[libcxx-commits] [libcxx] [libc++][ranges] implement `std::ranges::zip_transform_view` (PR #79605)

[Louis Dionne via libcxx-commits]

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@@ -0,0 +1,90 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// constexpr auto size() requires sized_range<InnerView>
+// constexpr auto size() const requires sized_range<const InnerView>
+
+#include <ranges>
+
+#include <cassert>
+
+#include "test_iterators.h"
+#include "types.h"
+
+int buffer[] = {1, 2, 3, 4, 5, 6, 7, 8, 9};
+struct SizedView : std::ranges::view_base {
+  std::size_t size_ = 0;
+  constexpr SizedView(std::size_t s) : size_(s) {}
+  constexpr auto begin() const { return buffer; }
+  constexpr auto end() const { return buffer + size_; }
+};
+
+struct SizedNonConst : std::ranges::view_base {
+  using iterator    = forward_iterator<int*>;
+  std::size_t size_ = 0;
+  constexpr SizedNonConst(std::size_t s) : size_(s) {}
+  constexpr auto begin() const { return iterator{buffer}; }
+  constexpr auto end() const { return iterator{buffer + size_}; }
+  constexpr std::size_t size() { return size_; }
+};
+
+struct ConstNonConstDifferentSize : std::ranges::view_base {
+  constexpr auto begin() const { return buffer; }
+  constexpr auto end() const { return buffer + 8; }
+
+  constexpr auto size() { return 5; }
+  constexpr auto size() const { return 6; }
+};
+
+constexpr bool test() {
+  {
+    // single range
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ldionne wrote:

Let's also test with an empty range in various positions, and with a single empty range.

https://github.com/llvm/llvm-project/pull/79605