Fp, class _Tp, class _Ip>
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concept __indirectly_binary_left_foldable =
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copy_constructible<_Fp> && //
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invocable<_Fp&, _Tp, iter_reference_t<_Ip>> && //
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__indirectly_binary_left_foldable_impl<_Fp, _Tp, _Ip, invoke_result_t<_Fp&, _Tp, iter_reference_t<_Ip>>>;
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struct __fold_left_with_iter {
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template <input_iterator _Ip, sentinel_for<_Ip> _Sp, class _Tp, __indirectly_binary_left_foldable<_Tp, _Ip> _Fp>
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI static constexpr auto operator()(_Ip __first, _Sp __last, _Tp __init, _Fp __f) {
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using _Up = decay_t<invoke_result_t<_Fp&, _Tp, iter_reference_t<_Ip>>>;
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if (__first == __last) {
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return fold_left_with_iter_result<_Ip, _Up>{std::move(__first), _Up(std::move(__init))};
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}
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_Up __result = std::invoke(__f, std::move(__init), *__first);
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for (++__first; __first != __last; ++__first) {
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__result = std::invoke(__f, std::move(__result), *__first);
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}
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return fold_left_with_iter_result<_Ip, _Up>{std::move(__first), std::move(__result)};
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}
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template <input_range _Rp, class _Tp, __indirectly_binary_left_foldable<_Tp, iterator_t<_Rp>> _Fp>
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI static constexpr auto operator()(_Rp&& __r, _Tp __init, _Fp __f) {
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auto __result = operator()(ranges::begin(__r), ranges::end(__r), std::move(__init), std::ref(__f));
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using _Up = decay_t<invoke_result_t<_Fp&, _Tp, range_reference_t<_Rp>>>;
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return fold_left_with_iter_result<borrowed_iterator_t<_Rp>, _Up>{std::move(__result.in), std::move(__result.value)};
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}
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};
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inline constexpr auto fold_left_with_iter = __fold_left_with_iter();
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struct __fold_left {
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template <input_iterator _Ip, sentinel_for<_Ip> _Sp, class _Tp, __indirectly_binary_left_foldable<_Tp, _Ip> _Fp>
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI static constexpr auto operator()(_Ip __first, _Sp __last, _Tp __init, _Fp __f) {
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return fold_left_with_iter(std::move(__first), std::move(__last), std::move(__init), std::ref(__f)).value;
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}
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template <input_range _Rp, class _Tp, __indirectly_binary_left_foldable<_Tp, iterator_t<_Rp>> _Fp>
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI static constexpr auto operator()(_Rp&& __r, _Tp __init, _Fp __f) {
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return fold_left_with_iter(ranges::begin(__r), ranges::end(__r), std::move(__init), std::ref(__f)).value;
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}
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};
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inline constexpr auto fold_left = __fold_left();
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} // namespace ranges
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#endif // _LIBCPP_STD_VER >= 23
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___ALGORITHM_FOLD_H
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