src/kitemviews/private/kfileitemmodelsortalgorithm.h

   1 /***************************************************************************
   2  *   Copyright (C) 2012 by Peter Penz <peter.penz19@gmail.com>             *
   3  *                                                                         *
   4  *   This program is free software; you can redistribute it and/or modify  *
   5  *   it under the terms of the GNU General Public License as published by  *
   6  *   the Free Software Foundation; either version 2 of the License, or     *
   7  *   (at your option) any later version.                                   *
   8  *                                                                         *
   9  *   This program is distributed in the hope that it will be useful,       *
  10  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  11  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  12  *   GNU General Public License for more details.                          *
  13  *                                                                         *
  14  *   You should have received a copy of the GNU General Public License     *
  15  *   along with this program; if not, write to the                         *
  16  *   Free Software Foundation, Inc.,                                       *
  17  *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA            *
  18  ***************************************************************************/
  19
  20 #ifndef KFILEITEMMODELSORTALGORITHM_H
  21 #define KFILEITEMMODELSORTALGORITHM_H
  22
  23 #include <libdolphin_export.h>
  24
  25 #include <kitemviews/kfileitemmodel.h>
  26
  27 /**
  28  * @brief Sort algorithm for sorting items of KFileItemModel.
  29  *
  30  * Sorts the items by using KFileItemModel::lessThan() as comparison criteria.
  31  * The merge sort algorithm is used to assure a worst-case
  32  * of O(n * log(n)) and to keep the number of comparisons low.
  33  *
  34  * The implementation is based on qStableSortHelper() from qalgorithms.h
  35  * Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
  36  * The sorting implementations of qAlgorithms could not be used as they
  37  * don't support having a member-function as comparison criteria.
  38  */
  39 class LIBDOLPHINPRIVATE_EXPORT KFileItemModelSortAlgorithm
  40 {
  41 public:
  42     static void sort(KFileItemModel* model,
  43                      QList<KFileItemModel::ItemData*>::iterator begin,
  44                      QList<KFileItemModel::ItemData*>::iterator end);
  45
  46 private:
  47     static void sequentialSort(KFileItemModel* model,
  48                                QList<KFileItemModel::ItemData*>::iterator begin,
  49                                QList<KFileItemModel::ItemData*>::iterator end);
  50
  51     static void parallelSort(KFileItemModel* model,
  52                              QList<KFileItemModel::ItemData*>::iterator begin,
  53                              QList<KFileItemModel::ItemData*>::iterator end,
  54                              const int numberOfThreads);
  55
  56     static void merge(KFileItemModel* model,
  57                       QList<KFileItemModel::ItemData*>::iterator begin,
  58                       QList<KFileItemModel::ItemData*>::iterator pivot,
  59                       QList<KFileItemModel::ItemData*>::iterator end);
  60
  61     static QList<KFileItemModel::ItemData*>::iterator
  62                 lowerBound(KFileItemModel* model,
  63                            QList<KFileItemModel::ItemData*>::iterator begin,
  64                            QList<KFileItemModel::ItemData*>::iterator end,
  65                            const KFileItemModel::ItemData* value);
  66
  67     static QList<KFileItemModel::ItemData*>::iterator
  68                 upperBound(KFileItemModel* model,
  69                            QList<KFileItemModel::ItemData*>::iterator begin,
  70                            QList<KFileItemModel::ItemData*>::iterator end,
  71                            const KFileItemModel::ItemData* value);
  72
  73     static void reverse(QList<KFileItemModel::ItemData*>::iterator begin,
  74                         QList<KFileItemModel::ItemData*>::iterator end);
  75 };
  76
  77 #endif
  78
  79