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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
//
//===----------------------------------------------------------------------===//
// <algorithm>
// UNSUPPORTED: c++03, c++11, c++14, c++17
// UNSUPPORTED: libcpp-has-no-incomplete-ranges
// template<bidirectional_iterator I1, sentinel_for<I1> S1, bidirectional_iterator I2>
// requires indirectly_copyable<I1, I2>
// constexpr ranges::copy_backward_result<I1, I2>
// ranges::copy_backward(I1 first, S1 last, I2 result);
// template<bidirectional_range R, bidirectional_iterator I>
// requires indirectly_copyable<iterator_t<R>, I>
// constexpr ranges::copy_backward_result<borrowed_iterator_t<R>, I>
// ranges::copy_backward(R&& r, I result);
#include <algorithm>
#include <array>
#include <cassert>
#include <ranges>
#include "almost_satisfies_types.h"
#include "test_iterators.h"
template <class In, class Out = In, class Sent = sentinel_wrapper<In>>
concept HasCopyBackwardIt = requires(In in, Sent sent, Out out) { std::ranges::copy_backward(in, sent, out); };
static_assert(HasCopyBackwardIt<int*>);
static_assert(!HasCopyBackwardIt<InputIteratorNotDerivedFrom>);
static_assert(!HasCopyBackwardIt<InputIteratorNotIndirectlyReadable>);
static_assert(!HasCopyBackwardIt<InputIteratorNotInputOrOutputIterator>);
static_assert(!HasCopyBackwardIt<int*, WeaklyIncrementableNotMovable>);
struct NotIndirectlyCopyable {};
static_assert(!HasCopyBackwardIt<int*, NotIndirectlyCopyable*>);
static_assert(!HasCopyBackwardIt<int*, int*, SentinelForNotSemiregular>);
static_assert(!HasCopyBackwardIt<int*, int*, SentinelForNotWeaklyEqualityComparableWith>);
template <class Range, class Out>
concept HasCopyBackwardR = requires(Range range, Out out) { std::ranges::copy_backward(range, out); };
static_assert(HasCopyBackwardR<std::array<int, 10>, int*>);
static_assert(!HasCopyBackwardR<InputRangeNotDerivedFrom, int*>);
static_assert(!HasCopyBackwardR<InputRangeNotIndirectlyReadable, int*>);
static_assert(!HasCopyBackwardR<InputRangeNotInputOrOutputIterator, int*>);
static_assert(!HasCopyBackwardR<WeaklyIncrementableNotMovable, int*>);
static_assert(!HasCopyBackwardR<UncheckedRange<NotIndirectlyCopyable*>, int*>);
static_assert(!HasCopyBackwardR<InputRangeNotSentinelSemiregular, int*>);
static_assert(!HasCopyBackwardR<InputRangeNotSentinelEqualityComparableWith, int*>);
static_assert(std::is_same_v<std::ranges::copy_result<int, long>, std::ranges::in_out_result<int, long>>);
template <class In, class Out, class Sent>
constexpr void test_iterators() {
{ // simple test
{
std::array in {1, 2, 3, 4};
std::array<int, 4> out;
std::same_as<std::ranges::in_out_result<In, Out>> auto ret =
std::ranges::copy_backward(In(in.data()), Sent(In(in.data() + in.size())), Out(out.data() + out.size()));
assert(in == out);
assert(base(ret.in) == in.data() + in.size());
assert(base(ret.out) == out.data());
}
{
std::array in {1, 2, 3, 4};
std::array<int, 4> out;
auto range = std::ranges::subrange(In(in.data()), Sent(In(in.data() + in.size())));
std::same_as<std::ranges::in_out_result<In, Out>> auto ret =
std::ranges::copy_backward(range, Out(out.data() + out.size()));
assert(in == out);
assert(base(ret.in) == in.data() + in.size());
assert(base(ret.out) == out.data());
}
}
{ // check that an empty range works
{
std::array<int, 0> in;
std::array<int, 0> out;
auto ret =
std::ranges::copy_backward(In(in.data()), Sent(In(in.data() + in.size())), Out(out.data() + out.size()));
assert(base(ret.in) == in.data() + in.size());
assert(base(ret.out) == out.data());
}
{
std::array<int, 0> in;
std::array<int, 0> out;
auto range = std::ranges::subrange(In(in.data()), Sent(In(in.data() + in.size())));
auto ret = std::ranges::copy_backward(range, Out(out.data()));
assert(base(ret.in) == in.data() + in.size());
assert(base(ret.out) == out.data());
}
}
}
template <class InIter, class OutIter>
constexpr void test_sentinels() {
test_iterators<InIter, OutIter, InIter>();
test_iterators<InIter, OutIter, sentinel_wrapper<InIter>>();
test_iterators<InIter, OutIter, sized_sentinel<InIter>>();
}
template <class Out>
constexpr void test_in_iterators() {
test_sentinels<bidirectional_iterator<int*>, Out>();
test_sentinels<random_access_iterator<int*>, Out>();
test_sentinels<contiguous_iterator<int*>, Out>();
}
template <class Out>
constexpr void test_proxy_in_iterators() {
test_sentinels<ProxyIterator<bidirectional_iterator<int*>>, Out>();
test_sentinels<ProxyIterator<random_access_iterator<int*>>, Out>();
test_sentinels<ProxyIterator<contiguous_iterator<int*>>, Out>();
}
constexpr bool test() {
test_in_iterators<bidirectional_iterator<int*>>();
test_in_iterators<random_access_iterator<int*>>();
test_in_iterators<contiguous_iterator<int*>>();
test_proxy_in_iterators<ProxyIterator<bidirectional_iterator<int*>>>();
test_proxy_in_iterators<ProxyIterator<random_access_iterator<int*>>>();
test_proxy_in_iterators<ProxyIterator<contiguous_iterator<int*>>>();
{ // check that ranges::dangling is returned
std::array<int, 4> out;
std::same_as<std::ranges::in_out_result<std::ranges::dangling, int*>> auto ret =
std::ranges::copy_backward(std::array {1, 2, 3, 4}, out.data() + out.size());
assert(ret.out == out.data());
assert((out == std::array{1, 2, 3, 4}));
}
{ // check that an iterator is returned with a borrowing range
std::array in {1, 2, 3, 4};
std::array<int, 4> out;
std::same_as<std::ranges::in_out_result<int*, int*>> auto ret =
std::ranges::copy_backward(std::views::all(in), out.data() + out.size());
assert(ret.in == in.data() + in.size());
assert(ret.out == out.data());
assert(in == out);
}
{ // check that every element is copied exactly once
struct CopyOnce {
bool copied = false;
constexpr CopyOnce() = default;
constexpr CopyOnce(const CopyOnce& other) = delete;
constexpr CopyOnce& operator=(const CopyOnce& other) {
assert(!other.copied);
copied = true;
return *this;
}
};
{
std::array<CopyOnce, 4> in {};
std::array<CopyOnce, 4> out {};
auto ret = std::ranges::copy_backward(in.begin(), in.end(), out.end());
assert(ret.in == in.end());
assert(ret.out == out.begin());
assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.copied; }));
}
{
std::array<CopyOnce, 4> in {};
std::array<CopyOnce, 4> out {};
auto ret = std::ranges::copy_backward(in, out.end());
assert(ret.in == in.end());
assert(ret.out == out.begin());
assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.copied; }));
}
}
{ // check that the range is copied backwards
struct OnlyBackwardsCopyable {
OnlyBackwardsCopyable* next = nullptr;
bool canCopy = false;
OnlyBackwardsCopyable() = default;
constexpr OnlyBackwardsCopyable& operator=(const OnlyBackwardsCopyable&) {
assert(canCopy);
if (next != nullptr)
next->canCopy = true;
return *this;
}
};
{
std::array<OnlyBackwardsCopyable, 3> in {};
std::array<OnlyBackwardsCopyable, 3> out {};
out[1].next = &out[0];
out[2].next = &out[1];
out[2].canCopy = true;
auto ret = std::ranges::copy_backward(in, out.end());
assert(ret.in == in.end());
assert(ret.out == out.begin());
assert(out[0].canCopy);
assert(out[1].canCopy);
assert(out[2].canCopy);
}
{
std::array<OnlyBackwardsCopyable, 3> in {};
std::array<OnlyBackwardsCopyable, 3> out {};
out[1].next = &out[0];
out[2].next = &out[1];
out[2].canCopy = true;
auto ret = std::ranges::copy_backward(in.begin(), in.end(), out.end());
assert(ret.in == in.end());
assert(ret.out == out.begin());
assert(out[0].canCopy);
assert(out[1].canCopy);
assert(out[2].canCopy);
}
}
return true;
}
int main(int, char**) {
test();
static_assert(test());
return 0;
}
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