| //===----------------------------------------------------------------------===// |
| // |
| // 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 |