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AK: Ensure dual_pivot_quick_sort does not copy the pivots

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Also add a test that would fail to compile if quick_sort tries to copy
anything :P
This commit is contained in:
AnotherTest 2020-12-10 06:42:11 +03:30 committed by Andreas Kling
parent 5b104eedaf
commit ec4980e875
Notes: sideshowbarker 2024-07-19 00:56:32 +09:00 
Author: https://github.com/alimpfard
Commit: https://github.com/SerenityOS/serenity/commit/ec4980e8756
Pull-request: https://github.com/SerenityOS/serenity/pull/4375
Reviewed-by: https://github.com/ccapitalK ✅
2 changed files with 60 additions and 2 deletions
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4
AK/QuickSort.h
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@ -51,8 +51,8 @@ void dual_pivot_quick_sort(Collection& col, int start, int end, LessThan less_th
int k = start + 1;
int g = end - 1;
auto left_pivot = col[start];
auto right_pivot = col[end];
auto&& left_pivot = col[start];
auto&& right_pivot = col[end];
while (k <= g) {
if (less_than(col[k], left_pivot)) {

58
AK/Tests/TestQuickSort.cpp Normal file
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@ -0,0 +1,58 @@
/*
* Copyright (c) 2020, the SerenityOS developers.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/TestSuite.h>
#include <AK/Checked.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() { }
NoCopy(NoCopy&&) = default;
NoCopy& operator=(NoCopy&&) = default;
int value { 0 };
};
Array<NoCopy, 64> array;
for (size_t i = 0; i < 64; ++i)
array[i].value = (64 - i) % 32 + 32;
quick_sort(array, [](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_MAIN(QuickSort)