[libc++] Added segmented iterator for std::equal #106254
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@llvm/pr-subscribers-libcxx Author: NoumanAmir-10xe (NoumanAmir657) ChangesFor the issue #102817 Full diff: https://github.com/llvm/llvm-project/pull/106254.diff 1 Files Affected:
diff --git a/libcxx/include/__algorithm/equal.h b/libcxx/include/__algorithm/equal.h
index bfc8f72f6eb195..c7d8eb54026bba 100644
--- a/libcxx/include/__algorithm/equal.h
+++ b/libcxx/include/__algorithm/equal.h
@@ -24,6 +24,7 @@
#include <__type_traits/is_equality_comparable.h>
#include <__type_traits/is_volatile.h>
#include <__utility/move.h>
+#include <__iterator/segmented_iterator.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
@@ -54,9 +55,68 @@ __equal_iter_impl(_Tp* __first1, _Tp* __last1, _Up* __first2, _BinaryPredicate&)
return std::__constexpr_memcmp_equal(__first1, __first2, __element_count(__last1 - __first1));
}
+template <class _SegmentedIterator1, class _SegmentedIterator2, class _BinaryPredicate>
+_LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool
+__equal_segment_iter(_SegmentedIterator1 __first1, _SegmentedIterator1 __last1, _SegmentedIterator2 __first2, _BinaryPredicate __pred) {
+ using _Traits1 = __segmented_iterator_traits<_SegmentedIterator1>;
+ using _Traits2 = __segmented_iterator_traits<_SegmentedIterator2>;
+
+ auto __sfirst1 = _Traits1::__segment(__first1);
+ auto __slast1 = _Traits1::__segment(__last1);
+
+ auto __sfirst2 = _Traits2::__segment(__first2);
+
+ // Both have only 1 segment
+ if (__sfirst1 == __slast1)
+ return std::__equal_iter_impl(
+ std::__unwrap_iter(_Traits1::__local(__first1)),
+ std::__unwrap_iter(_Traits1::__local(__last1)),
+ std::__unwrap_iter(_Traits2::__local(__first2)),
+ __pred);
+
+ { // We have more than one segment. Iterate over the first segment, since we might not start at the beginning
+ if (!std::__equal_iter_impl(
+ std::__unwrap_iter(_Traits1::__local(__first1)),
+ std::__unwrap_iter(_Traits1::__end(__sfirst1)),
+ std::__unwrap_iter(_Traits2::__local(__first2)),
+ __pred)) {
+ return false;
+ }
+ }
+ ++__sfirst1;
+ ++__sfirst2;
+
+ // Iterate over the segments which are guaranteed to be completely in the range
+ while (__sfirst1 != __slast1) {
+ if (!std::__equal_iter_impl(
+ std::__unwrap_iter(_Traits1::__begin(__sfirst1)),
+ std::__unwrap_iter(_Traits1::__end(__sfirst1)),
+ std::__unwrap_iter(_Traits2::__begin(__sfirst2)),
+ __pred)) {
+ return false;
+ }
+ ++__sfirst1;
+ ++__sfirst2;
+ }
+
+ // Iterate over the last segment
+ if (!std::__equal_iter_impl(
+ std::__unwrap_iter(_Traits1::__begin(__sfirst1)),
+ std::__unwrap_iter(_Traits1::__local(__last1)),
+ std::__unwrap_iter(_Traits2::__begin(__sfirst2)),
+ __pred)) {
+ return false;
+ }
+
+ return true;
+}
+
template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
_LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool
equal(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _BinaryPredicate __pred) {
+ if constexpr (__is_segmented_iterator<_InputIterator1>::value && __is_segmented_iterator<_InputIterator2>::value) {
+ return std::__equal_segment_iter(__first1, __last1, __first2, __pred);
+ }
return std::__equal_iter_impl(
std::__unwrap_iter(__first1), std::__unwrap_iter(__last1), std::__unwrap_iter(__first2), __pred);
}
@@ -95,6 +155,75 @@ __equal_impl(_Tp* __first1, _Tp* __last1, _Up* __first2, _Up*, _Pred&, _Proj1&,
return std::__constexpr_memcmp_equal(__first1, __first2, __element_count(__last1 - __first1));
}
+template <class _SegmentedIterator1, class _SegmentedIterator2, class _BinaryPredicate, class _Proj1, class _Proj2>
+_LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool
+__equal_segment(_SegmentedIterator1 __first1, _SegmentedIterator1 __last1, _SegmentedIterator2 __first2, _SegmentedIterator2 __last2, _BinaryPredicate __pred, _Proj1& __proj1, _Proj2& __proj2) {
+ using _Traits1 = __segmented_iterator_traits<_SegmentedIterator1>;
+ using _Traits2 = __segmented_iterator_traits<_SegmentedIterator2>;
+
+ auto __sfirst1 = _Traits1::__segment(__first1);
+ auto __slast1 = _Traits1::__segment(__last1);
+
+ auto __sfirst2 = _Traits2::__segment(__first2);
+ auto __slast2 = _Traits2::__segment(__last2);
+
+ // Both have only 1 segment
+ if (__sfirst1 == __slast1 && __sfirst2 == __slast2)
+ return std::__equal_impl(
+ std::__unwrap_iter(_Traits1::__local(__first1)),
+ std::__unwrap_iter(_Traits1::__local(__last1)),
+ std::__unwrap_iter(_Traits2::__local(__first2)),
+ std::__unwrap_iter(_Traits2::__local(__last2)),
+ __pred,
+ __proj1,
+ __proj2);
+
+ { // We have more than one segment. Iterate over the first segment, since we might not start at the beginning
+ if (!std::__equal_impl(
+ std::__unwrap_iter(_Traits1::__local(__first1)),
+ std::__unwrap_iter(_Traits1::__end(__sfirst1)),
+ std::__unwrap_iter(_Traits2::__local(__first2)),
+ std::__unwrap_iter(_Traits2::__end(__sfirst2)),
+ __pred,
+ __proj1,
+ __proj2)) {
+ return false;
+ }
+ }
+ ++__sfirst1;
+ ++__sfirst2;
+
+ // Iterate over the segments which are guaranteed to be completely in the range
+ while (__sfirst1 != __slast1 && __sfirst2 != __slast2) {
+ if (!std::__equal_impl(
+ std::__unwrap_iter(_Traits1::__begin(__sfirst1)),
+ std::__unwrap_iter(_Traits1::__end(__sfirst1)),
+ std::__unwrap_iter(_Traits2::__begin(__sfirst2)),
+ std::__unwrap_iter(_Traits2::__end(__sfirst2)),
+ __pred,
+ __proj1,
+ __proj2)) {
+ return false;
+ }
+ ++__sfirst1;
+ ++__sfirst2;
+ }
+
+ // Iterate over the last segment
+ if (!std::__equal_impl(
+ std::__unwrap_iter(_Traits1::__begin(__sfirst1)),
+ std::__unwrap_iter(_Traits1::__local(__last1)),
+ std::__unwrap_iter(_Traits2::__begin(__sfirst2)),
+ std::__unwrap_iter(_Traits2::__local(__last2)),
+ __pred,
+ __proj1,
+ __proj2)) {
+ return false;
+ }
+
+ return __sfirst1 == __slast1 && __sfirst2 == __slast2;
+}
+
template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
_LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool
equal(_InputIterator1 __first1,
@@ -108,6 +237,11 @@ equal(_InputIterator1 __first1,
return false;
}
__identity __proj;
+
+ if constexpr (__is_segmented_iterator<_InputIterator1>::value && __is_segmented_iterator<_InputIterator2>::value) {
+ return std::__equal_segment(__first1, __last1, __first2, __last2, __pred, __proj, __proj);
+ }
+
return std::__equal_impl(
std::__unwrap_iter(__first1),
std::__unwrap_iter(__last1),
|
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
NoumanAmir657
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For the issue #102817
@philnik777
Hi, not sure if my implementation for this is correct or not. Would appreciate some pointers regarding it.