b4ff893877
This commit implements layout_left in support of C++23 mdspan (https://wg21.link/p0009). layout_left is a layout mapping policy whose index mapping corresponds to the memory layout of Fortran arrays. Thus the left most index has stride-1 access, and the right most index is associated with the largest stride. Co-authored-by: Damien L-G <dalg24@gmail.com> Differential Revision: https://reviews.llvm.org/D153783
52 lines
1.5 KiB
C++
52 lines
1.5 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
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// <mdspan>
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// constexpr index_type stride(rank_type i) const noexcept;
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//
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// Constraints: extents_type::rank() > 0 is true.
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//
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// Preconditions: i < extents_type::rank() is true.
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//
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// Returns: extents().rev-prod-of-extents(i).
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#include <mdspan>
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#include <cassert>
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#include <array>
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#include <cstdint>
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#include <cstdio>
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#include "test_macros.h"
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template <class E, class... Args>
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constexpr void test_stride(std::array<typename E::index_type, E::rank()> strides, Args... args) {
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using M = std::layout_left::mapping<E>;
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M m(E(args...));
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ASSERT_NOEXCEPT(m.stride(0));
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for (size_t r = 0; r < E::rank(); r++)
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assert(strides[r] == m.stride(r));
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}
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constexpr bool test() {
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constexpr size_t D = std::dynamic_extent;
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test_stride<std::extents<unsigned, D>>(std::array<unsigned, 1>{1}, 7);
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test_stride<std::extents<unsigned, 7>>(std::array<unsigned, 1>{1});
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test_stride<std::extents<unsigned, 7, 8>>(std::array<unsigned, 2>{8, 1});
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test_stride<std::extents<int64_t, D, 8, D, D>>(std::array<int64_t, 4>{720, 90, 10, 1}, 7, 9, 10);
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return true;
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}
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int main(int, char**) {
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test();
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static_assert(test());
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return 0;
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}
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