[libcxx-commits] [libcxx] [libc++][ranges] Implement ranges::contains_subrange (PR #66963)

[Konstantin Varlamov via libcxx-commits]

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@@ -0,0 +1,303 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// <algorithm>
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// ADDITIONAL_COMPILE_FLAGS(has-fconstexpr-steps): -fconstexpr-steps=2000000
+
+// template<input_iterator I, sentinel_for<I> S, class T, class Proj = identity>
+//     requires indirect_binary_predicate<ranges::equal_to, projected<I, Proj>, const T*>
+//     constexpr bool ranges::contains(I first, S last, const T& value, Proj proj = {});       // since C++23
+
+// template<input_range R, class T, class Proj = identity>
+//     requires indirect_binary_predicate<ranges::equal_to, projected<iterator_t<R>, Proj>, const T*>
+//     constexpr bool ranges::contains(R&& r, const T& value, Proj proj = {});                 // since C++23
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <ranges>
+#include <vector>
+
+#include "almost_satisfies_types.h"
+#include "boolean_testable.h"
+#include "test_iterators.h"
+
+struct NotEqualityComparable {};
+
+template <class Iter1, class Sent1 = Iter1, class Iter2 = int*, class Sent2 = Iter2>
+concept HasContainsSubrangeIt = requires(Iter1 first1, Sent1 last1, Iter2 first2, Sent2 last2) {
+  std::ranges::contains_subrange(first1, last1, first2, last2);
+};
+
+static_assert(HasContainsSubrangeIt<int*>);
+static_assert(!HasContainsSubrangeIt<ForwardIteratorNotDerivedFrom>);
+static_assert(!HasContainsSubrangeIt<ForwardIteratorNotIncrementable>);
+static_assert(!HasContainsSubrangeIt<int*, SentinelForNotSemiregular>);
+static_assert(!HasContainsSubrangeIt<int*, int*, int**>); // not indirectly comparable
+static_assert(!HasContainsSubrangeIt<int*, SentinelForNotWeaklyEqualityComparableWith>);
+static_assert(!HasContainsSubrangeIt<int*, int*, ForwardIteratorNotDerivedFrom>);
+static_assert(!HasContainsSubrangeIt<int*, int*, ForwardIteratorNotIncrementable>);
+static_assert(!HasContainsSubrangeIt<int*, int*, int*, SentinelForNotSemiregular>);
+static_assert(!HasContainsSubrangeIt<int*, int*, int*, SentinelForNotWeaklyEqualityComparableWith>);
+
+template <class Range1, class Range2 = UncheckedRange<int*>>
+concept HasContainsSubrangeR = requires(Range1&& range1, Range2&& range2) {
+  std::ranges::contains_subrange(std::forward<Range1>(range1), std::forward<Range2>(range2)); };
----------------
var-const wrote:

Nit: please include `<utility>` (for `std::forward`).

https://github.com/llvm/llvm-project/pull/66963