113 lines
4.7 KiB
C++
113 lines
4.7 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_SEARCH_N_H
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#define _LIBCPP___ALGORITHM_SEARCH_N_H
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#include <__algorithm/comp.h>
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#include <__config>
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#include <__iterator/iterator_traits.h>
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#include <type_traits> // __convert_to_integral
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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 _BinaryPredicate, class _ForwardIterator, class _Size, class _Tp>
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_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator __search_n(_ForwardIterator __first, _ForwardIterator __last,
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_Size __count, const _Tp& __value_, _BinaryPredicate __pred,
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forward_iterator_tag) {
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if (__count <= 0)
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return __first;
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while (true) {
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// Find first element in sequence that matchs __value_, with a mininum of loop checks
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while (true) {
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if (__first == __last) // return __last if no element matches __value_
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return __last;
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if (__pred(*__first, __value_))
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break;
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++__first;
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}
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// *__first matches __value_, now match elements after here
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_ForwardIterator __m = __first;
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_Size __c(0);
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while (true) {
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if (++__c == __count) // If pattern exhausted, __first is the answer (works for 1 element pattern)
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return __first;
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if (++__m == __last) // Otherwise if source exhaused, pattern not found
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return __last;
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if (!__pred(*__m, __value_)) // if there is a mismatch, restart with a new __first
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{
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__first = __m;
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++__first;
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break;
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} // else there is a match, check next elements
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}
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}
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}
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template <class _BinaryPredicate, class _RandomAccessIterator, class _Size, class _Tp>
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_LIBCPP_CONSTEXPR_AFTER_CXX17 _RandomAccessIterator __search_n(_RandomAccessIterator __first,
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_RandomAccessIterator __last, _Size __count,
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const _Tp& __value_, _BinaryPredicate __pred,
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random_access_iterator_tag) {
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typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
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if (__count <= 0)
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return __first;
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_Size __len = static_cast<_Size>(__last - __first);
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if (__len < __count)
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return __last;
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const _RandomAccessIterator __s = __last - difference_type(__count - 1); // Start of pattern match can't go beyond here
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while (true) {
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// Find first element in sequence that matchs __value_, with a mininum of loop checks
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while (true) {
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if (__first >= __s) // return __last if no element matches __value_
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return __last;
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if (__pred(*__first, __value_))
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break;
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++__first;
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}
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// *__first matches __value_, now match elements after here
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_RandomAccessIterator __m = __first;
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_Size __c(0);
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while (true) {
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if (++__c == __count) // If pattern exhausted, __first is the answer (works for 1 element pattern)
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return __first;
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++__m; // no need to check range on __m because __s guarantees we have enough source
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if (!__pred(*__m, __value_)) // if there is a mismatch, restart with a new __first
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{
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__first = __m;
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++__first;
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break;
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} // else there is a match, check next elements
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}
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}
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}
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template <class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
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_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator search_n(
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_ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value_, _BinaryPredicate __pred) {
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return _VSTD::__search_n<_BinaryPredicate&>(
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__first, __last, _VSTD::__convert_to_integral(__count), __value_, __pred,
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typename iterator_traits<_ForwardIterator>::iterator_category());
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}
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template <class _ForwardIterator, class _Size, class _Tp>
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_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
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search_n(_ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value_) {
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typedef typename iterator_traits<_ForwardIterator>::value_type __v;
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return _VSTD::search_n(__first, __last, _VSTD::__convert_to_integral(__count), __value_, __equal_to<__v, _Tp>());
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}
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___ALGORITHM_SEARCH_N_H
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