d10dc5a06f
We originally put implementation-detail function objects into individual namespaces for `std::ranges` without a good reason for doing so. This practice was continued, presumably because there was prior art. Since there's no reason to keep these namespaces, this commit removes them, which will slightly impact binary size. This commit does not apply to CPOs, some of which need additional work.
73 lines
2.3 KiB
C++
73 lines
2.3 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___ITERATOR_PREV_H
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#define _LIBCPP___ITERATOR_PREV_H
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#include <__assert>
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#include <__config>
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#include <__iterator/advance.h>
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#include <__iterator/concepts.h>
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#include <__iterator/incrementable_traits.h>
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#include <__iterator/iterator_traits.h>
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#include <__type_traits/enable_if.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_BEGIN_NAMESPACE_STD
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template <class _InputIter, __enable_if_t<__has_input_iterator_category<_InputIter>::value, int> = 0>
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inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 _InputIter
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prev(_InputIter __x, typename iterator_traits<_InputIter>::difference_type __n = 1) {
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// Calling `advance` with a negative value on a non-bidirectional iterator is a no-op in the current implementation.
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// Note that this check duplicates the similar check in `std::advance`.
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_LIBCPP_ASSERT_PEDANTIC(__n <= 0 || __has_bidirectional_iterator_category<_InputIter>::value,
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"Attempt to prev(it, n) with a positive n on a non-bidirectional iterator");
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std::advance(__x, -__n);
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return __x;
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}
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#if _LIBCPP_STD_VER >= 20
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// [range.iter.op.prev]
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namespace ranges {
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struct __prev {
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template <bidirectional_iterator _Ip>
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_LIBCPP_HIDE_FROM_ABI constexpr _Ip operator()(_Ip __x) const {
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--__x;
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return __x;
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}
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template <bidirectional_iterator _Ip>
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_LIBCPP_HIDE_FROM_ABI constexpr _Ip operator()(_Ip __x, iter_difference_t<_Ip> __n) const {
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ranges::advance(__x, -__n);
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return __x;
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}
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template <bidirectional_iterator _Ip>
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_LIBCPP_HIDE_FROM_ABI constexpr _Ip operator()(_Ip __x, iter_difference_t<_Ip> __n, _Ip __bound_iter) const {
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ranges::advance(__x, -__n, __bound_iter);
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return __x;
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}
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};
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inline namespace __cpo {
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inline constexpr auto prev = __prev{};
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} // namespace __cpo
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} // namespace ranges
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#endif // _LIBCPP_STD_VER >= 20
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___ITERATOR_PREV_H
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