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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::ranges::empty
#include <ranges>
#include <cassert>
#include <utility>
#include "test_macros.h"
#include "test_iterators.h"
using RangeEmptyT = decltype(std::ranges::empty);
static_assert(!std::is_invocable_v<RangeEmptyT, int[]>);
static_assert(!std::is_invocable_v<RangeEmptyT, int(&)[]>);
static_assert(!std::is_invocable_v<RangeEmptyT, int(&&)[]>);
static_assert( std::is_invocable_v<RangeEmptyT, int[1]>);
static_assert( std::is_invocable_v<RangeEmptyT, const int[1]>);
static_assert( std::is_invocable_v<RangeEmptyT, int (&&)[1]>);
static_assert( std::is_invocable_v<RangeEmptyT, int (&)[1]>);
static_assert( std::is_invocable_v<RangeEmptyT, const int (&)[1]>);
struct Incomplete;
static_assert(!std::is_invocable_v<RangeEmptyT, Incomplete[]>);
static_assert(!std::is_invocable_v<RangeEmptyT, Incomplete(&)[]>);
static_assert(!std::is_invocable_v<RangeEmptyT, Incomplete(&&)[]>);
extern Incomplete array_of_incomplete[42];
static_assert(!std::ranges::empty(array_of_incomplete));
static_assert(!std::ranges::empty(std::move(array_of_incomplete)));
static_assert(!std::ranges::empty(std::as_const(array_of_incomplete)));
static_assert(!std::ranges::empty(static_cast<const Incomplete(&&)[42]>(array_of_incomplete)));
struct InputRangeWithoutSize {
cpp17_input_iterator<int*> begin() const;
cpp17_input_iterator<int*> end() const;
};
static_assert(!std::is_invocable_v<RangeEmptyT, const InputRangeWithoutSize&>);
struct NonConstEmpty {
bool empty();
};
static_assert(!std::is_invocable_v<RangeEmptyT, const NonConstEmpty&>);
struct HasMemberAndFunction {
constexpr bool empty() const { return true; }
// We should never do ADL lookup for std::ranges::empty.
friend bool empty(const HasMemberAndFunction&) { return false; }
};
struct BadReturnType {
BadReturnType empty() { return {}; }
};
static_assert(!std::is_invocable_v<RangeEmptyT, BadReturnType&>);
struct BoolConvertible {
constexpr explicit operator bool() noexcept(false) { return true; }
};
struct BoolConvertibleReturnType {
constexpr BoolConvertible empty() noexcept { return {}; }
};
static_assert(!noexcept(std::ranges::empty(BoolConvertibleReturnType())));
struct InputIterators {
cpp17_input_iterator<int*> begin() const;
cpp17_input_iterator<int*> end() const;
};
static_assert(std::is_same_v<decltype(InputIterators().begin() == InputIterators().end()), bool>);
static_assert(!std::is_invocable_v<RangeEmptyT, const InputIterators&>);
constexpr bool testEmptyMember() {
HasMemberAndFunction a;
assert(std::ranges::empty(a));
BoolConvertibleReturnType b;
assert(std::ranges::empty(b));
return true;
}
struct SizeMember {
size_t size_;
constexpr size_t size() const { return size_; }
};
struct SizeFunction {
size_t size_;
friend constexpr size_t size(SizeFunction sf) { return sf.size_; }
};
struct BeginEndSizedSentinel {
constexpr int *begin() const { return nullptr; }
constexpr auto end() const { return sized_sentinel<int*>(nullptr); }
};
static_assert(std::ranges::forward_range<BeginEndSizedSentinel>);
static_assert(std::ranges::sized_range<BeginEndSizedSentinel>);
constexpr bool testUsingRangesSize() {
SizeMember a{1};
assert(!std::ranges::empty(a));
SizeMember b{0};
assert(std::ranges::empty(b));
SizeFunction c{1};
assert(!std::ranges::empty(c));
SizeFunction d{0};
assert(std::ranges::empty(d));
BeginEndSizedSentinel e;
assert(std::ranges::empty(e));
return true;
}
struct BeginEndNotSizedSentinel {
constexpr int *begin() const { return nullptr; }
constexpr auto end() const { return sentinel_wrapper<int*>(nullptr); }
};
static_assert( std::ranges::forward_range<BeginEndNotSizedSentinel>);
static_assert(!std::ranges::sized_range<BeginEndNotSizedSentinel>);
// size is disabled here, so we have to compare begin and end.
struct DisabledSizeRangeWithBeginEnd {
constexpr int *begin() const { return nullptr; }
constexpr auto end() const { return sentinel_wrapper<int*>(nullptr); }
size_t size() const;
};
template<>
inline constexpr bool std::ranges::disable_sized_range<DisabledSizeRangeWithBeginEnd> = true;
static_assert(std::ranges::contiguous_range<DisabledSizeRangeWithBeginEnd>);
static_assert(!std::ranges::sized_range<DisabledSizeRangeWithBeginEnd>);
struct BeginEndAndEmpty {
constexpr int *begin() const { return nullptr; }
constexpr auto end() const { return sentinel_wrapper<int*>(nullptr); }
constexpr bool empty() { return false; }
};
struct EvilBeginEnd {
bool empty() &&;
constexpr int *begin() & { return nullptr; }
constexpr int *end() & { return nullptr; }
};
constexpr bool testBeginEqualsEnd() {
BeginEndNotSizedSentinel a;
assert(std::ranges::empty(a));
DisabledSizeRangeWithBeginEnd d;
assert(std::ranges::empty(d));
BeginEndAndEmpty e;
assert(!std::ranges::empty(e)); // e.empty()
assert(std::ranges::empty(std::as_const(e))); // e.begin() == e.end()
assert(std::ranges::empty(EvilBeginEnd()));
return true;
}
// Test ADL-proofing.
struct Incomplete;
template<class T> struct Holder { T t; };
static_assert(!std::is_invocable_v<RangeEmptyT, Holder<Incomplete>*>);
static_assert(!std::is_invocable_v<RangeEmptyT, Holder<Incomplete>*&>);
int main(int, char**) {
testEmptyMember();
static_assert(testEmptyMember());
testUsingRangesSize();
static_assert(testUsingRangesSize());
testBeginEqualsEnd();
static_assert(testBeginEqualsEnd());
return 0;
}
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