//===----------------------------------------------------------------------===//
//
// 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
// <algorithm>
// template<input_iterator I1, sentinel_for<I1> S1,
// random_access_iterator I2, sentinel_for<I2> S2,
// class Comp = ranges::less, class Proj1 = identity, class Proj2 = identity>
// requires indirectly_copyable<I1, I2> && sortable<I2, Comp, Proj2> &&
// indirect_strict_weak_order<Comp, projected<I1, Proj1>, projected<I2, Proj2>>
// constexpr partial_sort_copy_result<I1, I2>
// partial_sort_copy(I1 first, S1 last, I2 result_first, S2 result_last,
// Comp comp = {}, Proj1 proj1 = {}, Proj2 proj2 = {}); // Since C++20
//
// template<input_range R1, random_access_range R2, class Comp = ranges::less,
// class Proj1 = identity, class Proj2 = identity>
// requires indirectly_copyable<iterator_t<R1>, iterator_t<R2>> &&
// sortable<iterator_t<R2>, Comp, Proj2> &&
// indirect_strict_weak_order<Comp, projected<iterator_t<R1>, Proj1>,
// projected<iterator_t<R2>, Proj2>>
// constexpr partial_sort_copy_result<borrowed_iterator_t<R1>, borrowed_iterator_t<R2>>
// partial_sort_copy(R1&& r, R2&& result_r, Comp comp = {},
// Proj1 proj1 = {}, Proj2 proj2 = {}); // Since C++20
#include <algorithm>
#include <array>
#include <concepts>
#include <functional>
#include <ranges>
#include <utility>
#include "MoveOnly.h"
#include "almost_satisfies_types.h"
#include "test_iterators.h"
// Test constraints of the (iterator, sentinel) overload.
// ======================================================
template <class Iter1 = int*, class Sent1 = int*, class Iter2 = int*, class Sent2 = int*,
class Comp = std::ranges::less>
concept HasPartialSortCopyIter =
requires(Iter1&& first1, Sent1&& last1, Iter2&& first2, Sent2&& last2, Comp&& comp) {
std::ranges::partial_sort_copy(std::forward<Iter1>(first1), std::forward<Sent1>(last1),
std::forward<Iter2>(first2), std::forward<Sent2>(last2), std::forward<Comp>(comp));
};
static_assert(HasPartialSortCopyIter<int*, int*, int*, int*, std::ranges::less>);
// !input_iterator<I1>
static_assert(!HasPartialSortCopyIter<InputIteratorNotDerivedFrom>);
static_assert(!HasPartialSortCopyIter<InputIteratorNotIndirectlyReadable>);
static_assert(!HasPartialSortCopyIter<InputIteratorNotInputOrOutputIterator>);
// !sentinel_for<S1, I1>
static_assert(!HasPartialSortCopyIter<int*, SentinelForNotSemiregular>);
static_assert(!HasPartialSortCopyIter<int*, SentinelForNotWeaklyEqualityComparableWith>);
// !random_access_iterator<I2>
static_assert(!HasPartialSortCopyIter<int*, int*, RandomAccessIteratorNotDerivedFrom>);
static_assert(!HasPartialSortCopyIter<int*, int*, RandomAccessIteratorBadIndex>);
// !sentinel_for<S2, I2>
static_assert(!HasPartialSortCopyIter<int*, int*, int*, SentinelForNotSemiregular>);
static_assert(!HasPartialSortCopyIter<int*, int*, int*, SentinelForNotWeaklyEqualityComparableWith>);
// !indirect_unary_predicate<projected<I, Proj>>
static_assert(!HasPartialSortCopyIter<int*, int*, int*, int*, IndirectUnaryPredicateNotPredicate>);
static_assert(!HasPartialSortCopyIter<int*, int*, int*, int*, IndirectUnaryPredicateNotCopyConstructible>);
// !indirectly_copyable<I1, I2>
static_assert(!HasPartialSortCopyIter<int*, int*, MoveOnly*>);
// !sortable<I2, Comp, Proj2>
static_assert(!HasPartialSortCopyIter<int*, int*, const int*, const int*>);
struct NoComparator {};
// !indirect_strict_weak_order<Comp, projected<I1, Proj1>, projected<I2, Proj2>>
static_assert(!HasPartialSortCopyIter<NoComparator*, NoComparator*, NoComparator*, NoComparator*>);
// Test constraints of the (range) overload.
// ======================================================
template <class T>
using R = UncheckedRange<T>;
template <class Range1 = R<int*>, class Range2 = R<int*>, class Comp = std::ranges::less>
concept HasPartialSortCopyRange =
requires(Range1&& range1, Range2&& range2, Comp&& comp) {
std::ranges::partial_sort_copy(std::forward<Range1>(range1), std::forward<Range2>(range2),
std::forward<Comp>(comp));
};
static_assert(HasPartialSortCopyRange<R<int*>, R<int*>, std::ranges::less>);
// !input_range<R1>
static_assert(!HasPartialSortCopyRange<InputRangeNotDerivedFrom>);
static_assert(!HasPartialSortCopyRange<InputRangeNotIndirectlyReadable>);
static_assert(!HasPartialSortCopyRange<InputRangeNotInputOrOutputIterator>);
// !random_access_range<R2>
static_assert(!HasPartialSortCopyRange<R<int*>, RandomAccessRangeNotDerivedFrom>);
static_assert(!HasPartialSortCopyRange<R<int*>, RandomAccessRangeBadIndex>);
// !indirectly_copyable<iterator_t<R1>, iterator_t<R2>>
static_assert(!HasPartialSortCopyRange<R<int*>, R<MoveOnly*>>);
// !sortable<iterator_t<R2>, Comp, Proj2>
static_assert(!HasPartialSortCopyRange<R<int*>, R<const int*>>);
// !indirect_strict_weak_order<Comp, projected<iterator_t<R1>, Proj1>, projected<iterator_t<R2>, Proj2>>
static_assert(!HasPartialSortCopyRange<R<NoComparator*>, R<NoComparator*>>);
static_assert(std::is_same_v<std::ranges::partial_sort_copy_result<int, int>, std::ranges::in_out_result<int, int>>);
template <class Iter, class Sent, class OutIter, class OutSent, std::size_t N>
constexpr void test_one(
std::array<int, N> input, std::size_t input_size, size_t output_size, std::array<int, N> sorted) {
assert(input_size <= N);
assert(output_size <= N + 1); // To support testing the case where output size exceeds input size.
using ResultT = std::ranges::partial_sort_copy_result<Iter, OutIter>;
// To support testing the case where output size exceeds input size; also makes sure calling `out.data() + int()` is
// valid.
constexpr std::size_t OutputSize = N + 1;
std::size_t result_size = std::ranges::min(input_size, output_size);
auto begin = input.data();
auto end = input.data() + input_size;
{ // (iterator, sentinel) overload.
std::array<int, OutputSize> out;
auto out_begin = out.data();
auto out_end = out.data() + output_size;
std::same_as<ResultT> decltype(auto) result = std::ranges::partial_sort_copy(
Iter(begin), Sent(Iter(end)), OutIter(out_begin), OutSent(OutIter(out_end)));
assert(base(result.in) == input.data() + input_size);
assert(base(result.out) == out.data() + result_size);
assert(std::ranges::equal(std::ranges::subrange(out.begin(), out.begin() + result_size),
std::ranges::subrange(sorted.begin(), sorted.begin() + result_size)));
}
{ // (range) overload.
std::array<int, OutputSize> out;
auto out_begin = out.data();
auto out_end = out.data() + output_size;
auto in_range = std::ranges::subrange(Iter(begin), Sent(Iter(end)));
auto out_range = std::ranges::subrange(OutIter(out_begin), OutSent(OutIter(out_end)));
std::same_as<ResultT> decltype(auto) result = std::ranges::partial_sort_copy(in_range, out_range);
assert(base(result.in) == input.data() + input_size);
assert(base(result.out) == out.data() + result_size);
assert(std::ranges::equal(std::ranges::subrange(out.begin(), out.begin() + result_size),
std::ranges::subrange(sorted.begin(), sorted.begin() + result_size)));
}
}
template <class Iter, class Sent, class OutIter, class OutSent, std::size_t N>
constexpr void test_all_subsequences(const std::array<int, N> input) {
auto sorted = input;
std::sort(sorted.begin(), sorted.end());
// Whole input, increasing output size. Also check the case when `output_size` exceeds input size.
for (std::size_t out_size = 0; out_size <= N + 1; ++out_size) {
test_one<Iter, Sent, OutIter, OutSent>(input, N, out_size, sorted);
}
}
template <class InIter, class Sent1, class OutIter, class Sent2>
constexpr void test_iterators_in_sent1_out_sent2() {
// Empty sequence.
test_all_subsequences<InIter, Sent1, OutIter, Sent2, 0>({});
// 1-element sequence.
test_all_subsequences<InIter, Sent1, OutIter, Sent2>(std::array{1});
// 2-element sequence.
test_all_subsequences<InIter, Sent1, OutIter, Sent2>(std::array{2, 1});
// 3-element sequence.
test_all_subsequences<InIter, Sent1, OutIter, Sent2>(std::array{2, 1, 3});
// Longer sequence.
test_all_subsequences<InIter, Sent1, OutIter, Sent2>(std::array{2, 1, 3, 6, 8, 4, 11, 5});
// Longer sequence with duplicates.
test_all_subsequences<InIter, Sent1, OutIter, Sent2>(std::array{2, 1, 3, 6, 2, 8, 6});
// All elements are the same.
test_all_subsequences<InIter, Sent1, OutIter, Sent2>(std::array{1, 1, 1});
// Already sorted.
test_all_subsequences<InIter, Sent1, OutIter, Sent2>(std::array{1, 2, 3, 4, 5});
// Descending.
test_all_subsequences<InIter, Sent1, OutIter, Sent2>(std::array{5, 4, 3, 2, 1});
}
template <class InIter, class Sent1, class OutIter>
constexpr void test_iterators_in_sent1_out() {
test_iterators_in_sent1_out_sent2<InIter, Sent1, OutIter, OutIter>();
test_iterators_in_sent1_out_sent2<InIter, Sent1, OutIter, sentinel_wrapper<OutIter>>();
}
template <class InIter, class Sent1>
constexpr void test_iterators_in_sent1() {
test_iterators_in_sent1_out<InIter, Sent1, random_access_iterator<int*>>();
}
template <class InIter>
constexpr void test_iterators_in() {
if constexpr (std::sentinel_for<InIter, InIter>) {
test_iterators_in_sent1<InIter, InIter>();
}
test_iterators_in_sent1<InIter, sentinel_wrapper<InIter>>();
}
constexpr void test_iterators() {
test_iterators_in<cpp20_input_iterator<int*>>();
// Omitting other iterator types to reduce the combinatorial explosion.
test_iterators_in<random_access_iterator<int*>>();
test_iterators_in<const int*>();
}
constexpr bool test() {
test_iterators();
{ // A custom comparator works.
const std::array in = {1, 2, 3, 4, 5};
std::ranges::greater comp;
{
std::array<int, 2> out;
auto result = std::ranges::partial_sort_copy(in.begin(), in.end(), out.begin(), out.end(), comp);
assert(std::ranges::equal(std::ranges::subrange(out.begin(), result.out), std::array{5, 4}));
}
{
std::array<int, 2> out;
auto result = std::ranges::partial_sort_copy(in, out, comp);
assert(std::ranges::equal(std::ranges::subrange(out.begin(), result.out), std::array{5, 4}));
}
}
{ // A custom projection works.
struct A {
int a;
constexpr A() = default;
constexpr A(int value) : a(value) {}
constexpr auto operator<=>(const A&) const = default;
};
const std::array in = {2, 1, 3};
auto proj1 = [](int value) { return value * -1; };
auto proj2 = [](A value) { return value.a * -1; };
// The projections negate the argument, so the array will appear to be sorted in descending order: [3, 2, 1]
// (the projections make it appear to the algorithm as [-3, -2, -1]).
{
std::array<A, 2> out;
// No projections: ascending order.
auto result = std::ranges::partial_sort_copy(in.begin(), in.end(), out.begin(), out.end(), {});
assert(std::ranges::equal(std::ranges::subrange(out.begin(), result.out), std::array{1, 2}));
// Using projections: descending order.
result = std::ranges::partial_sort_copy(in.begin(), in.end(), out.begin(), out.end(), {}, proj1, proj2);
assert(std::ranges::equal(std::ranges::subrange(out.begin(), result.out), std::array{3, 2}));
}
{
std::array<int, 2> out;
auto result = std::ranges::partial_sort_copy(in, out, {});
assert(std::ranges::equal(std::ranges::subrange(out.begin(), result.out), std::array{1, 2}));
result = std::ranges::partial_sort_copy(in, out, {}, proj1, proj2);
assert(std::ranges::equal(std::ranges::subrange(out.begin(), result.out), std::array{3, 2}));
}
}
return true;
}
int main(int, char**) {
test();
static_assert(test());
return 0;
}
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