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1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef _LIBCPP___CXX03___ALGORITHM_FOR_EACH_SEGMENT_H
10#define _LIBCPP___CXX03___ALGORITHM_FOR_EACH_SEGMENT_H
11
12#include <__cxx03/__config>
13#include <__cxx03/__iterator/segmented_iterator.h>
14
15#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
16# pragma GCC system_header
17#endif
18
19_LIBCPP_BEGIN_NAMESPACE_STD
20
21// __for_each_segment is a utility function for optimizing iterating over segmented iterators linearly.
22// __first and __last are expected to be a segmented range. __func is expected to take a range of local iterators.
23// Anything that is returned from __func is ignored.
24
25template <class _SegmentedIterator, class _Functor>
26_LIBCPP_HIDE_FROM_ABI void __for_each_segment(_SegmentedIterator __first, _SegmentedIterator __last, _Functor __func) {
27 using _Traits = __segmented_iterator_traits<_SegmentedIterator>;
28
29 auto __sfirst = _Traits::__segment(__first);
30 auto __slast = _Traits::__segment(__last);
31
32 // We are in a single segment, so we might not be at the beginning or end
33 if (__sfirst == __slast) {
34 __func(_Traits::__local(__first), _Traits::__local(__last));
35 return;
36 }
37
38 // We have more than one segment. Iterate over the first segment, since we might not start at the beginning
39 __func(_Traits::__local(__first), _Traits::__end(__sfirst));
40 ++__sfirst;
41 // iterate over the segments which are guaranteed to be completely in the range
42 while (__sfirst != __slast) {
43 __func(_Traits::__begin(__sfirst), _Traits::__end(__sfirst));
44 ++__sfirst;
45 }
46 // iterate over the last segment
47 __func(_Traits::__begin(__sfirst), _Traits::__local(__last));
48}
49
50_LIBCPP_END_NAMESPACE_STD
51
52#endif // _LIBCPP___CXX03___ALGORITHM_FOR_EACH_SEGMENT_H
53

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source code of libcxx/include/__cxx03/__algorithm/for_each_segment.h