| //===----------------------------------------------------------------------===// |
| // |
| // 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 |
| |
| // constexpr iterator& operator-=(difference_type n) |
| // requires advanceable<W>; |
| |
| #include <cassert> |
| #include <ranges> |
| #include <type_traits> |
| |
| #include "test_macros.h" |
| #include "../types.h" |
| |
| constexpr bool test() { |
| // When "_Start" is signed integer like. |
| { |
| std::ranges::iota_view<int> io(0); |
| auto iter1 = std::next(io.begin(), 10); |
| auto iter2 = std::next(io.begin(), 10); |
| assert(iter1 == iter2); |
| iter1 -= 5; |
| assert(iter1 != iter2); |
| assert(iter1 == std::ranges::prev(iter2, 5)); |
| |
| static_assert(std::is_reference_v<decltype(iter2 -= 5)>); |
| } |
| |
| // When "_Start" is not integer like. |
| { |
| std::ranges::iota_view io(SomeInt(0)); |
| auto iter1 = std::next(io.begin(), 10); |
| auto iter2 = std::next(io.begin(), 10); |
| assert(iter1 == iter2); |
| iter1 -= 5; |
| assert(iter1 != iter2); |
| assert(iter1 == std::ranges::prev(iter2, 5)); |
| |
| static_assert(std::is_reference_v<decltype(iter2 -= 5)>); |
| } |
| |
| // When "_Start" is unsigned integer like and n is greater than or equal to zero. |
| { |
| std::ranges::iota_view<unsigned> io(0); |
| auto iter1 = std::next(io.begin(), 10); |
| auto iter2 = std::next(io.begin(), 10); |
| assert(iter1 == iter2); |
| iter1 -= 5; |
| assert(iter1 != iter2); |
| assert(iter1 == std::ranges::prev(iter2, 5)); |
| |
| static_assert(std::is_reference_v<decltype(iter2 -= 5)>); |
| } |
| { |
| std::ranges::iota_view<unsigned> io(0); |
| auto iter1 = std::next(io.begin(), 10); |
| auto iter2 = std::next(io.begin(), 10); |
| assert(iter1 == iter2); |
| iter1 -= 0; |
| assert(iter1 == iter2); |
| } |
| |
| // When "_Start" is unsigned integer like and n is less than zero. |
| { |
| std::ranges::iota_view<unsigned> io(0); |
| auto iter1 = std::next(io.begin(), 10); |
| auto iter2 = std::next(io.begin(), 10); |
| assert(iter1 == iter2); |
| iter1 -= -5; |
| assert(iter1 != iter2); |
| assert(iter1 == std::ranges::next(iter2, 5)); |
| |
| static_assert(std::is_reference_v<decltype(iter2 -= -5)>); |
| } |
| |
| return true; |
| } |
| |
| int main(int, char**) { |
| test(); |
| static_assert(test()); |
| |
| return 0; |
| } |