[libc-commits] [libc] [libc++] Implement ranges::contains (PR #65148)
Konstantin Varlamov via libc-commits
libc-commits at lists.llvm.org
Mon Oct 2 15:17:32 PDT 2023
================
@@ -0,0 +1,190 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+// 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 Iter, class Sent = Iter>
+concept HasContainsIt = requires(Iter iter, Sent sent) { std::ranges::contains(iter, sent, *iter); };
+
+static_assert(HasContainsIt<int*>);
+static_assert(!HasContainsIt<NotEqualityComparable*>);
+static_assert(!HasContainsIt<InputIteratorNotDerivedFrom>);
+static_assert(!HasContainsIt<InputIteratorNotIndirectlyReadable>);
+static_assert(!HasContainsIt<InputIteratorNotInputOrOutputIterator>);
+static_assert(!HasContainsIt<cpp20_input_iterator<int*>, SentinelForNotSemiregular>);
+static_assert(!HasContainsIt<cpp20_input_iterator<int*>, InputRangeNotSentinelEqualityComparableWith>);
+
+static_assert(!HasContainsIt<int*, int>);
+static_assert(!HasContainsIt<int, int*>);
+
+template <class Range, class ValT>
+concept HasContainsR = requires(Range range) { std::ranges::contains(range, ValT{}); };
+
+static_assert(HasContainsR<std::array<int, 1>, int>);
+static_assert(!HasContainsR<int, int>);
+static_assert(!HasContainsR<std::array<NotEqualityComparable, 1>, NotEqualityComparable>);
+static_assert(!HasContainsR<InputRangeNotDerivedFrom, int>);
+static_assert(!HasContainsR<InputRangeNotIndirectlyReadable, int>);
+static_assert(!HasContainsR<InputRangeNotInputOrOutputIterator, int>);
+static_assert(!HasContainsR<InputRangeNotSentinelSemiregular, int>);
+static_assert(!HasContainsR<InputRangeNotSentinelEqualityComparableWith, int>);
+
+static std::vector<int> comparable_data;
+
+// clang-format off
+template <class Iter, class Sent = Iter>
+constexpr void test_iterators() {
+ using ValueT = std::iter_value_t<Iter>;
+ { // simple tests
+ {
+ ValueT a[] = {1, 2, 3, 4, 5, 6};
+ std::same_as<bool> auto ret =
+ std::ranges::contains(Iter(a), Sent(Iter(a + 6)), 3);
+ assert(ret);
+ }
+ {
+ ValueT a[] = {1, 2, 3, 4, 5, 6};
+ auto range = std::ranges::subrange(Iter(a), Sent(Iter(a + 6)));
+ std::same_as<bool> decltype(auto) ret =
+ std::ranges::contains(range, 3);
+ assert(ret);
+ }
+ }
+
+ { // check that an empty range works
+ {
+ ValueT a[] = {};
+ auto ret = std::ranges::contains(Iter(a), Sent(Iter(a)), 1);
+ assert(!ret);
+ }
+ {
+ ValueT a[] = {};
+ auto range = std::ranges::subrange(Iter(a), Sent(Iter(a)));
+ auto ret = std::ranges::contains(range, 1);
+ assert(!ret);
+ }
+ }
+
+ { // check that no match
+ {
+ ValueT a[] = {13, 1, 21, 4, 5};
+ auto ret = std::ranges::contains(Iter(a), Sent(Iter(a + 5)), 10);
+ assert(!ret);
+ }
+ {
+ ValueT a[] = {13, 1, 21, 4, 5};
+ auto range = std::ranges::subrange(Iter(a), Sent(Iter(a + 5)));
+ auto ret = std::ranges::contains(range, 10);
+ assert(!ret);
+ }
+ }
+
+ if (!std::is_constant_evaluated())
+ comparable_data.clear();
+}
+template <class ElementT>
+class TriviallyComparable {
----------------
var-const wrote:
Thanks for pointing me to the patch. It looks like this is to test an optimization that's specific to `find`. IMO we shouldn't duplicate those tests here, so I'd just remove the `Comparable` and `TriviallyComparable` tests. It might make sense to add a benchmark for `ranges::contains`, though.
https://github.com/llvm/llvm-project/pull/65148
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