//===----------------------------------------------------------------------===//
//
// 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--() requires bidirectional_range<V>;
// constexpr iterator operator--(int) requires bidirectional_range<V>;
#include <ranges>
#include <array>
#include <cassert>
#include <concepts>
#include <iterator>
#include <utility>
#include "test_iterators.h"
#include "test_macros.h"
#include "../types.h"
struct EqualTo {
int x;
constexpr bool operator()(int y) const { return x == y; }
};
template <class T>
concept has_pre_decrement = requires (T t) { { --t }; };
template <class T>
concept has_post_decrement = requires (T t) { { t-- }; };
template <class Iterator>
using FilterIteratorFor = std::ranges::iterator_t<
std::ranges::filter_view<minimal_view<Iterator, sentinel_wrapper<Iterator>>, EqualTo>
>;
template <class Iter, class Sent = sentinel_wrapper<Iter>>
constexpr void test() {
using View = minimal_view<Iter, Sent>;
using FilterView = std::ranges::filter_view<View, EqualTo>;
using FilterIterator = std::ranges::iterator_t<FilterView>;
auto make_filter_view = [](auto begin, auto end, auto pred) {
View view{Iter(begin), Sent(Iter(end))};
return FilterView(std::move(view), pred);
};
// Test with a single satisfied value
{
std::array<int, 5> array{0, 1, 2, 3, 4};
FilterView view = make_filter_view(array.data(), array.data() + array.size(), EqualTo{1});
FilterIterator it = std::ranges::next(view.begin(), view.end());
assert(base(it.base()) == array.data() + array.size()); // test the test
FilterIterator& result = --it;
ASSERT_SAME_TYPE(FilterIterator&, decltype(--it));
assert(&result == &it);
assert(base(result.base()) == array.data() + 1);
}
// Test with more than one satisfied value
{
std::array<int, 6> array{0, 1, 2, 3, 1, 4};
FilterView view = make_filter_view(array.data(), array.data() + array.size(), EqualTo{1});
FilterIterator it = std::ranges::next(view.begin(), view.end());
assert(base(it.base()) == array.data() + array.size()); // test the test
FilterIterator& result = --it;
assert(&result == &it);
assert(base(result.base()) == array.data() + 4);
--it;
assert(base(it.base()) == array.data() + 1);
}
// Test going forward and then backward on the same iterator
{
std::array<int, 10> array{0, 1, 2, 3, 1, 1, 4, 5, 1, 6};
FilterView view = make_filter_view(array.data(), array.data() + array.size(), EqualTo{1});
FilterIterator it = view.begin();
++it;
--it; assert(base(it.base()) == array.data() + 1);
++it; ++it;
--it; assert(base(it.base()) == array.data() + 4);
++it; ++it;
--it; assert(base(it.base()) == array.data() + 5);
++it; ++it;
--it; assert(base(it.base()) == array.data() + 8);
}
// Test post-decrement
{
std::array<int, 6> array{0, 1, 2, 3, 1, 4};
FilterView view = make_filter_view(array.data(), array.data() + array.size(), EqualTo{1});
FilterIterator it = std::ranges::next(view.begin(), view.end());
assert(base(it.base()) == array.data() + array.size()); // test the test
FilterIterator result = it--;
ASSERT_SAME_TYPE(FilterIterator, decltype(it--));
assert(base(result.base()) == array.data() + array.size());
assert(base(it.base()) == array.data() + 4);
result = it--;
assert(base(result.base()) == array.data() + 4);
assert(base(it.base()) == array.data() + 1);
}
}
constexpr bool tests() {
test<bidirectional_iterator<int*>>();
test<random_access_iterator<int*>>();
test<contiguous_iterator<int*>>();
test<int*>();
test<bidirectional_iterator<int const*>>();
test<random_access_iterator<int const*>>();
test<contiguous_iterator<int const*>>();
test<int const*>();
// Make sure `operator--` isn't provided for non bidirectional ranges
{
static_assert(!has_pre_decrement<FilterIteratorFor<cpp17_input_iterator<int*>>>);
static_assert(!has_pre_decrement<FilterIteratorFor<cpp20_input_iterator<int*>>>);
static_assert(!has_pre_decrement<FilterIteratorFor<forward_iterator<int*>>>);
static_assert(!has_post_decrement<FilterIteratorFor<cpp17_input_iterator<int*>>>);
static_assert(!has_post_decrement<FilterIteratorFor<cpp20_input_iterator<int*>>>);
static_assert(!has_post_decrement<FilterIteratorFor<forward_iterator<int*>>>);
}
return true;
}
int main(int, char**) {
tests();
static_assert(tests());
return 0;
}