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https://github.com/jart/cosmopolitan.git
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99 lines
3 KiB
C++
99 lines
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_DISTANCE_H
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#define _LIBCPP___ITERATOR_DISTANCE_H
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#include <__config>
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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 <__ranges/access.h>
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#include <__ranges/concepts.h>
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#include <__ranges/size.h>
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#include <__type_traits/decay.h>
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#include <__type_traits/remove_cvref.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>
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inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 typename iterator_traits<_InputIter>::difference_type
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__distance(_InputIter __first, _InputIter __last, input_iterator_tag) {
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typename iterator_traits<_InputIter>::difference_type __r(0);
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for (; __first != __last; ++__first)
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++__r;
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return __r;
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}
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template <class _RandIter>
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inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 typename iterator_traits<_RandIter>::difference_type
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__distance(_RandIter __first, _RandIter __last, random_access_iterator_tag) {
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return __last - __first;
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}
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template <class _InputIter>
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inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 typename iterator_traits<_InputIter>::difference_type
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distance(_InputIter __first, _InputIter __last) {
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return std::__distance(__first, __last, typename iterator_traits<_InputIter>::iterator_category());
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}
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#if _LIBCPP_STD_VER >= 20
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// [range.iter.op.distance]
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namespace ranges {
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namespace __distance {
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struct __fn {
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template <class _Ip, sentinel_for<_Ip> _Sp>
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requires(!sized_sentinel_for<_Sp, _Ip>)
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_LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<_Ip> operator()(_Ip __first, _Sp __last) const {
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iter_difference_t<_Ip> __n = 0;
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while (__first != __last) {
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++__first;
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++__n;
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}
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return __n;
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}
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template <class _Ip, sized_sentinel_for<decay_t<_Ip>> _Sp>
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_LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<_Ip> operator()(_Ip&& __first, _Sp __last) const {
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if constexpr (sized_sentinel_for<_Sp, __remove_cvref_t<_Ip>>) {
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return __last - __first;
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} else {
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return __last - decay_t<_Ip>(__first);
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}
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}
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template <range _Rp>
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_LIBCPP_HIDE_FROM_ABI constexpr range_difference_t<_Rp> operator()(_Rp&& __r) const {
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if constexpr (sized_range<_Rp>) {
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return static_cast<range_difference_t<_Rp>>(ranges::size(__r));
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} else {
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return operator()(ranges::begin(__r), ranges::end(__r));
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}
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}
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};
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} // namespace __distance
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inline namespace __cpo {
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inline constexpr auto distance = __distance::__fn{};
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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_DISTANCE_H
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