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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, c++20
// <ranges>
// constexpr iterator begin();
#include <ranges>
#include <cassert>
#include <utility>
#include "test_iterators.h"
#include "types.h"
struct Range : std::ranges::view_base {
using Iterator = forward_iterator<int*>;
using Sentinel = sentinel_wrapper<Iterator>;
constexpr explicit Range(int* b, int* e) : begin_(b), end_(e) {}
constexpr Iterator begin() const { return Iterator(begin_); }
constexpr Sentinel end() const { return Sentinel(Iterator(end_)); }
private:
int* begin_;
int* end_;
};
struct TrackingPred : TrackInitialization {
using TrackInitialization::TrackInitialization;
constexpr bool operator()(int x, int y) { return x != -y; }
};
template <class T>
concept HasBegin = requires(T t) { t.begin(); };
static_assert(HasBegin<std::ranges::chunk_by_view<Range, TrackingPred>>);
static_assert(!HasBegin<const std::ranges::chunk_by_view<Range, TrackingPred>>);
constexpr bool test() {
int buff[] = {-4, -3, -2, -1, 1, 2, 3, 4};
// Check the return type of `begin()`
{
Range range(buff, buff + 1);
auto pred = [](int, int) { return true; };
std::ranges::chunk_by_view view(range, pred);
using ChunkByIterator = std::ranges::iterator_t<decltype(view)>;
ASSERT_SAME_TYPE(ChunkByIterator, decltype(view.begin()));
}
// begin() over an empty range
{
Range range(buff, buff);
auto pred = [](int, int) { return true; };
std::ranges::chunk_by_view view(range, pred);
auto it = view.begin();
assert(it == view.begin());
assert(it == view.end());
}
// begin() over a 1-element range
{
Range range(buff, buff + 1);
auto pred = [](int x, int y) { return x == y; };
std::ranges::chunk_by_view view(range, pred);
auto it = view.begin();
assert(base((*it).begin()) == buff);
assert(base((*it).end()) == buff + 1);
}
// begin() over a 2-element range
{
Range range(buff, buff + 2);
auto pred = [](int x, int y) { return x == y; };
std::ranges::chunk_by_view view(range, pred);
auto it = view.begin();
assert(base((*it).begin()) == buff);
assert(base((*it).end()) == buff + 1);
assert(base((*++it).begin()) == buff + 1);
assert(base((*it).end()) == buff + 2);
}
// begin() over a longer range
{
Range range(buff, buff + 8);
auto pred = [](int x, int y) { return x != -y; };
std::ranges::chunk_by_view view(range, pred);
auto it = view.begin();
assert(base((*it).end()) == buff + 4);
}
// Make sure we do not make a copy of the predicate when we call begin()
// (we should be passing it to ranges::adjacent_find using std::ref)
{
bool moved = false, copied = false;
Range range(buff, buff + 2);
std::ranges::chunk_by_view view(range, TrackingPred(&moved, &copied));
std::exchange(moved, false);
[[maybe_unused]] auto it = view.begin();
assert(!moved);
assert(!copied);
}
// Test with a non-const predicate
{
Range range(buff, buff + 8);
auto pred = [](int x, int y) mutable { return x != -y; };
std::ranges::chunk_by_view view(range, pred);
auto it = view.begin();
assert(base((*it).end()) == buff + 4);
}
// Test with a predicate that takes by non-const reference
{
Range range(buff, buff + 8);
auto pred = [](int& x, int& y) { return x != -y; };
std::ranges::chunk_by_view view(range, pred);
auto it = view.begin();
assert(base((*it).end()) == buff + 4);
}
// Test caching
{
// Make sure that we cache the result of begin() on subsequent calls
Range range(buff, buff + 8);
int called = 0;
auto pred = [&](int x, int y) {
++called;
return x != -y;
};
std::ranges::chunk_by_view view(range, pred);
assert(called == 0);
for (int k = 0; k != 3; ++k) {
auto it = view.begin();
assert(base((*it).end()) == buff + 4);
assert(called == 4); // 4, because the cached iterator is 'buff + 4' (end of the first chunk)
}
}
return true;
}
int main(int, char**) {
test();
static_assert(test());
return 0;
}
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