//===----------------------------------------------------------------------===//
//
// 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<random_access_iterator I, sentinel_for<I> S, class Comp = ranges::less,
// class Proj = identity>
// requires sortable<I, Comp, Proj>
// I ranges::stable_sort(I first, S last, Comp comp = {}, Proj proj = {}); // since C++20
//
// template<random_access_range R, class Comp = ranges::less, class Proj = identity>
// requires sortable<iterator_t<R>, Comp, Proj>
// borrowed_iterator_t<R>
// ranges::stable_sort(R&& r, Comp comp = {}, Proj proj = {}); // since C++20
#include <algorithm>
#include <array>
#include <concepts>
#include <functional>
#include <ranges>
#include "almost_satisfies_types.h"
#include "test_iterators.h"
// SFINAE tests.
using BadComparator = ComparatorNotCopyable<int*>;
static_assert(!std::sortable<int*, BadComparator>);
template <class Iter, class Sent = sentinel_wrapper<Iter>, class Comp = std::ranges::less>
concept HasStableSortIt = requires(Iter first, Sent last, Comp comp) { std::ranges::stable_sort(first, last, comp); };
static_assert(HasStableSortIt<int*>);
static_assert(!HasStableSortIt<RandomAccessIteratorNotDerivedFrom>);
static_assert(!HasStableSortIt<RandomAccessIteratorBadIndex>);
static_assert(!HasStableSortIt<int*, SentinelForNotSemiregular>);
static_assert(!HasStableSortIt<int*, SentinelForNotWeaklyEqualityComparableWith>);
static_assert(!HasStableSortIt<int*, int*, BadComparator>);
static_assert(!HasStableSortIt<const int*>); // Doesn't satisfy `sortable`.
template <class Range, class Comp = std::ranges::less>
concept HasStableSortR = requires(Range range, Comp comp) { std::ranges::stable_sort(range, comp); };
static_assert(HasStableSortR<UncheckedRange<int*>>);
static_assert(!HasStableSortR<RandomAccessRangeNotDerivedFrom>);
static_assert(!HasStableSortR<RandomAccessRangeBadIndex>);
static_assert(!HasStableSortR<UncheckedRange<int*, SentinelForNotSemiregular>>);
static_assert(!HasStableSortR<UncheckedRange<int*, SentinelForNotWeaklyEqualityComparableWith>>);
static_assert(!HasStableSortR<UncheckedRange<int*>, BadComparator>);
static_assert(!HasStableSortR<UncheckedRange<const int*>>); // Doesn't satisfy `sortable`.
template <class Iter, class Sent, std::size_t N>
void test_one(std::array<int, N> input, std::array<int, N> expected) {
{ // (iterator, sentinel) overload.
auto sorted = input;
auto b = Iter(sorted.data());
auto e = Sent(Iter(sorted.data() + sorted.size()));
std::same_as<Iter> decltype(auto) last = std::ranges::stable_sort(b, e);
assert(sorted == expected);
assert(base(last) == sorted.data() + sorted.size());
}
{ // (range) overload.
auto sorted = input;
auto b = Iter(sorted.data());
auto e = Sent(Iter(sorted.data() + sorted.size()));
auto range = std::ranges::subrange(b, e);
std::same_as<Iter> decltype(auto) last = std::ranges::stable_sort(range);
assert(sorted == expected);
assert(base(last) == sorted.data() + sorted.size());
}
}
template <class Iter, class Sent>
void test_iterators_2() {
// Empty sequence.
test_one<Iter, Sent, 0>({}, {});
// 1-element sequence.
test_one<Iter, Sent, 1>({1}, {1});
// 2-element sequence.
test_one<Iter, Sent, 2>({2, 1}, {1, 2});
// 3-element sequence.
test_one<Iter, Sent, 3>({2, 1, 3}, {1, 2, 3});
// Longer sequence.
test_one<Iter, Sent, 8>({2, 1, 3, 6, 8, 4, 11, 5}, {1, 2, 3, 4, 5, 6, 8, 11});
// Longer sequence with duplicates.
test_one<Iter, Sent, 7>({2, 1, 3, 6, 2, 8, 6}, {1, 2, 2, 3, 6, 6, 8});
// All elements are the same.
test_one<Iter, Sent, 3>({1, 1, 1}, {1, 1, 1});
// Already sorted.
test_one<Iter, Sent, 5>({1, 2, 3, 4, 5}, {1, 2, 3, 4, 5});
// Reverse-sorted.
test_one<Iter, Sent, 5>({5, 4, 3, 2, 1}, {1, 2, 3, 4, 5});
// Repeating pattern.
test_one<Iter, Sent, 6>({1, 2, 1, 2, 1, 2}, {1, 1, 1, 2, 2, 2});
}
template <class Iter>
void test_iterators_1() {
test_iterators_2<Iter, Iter>();
test_iterators_2<Iter, sentinel_wrapper<Iter>>();
}
void test_iterators() {
test_iterators_1<random_access_iterator<int*>>();
test_iterators_1<contiguous_iterator<int*>>();
test_iterators_1<int*>();
}
void test() {
test_iterators();
struct OrderedValue {
int value;
double original_order;
bool operator==(const OrderedValue&) const = default;
auto operator<=>(const OrderedValue& rhs) const { return value <=> rhs.value; }
};
{ // The sort is stable (equivalent elements remain in the same order).
using V = OrderedValue;
using Array = std::array<V, 20>;
Array orig_in = {
V{10, 10.1}, {12, 12.1}, {3, 3.1}, {5, 5.1}, {3, 3.2}, {3, 3.3}, {11, 11.1}, {12, 12.2}, {4, 4.1}, {4, 4.2},
{4, 4.3}, {1, 1.1}, {6, 6.1}, {3, 3.4}, {10, 10.2}, {8, 8.1}, {12, 12.3}, {1, 1.2}, {1, 1.3}, {5, 5.2}
};
Array expected = {
V{1, 1.1}, {1, 1.2}, {1, 1.3},
{3, 3.1}, {3, 3.2}, {3, 3.3}, {3, 3.4},
{4, 4.1}, {4, 4.2}, {4, 4.3},
{5, 5.1}, {5, 5.2},
{6, 6.1},
{8, 8.1},
{10, 10.1}, {10, 10.2},
{11, 11.1},
{12, 12.1}, {12, 12.2}, {12, 12.3}
};
{
auto in = orig_in;
auto last = std::ranges::stable_sort(in.begin(), in.end());
assert(in == expected);
assert(last == in.end());
}
{
auto in = orig_in;
auto last = std::ranges::stable_sort(in);
assert(in == expected);
assert(last == in.end());
}
}
{ // A custom comparator works and is stable.
using V = OrderedValue;
using Array = std::array<V, 11>;
Array orig_in = {
V{1, 1.1}, {2, 2.1}, {2, 2.2}, {3, 3.1}, {2, 2.3}, {3, 3.2}, {4, 4.1}, {5, 5.1}, {2, 2.4}, {5, 5.2}, {1, 1.2}
};
Array expected = {
V{5, 5.1}, {5, 5.2},
{4, 4.1},
{3, 3.1}, {3, 3.2},
{2, 2.1}, {2, 2.2}, {2, 2.3}, {2, 2.4},
{1, 1.1}, {1, 1.2}
};
{
auto in = orig_in;
auto last = std::ranges::stable_sort(in.begin(), in.end(), std::greater{});
assert(in == expected);
assert(last == in.end());
}
{
auto in = orig_in;
auto last = std::ranges::stable_sort(in, std::greater{});
assert(in == expected);
assert(last == in.end());
}
}
{ // A custom projection works.
struct A {
int a;
bool operator==(const A&) const = default;
};
{
std::array in = {A{2}, A{3}, A{1}};
auto last = std::ranges::stable_sort(in.begin(), in.end(), {}, &A::a);
assert((in == std::array{A{1}, A{2}, A{3}}));
assert(last == in.end());
}
{
std::array in = {A{2}, A{3}, A{1}};
auto last = std::ranges::stable_sort(in, {}, &A::a);
assert((in == std::array{A{1}, A{2}, A{3}}));
assert(last == in.end());
}
}
{ // `std::invoke` is used in the implementation.
struct S {
int i;
S(int i_) : i(i_) {}
bool comparator(const S& rhs) const { return i < rhs.i; }
const S& projection() const { return *this; }
bool operator==(const S&) const = default;
};
{
std::array in = {S{2}, S{3}, S{1}};
auto last = std::ranges::stable_sort(in.begin(), in.end(), &S::comparator, &S::projection);
assert((in == std::array{S{1}, S{2}, S{3}}));
assert(last == in.end());
}
{
std::array in = {S{2}, S{3}, S{1}};
auto last = std::ranges::stable_sort(in, &S::comparator, &S::projection);
assert((in == std::array{S{1}, S{2}, S{3}}));
assert(last == in.end());
}
}
{ // `std::ranges::dangling` is returned.
[[maybe_unused]] std::same_as<std::ranges::dangling> decltype(auto) result =
std::ranges::stable_sort(std::array{1, 2, 3});
}
// TODO: Enable the tests once the implementation switched to use iter_move/iter_swap
/*
{ // ProxyIterator
{
std::array in = {2, 1, 3};
ProxyRange proxy{in};
std::ranges::stable_sort(proxy.begin(), proxy.end(), [](auto i, auto j) { return i.data < j.data; });
assert((in == std::array{1, 2, 3}));
}
{
std::array in = {2, 1, 3};
ProxyRange proxy{in};
std::ranges::stable_sort(proxy, [](auto i, auto j) { return i.data < j.data; });
assert((in == std::array{1, 2, 3}));
}
}
*/
}
int main(int, char**) {
test();
// Note: `stable_sort` is not `constexpr`.
return 0;
}
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