[libcxx-commits] [libcxx] [libc++][ranges] Implement `ranges::stride_view`. (PR #65200)

[Christopher Di Bella via libcxx-commits]

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@@ -0,0 +1,87 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// std::views::stride_view
+
+#include <cassert>
+#include <ranges>
+
+#include "test_iterators.h"
+
+template <class Iter>
+constexpr void testOne() {
+  using Range      = std::ranges::subrange<Iter>;
+  using StrideView = std::ranges::stride_view<Range>;
+  static_assert(std::ranges::common_range<StrideView>);
+
+  {
+    // simple test
+    {
+      int buffer[] = {0, 1, 2, -1, 4, 5, 6, 7};
+      Range input(Iter{buffer}, Iter{buffer + 8});
+      StrideView sv(input, 1);
+      StrideView sv_too(input, 2);
+      auto b = sv.begin(), e = sv.end();
+      auto b_too = sv_too.begin();
+
+      assert(b == b);
+      assert(!(b != b));
+
+      assert(e == e);
+      assert(!(e != e));
+
+      assert(!(b == e));
+      assert(b != e);
+
+      std::advance(b, 8);
+      std::advance(b_too, 4);
+
+      assert(b == b_too);
+      assert(!(b != b_too));
+
+      assert(b == b);
+      assert(!(b != b));
+
+      assert(e == e);
+      assert(!(e != e));
+
+      assert(b == e);
+      assert(!(b != e));
+    }
+
+    // Default-constructed iterators compare equal.
+    {
+      int buffer[] = {0, 1, 2, -1, 4, 5, 6};
+      Range input(Iter{buffer}, Iter{buffer + 7});
+      std::ranges::stride_view sv(input, 1);
+      using StrideViewIter = decltype(sv.begin());
+      StrideViewIter i1, i2;
+      assert(i1 == i2);
+      assert(!(i1 != i2));
+    }
+  }
+}
+
+constexpr bool test() {
+  testOne<forward_iterator<int*>>();
+  //testOne<bidirectional_iterator<int*>>();
+  //testOne<random_access_iterator<int*>>();
+  //testOne<contiguous_iterator<int*>>();
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cjdb wrote:

These will need to be uncommented.

https://github.com/llvm/llvm-project/pull/65200