[libcxx-commits] [libcxx] [libc++][ranges] P2164R9: Implements `views::enumerate` (PR #73617)

[A. Jiang via libcxx-commits]

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@@ -0,0 +1,127 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// <ranges>
+
+// class enumerate_view
+
+// class enumerate_view::iterator
+
+// constexpr iterator& operator+=(difference_type x)
+//   requires random_access_range<Base>;
+// constexpr iterator& operator-=(difference_type x)
+//   requires random_access_range<Base>;
+
+// friend constexpr iterator operator+(const iterator& x, difference_type y)
+//   requires random_access_range<Base>;
+// friend constexpr iterator operator+(difference_type x, const iterator& y)
+//   requires random_access_range<Base>;
+// friend constexpr iterator operator-(const iterator& x, difference_type y)
+//   requires random_access_range<Base>;
+// friend constexpr difference_type operator-(const iterator& x, const iterator& y);
+
+#include <ranges>
+
+#include "test_iterators.h"
+
+// Concepts
+
+template <class T, class U>
+concept CanPlus = requires(T t, U u) { t + u; };
+
+template <class T, class U>
+concept CanPlusEqual = requires(T t, U u) { t += u; };
+
+template <class T, class U>
+concept CanMinus = requires(T t, U u) { t - u; };
+
+template <class T, class U>
+concept CanMinusEqual = requires(T t, U u) { t -= u; };
+
+template <class BaseRange>
+using EnumerateIter = std::ranges::iterator_t<std::ranges::enumerate_view<BaseRange>>;
+
+using RandomAccessRange = std::ranges::subrange<int*>;
+
+// SFINAE.
+
+static_assert(std::ranges::random_access_range<RandomAccessRange>);
+static_assert(
+    std::sized_sentinel_for<std::ranges::iterator_t<RandomAccessRange>, std::ranges::iterator_t<RandomAccessRange>>);
+
+static_assert(CanPlus<EnumerateIter<RandomAccessRange>, int>);
+static_assert(CanPlus<int, EnumerateIter<RandomAccessRange>>);
+static_assert(CanPlusEqual<EnumerateIter<RandomAccessRange>, int>);
+static_assert(CanMinus<EnumerateIter<RandomAccessRange>, int>);
+static_assert(CanMinus<EnumerateIter<RandomAccessRange>, EnumerateIter<RandomAccessRange>>);
+static_assert(CanMinusEqual<EnumerateIter<RandomAccessRange>, int>);
+
+using BidirectionalRange = std::ranges::subrange<bidirectional_iterator<int*>>;
+static_assert(!std::ranges::random_access_range<BidirectionalRange>);
+static_assert(
+    !std::sized_sentinel_for<std::ranges::iterator_t<BidirectionalRange>, std::ranges::iterator_t<BidirectionalRange>>);
+
+static_assert(!CanPlus<EnumerateIter<BidirectionalRange>, int>);
+static_assert(!CanPlus<int, EnumerateIter<BidirectionalRange>>);
+static_assert(!CanPlusEqual<EnumerateIter<BidirectionalRange>, int>);
+static_assert(!CanMinus<EnumerateIter<BidirectionalRange>, int>);
+static_assert(!CanMinusEqual<EnumerateIter<BidirectionalRange>, int>);
+
+constexpr bool test() {
+  int ts[] = {1, 2, 3, 4, 5};
----------------
frederick-vs-ja wrote:

Test coverage for non-common ranges seems already added.

https://github.com/llvm/llvm-project/pull/73617