libstdc++: Implement ranges::contains/contains_subrange from P2302R4

libstdc++-v3/ChangeLog:

	* include/bits/ranges_algo.h (__contains_fn, contains): Define.
	(__contains_subrange_fn, contains_subrange): Define.
	* testsuite/25_algorithms/contains/1.cc: New test.
	* testsuite/25_algorithms/contains_subrange/1.cc: New test.

3 files changed, 124 insertions, 0 deletions

diff --git a/libstdc++-v3/include/bits/ranges_algo.h b/libstdc++-v3/include/bits/ranges_algo.h
index b33c9ab..b2c9902 100644
--- a/libstdc++-v3/include/bits/ranges_algo.h
+++ b/libstdc++-v3/include/bits/ranges_algo.h
@@ -3464,6 +3464,60 @@ namespace ranges
 
   inline constexpr __prev_permutation_fn prev_permutation{};
 
+#if __cplusplus > 202002L
+  struct __contains_fn
+  {
+    template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
+	    typename _Tp, typename _Proj = identity>
+      requires indirect_binary_predicate<ranges::equal_to,
+					 projected<_Iter, _Proj>, const _Tp*>
+      constexpr bool
+      operator()(_Iter __first, _Sent __last, const _Tp& __value, _Proj __proj = {}) const
+      { return ranges::find(std::move(__first), __last, __value, std::move(__proj)) != __last; }
+
+    template<input_range _Range, typename _Tp, typename _Proj = identity>
+      requires indirect_binary_predicate<ranges::equal_to,
+					 projected<iterator_t<_Range>, _Proj>, const _Tp*>
+      constexpr bool
+      operator()(_Range&& __r, const _Tp& __value, _Proj __proj = {}) const
+      { return (*this)(ranges::begin(__r), ranges::end(__r), __value, std::move(__proj)); }
+  };
+
+  inline constexpr __contains_fn contains{};
+
+  struct __contains_subrange_fn
+  {
+    template<forward_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
+	     forward_iterator _Iter2, sentinel_for<_Iter2> _Sent2,
+	     typename _Pred = ranges::equal_to,
+	     typename Proj1 = identity, typename Proj2 = identity>
+      requires indirectly_comparable<_Iter1, _Iter2, _Pred, Proj1, Proj2>
+      constexpr bool
+      operator()(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2,
+		 _Pred __pred = {}, Proj1 __proj1 = {}, Proj2 __proj2 = {}) const
+      {
+	return __first2 == __last2
+	  || !ranges::search(__first1, __last1, __first2, __last2,
+			     std::move(__pred), std::move(__proj1), std::move(__proj2)).empty();
+      }
+
+    template<forward_range _Range1, forward_range _Range2,
+	     typename _Pred = ranges::equal_to,
+	     typename _Proj1 = identity, typename _Proj2 = identity>
+      requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>,
+				     _Pred, _Proj1, _Proj2>
+      constexpr bool
+      operator()(_Range1&& __r1, _Range2&& __r2, _Pred __pred = {},
+		 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
+      {
+	return (*this)(ranges::begin(__r1), ranges::end(__r1),
+		       ranges::begin(__r2), ranges::end(__r2),
+		       std::move(__pred), std::move(__proj1), std::move(__proj2));
+      }
+  };
+
+  inline constexpr __contains_subrange_fn contains_subrange{};
+#endif // C++23
 } // namespace ranges
 
 #define __cpp_lib_shift 201806L
diff --git a/libstdc++-v3/testsuite/25_algorithms/contains/1.cc b/libstdc++-v3/testsuite/25_algorithms/contains/1.cc
new file mode 100644
index 0000000..146ab59
--- /dev/null
+++ b/libstdc++-v3/testsuite/25_algorithms/contains/1.cc
@@ -0,0 +1,33 @@
+// { dg-options "-std=gnu++23" }
+// { dg-do run { target c++23 } }
+
+#include <algorithm>
+#include <testsuite_hooks.h>
+#include <testsuite_iterators.h>
+
+namespace ranges = std::ranges;
+
+void
+test01()
+{
+  int x[] = {1,2,3};
+  using to_input = __gnu_test::test_input_range<int>;
+  VERIFY( ranges::contains(to_input(x), 1) );
+  VERIFY( ranges::contains(to_input(x), 2) );
+  VERIFY( ranges::contains(to_input(x), 3) );
+  VERIFY( !ranges::contains(to_input(x), 4) );
+  VERIFY( !ranges::contains(x, x+2, 3) );
+  auto neg = [](int n) { return -n; };
+  VERIFY( ranges::contains(to_input(x), -1, neg) );
+  VERIFY( ranges::contains(to_input(x), -2, neg) );
+  VERIFY( ranges::contains(to_input(x), -3, neg) );
+  VERIFY( !ranges::contains(to_input(x), -4, neg) );
+
+  VERIFY( !ranges::contains(x, x+2, -3, neg) );
+}
+
+int
+main()
+{
+  test01();
+}
diff --git a/libstdc++-v3/testsuite/25_algorithms/contains_subrange/1.cc b/libstdc++-v3/testsuite/25_algorithms/contains_subrange/1.cc
new file mode 100644
index 0000000..6c3c99c
--- /dev/null
+++ b/libstdc++-v3/testsuite/25_algorithms/contains_subrange/1.cc
@@ -0,0 +1,37 @@
+// { dg-options "-std=gnu++23" }
+// { dg-do run { target c++23 } }
+
+#include <algorithm>
+#include <testsuite_hooks.h>
+#include <testsuite_iterators.h>
+
+namespace ranges = std::ranges;
+
+void
+test01()
+{
+  int x[] = {1,2,3,4,5};
+  int y[] = {2,3,4};
+  int z[] = {4,5,6};
+  __gnu_test::test_forward_range<int> rx(x);
+  __gnu_test::test_forward_range<int> ry(y);
+  __gnu_test::test_forward_range<int> rz(z);
+  VERIFY( ranges::contains_subrange(rx, ry) );
+  VERIFY( !ranges::contains_subrange(rx, rz) );
+  VERIFY( ranges::contains_subrange(rx, ry, ranges::less{}) );
+  VERIFY( ranges::contains_subrange(rx, rz, ranges::less{}) );
+  auto plus3 = [](int n) { return n+3; };
+  VERIFY( !ranges::contains_subrange(rx, ry, {}, plus3) );
+  VERIFY( ranges::contains_subrange(rx, rz, {}, plus3) );
+  VERIFY( ranges::contains_subrange(rx, ry, {}, plus3, plus3) );
+  VERIFY( !ranges::contains_subrange(rx, rz, {}, plus3, plus3) );
+
+  VERIFY( ranges::contains_subrange(x, x+2, y, y+1) );
+  VERIFY( !ranges::contains_subrange(x, x+2, y, y+2) );
+}
+
+int
+main()
+{
+  test01();
+}