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//===----------------------------------------------------------------------===//
//
// 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_FIND_SEGMENT_IF_H
#define _LIBCPP___ALGORITHM_FIND_SEGMENT_IF_H
#include <__config>
#include <__iterator/segmented_iterator.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
// __find_segment_if is a utility function for optimizing iteration over segmented iterators linearly.
// [__first, __last) has to be a segmented range. __pred is expected to take a range of local iterators and the __proj.
// It returns an iterator to the first element that satisfies the predicate, or a one-past-the-end iterator if there was
// no match. __proj may be anything that should be passed to __pred, but is expected to be a projection to support
// ranges algorithms, or __identity for classic algorithms.
template <class _SegmentedIterator, class _Pred, class _Proj>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _SegmentedIterator
__find_segment_if(_SegmentedIterator __first, _SegmentedIterator __last, _Pred __pred, _Proj& __proj) {
using _Traits = __segmented_iterator_traits<_SegmentedIterator>;
auto __sfirst = _Traits::__segment(__first);
auto __slast = _Traits::__segment(__last);
// We are in a single segment, so we might not be at the beginning or end
if (__sfirst == __slast)
return _Traits::__compose(__sfirst, __pred(_Traits::__local(__first), _Traits::__local(__last), __proj));
{ // We have more than one segment. Iterate over the first segment, since we might not start at the beginning
auto __llast = _Traits::__end(__sfirst);
auto __liter = __pred(_Traits::__local(__first), __llast, __proj);
if (__liter != __llast)
return _Traits::__compose(__sfirst, __liter);
}
++__sfirst;
// Iterate over the segments which are guaranteed to be completely in the range
while (__sfirst != __slast) {
auto __llast = _Traits::__end(__sfirst);
auto __liter = __pred(_Traits::__begin(__sfirst), _Traits::__end(__sfirst), __proj);
if (__liter != __llast)
return _Traits::__compose(__sfirst, __liter);
++__sfirst;
}
// Iterate over the last segment
return _Traits::__compose(__sfirst, __pred(_Traits::__begin(__sfirst), _Traits::__local(__last), __proj));
}
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___ALGORITHM_FIND_SEGMENT_IF_H
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