102 lines
3.4 KiB
C++
102 lines
3.4 KiB
C++
//===----------------------------------------------------------------------===//
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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_MINMAX_ELEMENT_H
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#define _LIBCPP___ALGORITHM_MINMAX_ELEMENT_H
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#include <__algorithm/comp.h>
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#include <__config>
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#include <__functional/identity.h>
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#include <__iterator/iterator_traits.h>
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#include <__utility/pair.h>
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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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template <class _Comp, class _Proj>
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class _MinmaxElementLessFunc {
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_Comp& __comp_;
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_Proj& __proj_;
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public:
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR
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_MinmaxElementLessFunc(_Comp& __comp, _Proj& __proj) : __comp_(__comp), __proj_(__proj) {}
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template <class _Iter>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
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bool operator()(_Iter& __it1, _Iter& __it2) {
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return std::__invoke(__comp_, std::__invoke(__proj_, *__it1), std::__invoke(__proj_, *__it2));
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}
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};
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template <class _Iter, class _Sent, class _Proj, class _Comp>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
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pair<_Iter, _Iter> __minmax_element_impl(_Iter __first, _Sent __last, _Comp& __comp, _Proj& __proj) {
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auto __less = _MinmaxElementLessFunc<_Comp, _Proj>(__comp, __proj);
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pair<_Iter, _Iter> __result(__first, __first);
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if (__first == __last || ++__first == __last)
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return __result;
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if (__less(__first, __result.first))
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__result.first = __first;
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else
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__result.second = __first;
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while (++__first != __last) {
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_Iter __i = __first;
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if (++__first == __last) {
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if (__less(__i, __result.first))
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__result.first = __i;
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else if (!__less(__i, __result.second))
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__result.second = __i;
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return __result;
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}
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if (__less(__first, __i)) {
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if (__less(__first, __result.first))
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__result.first = __first;
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if (!__less(__i, __result.second))
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__result.second = __i;
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} else {
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if (__less(__i, __result.first))
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__result.first = __i;
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if (!__less(__first, __result.second))
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__result.second = __first;
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}
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}
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return __result;
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}
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template <class _ForwardIterator, class _Compare>
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_LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
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pair<_ForwardIterator, _ForwardIterator>
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minmax_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp) {
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static_assert(__is_cpp17_forward_iterator<_ForwardIterator>::value,
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"std::minmax_element requires a ForwardIterator");
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static_assert(__is_callable<_Compare, decltype(*__first), decltype(*__first)>::value,
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"The comparator has to be callable");
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auto __proj = __identity();
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return std::__minmax_element_impl(__first, __last, __comp, __proj);
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}
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template <class _ForwardIterator>
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_LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
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pair<_ForwardIterator, _ForwardIterator> minmax_element(_ForwardIterator __first, _ForwardIterator __last) {
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return std::minmax_element(__first, __last, __less<typename iterator_traits<_ForwardIterator>::value_type>());
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}
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___ALGORITHM_MINMAX_ELEMENT_H
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