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// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___ALGORITHM_FOLD_H
#define _LIBCPP___ALGORITHM_FOLD_H
#include <__concepts/assignable.h>
#include <__concepts/convertible_to.h>
#include <__concepts/invocable.h>
#include <__concepts/movable.h>
#include <__config>
#include <__functional/invoke.h>
#include <__functional/reference_wrapper.h>
#include <__iterator/concepts.h>
#include <__iterator/iterator_traits.h>
#include <__iterator/next.h>
#include <__ranges/access.h>
#include <__ranges/concepts.h>
#include <__ranges/dangling.h>
#include <__type_traits/decay.h>
#include <__type_traits/invoke.h>
#include <__utility/forward.h>
#include <__utility/move.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER >= 23
namespace ranges {
template <class _Ip, class _Tp>
struct in_value_result {
_LIBCPP_NO_UNIQUE_ADDRESS _Ip in;
_LIBCPP_NO_UNIQUE_ADDRESS _Tp value;
template <class _I2, class _T2>
requires convertible_to<const _Ip&, _I2> && convertible_to<const _Tp&, _T2>
_LIBCPP_HIDE_FROM_ABI constexpr operator in_value_result<_I2, _T2>() const& {
return {in, value};
}
template <class _I2, class _T2>
requires convertible_to<_Ip, _I2> && convertible_to<_Tp, _T2>
_LIBCPP_HIDE_FROM_ABI constexpr operator in_value_result<_I2, _T2>() && {
return {std::move(in), std::move(value)};
}
};
template <class _Ip, class _Tp>
using fold_left_with_iter_result = in_value_result<_Ip, _Tp>;
template <class _Fp, class _Tp, class _Ip, class _Rp, class _Up = decay_t<_Rp>>
concept __indirectly_binary_left_foldable_impl =
convertible_to<_Rp, _Up> && //
movable<_Tp> && //
movable<_Up> && //
convertible_to<_Tp, _Up> && //
invocable<_Fp&, _Up, iter_reference_t<_Ip>> && //
assignable_from<_Up&, invoke_result_t<_Fp&, _Up, iter_reference_t<_Ip>>>;
template <class _Fp, class _Tp, class _Ip>
concept __indirectly_binary_left_foldable =
copy_constructible<_Fp> && //
invocable<_Fp&, _Tp, iter_reference_t<_Ip>> && //
__indirectly_binary_left_foldable_impl<_Fp, _Tp, _Ip, invoke_result_t<_Fp&, _Tp, iter_reference_t<_Ip>>>;
struct __fold_left_with_iter {
template <input_iterator _Ip, sentinel_for<_Ip> _Sp, class _Tp, __indirectly_binary_left_foldable<_Tp, _Ip> _Fp>
_LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr auto
operator()(_Ip __first, _Sp __last, _Tp __init, _Fp __f) {
using _Up = decay_t<invoke_result_t<_Fp&, _Tp, iter_reference_t<_Ip>>>;
if (__first == __last) {
return fold_left_with_iter_result<_Ip, _Up>{std::move(__first), _Up(std::move(__init))};
}
_Up __result = std::invoke(__f, std::move(__init), *__first);
for (++__first; __first != __last; ++__first) {
__result = std::invoke(__f, std::move(__result), *__first);
}
return fold_left_with_iter_result<_Ip, _Up>{std::move(__first), std::move(__result)};
}
template <input_range _Rp, class _Tp, __indirectly_binary_left_foldable<_Tp, iterator_t<_Rp>> _Fp>
_LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr auto operator()(_Rp&& __r, _Tp __init, _Fp __f) {
auto __result = operator()(ranges::begin(__r), ranges::end(__r), std::move(__init), std::ref(__f));
using _Up = decay_t<invoke_result_t<_Fp&, _Tp, range_reference_t<_Rp>>>;
return fold_left_with_iter_result<borrowed_iterator_t<_Rp>, _Up>{std::move(__result.in), std::move(__result.value)};
}
};
inline constexpr auto fold_left_with_iter = __fold_left_with_iter();
struct __fold_left {
template <input_iterator _Ip, sentinel_for<_Ip> _Sp, class _Tp, __indirectly_binary_left_foldable<_Tp, _Ip> _Fp>
_LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr auto
operator()(_Ip __first, _Sp __last, _Tp __init, _Fp __f) {
return fold_left_with_iter(std::move(__first), std::move(__last), std::move(__init), std::ref(__f)).value;
}
template <input_range _Rp, class _Tp, __indirectly_binary_left_foldable<_Tp, iterator_t<_Rp>> _Fp>
_LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr auto operator()(_Rp&& __r, _Tp __init, _Fp __f) {
return fold_left_with_iter(ranges::begin(__r), ranges::end(__r), std::move(__init), std::ref(__f)).value;
}
};
inline constexpr auto fold_left = __fold_left();
} // namespace ranges
#endif // _LIBCPP_STD_VER >= 23
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___ALGORITHM_FOLD_H
|
