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//===----------------------------------------------------------------------===//
//
// 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 <ranges>
#include <cassert>
#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;
}
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