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/*
* Copyright (c) 2020, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibTest/TestCase.h>
#include <AK/Noncopyable.h>
#include <AK/QuickSort.h>
#include <AK/StdLibExtras.h>
TEST_CASE(sorts_without_copy)
{
struct NoCopy {
AK_MAKE_NONCOPYABLE(NoCopy);
public:
NoCopy() = default;
NoCopy(NoCopy&&) = default;
NoCopy& operator=(NoCopy&&) = default;
int value { 0 };
};
Array<NoCopy, 64> array;
// Test the dual pivot quick sort.
for (size_t i = 0; i < 64; ++i)
array[i].value = (64 - i) % 32 + 32;
dual_pivot_quick_sort(array, 0, array.size() - 1, [](auto& a, auto& b) { return a.value < b.value; });
for (size_t i = 0; i < 63; ++i)
EXPECT(array[i].value <= array[i + 1].value);
// Test the single pivot quick sort.
for (size_t i = 0; i < 64; ++i)
array[i].value = (64 - i) % 32 + 32;
AK::single_pivot_quick_sort(array.begin(), array.end(), [](auto& a, auto& b) { return a.value < b.value; });
for (size_t i = 0; i < 63; ++i)
EXPECT(array[i].value <= array[i + 1].value);
}
// This test case may fail to construct a worst-case input if the pivot choice
// of the underlying quick_sort no longer matches the one used here.
// So it provides no strong guarantees about the properties of quick_sort.
TEST_CASE(maximum_stack_depth)
{
int const size = 256;
int* data = new int[size];
for (int i = 0; i < size; i++) {
data[i] = i;
}
// Construct the data in such a way that the assumed pivot choice
// of (size / 2) causes the partitions to be of worst case size.
for (int i = 0; i < size / 2; i++) {
swap(data[i], data[i + (size - i) / 2]);
}
// Measure the depth of the call stack through the less_than argument
// of quick_sort as it gets copied for each recursive call.
struct DepthMeasurer {
int& max_depth;
int depth { 0 };
DepthMeasurer(int& max_depth)
: max_depth(max_depth)
{
}
DepthMeasurer(DepthMeasurer const& obj)
: max_depth(obj.max_depth)
{
depth = obj.depth + 1;
if (depth > max_depth) {
max_depth = depth;
}
}
bool operator()(int& a, int& b)
{
return a < b;
}
};
int max_depth = 0;
DepthMeasurer measurer(max_depth);
AK::single_pivot_quick_sort(data, data + size, measurer);
EXPECT(max_depth <= 64);
for (int i = 0; i < size; i++)
EXPECT(data[i] == i);
delete[] data;
}
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