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