[libc++] Implement ranges::find_end, ranges::search{, _n}

Reviewed By: var-const, #libc, huixie90

Spies: thakis, h-vetinari, huixie90, libcxx-commits, mgorny

Differential Revision: https://reviews.llvm.org/D124079

Author: philnik777

libcxx/docs/Status/RangesAlgorithms.csv

@@ -23,9 +23,9 @@ Search,max_element,Nikolas Klauser,`D117523 <https://llvm.org/D117523>`_,✅
 Search,minmax_element,Nikolas Klauser,`D120637 <https://llvm.org/D120637>`_,✅
 Search,count,Nikolas Klauser,`D121523 <https://llvm.org/D121523>`_,✅
 Search,count_if,Nikolas Klauser,`D121523 <https://llvm.org/D121523>`_,✅
-Search,search,Nikolas Klauser,`D124079 <https://llvm.org/D124079>`_,Under review
-Search,search_n,Nikolas Klauser,`D124079 <https://llvm.org/D124079>`_,Under review
-Search,find_end,Nikolas Klauser,`D124079 <https://llvm.org/D124079>`_,Under review
+Search,search,Nikolas Klauser,`D124079 <https://llvm.org/D124079>`_,✅
+Search,search_n,Nikolas Klauser,`D124079 <https://llvm.org/D124079>`_,✅
+Search,find_end,Nikolas Klauser,`D124079 <https://llvm.org/D124079>`_,✅
 Read-only,is_partitioned,Nikolas Klauser,`D124440 <https://llvm.org/D124440>`_,✅
 Read-only,is_sorted,Nikolas Klauser,`D125608 <https://llvm.org/D125608>`_,✅
 Read-only,is_sorted_until,Nikolas Klauser,`D125608 <https://llvm.org/D125608>`_,✅

libcxx/include/CMakeLists.txt

@@ -83,6 +83,7 @@ set(files
   __algorithm/ranges_fill.h
   __algorithm/ranges_fill_n.h
   __algorithm/ranges_find.h
+  __algorithm/ranges_find_end.h
   __algorithm/ranges_find_first_of.h
   __algorithm/ranges_find_if.h
   __algorithm/ranges_find_if_not.h
@@ -129,6 +130,8 @@ set(files
   __algorithm/ranges_reverse.h
   __algorithm/ranges_reverse_copy.h
   __algorithm/ranges_rotate_copy.h
+  __algorithm/ranges_search.h
+  __algorithm/ranges_search_n.h
   __algorithm/ranges_set_difference.h
   __algorithm/ranges_set_intersection.h
   __algorithm/ranges_set_union.h

libcxx/include/__algorithm/find_end.h

@@ -11,44 +11,69 @@
 #define _LIBCPP___ALGORITHM_FIND_END_OF_H
 
 #include <__algorithm/comp.h>
+#include <__algorithm/iterator_operations.h>
+#include <__algorithm/search.h>
 #include <__config>
+#include <__functional/identity.h>
+#include <__iterator/advance.h>
 #include <__iterator/iterator_traits.h>
+#include <__iterator/next.h>
+#include <__iterator/reverse_iterator.h>
+#include <__utility/pair.h>
+#include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-template <class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1 __find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
-                                                           _ForwardIterator2 __first2, _ForwardIterator2 __last2,
-                                                           _BinaryPredicate __pred, forward_iterator_tag,
-                                                           forward_iterator_tag) {
+template <
+    class _AlgPolicy,
+    class _Iter1,
+    class _Sent1,
+    class _Iter2,
+    class _Sent2,
+    class _Pred,
+    class _Proj1,
+    class _Proj2>
+_LIBCPP_HIDE_FROM_ABI inline _LIBCPP_CONSTEXPR_AFTER_CXX11 pair<_Iter1, _Iter1> __find_end_impl(
+    _Iter1 __first1,
+    _Sent1 __last1,
+    _Iter2 __first2,
+    _Sent2 __last2,
+    _Pred& __pred,
+    _Proj1& __proj1,
+    _Proj2& __proj2,
+    forward_iterator_tag,
+    forward_iterator_tag) {
   // modeled after search algorithm
-  _ForwardIterator1 __r = __last1; // __last1 is the "default" answer
+  _Iter1 __match_first = _IterOps<_AlgPolicy>::next(__first1, __last1); // __last1 is the "default" answer
+  _Iter1 __match_last = __match_first;
   if (__first2 == __last2)
-    return __r;
+    return pair<_Iter1, _Iter1>(__match_last, __match_last);
   while (true) {
     while (true) {
-      if (__first1 == __last1) // if source exhausted return last correct answer
-        return __r;            //    (or __last1 if never found)
-      if (__pred(*__first1, *__first2))
+      if (__first1 == __last1) // if source exhausted return last correct answer (or __last1 if never found)
+        return pair<_Iter1, _Iter1>(__match_first, __match_last);
+      if (std::__invoke(__pred, std::__invoke(__proj1, *__first1), std::__invoke(__proj2, *__first2)))
         break;
       ++__first1;
     }
     // *__first1 matches *__first2, now match elements after here
-    _ForwardIterator1 __m1 = __first1;
-    _ForwardIterator2 __m2 = __first2;
+    _Iter1 __m1 = __first1;
+    _Iter2 __m2 = __first2;
     while (true) {
       if (++__m2 == __last2) { // Pattern exhaused, record answer and search for another one
-        __r = __first1;
+        __match_first = __first1;
+        __match_last = ++__m1;
         ++__first1;
         break;
       }
       if (++__m1 == __last1) // Source exhausted, return last answer
-        return __r;
-      if (!__pred(*__m1, *__m2)) // mismatch, restart with a new __first
+        return pair<_Iter1, _Iter1>(__match_first, __match_last);
+       // mismatch, restart with a new __first
+      if (!std::__invoke(__pred, std::__invoke(__proj1, *__m1), std::__invoke(__proj2, *__m2)))
       {
         ++__first1;
         break;
@@ -57,92 +82,146 @@ _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1 __find_end(_ForwardIterator1 __f
   }
 }
 
-template <class _BinaryPredicate, class _BidirectionalIterator1, class _BidirectionalIterator2>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _BidirectionalIterator1 __find_end(
-    _BidirectionalIterator1 __first1, _BidirectionalIterator1 __last1, _BidirectionalIterator2 __first2,
-    _BidirectionalIterator2 __last2, _BinaryPredicate __pred, bidirectional_iterator_tag, bidirectional_iterator_tag) {
+template <
+    class _IterOps,
+    class _Pred,
+    class _Iter1,
+    class _Sent1,
+    class _Iter2,
+    class _Sent2,
+    class _Proj1,
+    class _Proj2>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _Iter1 __find_end(
+    _Iter1 __first1,
+    _Sent1 __sent1,
+    _Iter2 __first2,
+    _Sent2 __sent2,
+    _Pred& __pred,
+    _Proj1& __proj1,
+    _Proj2& __proj2,
+    bidirectional_iterator_tag,
+    bidirectional_iterator_tag) {
+  auto __last1 = _IterOps::next(__first1, __sent1);
+  auto __last2 = _IterOps::next(__first2, __sent2);
   // modeled after search algorithm (in reverse)
   if (__first2 == __last2)
     return __last1; // Everything matches an empty sequence
-  _BidirectionalIterator1 __l1 = __last1;
-  _BidirectionalIterator2 __l2 = __last2;
+  _Iter1 __l1 = __last1;
+  _Iter2 __l2 = __last2;
   --__l2;
   while (true) {
     // Find last element in sequence 1 that matchs *(__last2-1), with a mininum of loop checks
     while (true) {
       if (__first1 == __l1) // return __last1 if no element matches *__first2
         return __last1;
-      if (__pred(*--__l1, *__l2))
+      if (std::__invoke(__pred, std::__invoke(__proj1, *--__l1), std::__invoke(__proj2, *__l2)))
         break;
     }
     // *__l1 matches *__l2, now match elements before here
-    _BidirectionalIterator1 __m1 = __l1;
-    _BidirectionalIterator2 __m2 = __l2;
+    _Iter1 __m1 = __l1;
+    _Iter2 __m2 = __l2;
     while (true) {
       if (__m2 == __first2) // If pattern exhausted, __m1 is the answer (works for 1 element pattern)
         return __m1;
       if (__m1 == __first1) // Otherwise if source exhaused, pattern not found
         return __last1;
-      if (!__pred(*--__m1, *--__m2)) // if there is a mismatch, restart with a new __l1
+
+      // if there is a mismatch, restart with a new __l1
+      if (!std::__invoke(__pred, std::__invoke(__proj1, *--__m1), std::__invoke(__proj2, *--__m2)))
       {
         break;
       } // else there is a match, check next elements
     }
   }
 }
 
-template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
-_LIBCPP_CONSTEXPR_AFTER_CXX11 _RandomAccessIterator1 __find_end(
-    _RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1, _RandomAccessIterator2 __first2,
-    _RandomAccessIterator2 __last2, _BinaryPredicate __pred, random_access_iterator_tag, random_access_iterator_tag) {
-  typedef typename iterator_traits<_RandomAccessIterator1>::difference_type _D1;
-  typedef typename iterator_traits<_RandomAccessIterator2>::difference_type _D2;
+template <
+    class _AlgPolicy,
+    class _Pred,
+    class _Iter1,
+    class _Sent1,
+    class _Iter2,
+    class _Sent2,
+    class _Proj1,
+    class _Proj2>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _Iter1 __find_end(
+    _Iter1 __first1,
+    _Sent1 __sent1,
+    _Iter2 __first2,
+    _Sent2 __sent2,
+    _Pred& __pred,
+    _Proj1& __proj1,
+    _Proj2& __proj2,
+    random_access_iterator_tag,
+    random_access_iterator_tag) {
+  typedef typename iterator_traits<_Iter1>::difference_type _D1;
+  auto __last1 = _IterOps<_AlgPolicy>::next(__first1, __sent1);
+  auto __last2 = _IterOps<_AlgPolicy>::next(__first2, __sent2);
   // Take advantage of knowing source and pattern lengths.  Stop short when source is smaller than pattern
-  _D2 __len2 = __last2 - __first2;
+  auto __len2 = __last2 - __first2;
   if (__len2 == 0)
     return __last1;
-  _D1 __len1 = __last1 - __first1;
+  auto __len1 = __last1 - __first1;
   if (__len1 < __len2)
     return __last1;
-  const _RandomAccessIterator1 __s = __first1 + _D1(__len2 - 1); // End of pattern match can't go before here
-  _RandomAccessIterator1 __l1 = __last1;
-  _RandomAccessIterator2 __l2 = __last2;
+  const _Iter1 __s = __first1 + _D1(__len2 - 1); // End of pattern match can't go before here
+  _Iter1 __l1 = __last1;
+  _Iter2 __l2 = __last2;
   --__l2;
   while (true) {
     while (true) {
       if (__s == __l1)
         return __last1;
-      if (__pred(*--__l1, *__l2))
+      if (std::__invoke(__pred, std::__invoke(__proj1, *--__l1), std::__invoke(__proj2, *__l2)))
         break;
     }
-    _RandomAccessIterator1 __m1 = __l1;
-    _RandomAccessIterator2 __m2 = __l2;
+    _Iter1 __m1 = __l1;
+    _Iter2 __m2 = __l2;
     while (true) {
       if (__m2 == __first2)
         return __m1;
       // no need to check range on __m1 because __s guarantees we have enough source
-      if (!__pred(*--__m1, *--__m2)) {
+      if (!std::__invoke(__pred, std::__invoke(__proj1, *--__m1), std::__invoke(*--__m2))) {
         break;
       }
     }
   }
 }
 
 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1
-find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2,
-         _BinaryPredicate __pred) {
-  return _VSTD::__find_end<_BinaryPredicate&>(
-      __first1, __last1, __first2, __last2, __pred, typename iterator_traits<_ForwardIterator1>::iterator_category(),
-      typename iterator_traits<_ForwardIterator2>::iterator_category());
+_LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
+_ForwardIterator1 __find_end_classic(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
+                                     _ForwardIterator2 __first2, _ForwardIterator2 __last2,
+                                     _BinaryPredicate& __pred) {
+  auto __proj = __identity();
+  return std::__find_end_impl<_ClassicAlgPolicy>(
+             __first1,
+             __last1,
+             __first2,
+             __last2,
+             __pred,
+             __proj,
+             __proj,
+             typename iterator_traits<_ForwardIterator1>::iterator_category(),
+             typename iterator_traits<_ForwardIterator2>::iterator_category())
+      .first;
+}
+
+template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
+_ForwardIterator1 find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
+                           _ForwardIterator2 __first2, _ForwardIterator2 __last2,
+                           _BinaryPredicate __pred) {
+  return std::__find_end_classic(__first1, __last1, __first2, __last2, __pred);
 }
 
 template <class _ForwardIterator1, class _ForwardIterator2>
-_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1
-find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2) {
-  typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
-  typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
-  return _VSTD::find_end(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
+_ForwardIterator1 find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
+                           _ForwardIterator2 __first2, _ForwardIterator2 __last2) {
+  using __v1 = typename iterator_traits<_ForwardIterator1>::value_type;
+  using __v2 = typename iterator_traits<_ForwardIterator2>::value_type;
+  return std::find_end(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
 }
 
 _LIBCPP_END_NAMESPACE_STD

libcxx/include/__algorithm/iterator_operations.h

@@ -39,6 +39,7 @@ struct _IterOps<_RangeAlgPolicy> {
   static constexpr auto __iter_move = ranges::iter_move;
   static constexpr auto iter_swap = ranges::iter_swap;
   static constexpr auto next = ranges::next;
+  static constexpr auto __advance_to = ranges::advance;
 };
 #endif
 
@@ -82,6 +83,11 @@ struct _IterOps<_ClassicAlgPolicy> {
   _Iterator next(_Iterator, _Iterator __last) {
     return __last;
   }
+
+  template <class _Iter>
+  _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR_AFTER_CXX11 void __advance_to(_Iter& __first, _Iter __last) {
+    __first = __last;
+  }
 };
 
 _LIBCPP_END_NAMESPACE_STD