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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
// std::views::drop_while
#include <algorithm>
#include <cassert>
#include <ranges>
#include <type_traits>
#include <utility>
struct Pred {
constexpr bool operator()(int i) const { return i < 3; }
};
struct Foo {};
template <class T>
struct BufferView : std::ranges::view_base {
T* buffer_;
std::size_t size_;
template <std::size_t N>
constexpr BufferView(T (&b)[N]) : buffer_(b), size_(N) {}
};
using IntBufferView = BufferView<int>;
struct MoveOnlyView : IntBufferView {
using IntBufferView::IntBufferView;
MoveOnlyView(const MoveOnlyView&) = delete;
MoveOnlyView& operator=(const MoveOnlyView&) = delete;
MoveOnlyView(MoveOnlyView&&) = default;
MoveOnlyView& operator=(MoveOnlyView&&) = default;
constexpr const int* begin() const { return buffer_; }
constexpr const int* end() const { return buffer_ + size_; }
};
static_assert(!std::is_invocable_v<decltype((std::views::drop_while))>);
static_assert(std::is_invocable_v<decltype((std::views::drop_while)), int>);
static_assert(std::is_invocable_v<decltype((std::views::drop_while)), Pred>);
static_assert(!std::is_invocable_v<decltype((std::views::drop_while)), int, Pred>);
static_assert(std::is_invocable_v<decltype((std::views::drop_while)), int (&)[2], Pred>);
static_assert(!std::is_invocable_v<decltype((std::views::drop_while)), Foo (&)[2], Pred>);
static_assert(std::is_invocable_v<decltype((std::views::drop_while)), MoveOnlyView, Pred>);
template <class View, class T>
concept CanBePiped =
requires(View&& view, T&& t) {
{ std::forward<View>(view) | std::forward<T>(t) };
};
static_assert(!CanBePiped<MoveOnlyView, decltype(std::views::drop_while)>);
static_assert(CanBePiped<MoveOnlyView, decltype(std::views::drop_while(Pred{}))>);
static_assert(!CanBePiped<int, decltype(std::views::drop_while(Pred{}))>);
static_assert(CanBePiped<int (&)[2], decltype(std::views::drop_while(Pred{}))>);
static_assert(!CanBePiped<Foo (&)[2], decltype(std::views::drop_while(Pred{}))>);
constexpr bool test() {
int buff[] = {1, 2, 3, 4, 3, 2, 1};
// Test `views::drop_while(p)(v)`
{
using Result = std::ranges::drop_while_view<MoveOnlyView, Pred>;
std::same_as<Result> auto result = std::views::drop_while(Pred{})(MoveOnlyView{buff});
auto expected = {3, 4, 3, 2, 1};
assert(std::ranges::equal(result, expected));
}
{
auto const partial = std::views::drop_while(Pred{});
using Result = std::ranges::drop_while_view<MoveOnlyView, Pred>;
std::same_as<Result> auto result = partial(MoveOnlyView{buff});
auto expected = {3, 4, 3, 2, 1};
assert(std::ranges::equal(result, expected));
}
// Test `v | views::drop_while(p)`
{
using Result = std::ranges::drop_while_view<MoveOnlyView, Pred>;
std::same_as<Result> auto result = MoveOnlyView{buff} | std::views::drop_while(Pred{});
auto expected = {3, 4, 3, 2, 1};
assert(std::ranges::equal(result, expected));
}
{
auto const partial = std::views::drop_while(Pred{});
using Result = std::ranges::drop_while_view<MoveOnlyView, Pred>;
std::same_as<Result> auto result = MoveOnlyView{buff} | partial;
auto expected = {3, 4, 3, 2, 1};
assert(std::ranges::equal(result, expected));
}
// Test `views::drop_while(v, p)`
{
using Result = std::ranges::drop_while_view<MoveOnlyView, Pred>;
std::same_as<Result> auto result = std::views::drop_while(MoveOnlyView{buff}, Pred{});
auto expected = {3, 4, 3, 2, 1};
assert(std::ranges::equal(result, expected));
}
// Test adaptor | adaptor
{
struct Pred2 {
constexpr bool operator()(int i) const { return i < 4; }
};
auto const partial = std::views::drop_while(Pred{}) | std::views::drop_while(Pred2{});
using Result = std::ranges::drop_while_view<std::ranges::drop_while_view<MoveOnlyView, Pred>, Pred2>;
std::same_as<Result> auto result = MoveOnlyView{buff} | partial;
auto expected = {4, 3, 2, 1};
assert(std::ranges::equal(result, expected));
}
return true;
}
int main(int, char**) {
test();
static_assert(test());
return 0;
}
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