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/***************************************************************************
* Copyright (C) 2012 by Peter Penz <[email protected]> *
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License for more details. *
* *
* You should have received a copy of the GNU General Public License *
* along with this program; if not, write to the *
* Free Software Foundation, Inc., *
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA *
***************************************************************************/
#include "kfileitemmodelsortalgorithm_p.h"
void KFileItemModelSortAlgorithm::sort(KFileItemModel* model,
QList<KFileItemModel::ItemData*>::iterator begin,
QList<KFileItemModel::ItemData*>::iterator end)
{
// The implementation is based on qStableSortHelper() from qalgorithms.h
// Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
const int span = end - begin;
if (span < 2) {
return;
}
const QList<KFileItemModel::ItemData*>::iterator middle = begin + span / 2;
sort(model, begin, middle);
sort(model, middle, end);
merge(model, begin, middle, end);
}
void KFileItemModelSortAlgorithm::merge(KFileItemModel* model,
QList<KFileItemModel::ItemData*>::iterator begin,
QList<KFileItemModel::ItemData*>::iterator pivot,
QList<KFileItemModel::ItemData*>::iterator end)
{
// The implementation is based on qMerge() from qalgorithms.h
// Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
const int len1 = pivot - begin;
const int len2 = end - pivot;
if (len1 == 0 || len2 == 0) {
return;
}
if (len1 + len2 == 2) {
if (model->lessThan(*(begin + 1), *(begin))) {
qSwap(*begin, *(begin + 1));
}
return;
}
QList<KFileItemModel::ItemData*>::iterator firstCut;
QList<KFileItemModel::ItemData*>::iterator secondCut;
int len2Half;
if (len1 > len2) {
const int len1Half = len1 / 2;
firstCut = begin + len1Half;
secondCut = lowerBound(model, pivot, end, *firstCut);
len2Half = secondCut - pivot;
} else {
len2Half = len2 / 2;
secondCut = pivot + len2Half;
firstCut = upperBound(model, begin, pivot, *secondCut);
}
reverse(firstCut, pivot);
reverse(pivot, secondCut);
reverse(firstCut, secondCut);
const QList<KFileItemModel::ItemData*>::iterator newPivot = firstCut + len2Half;
merge(model, begin, firstCut, newPivot);
merge(model, newPivot, secondCut, end);
}
QList<KFileItemModel::ItemData*>::iterator
KFileItemModelSortAlgorithm::lowerBound(KFileItemModel* model,
QList<KFileItemModel::ItemData*>::iterator begin,
QList<KFileItemModel::ItemData*>::iterator end,
const KFileItemModel::ItemData* value)
{
// The implementation is based on qLowerBound() from qalgorithms.h
// Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
QList<KFileItemModel::ItemData*>::iterator middle;
int n = int(end - begin);
int half;
while (n > 0) {
half = n >> 1;
middle = begin + half;
if (model->lessThan(*middle, value)) {
begin = middle + 1;
n -= half + 1;
} else {
n = half;
}
}
return begin;
}
QList<KFileItemModel::ItemData*>::iterator
KFileItemModelSortAlgorithm::upperBound(KFileItemModel* model,
QList<KFileItemModel::ItemData*>::iterator begin,
QList<KFileItemModel::ItemData*>::iterator end,
const KFileItemModel::ItemData* value)
{
// The implementation is based on qUpperBound() from qalgorithms.h
// Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
QList<KFileItemModel::ItemData*>::iterator middle;
int n = end - begin;
int half;
while (n > 0) {
half = n >> 1;
middle = begin + half;
if (model->lessThan(value, *middle)) {
n = half;
} else {
begin = middle + 1;
n -= half + 1;
}
}
return begin;
}
void KFileItemModelSortAlgorithm::reverse(QList<KFileItemModel::ItemData*>::iterator begin,
QList<KFileItemModel::ItemData*>::iterator end)
{
// The implementation is based on qReverse() from qalgorithms.h
// Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
--end;
while (begin < end) {
qSwap(*begin++, *end--);
}
}
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