Long live Qt 4.5!

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diff --git a/src/corelib/kernel/qabstractitemmodel.cpp b/src/corelib/kernel/qabstractitemmodel.cpp
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+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Qt Software Information (qt-info@nokia.com)
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the either Technology Preview License Agreement or the
+** Beta Release License Agreement.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain
+** additional rights. These rights are described in the Nokia Qt LGPL
+** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at qt-sales@nokia.com.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qabstractitemmodel.h"
+#include <private/qabstractitemmodel_p.h>
+#include <qdatastream.h>
+#include <qstringlist.h>
+#include <qsize.h>
+#include <qmimedata.h>
+#include <qdebug.h>
+#include <qvector.h>
+#include <qstack.h>
+#include <qbitarray.h>
+
+#include <limits.h>
+
+QT_BEGIN_NAMESPACE
+
+QPersistentModelIndexData *QPersistentModelIndexData::create(const QModelIndex &index)
+{
+    Q_ASSERT(index.isValid()); // we will _never_ insert an invalid index in the list
+    QPersistentModelIndexData *d = 0;
+    QAbstractItemModel *model = const_cast<QAbstractItemModel *>(index.model());
+    QHash<QModelIndex, QPersistentModelIndexData *> &indexes = model->d_func()->persistent.indexes;
+    const QHash<QModelIndex, QPersistentModelIndexData *>::iterator it = indexes.find(index);
+    if (it != indexes.end()) {
+        d = (*it);
+    } else {
+        d = new QPersistentModelIndexData(index);
+        indexes.insert(index, d);
+    }
+    Q_ASSERT(d);
+    return d;
+}
+
+void QPersistentModelIndexData::destroy(QPersistentModelIndexData *data)
+{
+    Q_ASSERT(data);
+    Q_ASSERT(data->ref == 0);
+    QAbstractItemModel *model = const_cast<QAbstractItemModel *>(data->model);
+    // a valid persistent model index with a null model pointer can only happen if the model was destroyed
+    if (model) {
+        QAbstractItemModelPrivate *p = model->d_func();
+        Q_ASSERT(p);
+        p->removePersistentIndexData(data);
+    }
+    delete data;
+}
+
+/*!
+  \class QPersistentModelIndex
+
+  \brief The QPersistentModelIndex class is used to locate data in a data model.
+
+  \ingroup model-view
+
+  A QPersistentModelIndex is a model index that can be stored by an
+  application, and later used to access information in a model.
+  Unlike the QModelIndex class, it is safe to store a
+  QPersistentModelIndex since the model will ensure that references
+  to items will continue to be valid as long as they can be accessed
+  by the model.
+
+  It is good practice to check that persistent model indexes are valid
+  before using them.
+
+  \sa {Model/View Programming}, QModelIndex, QAbstractItemModel
+*/
+
+
+/*!
+  \fn QPersistentModelIndex::QPersistentModelIndex()
+
+  \internal
+*/
+
+QPersistentModelIndex::QPersistentModelIndex()
+    : d(0)
+{
+}
+
+/*!
+  \fn QPersistentModelIndex::QPersistentModelIndex(const QPersistentModelIndex &other)
+
+  Creates a new QPersistentModelIndex that is a copy of the \a other persistent
+  model index.
+*/
+
+QPersistentModelIndex::QPersistentModelIndex(const QPersistentModelIndex &other)
+    : d(other.d)
+{
+    if (d) d->ref.ref();
+}
+
+/*!
+    Creates a new QPersistentModelIndex that is a copy of the model \a index.
+*/
+
+QPersistentModelIndex::QPersistentModelIndex(const QModelIndex &index)
+    : d(0)
+{
+    if (index.isValid()) {
+        d = QPersistentModelIndexData::create(index);
+        d->ref.ref();
+    }
+}
+
+/*!
+    \fn QPersistentModelIndex::~QPersistentModelIndex()
+
+    \internal
+*/
+
+QPersistentModelIndex::~QPersistentModelIndex()
+{
+    if (d && !d->ref.deref()) {
+        QPersistentModelIndexData::destroy(d);
+        d = 0;
+    }
+}
+
+/*!
+  Returns true if this persistent model index is equal to the \a other
+  persistent model index; otherwise returns false.
+
+  All values in the persistent model index are used when comparing
+  with another persistent model index.
+*/
+
+bool QPersistentModelIndex::operator==(const QPersistentModelIndex &other) const
+{
+    if (d && other.d)
+        return d->index == other.d->index;
+    return d == other.d;
+}
+
+/*!
+    \since 4.1
+
+    Returns true if this persistent model index is smaller than the \a other
+    persistent model index; otherwise returns false.
+
+    All values in the persistent model index are used when comparing
+    with another persistent model index.
+*/
+
+bool QPersistentModelIndex::operator<(const QPersistentModelIndex &other) const
+{
+    if (d && other.d)
+        return d->index < other.d->index;
+
+    return d < other.d;
+}
+
+/*!
+    \fn bool QPersistentModelIndex::operator!=(const QPersistentModelIndex &other) const
+    \since 4.2
+
+    Returns true if this persistent model index is not equal to the \a
+    other persistent model index; otherwise returns false.
+*/
+
+/*!
+    Sets the persistent model index to refer to the same item in a model
+    as the \a other persistent model index.
+*/
+
+QPersistentModelIndex &QPersistentModelIndex::operator=(const QPersistentModelIndex &other)
+{
+    if (d == other.d)
+        return *this;
+    if (d && !d->ref.deref())
+        QPersistentModelIndexData::destroy(d);
+    d = other.d;
+    if (d) d->ref.ref();
+    return *this;
+}
+
+/*!
+    Sets the persistent model index to refer to the same item in a model
+    as the \a other model index.
+*/
+
+QPersistentModelIndex &QPersistentModelIndex::operator=(const QModelIndex &other)
+{
+    if (d && !d->ref.deref())
+        QPersistentModelIndexData::destroy(d);
+    if (other.isValid()) {
+        d = QPersistentModelIndexData::create(other);
+        if (d) d->ref.ref();
+    } else {
+        d = 0;
+    }
+    return *this;
+}
+
+/*!
+  \fn QPersistentModelIndex::operator const QModelIndex&() const
+
+  Cast operator that returns a const QModelIndex&.
+*/
+
+QPersistentModelIndex::operator const QModelIndex&() const
+{
+    static const QModelIndex invalid;
+    if (d)
+        return d->index;
+    return invalid;
+}
+
+/*!
+    \fn bool QPersistentModelIndex::operator==(const QModelIndex &other) const
+
+    Returns true if this persistent model index refers to the same location as
+    the \a other model index; otherwise returns false.
+    Note that all values in the persistent model index are used when comparing
+    with another model index.
+*/
+
+bool QPersistentModelIndex::operator==(const QModelIndex &other) const
+{
+    if (d)
+        return d->index == other;
+    return !other.isValid();
+}
+
+/*!
+    \fn bool QPersistentModelIndex::operator!=(const QModelIndex &other) const
+
+    Returns true if this persistent model index does not refer to the same
+    location as the \a other model index; otherwise returns false.
+*/
+
+bool QPersistentModelIndex::operator!=(const QModelIndex &other) const
+{
+    if (d)
+        return d->index != other;
+    return other.isValid();
+}
+
+/*!
+    \fn int QPersistentModelIndex::row() const
+
+    Returns the row this persistent model index refers to.
+*/
+
+int QPersistentModelIndex::row() const
+{
+    if (d)
+        return d->index.row();
+    return -1;
+}
+
+/*!
+    \fn int QPersistentModelIndex::column() const
+
+    Returns the column this persistent model index refers to.
+*/
+
+int QPersistentModelIndex::column() const
+{
+    if (d)
+        return d->index.column();
+    return -1;
+}
+
+/*!
+    \fn void *QPersistentModelIndex::internalPointer() const
+
+    \internal
+
+    Returns a \c{void} \c{*} pointer used by the model to associate the index with
+    the internal data structure.
+*/
+
+void *QPersistentModelIndex::internalPointer() const
+{
+    if (d)
+        return d->index.internalPointer();
+    return 0;
+}
+
+/*!
+    \fn void *QPersistentModelIndex::internalId() const
+
+    \internal
+
+    Returns a \c{qint64} used by the model to associate the index with
+    the internal data structure.
+*/
+
+qint64 QPersistentModelIndex::internalId() const
+{
+    if (d)
+        return d->index.internalId();
+    return 0;
+}
+
+/*!
+  Returns the parent QModelIndex for this persistent index, or
+  QModelIndex() if it has no parent.
+
+  \sa child() sibling() model()
+*/
+QModelIndex QPersistentModelIndex::parent() const
+{
+    if (d)
+        return d->index.parent();
+    return QModelIndex();
+}
+
+/*!
+  Returns the sibling at \a row and \a column or an invalid
+  QModelIndex if there is no sibling at this position.
+
+  \sa parent() child()
+*/
+
+QModelIndex QPersistentModelIndex::sibling(int row, int column) const
+{
+    if (d)
+        return d->index.sibling(row, column);
+    return QModelIndex();
+}
+
+/*!
+  Returns the child of the model index that is stored in the given
+  \a row and \a column.
+
+  \sa parent() sibling()
+*/
+
+QModelIndex QPersistentModelIndex::child(int row, int column) const
+{
+    if (d)
+        return d->index.child(row, column);
+    return QModelIndex();
+}
+
+/*!
+  Returns the data for the given \a role for the item referred to by the index.
+
+  \sa Qt::ItemDataRole, QAbstractItemModel::setData()
+*/
+QVariant QPersistentModelIndex::data(int role) const
+{
+    if (d)
+        return d->index.data(role);
+    return QVariant();
+}
+
+/*!
+  \since 4.2
+
+  Returns the flags for the item referred to by the index.
+*/
+Qt::ItemFlags QPersistentModelIndex::flags() const
+{
+    if (d)
+        return d->index.flags();
+    return 0;
+}
+
+/*!
+  Returns the model that the index belongs to.
+*/
+const QAbstractItemModel *QPersistentModelIndex::model() const
+{
+    if (d)
+        return d->index.model();
+    return 0;
+}
+
+/*!
+    \fn bool QPersistentModelIndex::isValid() const
+
+    Returns true if this persistent model index is valid; otherwise returns
+    false.
+    A valid index belongs to a model, and has non-negative row and column numbers.
+
+    \sa model(), row(), column()
+*/
+
+bool QPersistentModelIndex::isValid() const
+{
+    return d && d->index.isValid();
+}
+
+#ifndef QT_NO_DEBUG_STREAM
+QDebug operator<<(QDebug dbg, const QModelIndex &idx)
+{
+#ifndef Q_BROKEN_DEBUG_STREAM
+    dbg.nospace() << "QModelIndex(" << idx.row() << "," << idx.column()
+                  << "," << idx.internalPointer() << "," << idx.model() << ")";
+    return dbg.space();
+#else
+    qWarning("This compiler doesn't support streaming QModelIndex to QDebug");
+    return dbg;
+    Q_UNUSED(idx);
+#endif
+}
+
+QDebug operator<<(QDebug dbg, const QPersistentModelIndex &idx)
+{
+    if (idx.d)
+        dbg << idx.d->index;
+    else
+        dbg << QModelIndex();
+    return dbg;
+}
+#endif
+
+class QEmptyItemModel : public QAbstractItemModel
+{
+public:
+    explicit QEmptyItemModel(QObject *parent = 0) : QAbstractItemModel(parent) {}
+    QModelIndex index(int, int, const QModelIndex &) const { return QModelIndex(); }
+    QModelIndex parent(const QModelIndex &) const { return QModelIndex(); }
+    int rowCount(const QModelIndex &) const { return 0; }
+    int columnCount(const QModelIndex &) const { return 0; }
+    bool hasChildren(const QModelIndex &) const { return false; }
+    QVariant data(const QModelIndex &, int) const { return QVariant(); }
+};
+
+Q_GLOBAL_STATIC(QEmptyItemModel, qEmptyModel)
+
+QAbstractItemModel *QAbstractItemModelPrivate::staticEmptyModel()
+{
+    return qEmptyModel();
+}
+
+void QAbstractItemModelPrivate::removePersistentIndexData(QPersistentModelIndexData *data)
+{
+    if (data->index.isValid()) {
+        int removed = persistent.indexes.remove(data->index);
+        Q_ASSERT_X(removed == 1, "QPersistentModelIndex::~QPersistentModelIndex",
+                   "persistent model indexes corrupted"); //maybe the index was somewhat invalid?
+        // This assert may happen if the model use changePersistentIndex in a way that could result on two
+        // QPersistentModelIndex pointing to the same index.
+        Q_UNUSED(removed);
+    }
+    // make sure our optimization still works
+    for (int i = persistent.moved.count() - 1; i >= 0; --i) {
+        int idx = persistent.moved[i].indexOf(data);
+        if (idx >= 0)
+            persistent.moved[i].remove(idx);
+    }
+    // update the references to invalidated persistent indexes
+    for (int i = persistent.invalidated.count() - 1; i >= 0; --i) {
+        int idx = persistent.invalidated[i].indexOf(data);
+        if (idx >= 0)
+            persistent.invalidated[i].remove(idx);
+    }
+
+}
+
+void QAbstractItemModelPrivate::rowsAboutToBeInserted(const QModelIndex &parent,
+                                                      int first, int last)
+{
+    Q_Q(QAbstractItemModel);
+    Q_UNUSED(last);
+    QVector<QPersistentModelIndexData *> persistent_moved;
+    if (first < q->rowCount(parent)) {
+        for (QHash<QModelIndex, QPersistentModelIndexData *>::const_iterator it = persistent.indexes.constBegin();
+             it != persistent.indexes.constEnd(); ++it) {
+            QPersistentModelIndexData *data = *it;
+            const QModelIndex &index = data->index;
+            if (index.row() >= first && index.isValid() && index.parent() == parent) {
+                persistent_moved.append(data);
+            }
+        }
+    }
+    persistent.moved.push(persistent_moved);
+}
+
+void QAbstractItemModelPrivate::rowsInserted(const QModelIndex &parent,
+                                             int first, int last)
+{
+    QVector<QPersistentModelIndexData *> persistent_moved = persistent.moved.pop();
+    int count = (last - first) + 1; // it is important to only use the delta, because the change could be nested
+    for (QVector<QPersistentModelIndexData *>::const_iterator it = persistent_moved.constBegin();
+         it != persistent_moved.constEnd(); ++it) {
+        QPersistentModelIndexData *data = *it;
+        QModelIndex old = data->index;
+        persistent.indexes.erase(persistent.indexes.find(old));
+        data->index = q_func()->index(old.row() + count, old.column(), parent);
+        if (data->index.isValid()) {
+            persistent.insertMultiAtEnd(data->index, data);
+        } else {
+            qWarning() << "QAbstractItemModel::endInsertRows:  Invalid index (" << old.row() + count << "," << old.column() << ") in model" << q_func();
+        }
+    }
+}
+
+void QAbstractItemModelPrivate::rowsAboutToBeRemoved(const QModelIndex &parent,
+                                                     int first, int last)
+{
+    QVector<QPersistentModelIndexData *>  persistent_moved;
+    QVector<QPersistentModelIndexData *>  persistent_invalidated;
+    // find the persistent indexes that are affected by the change, either by being in the removed subtree
+    // or by being on the same level and below the removed rows
+    for (QHash<QModelIndex, QPersistentModelIndexData *>::const_iterator it = persistent.indexes.constBegin();
+         it != persistent.indexes.constEnd(); ++it) {
+        QPersistentModelIndexData *data = *it;
+        bool level_changed = false;
+        QModelIndex current = data->index;
+        while (current.isValid()) {
+            QModelIndex current_parent = current.parent();
+            if (current_parent == parent) { // on the same level as the change
+                if (!level_changed && current.row() > last) // below the removed rows
+                    persistent_moved.append(data);
+                else if (current.row() <= last && current.row() >= first) // in the removed subtree
+                    persistent_invalidated.append(data);
+                break;
+            }
+            current = current_parent;
+            level_changed = true;
+        }
+    }
+
+    persistent.moved.push(persistent_moved);
+    persistent.invalidated.push(persistent_invalidated);
+}
+
+void QAbstractItemModelPrivate::rowsRemoved(const QModelIndex &parent,
+                                            int first, int last)
+{
+    QVector<QPersistentModelIndexData *> persistent_moved = persistent.moved.pop();
+    int count = (last - first) + 1; // it is important to only use the delta, because the change could be nested
+    for (QVector<QPersistentModelIndexData *>::const_iterator it = persistent_moved.constBegin();
+         it != persistent_moved.constEnd(); ++it) {
+        QPersistentModelIndexData *data = *it;
+        QModelIndex old = data->index;
+        persistent.indexes.erase(persistent.indexes.find(old));
+        data->index = q_func()->index(old.row() - count, old.column(), parent);
+        if (data->index.isValid()) {
+            persistent.insertMultiAtEnd(data->index, data);
+        } else {
+            qWarning() << "QAbstractItemModel::endRemoveRows:  Invalid index (" << old.row() - count << "," << old.column() << ") in model" << q_func();
+        }
+    }
+    QVector<QPersistentModelIndexData *> persistent_invalidated = persistent.invalidated.pop();
+    for (QVector<QPersistentModelIndexData *>::const_iterator it = persistent_invalidated.constBegin();
+         it != persistent_invalidated.constEnd(); ++it) {
+        QPersistentModelIndexData *data = *it;
+        persistent.indexes.erase(persistent.indexes.find(data->index));
+        data->index = QModelIndex();
+        data->model = 0;
+    }
+}
+
+void QAbstractItemModelPrivate::columnsAboutToBeInserted(const QModelIndex &parent,
+                                                         int first, int last)
+{
+    Q_Q(QAbstractItemModel);
+    Q_UNUSED(last);
+    QVector<QPersistentModelIndexData *> persistent_moved;
+    if (first < q->columnCount(parent)) {
+        for (QHash<QModelIndex, QPersistentModelIndexData *>::const_iterator it = persistent.indexes.constBegin();
+             it != persistent.indexes.constEnd(); ++it) {
+            QPersistentModelIndexData *data = *it;
+            const QModelIndex &index = data->index;
+            if (index.column() >= first && index.isValid() && index.parent() == parent)
+                persistent_moved.append(data);
+        }
+    }
+    persistent.moved.push(persistent_moved);
+}
+
+void QAbstractItemModelPrivate::columnsInserted(const QModelIndex &parent,
+                                                int first, int last)
+{
+    QVector<QPersistentModelIndexData *> persistent_moved = persistent.moved.pop();
+    int count = (last - first) + 1; // it is important to only use the delta, because the change could be nested
+    for (QVector<QPersistentModelIndexData *>::const_iterator it = persistent_moved.constBegin();
+         it != persistent_moved.constEnd(); ++it) {
+        QPersistentModelIndexData *data = *it;
+        QModelIndex old = data->index;
+        persistent.indexes.erase(persistent.indexes.find(old));
+        data->index = q_func()->index(old.row(), old.column() + count, parent);
+        if (data->index.isValid()) {
+            persistent.insertMultiAtEnd(data->index, data);
+        } else {
+            qWarning() << "QAbstractItemModel::endInsertColumns:  Invalid index (" << old.row() << "," << old.column() + count << ") in model" << q_func();
+        }
+     }
+}
+
+void QAbstractItemModelPrivate::columnsAboutToBeRemoved(const QModelIndex &parent,
+                                                        int first, int last)
+{
+    QVector<QPersistentModelIndexData *> persistent_moved;
+    QVector<QPersistentModelIndexData *> persistent_invalidated;
+    // find the persistent indexes that are affected by the change, either by being in the removed subtree
+    // or by being on the same level and to the right of the removed columns
+    for (QHash<QModelIndex, QPersistentModelIndexData *>::const_iterator it = persistent.indexes.constBegin();
+         it != persistent.indexes.constEnd(); ++it) {
+        QPersistentModelIndexData *data = *it;
+        bool level_changed = false;
+        QModelIndex current = data->index;
+        while (current.isValid()) {
+            QModelIndex current_parent = current.parent();
+            if (current_parent == parent) { // on the same level as the change
+                if (!level_changed && current.column() > last) // right of the removed columns
+                    persistent_moved.append(data);
+                else if (current.column() <= last && current.column() >= first) // in the removed subtree
+                    persistent_invalidated.append(data);
+                break;
+            }
+            current = current_parent;
+            level_changed = true;
+        }
+    }
+
+    persistent.moved.push(persistent_moved);
+    persistent.invalidated.push(persistent_invalidated);
+
+}
+
+void QAbstractItemModelPrivate::columnsRemoved(const QModelIndex &parent,
+                                               int first, int last)
+{
+    QVector<QPersistentModelIndexData *> persistent_moved = persistent.moved.pop();
+    int count = (last - first) + 1; // it is important to only use the delta, because the change could be nested
+    for (QVector<QPersistentModelIndexData *>::const_iterator it = persistent_moved.constBegin();
+         it != persistent_moved.constEnd(); ++it) {
+        QPersistentModelIndexData *data = *it;
+        QModelIndex old = data->index;
+        persistent.indexes.erase(persistent.indexes.find(old));
+        data->index = q_func()->index(old.row(), old.column() - count, parent);
+        if (data->index.isValid()) {
+            persistent.insertMultiAtEnd(data->index, data);
+        } else {
+            qWarning() << "QAbstractItemModel::endRemoveColumns:  Invalid index (" << old.row() << "," << old.column() - count << ") in model" << q_func();
+        }
+    }
+    QVector<QPersistentModelIndexData *> persistent_invalidated = persistent.invalidated.pop();
+    for (QVector<QPersistentModelIndexData *>::const_iterator it = persistent_invalidated.constBegin();
+         it != persistent_invalidated.constEnd(); ++it) {
+        QPersistentModelIndexData *data = *it;
+        persistent.indexes.erase(persistent.indexes.find(data->index));
+        data->index = QModelIndex();
+        data->model = 0;
+    }
+}
+
+/*!
+    \class QModelIndex
+
+    \brief The QModelIndex class is used to locate data in a data model.
+
+    \ingroup model-view
+    \mainclass
+
+    This class is used as an index into item models derived from
+    QAbstractItemModel. The index is used by item views, delegates, and
+    selection models to locate an item in the model.
+
+    New QModelIndex objects are created by the model using the
+    QAbstractItemModel::createIndex() function. An \e invalid model index
+    can be constructed with the QModelIndex constructor. Invalid indexes are
+    often used as parent indexes when referring to top-level items in a model.
+
+    Model indexes refer to items in models, and contain all the information
+    required to specify their locations in those models. Each index is located
+    in a given row and column, and may have a parent index; use row(), column(),
+    and parent() to obtain this information. Each top-level item in a model is
+    represented by a model index that does not have a parent index - in this
+    case, parent() will return an invalid model index, equivalent to an index
+    constructed with the zero argument form of the QModelIndex() constructor.
+
+    To obtain a model index that refers to an existing item in a model, call
+    QAbstractItemModel::index() with the required row and column
+    values, and the model index of the parent. When referring to
+    top-level items in a model, supply QModelIndex() as the parent index.
+
+    The model() function returns the model that the index references as a
+    QAbstractItemModel.
+    The child() function is used to examine the items held beneath the index
+    in the model.
+    The sibling() function allows you to traverse items in the model on the
+    same level as the index.
+
+    \note Model indexes should be used immediately and then discarded. You
+    should not rely on indexes to remain valid after calling model functions
+    that change the structure of the model or delete items. If you need to
+    keep a model index over time use a QPersistentModelIndex.
+
+    \sa \link model-view-programming.html Model/View Programming\endlink QPersistentModelIndex QAbstractItemModel
+*/
+
+/*!
+    \fn QModelIndex::QModelIndex()
+
+    Creates a new empty model index.
+    This type of model index is used to indicate
+    that the position in the model is invalid.
+
+    \sa isValid() QAbstractItemModel
+*/
+
+/*!
+    \fn QModelIndex::QModelIndex(int row, int column, void *data, const QAbstractItemModel *model)
+
+    \internal
+
+    Creates a new model index at the given \a row and \a column,
+    pointing to some \a data.
+*/
+
+/*!
+    \fn QModelIndex::QModelIndex(const QModelIndex &other)
+
+    Creates a new model index that is a copy of the \a other model
+    index.
+*/
+
+/*!
+    \fn QModelIndex::~QModelIndex()
+
+    Destroys the model index.
+*/
+
+/*!
+    \fn int QModelIndex::row() const
+
+    Returns the row this model index refers to.
+*/
+
+
+/*!
+    \fn int QModelIndex::column() const
+
+    Returns the column this model index refers to.
+*/
+
+
+/*!
+    \fn void *QModelIndex::internalPointer() const
+
+    Returns a \c{void} \c{*} pointer used by the model to associate
+    the index with the internal data structure.
+
+    \sa QAbstractItemModel::createIndex()
+*/
+
+/*!
+    \fn void *QModelIndex::internalId() const
+
+    Returns a \c{qint64} used by the model to associate
+    the index with the internal data structure.
+
+    \sa QAbstractItemModel::createIndex()
+*/
+
+/*!
+    \fn bool QModelIndex::isValid() const
+
+    Returns true if this model index is valid; otherwise returns false.
+    A valid index belongs to a model, and has non-negative row and column numbers.
+
+    \sa model(), row(), column()
+*/
+
+/*!
+    \fn const QAbstractItemModel *QModelIndex::model() const
+
+    Returns a pointer to the model containing the item that this index
+    refers to.
+
+    You receive a const pointer to the model because calls to
+    non-const functions of the model might invalidate the model index
+    - and possibly crash your application.
+*/
+
+/*!
+    \fn QModelIndex QModelIndex::sibling(int row, int column) const
+
+    Returns the sibling at \a row and \a column or an invalid
+    QModelIndex if there is no sibling at this position.
+
+    \sa parent() child()
+*/
+
+/*!
+    \fn QModelIndex QModelIndex::child(int row, int column) const
+
+    Returns the child of the model index that is stored in the given
+    \a row and \a column.
+
+    \sa parent() sibling()
+*/
+
+/*!
+    \fn QVariant QModelIndex::data(int role) const
+
+    Returns the data for the given \a role for the item referred to by the index.
+*/
+
+/*!
+    \fn Qt::ItemFlags QModelIndex::flags() const
+    \since 4.2
+
+    Returns the flags for the item referred to by the index.
+*/
+
+/*!
+    \fn bool QModelIndex::operator==(const QModelIndex &other) const
+
+    Returns true if this model index refers to the same location as
+    the \a other model index; otherwise returns false.
+    Note that all values in the model index are used when comparing
+    with another model index.
+*/
+
+
+/*!
+    \fn bool QModelIndex::operator!=(const QModelIndex &other) const
+
+    Returns true if this model index does not refer to the same
+    location as the \a other model index; otherwise returns false.
+*/
+
+
+/*!
+  \fn QModelIndex QModelIndex::parent() const
+
+  Returns the parent of the model index, or QModelIndex() if it has no
+  parent.
+
+  \sa child() sibling() model()
+*/
+
+/*!
+    \class QAbstractItemModel
+
+    \brief The QAbstractItemModel class provides the abstract interface for
+    item model classes.
+
+    \ingroup model-view
+    \mainclass
+
+    The QAbstractItemModel class defines the standard interface that item
+    models must use to be able to interoperate with other components in the
+    model/view architecture. It is not supposed to be instantiated directly.
+    Instead, you should subclass it to create new models.
+
+    The QAbstractItemModel class is one of the \l{Model/View Classes}
+    and is part of Qt's \l{Model/View Programming}{model/view framework}.
+
+    If you need a model to use with a QListView or a QTableView, you should
+    consider subclassing QAbstractListModel or QAbstractTableModel instead of
+    this class.
+
+    The underlying data model is exposed to views and delegates as a hierarchy
+    of tables. If you do not make use of the hierarchy, then the model is a
+    simple table of rows and columns. Each item has a unique index specified by
+    a QModelIndex.
+
+    \img modelindex-no-parent.png
+
+    Every item of data that can be accessed via a model has an associated model
+    index. You can obtain this model index using the index() function. Each
+    index may have a sibling() index; child items have a parent() index.
+
+    Each item has a number of data elements associated with it and they can be
+    retrieved by specifying a role (see \l Qt::ItemDataRole) to the model's
+    data() function. Data for all available roles can be obtained at the same
+    time using the itemData() function.
+
+    Data for each role is set using a particular \l Qt::ItemDataRole. Data for
+    individual roles are set individually with setData(), or they can be set
+    for all roles with setItemData().
+
+    Items can be queried with flags() (see \l Qt::ItemFlag) to see if they can
+    be selected, dragged, or manipulated in other ways.
+
+    If an item has child objects, hasChildren() returns true for the
+    corresponding index.
+
+    The model has a rowCount() and a columnCount() for each level of the
+    hierarchy. Rows and columns can be inserted and removed with insertRows(),
+    insertColumns(), removeRows(), and removeColumns().
+
+    The model emits signals to indicate changes. For example, dataChanged() is
+    emitted whenever items of data made available by the model are changed.
+    Changes to the headers supplied by the model cause headerDataChanged() to
+    be emitted. If the structure of the underlying data changes, the model can
+    emit layoutChanged() to indicate to any attached views that they should
+    redisplay any items shown, taking the new structure into account.
+
+    The items available through the model can be searched for particular data
+    using the match() function.
+
+    To sort the model, you can use sort().
+
+
+    \section1 Subclassing
+
+    \note Some general guidelines for subclassing models are available in the
+    \l{Model Subclassing Reference}.
+
+    When subclassing QAbstractItemModel, at the very least you must implement
+    index(), parent(), rowCount(), columnCount(), and data(). These functions
+    are used in all read-only models, and form the basis of editable models.
+
+    You can also reimplement hasChildren() to provide special behavior for
+    models where the implementation of rowCount() is expensive. This makes it
+    possible for models to restrict the amount of data requested by views, and
+    can be used as a way to implement lazy population of model data.
+
+    To enable editing in your model, you must also implement setData(), and
+    reimplement flags() to ensure that \c ItemIsEditable is returned.  You can
+    also reimplement headerData() and setHeaderData() to control the way the
+    headers for your model are presented.
+
+    The dataChanged() and headerDataChanged() signals must be emitted
+    explicitly when reimplementing the setData() and setHeaderData() functions,
+    respectively.
+
+    Custom models need to create model indexes for other components to use. To
+    do this, call createIndex() with suitable row and column numbers for the
+    item, and an identifier for it, either as a pointer or as an integer value.
+    The combination of these values must be unique for each item. Custom models
+    typically use these unique identifiers in other reimplemented functions to
+    retrieve item data and access information about the item's parents and
+    children. See the \l{Simple Tree Model Example} for more information about
+    unique identifiers.
+
+    It is not necessary to support every role defined in Qt::ItemDataRole.
+    Depending on the type of data contained within a model, it may only be
+    useful to implement the data() function to return valid information for
+    some of the more common roles. Most models provide at least a textual
+    representation of item data for the Qt::DisplayRole, and well-behaved
+    models should also provide valid information for the Qt::ToolTipRole and
+    Qt::WhatsThisRole. Supporting these roles enables models to be used with
+    standard Qt views. However, for some models that handle highly-specialized
+    data, it may be appropriate to provide data only for user-defined roles.
+
+    Models that provide interfaces to resizable data structures can provide
+    implementations of insertRows(), removeRows(), insertColumns(),and
+    removeColumns(). When implementing these functions, it is important to
+    notify any connected views about changes to the model's dimensions both
+    \e before and \e after they occur:
+
+    \list
+        \o An insertRows() implementation must call beginInsertRows() \e before
+           inserting new rows into the data structure, and endInsertRows()
+           \e{immediately afterwards}.
+        \o An insertColumns() implementation must call beginInsertColumns()
+           \e before inserting new columns into the data structure, and
+           endInsertColumns() \e{immediately afterwards}.
+        \o A removeRows() implementation must call beginRemoveRows() \e before
+           the rows are removed from the data structure, and endRemoveRows()
+           \e{immediately afterwards}.
+        \o A removeColumns() implementation must call beginRemoveColumns()
+           \e before the columns are removed from the data structure, and
+           endRemoveColumns() \e{immediately afterwards}.
+    \endlist
+
+    The \e private signals that these functions emit give attached components
+    the chance to take action before any data becomes unavailable. The
+    encapsulation of the insert and remove operations with these begin and end
+    functions also enables the model to manage \l{QPersistentModelIndex}
+    {persistent model indexes} correctly. \bold{If you want selections to be
+    handled properly, you must ensure that you call these functions.} If you
+    insert or remove an item with children, you do not need to call these
+    functions for the child items. In other words, the parent item will take
+    care of its child items.
+
+    To create models that populate incrementally, you can reimplement
+    fetchMore() and canFetchMore(). If the reimplementation of fetchMore() adds
+    rows to the model, \l{QAbstractItemModel::}{beginInsertRows()} and
+    \l{QAbstractItemModel::}{endInsertRows()} must be called.
+
+    \sa {Model Classes}, {Model Subclassing Reference}, QModelIndex,
+        QAbstractItemView, {Using Drag and Drop with Item Views},
+        {Simple DOM Model Example},
+        {Simple Tree Model Example}, {Editable Tree Model Example},
+        {Fetch More Example}
+*/
+
+/*!
+    \fn QModelIndex QAbstractItemModel::index(int row, int column, const QModelIndex &parent) const = 0
+
+    Returns the index of the item in the model specified by the given \a row,
+    \a column and \a parent index.
+
+    When reimplementing this function in a subclass, call createIndex() to generate
+    model indexes that other components can use to refer to items in your model.
+
+    \sa createIndex()
+*/
+
+/*!
+    \fn bool QAbstractItemModel::insertColumn(int column, const QModelIndex &parent)
+
+    Inserts a single column before the given \a column in the child items of
+    the \a parent specified. Returns true if the column is inserted; otherwise
+    returns false.
+
+    \sa insertColumns() insertRow() removeColumn()
+*/
+
+/*!
+    \fn bool QAbstractItemModel::insertRow(int row, const QModelIndex &parent)
+
+    Inserts a single row before the given \a row in the child items of the
+    \a parent specified. Returns true if the row is inserted; otherwise
+    returns false.
+
+    \sa insertRows() insertColumn() removeRow()
+*/
+
+/*!
+    \fn QObject *QAbstractItemModel::parent() const
+    \internal
+*/
+
+/*!
+    \fn QModelIndex QAbstractItemModel::parent(const QModelIndex &index) const = 0
+
+    Returns the parent of the model item with the given \a index, or QModelIndex()
+    if it has no parent.
+
+    A common convention used in models that expose tree data structures is that
+    only items in the first column have children. For that case, when reimplementing
+    this function in a subclass the column of the returned QModelIndex would be 0.
+
+    \note When reimplementing this function in a subclass, be careful to avoid
+    calling QModelIndex member functions, such as QModelIndex::parent(), since
+    indexes belonging to your model will simply call your implementation, leading
+    to infinite recursion.
+
+    \sa createIndex()
+*/
+
+/*!
+    \fn bool QAbstractItemModel::removeColumn(int column, const QModelIndex &parent)
+
+    Removes the given \a column from the child items of the \a parent specified.
+    Returns true if the column is removed; otherwise returns false.
+
+    \sa removeColumns(), removeRow(), insertColumn()
+*/
+
+/*!
+    \fn bool QAbstractItemModel::removeRow(int row, const QModelIndex &parent)
+
+    Removes the given \a row from the child items of the \a parent specified.
+    Returns true if the row is removed; otherwise returns false.
+
+    The removeRow() is a convenience function that calls removeRows().
+    The QAbstractItemModel implementation of removeRows does nothing.
+
+    \sa removeRows(), removeColumn(), insertRow()
+*/
+
+/*!
+    \fn void QAbstractItemModel::headerDataChanged(Qt::Orientation orientation, int first, int last)
+
+    This signal is emitted whenever a header is changed. The \a orientation
+    indicates whether the horizontal or vertical header has changed. The
+    sections in the header from the \a first to the \a last need to be updated.
+
+    Note that this signal must be emitted explicitly when
+    reimplementing the setHeaderData() function.
+
+    If you are changing the number of columns or rows you don't need
+    to emit this signal, but use the begin/end functions (see the
+    section on subclassing in the QAbstractItemModel class description
+    for details).
+
+    \sa headerData(), setHeaderData(), dataChanged()
+*/
+
+/*!
+    \fn void QAbstractItemModel::layoutAboutToBeChanged()
+    \since 4.2
+
+    This signal is emitted just before the layout of a model is changed.
+    Components connected to this signal use it to adapt to changes
+    in the model's layout.
+
+    Subclasses should update any persistent model indexes after emitting
+    layoutAboutToBeChanged().
+
+    \sa layoutChanged(), changePersistentIndex()
+*/
+
+/*!
+    \fn void QAbstractItemModel::layoutChanged()
+
+    This signal is emitted whenever the layout of items exposed by the model
+    has changed; for example, when the model has been sorted. When this signal is
+    received by a view, it should update the layout of items to reflect this
+    change.
+
+    When subclassing QAbstractItemModel or QAbstractProxyModel, ensure that
+    you emit layoutAboutToBeChanged() before changing the order of items or
+    altering the structure of the data you expose to views, and emit
+    layoutChanged() after changing the layout.
+
+    Subclasses should update any persistent model indexes before
+    emitting layoutChanged().
+
+    \sa layoutAboutToBeChanged(), dataChanged(), headerDataChanged(), reset(), changePersistentIndex()
+*/
+
+/*!
+    Constructs an abstract item model with the given \a parent.
+*/
+QAbstractItemModel::QAbstractItemModel(QObject *parent)
+    : QObject(*new QAbstractItemModelPrivate, parent)
+{
+}
+
+/*!
+  \internal
+*/
+QAbstractItemModel::QAbstractItemModel(QAbstractItemModelPrivate &dd, QObject *parent)
+    : QObject(dd, parent)
+{
+}
+
+/*!
+    Destroys the abstract item model.
+*/
+QAbstractItemModel::~QAbstractItemModel()
+{
+    d_func()->invalidatePersistentIndexes();
+}
+
+/*!
+    \fn QModelIndex QAbstractItemModel::sibling(int row, int column, const QModelIndex &index) const
+
+    Returns the sibling at \a row and \a column for the item at \a index, or
+    an invalid QModelIndex if there is no sibling at that location.
+
+    sibling() is just a convenience function that finds the item's parent, and
+    uses it to retrieve the index of the child item in the specified \a row
+    and \a column.
+
+    \sa index(), QModelIndex::row(), QModelIndex::column()
+*/
+
+
+/*!
+    \fn int QAbstractItemModel::rowCount(const QModelIndex &parent) const
+
+    Returns the number of rows under the given \a parent.   When the parent
+    is valid it means that rowCount is returning the number of children of parent.
+
+    \bold{Tip:} When implementing a table based model, rowCount() should return 0 when
+    the parent is valid.
+
+    \sa columnCount()
+*/
+
+/*!
+    \fn int QAbstractItemModel::columnCount(const QModelIndex &parent) const
+
+    Returns the number of columns for the children of the given \a parent.
+
+    In most subclasses, the number of columns is independent of the
+    \a parent. For example:
+
+    \snippet examples/itemviews/simpledommodel/dommodel.cpp 2
+
+    \bold{Tip:} When implementing a table based model, columnCount() should return 0 when
+    the parent is valid.
+
+    \sa rowCount()
+*/
+
+/*!
+    \fn void QAbstractItemModel::dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight)
+
+    This signal is emitted whenever the data in an existing item changes.
+
+    If the items are of the same parent, the affected ones are those between
+    \a topLeft and \a bottomRight inclusive. If the items do not have the same
+    parent, the behavior is undefined.
+
+    When reimplementing the setData() function, this signal must be emitted
+    explicitly.
+
+    \sa headerDataChanged(), setData(), layoutChanged()
+*/
+
+/*!
+    \fn void QAbstractItemModel::rowsInserted(const QModelIndex &parent, int start, int end)
+
+    This signal is emitted after rows have been inserted into the
+    model. The new items are those between \a start and \a end
+    inclusive, under the given \a parent item.
+
+    \bold{Note:} Components connected to this signal use it to adapt to changes
+    in the model's dimensions. It can only be emitted by the QAbstractItemModel
+    implementation, and cannot be explicitly emitted in subclass code.
+
+    \sa insertRows(), beginInsertRows()
+*/
+
+/*!
+    \fn void QAbstractItemModel::rowsAboutToBeInserted(const QModelIndex &parent, int start, int end)
+
+    This signal is emitted just before rows are inserted into the
+    model. The new items will be positioned between \a start and \a end
+    inclusive, under the given \a parent item.
+
+    \bold{Note:} Components connected to this signal use it to adapt to changes
+    in the model's dimensions. It can only be emitted by the QAbstractItemModel
+    implementation, and cannot be explicitly emitted in subclass code.
+
+    \sa insertRows(), beginInsertRows()
+*/
+
+/*!
+    \fn void QAbstractItemModel::rowsRemoved(const QModelIndex &parent, int start, int end)
+
+    This signal is emitted after rows have been removed from the
+    model. The removed items are those between \a start and \a end
+    inclusive, under the given \a parent item.
+
+    \bold{Note:} Components connected to this signal use it to adapt to changes
+    in the model's dimensions. It can only be emitted by the QAbstractItemModel
+    implementation, and cannot be explicitly emitted in subclass code.
+
+    \sa removeRows(), beginRemoveRows()
+*/
+
+/*!
+    \fn void QAbstractItemModel::rowsAboutToBeRemoved(const QModelIndex &parent, int start, int end)
+
+    This signal is emitted just before rows are removed from the
+    model. The items that will be removed are those between \a start and \a end
+    inclusive, under the given \a parent item.
+
+    \bold{Note:} Components connected to this signal use it to adapt to changes
+    in the model's dimensions. It can only be emitted by the QAbstractItemModel
+    implementation, and cannot be explicitly emitted in subclass code.
+
+    \sa removeRows(), beginRemoveRows()
+*/
+
+/*!
+    \fn void QAbstractItemModel::columnsInserted(const QModelIndex &parent, int start, int end)
+
+    This signal is emitted after columns have been inserted into the
+    model. The new items are those between \a start and \a end
+    inclusive, under the given \a parent item.
+
+    \bold{Note:} Components connected to this signal use it to adapt to changes
+    in the model's dimensions. It can only be emitted by the QAbstractItemModel
+    implementation, and cannot be explicitly emitted in subclass code.
+
+    \sa insertColumns(), beginInsertColumns()
+*/
+
+/*!
+    \fn void QAbstractItemModel::columnsAboutToBeInserted(const QModelIndex &parent, int start, int end)
+
+    This signal is emitted just before columns are inserted into the
+    model. The new items will be positioned between \a start and \a end
+    inclusive, under the given \a parent item.
+
+    \bold{Note:} Components connected to this signal use it to adapt to changes
+    in the model's dimensions. It can only be emitted by the QAbstractItemModel
+    implementation, and cannot be explicitly emitted in subclass code.
+
+    \sa insertColumns(), beginInsertColumns()
+*/
+
+/*!
+    \fn void QAbstractItemModel::columnsRemoved(const QModelIndex &parent, int start, int end)
+
+    This signal is emitted after columns have been removed from the
+    model. The removed items are those between \a start and \a end
+    inclusive, under the given \a parent item.
+
+    \bold{Note:} Components connected to this signal use it to adapt to changes
+    in the model's dimensions. It can only be emitted by the QAbstractItemModel
+    implementation, and cannot be explicitly emitted in subclass code.
+
+    \sa removeColumns(), beginRemoveColumns()
+*/
+
+/*!
+    \fn void QAbstractItemModel::columnsAboutToBeRemoved(const QModelIndex &parent, int start, int end)
+
+    This signal is emitted just before columns are removed
+    from the model. The items to be removed are those between \a start and
+    \a end inclusive, under the given \a parent item.
+
+    \bold{Note:} Components connected to this signal use it to adapt to changes
+    in the model's dimensions. It can only be emitted by the QAbstractItemModel
+    implementation, and cannot be explicitly emitted in subclass code.
+
+    \sa removeColumns(), beginRemoveColumns()
+*/
+
+/*!
+  Returns true if the model returns a valid QModelIndex for \a row and
+  \a column with \a parent, otherwise returns false.
+*/
+bool QAbstractItemModel::hasIndex(int row, int column, const QModelIndex &parent) const
+{
+    if (row < 0 || column < 0)
+        return false;
+    return row < rowCount(parent) && column < columnCount(parent);
+}
+
+
+/*!
+  Returns true if \a parent has any children; otherwise returns false.
+  Use rowCount() on the parent to find out the number of children.
+
+  \sa parent() index()
+*/
+bool QAbstractItemModel::hasChildren(const QModelIndex &parent) const
+{
+    return (rowCount(parent) > 0) && (columnCount(parent) > 0);
+}
+
+
+/*!
+    Returns a map with values for all predefined roles in the model
+    for the item at the given \a index.
+
+    Reimplemented this function if you want to extend the default behavior
+    of this function to include custom roles in the map.
+
+    \sa Qt::ItemDataRole, data()
+*/
+QMap<int, QVariant> QAbstractItemModel::itemData(const QModelIndex &index) const
+{
+    QMap<int, QVariant> roles;
+    for (int i = 0; i < Qt::UserRole; ++i) {
+        QVariant variantData = data(index, i);
+        if (variantData.type() != QVariant::Invalid)
+            roles.insert(i, variantData);
+    }
+    return roles;
+}
+
+/*!
+    Sets the \a role data for the item at \a index to \a value.
+    Returns true if successful; otherwise returns false.
+
+    The dataChanged() signal should be emitted if the data was successfully set.
+
+    The base class implementation returns false. This function and
+    data() must be reimplemented for editable models. Note that the
+    dataChanged() signal must be emitted explicitly when
+    reimplementing this function.
+
+    \sa Qt::ItemDataRole, data(), itemData()
+*/
+bool QAbstractItemModel::setData(const QModelIndex &index, const QVariant &value, int role)
+{
+    Q_UNUSED(index);
+    Q_UNUSED(value);
+    Q_UNUSED(role);
+    return false;
+}
+
+/*!
+    \fn QVariant QAbstractItemModel::data(const QModelIndex &index, int role) const = 0
+
+    Returns the data stored under the given \a role for the item referred to
+    by the \a index.
+
+    \note If you do not have a value to return, return an \bold invalid
+    QVariant() instead of returning 0.
+
+    \sa Qt::ItemDataRole, setData(), headerData()
+*/
+
+/*!
+    Sets the role data for the item at \a index to the associated value in
+    \a roles, for every Qt::ItemDataRole. Returns true if successful; otherwise
+    returns false.
+
+    Roles that are not in \a roles will not be modified.
+
+    \sa setData() data() itemData()
+*/
+bool QAbstractItemModel::setItemData(const QModelIndex &index, const QMap<int, QVariant> &roles)
+{
+    bool b = true;
+    for (QMap<int, QVariant>::ConstIterator it = roles.begin(); it != roles.end(); ++it)
+        b = b && setData(index, it.value(), it.key());
+    return b;
+}
+
+/*!
+    Returns a list of MIME types that can be used to describe a list of
+    model indexes.
+
+    \sa mimeData()
+*/
+QStringList QAbstractItemModel::mimeTypes() const
+{
+    QStringList types;
+    types << QLatin1String("application/x-qabstractitemmodeldatalist");
+    return types;
+}
+
+/*!
+    Returns an object that contains serialized items of data corresponding to the
+    list of \a indexes specified. The formats used to describe the encoded data
+    is obtained from the mimeTypes() function.
+
+    If the list of indexes is empty, or there are no supported MIME types,
+    0 is returned rather than a serialized empty list.
+
+    \sa mimeTypes(), dropMimeData()
+*/
+QMimeData *QAbstractItemModel::mimeData(const QModelIndexList &indexes) const
+{
+    if (indexes.count() <= 0)
+        return 0;
+    QStringList types = mimeTypes();
+    if (types.isEmpty())
+        return 0;
+    QMimeData *data = new QMimeData();
+    QString format = types.at(0);
+    QByteArray encoded;
+    QDataStream stream(&encoded, QIODevice::WriteOnly);
+    encodeData(indexes, stream);
+    data->setData(format, encoded);
+    return data;
+}
+
+/*!
+    Handles the \a data supplied by a drag and drop operation that ended with
+    the given \a action. Returns true if the data and action can be handled
+    by the model; otherwise returns false.
+
+    Although the specified \a row, \a column and \a parent indicate the location of
+    an item in the model where the operation ended, it is the responsibility of the
+    view to provide a suitable location for where the data should be inserted.
+
+    For instance, a drop action on an item in a QTreeView can result in new items
+    either being inserted as children of the item specified by \a row, \a column,
+    and \a parent, or as siblings of the item.
+
+    When row and column are -1 it means that it is up to the model to decide
+    where to place the data.  This can occur in a tree when data is dropped
+    on a parent.  Models will usually append the data to the parent in this case.
+
+    Returns true if the dropping was successful otherwise false.
+
+    \sa supportedDropActions(), {Using Drag and Drop with Item Views}
+*/
+bool QAbstractItemModel::dropMimeData(const QMimeData *data, Qt::DropAction action,
+                                      int row, int column, const QModelIndex &parent)
+{
+    // check if the action is supported
+    if (!data || !(action == Qt::CopyAction || action == Qt::MoveAction))
+        return false;
+    // check if the format is supported
+    QStringList types = mimeTypes();
+    if (types.isEmpty())
+        return false;
+    QString format = types.at(0);
+    if (!data->hasFormat(format))
+        return false;
+    if (row > rowCount(parent))
+        row = rowCount(parent);
+    if (row == -1)
+        row = rowCount(parent);
+    if (column == -1)
+        column = 0;
+    // decode and insert
+    QByteArray encoded = data->data(format);
+    QDataStream stream(&encoded, QIODevice::ReadOnly);
+    return decodeData(row, column, parent, stream);
+}
+
+/*!
+  \since 4.2
+
+  Returns the drop actions supported by this model.
+
+  The default implementation returns Qt::CopyAction. Reimplement this
+  function if you wish to support additional actions. Note that you
+  must also reimplement the dropMimeData() function to handle the
+  additional operations.
+
+  \sa dropMimeData(), Qt::DropActions, {Using Drag and Drop with Item
+  Views}
+*/
+Qt::DropActions QAbstractItemModel::supportedDropActions() const
+{
+    return Qt::CopyAction;
+}
+
+/*!
+  Returns the actions supported by the data in this model.
+
+  The default implementation returns supportedDropActions() unless
+  specific values have been set with setSupportedDragActions().
+
+  supportedDragActions() is used by QAbstractItemView::startDrag() as
+  the default values when a drag occurs.
+
+  \sa Qt::DropActions, {Using Drag and Drop with Item Views}
+*/
+Qt::DropActions QAbstractItemModel::supportedDragActions() const
+{
+    // ### Qt 5: make this virtual or these properties
+    Q_D(const QAbstractItemModel);
+    if (d->supportedDragActions != -1)
+        return d->supportedDragActions;
+    return supportedDropActions();
+}
+
+/*!
+    \since 4.2
+
+    Sets the supported drag \a actions for the items in the model.
+
+    \sa supportedDragActions(), {Using Drag and Drop with Item Views}
+*/
+void QAbstractItemModel::setSupportedDragActions(Qt::DropActions actions)
+{
+    Q_D(QAbstractItemModel);
+    d->supportedDragActions = actions;
+}
+
+/*!
+  On models that support this, inserts \a count rows into the model before the
+  given \a row.  The items in the new row will be children of the item
+  represented by the \a parent model index.
+
+  If \a row is 0, the rows are prepended to any existing rows in the parent.
+  If \a row is rowCount(), the rows are appended to any existing rows in the
+  parent.
+  If \a parent has no children, a single column with \a count rows is inserted.
+
+  Returns true if the rows were successfully inserted; otherwise returns
+  false.
+
+  The base class implementation does nothing and returns false.
+
+  If you implement your own model, you can reimplement this function
+  if you want to support insertions. Alternatively, you can provide
+  you own API for altering the data.
+
+  \sa insertColumns(), removeRows(), beginInsertRows(), endInsertRows()
+*/
+bool QAbstractItemModel::insertRows(int, int, const QModelIndex &)
+{
+    return false;
+}
+
+/*!
+  On models that support this, inserts \a count new columns into the model
+  before the given \a column.  The items in each new column will be children
+  of the item represented by the \a parent model index.
+
+  If \a column is 0, the columns are prepended to any existing columns.
+  If \a column is columnCount(), the columns are appended to any existing
+  columns.
+  If \a parent has no children, a single row with \a count columns is inserted.
+
+  Returns true if the columns were successfully inserted; otherwise returns
+  false.
+
+  The base class implementation does nothing and returns false.
+
+  If you implement your own model, you can reimplement this function
+  if you want to support insertions. Alternatively, you can provide
+  you own API for altering the data.
+
+  \sa insertRows(), removeColumns(), beginInsertColumns(), endInsertColumns()
+*/
+bool QAbstractItemModel::insertColumns(int, int, const QModelIndex &)
+{
+    return false;
+}
+
+/*!
+    On models that support this, removes \a count rows starting with the given
+    \a row under parent \a parent from the model. Returns true if the rows
+    were successfully removed; otherwise returns false.
+
+    The base class implementation does nothing and returns false.
+
+    If you implement your own model, you can reimplement this function
+    if you want to support removing. Alternatively, you can provide
+    you own API for altering the data.
+
+    \sa removeRow(), removeColumns(), insertColumns(), beginRemoveRows(), endRemoveRows()
+*/
+bool QAbstractItemModel::removeRows(int, int, const QModelIndex &)
+{
+    return false;
+}
+
+/*!
+    On models that support this, removes \a count columns starting with the
+    given \a column under parent \a parent from the model. Returns true if the
+    columns were successfully removed; otherwise returns false.
+
+    The base class implementation does nothing and returns false.
+
+    If you implement your own model, you can reimplement this function
+    if you want to support removing. Alternatively, you can provide
+    you own API for altering the data.
+
+    \sa removeColumn(), removeRows(), insertColumns(), beginRemoveColumns(), endRemoveColumns()
+*/
+bool QAbstractItemModel::removeColumns(int, int, const QModelIndex &)
+{
+    return false;
+}
+
+/*!
+    Fetches any available data for the items with the parent specified by the
+    \a parent index.
+
+    Reimplement this if you are populating your model incrementally.
+
+    The default implementation does nothing.
+
+    \sa canFetchMore()
+*/
+void QAbstractItemModel::fetchMore(const QModelIndex &)
+{
+    // do nothing
+}
+
+/*!
+    Returns true if there is more data available for \a parent; otherwise returns
+    false.
+    
+    The default implementation always returns false.
+
+    If canFetchMore() returns true, QAbstractItemView will call fetchMore().
+    However, the fetchMore() function is only called when the model is being
+    populated incrementally.
+
+    \sa fetchMore()
+*/
+bool QAbstractItemModel::canFetchMore(const QModelIndex &) const
+{
+    return false;
+}
+
+/*!
+    Returns the item flags for the given \a index.
+
+    The base class implementation returns a combination of flags that
+    enables the item (\c ItemIsEnabled) and allows it to be
+    selected (\c ItemIsSelectable).
+
+    \sa Qt::ItemFlags
+*/
+Qt::ItemFlags QAbstractItemModel::flags(const QModelIndex &index) const
+{
+    Q_D(const QAbstractItemModel);
+    if (!d->indexValid(index))
+        return 0;
+
+    return Qt::ItemIsSelectable|Qt::ItemIsEnabled;
+}
+
+/*!
+    Sorts the model by \a column in the given \a order.
+
+    The base class implementation does nothing.
+*/
+void QAbstractItemModel::sort(int column, Qt::SortOrder order)
+{
+    Q_UNUSED(column);
+    Q_UNUSED(order);
+    // do nothing
+}
+
+/*!
+  Returns a model index for the buddy of the item represented by \a index.
+  When the user wants to edit an item, the view will call this function to
+  check whether another item in the model should be edited instead, and
+  construct a delegate using the model index returned by the buddy item.
+
+  In the default implementation each item is its own buddy.
+*/
+QModelIndex QAbstractItemModel::buddy(const QModelIndex &index) const
+{
+    return index;
+}
+
+/*!
+    Returns a list of indexes for the items in the column of the \a
+    start index where the data stored under the given \a role matches
+    the specified \a value. The way the search is performed is defined
+    by the \a flags given. The list that is returned may be empty.
+
+    The search starts from the \a start index, and continues until the
+    number of matching data items equals \a hits, the search reaches
+    the last row, or the search reaches \a start again, depending on
+    whether \c MatchWrap is specified in \a flags. If you want to search
+    for all matching items, use \a hits = -1.
+
+    By default, this function will perform a wrapping, string-based comparison
+    on all items, searching for items that begin with the search term specified
+    by \a value.
+    
+    \note The default implementation of this function only searches columns,
+    This function can be reimplemented to include other search behavior.
+*/
+QModelIndexList QAbstractItemModel::match(const QModelIndex &start, int role,
+                                          const QVariant &value, int hits,
+                                          Qt::MatchFlags flags) const
+{
+    QModelIndexList result;
+    uint matchType = flags & 0x0F;
+    Qt::CaseSensitivity cs = flags & Qt::MatchCaseSensitive ? Qt::CaseSensitive : Qt::CaseInsensitive;
+    bool recurse = flags & Qt::MatchRecursive;
+    bool wrap = flags & Qt::MatchWrap;
+    bool allHits = (hits == -1);
+    QString text; // only convert to a string if it is needed
+    QModelIndex p = parent(start);
+    int from = start.row();
+    int to = rowCount(p);
+
+    // iterates twice if wrapping
+    for (int i = 0; (wrap && i < 2) || (!wrap && i < 1); ++i) {
+        for (int r = from; (r < to) && (allHits || result.count() < hits); ++r) {
+            QModelIndex idx = index(r, start.column(), p);
+            if (!idx.isValid())
+                 continue;
+            QVariant v = data(idx, role);
+            // QVariant based matching
+            if (matchType == Qt::MatchExactly) {
+                if (value == v)
+                    result.append(idx);
+            } else { // QString based matching
+                if (text.isEmpty()) // lazy conversion
+                    text = value.toString();
+                QString t = v.toString();
+                switch (matchType) {
+                case Qt::MatchRegExp:
+                    if (QRegExp(text, cs).exactMatch(t))
+                        result.append(idx);
+                    break;
+                case Qt::MatchWildcard:
+                    if (QRegExp(text, cs, QRegExp::Wildcard).exactMatch(t))
+                        result.append(idx);
+                    break;
+                case Qt::MatchStartsWith:
+                    if (t.startsWith(text, cs))
+                        result.append(idx);
+                    break;
+                case Qt::MatchEndsWith:
+                    if (t.endsWith(text, cs))
+                        result.append(idx);
+                    break;
+                case Qt::MatchFixedString:
+                    if (t.compare(text, cs) == 0)
+                        result.append(idx);
+                    break;
+                case Qt::MatchContains:
+                default:
+                    if (t.contains(text, cs))
+                        result.append(idx);
+                }
+            }
+            if (recurse && hasChildren(idx)) { // search the hierarchy
+                result += match(index(0, idx.column(), idx), role,
+                                (text.isEmpty() ? value : text),
+                                (allHits ? -1 : hits - result.count()), flags);
+            }
+        }
+        // prepare for the next iteration
+        from = 0;
+        to = start.row();
+    }
+    return result;
+}
+
+/*!
+    Returns the row and column span of the item represented by \a index.
+
+    Note: span is not used currently, but will be in the future.
+*/
+
+QSize QAbstractItemModel::span(const QModelIndex &) const
+{
+    return QSize(1, 1);
+}
+
+/*!
+  Called to let the model know that it should submit whatever it has cached
+  to the permanent storage. Typically used for row editing.
+
+  Returns false on error, otherwise true.
+*/
+
+bool QAbstractItemModel::submit()
+{
+    return true;
+}
+
+/*!
+  Called to let the model know that it should discard whatever it has cached.
+  Typically used for row editing.
+*/
+
+void QAbstractItemModel::revert()
+{
+    // do nothing
+}
+
+/*!
+  Returns the data for the given \a role and \a section in the header
+  with the specified \a orientation.
+
+  For horizontal headers, the section number corresponds to the column
+  number of items shown beneath it. For vertical headers, the section
+  number typically to the row number of items shown alongside it.
+
+  \sa Qt::ItemDataRole, setHeaderData(), QHeaderView
+*/
+
+QVariant QAbstractItemModel::headerData(int section, Qt::Orientation orientation, int role) const
+{
+    Q_UNUSED(orientation);
+    if (role == Qt::DisplayRole)
+        return section + 1;
+    return QVariant();
+}
+
+/*!
+  Sets the data for the given \a role and \a section in the header with
+  the specified \a orientation to the \a value supplied.
+  Returns true if the header's data was updated; otherwise returns false.
+
+  Note that the headerDataChanged() signal must be emitted explicitly
+  when reimplementing this function.
+
+  \sa Qt::ItemDataRole, headerData()
+*/
+
+bool QAbstractItemModel::setHeaderData(int section, Qt::Orientation orientation,
+                                       const QVariant &value, int role)
+{
+    Q_UNUSED(section);
+    Q_UNUSED(orientation);
+    Q_UNUSED(value);
+    Q_UNUSED(role);
+    return false;
+}
+
+/*!
+    \fn QModelIndex QAbstractItemModel::createIndex(int row, int column, void *ptr) const
+
+    Creates a model index for the given \a row and \a column with the internal pointer \a ptr.
+
+    Note that when you are using a QSortFilterProxyModel its indexes have their own
+    internal pointer.  It is not advisable to access the internal pointer in the index
+    outside of the model.  Use the data() function instead.
+
+    This function provides a consistent interface that model subclasses must
+    use to create model indexes.
+*/
+
+/*!
+    \fn QModelIndex QAbstractItemModel::createIndex(int row, int column, int id) const
+    \obsolete
+
+    Use QModelIndex QAbstractItemModel::createIndex(int row, int column, quint32 id) instead.
+*/
+
+/*!
+    \fn QModelIndex QAbstractItemModel::createIndex(int row, int column, quint32 id) const
+
+    Creates a model index for the given \a row and \a column with the internal
+    identifier, \a id.
+
+    This function provides a consistent interface that model subclasses must
+    use to create model indexes.
+    \sa QModelIndex::internalId()
+*/
+
+/*!
+  \internal
+*/
+void QAbstractItemModel::encodeData(const QModelIndexList &indexes, QDataStream &stream) const
+{
+    QModelIndexList::ConstIterator it = indexes.begin();
+    for (; it != indexes.end(); ++it)
+        stream << (*it).row() << (*it).column() << itemData(*it);
+}
+
+/*!
+  \internal
+ */
+bool QAbstractItemModel::decodeData(int row, int column, const QModelIndex &parent,
+                                    QDataStream &stream)
+{
+    int top = INT_MAX;
+    int left = INT_MAX;
+    int bottom = 0;
+    int right = 0;
+    QVector<int> rows, columns;
+    QVector<QMap<int, QVariant> > data;
+
+    while (!stream.atEnd()) {
+        int r, c;
+        QMap<int, QVariant> v;
+        stream >> r >> c >> v;
+        rows.append(r);
+        columns.append(c);
+        data.append(v);
+        top = qMin(r, top);
+        left = qMin(c, left);
+        bottom = qMax(r, bottom);
+        right = qMax(c, right);
+    }
+
+    // insert the dragged items into the table, use a bit array to avoid overwriting items,
+    // since items from different tables can have the same row and column
+    int dragRowCount = 0;
+    int dragColumnCount = right - left + 1;
+
+    // Compute the number of continuous rows upon insertion and modify the rows to match
+    QVector<int> rowsToInsert(bottom + 1);
+    for (int i = 0; i < rows.count(); ++i)
+        rowsToInsert[rows.at(i)] = 1;
+    for (int i = 0; i < rowsToInsert.count(); ++i) {
+        if (rowsToInsert[i] == 1){
+            rowsToInsert[i] = dragRowCount;
+            ++dragRowCount;
+        }
+    }
+    for (int i = 0; i < rows.count(); ++i)
+        rows[i] = top + rowsToInsert[rows[i]];
+
+    QBitArray isWrittenTo(dragRowCount * dragColumnCount);
+
+    // make space in the table for the dropped data
+    int colCount = columnCount(parent);
+    if (colCount == 0) {
+        insertColumns(colCount, dragColumnCount - colCount, parent);
+        colCount = columnCount(parent);
+    }
+    insertRows(row, dragRowCount, parent);
+
+    row = qMax(0, row);
+    column = qMax(0, column);
+
+    QVector<QPersistentModelIndex> newIndexes(data.size());
+    // set the data in the table
+    for (int j = 0; j < data.size(); ++j) {
+        int relativeRow = rows.at(j) - top;
+        int relativeColumn = columns.at(j) - left;
+        int destinationRow = relativeRow + row;
+        int destinationColumn = relativeColumn + column;
+        int flat = (relativeRow * dragColumnCount) + relativeColumn;
+        // if the item was already written to, or we just can't fit it in the table, create a new row
+        if (destinationColumn >= colCount || isWrittenTo.testBit(flat)) {
+            destinationColumn = qBound(column, destinationColumn, colCount - 1);
+            destinationRow = row + dragRowCount;
+            insertRows(row + dragRowCount, 1, parent);
+            flat = (dragRowCount * dragColumnCount) + relativeColumn;
+            isWrittenTo.resize(++dragRowCount * dragColumnCount);
+        }
+        if (!isWrittenTo.testBit(flat)) {
+            newIndexes[j] = index(destinationRow, destinationColumn, parent);
+            isWrittenTo.setBit(flat);
+        }
+    }
+
+    for(int k = 0; k < newIndexes.size(); k++) {
+        if (newIndexes.at(k).isValid())
+            setItemData(newIndexes.at(k), data.at(k));
+    }
+
+    return true;
+}
+
+/*!
+    Begins a row insertion operation.
+
+    When reimplementing insertRows() in a subclass, you must call this
+    function \e before inserting data into the model's underlying data
+    store.
+
+    The \a parent index corresponds to the parent into which the new
+    rows are inserted; \a first and \a last are the row numbers that the
+    new rows will have after they have been inserted.
+
+    \table 80%
+    \row \o \inlineimage modelview-begin-insert-rows.png Inserting rows
+    \o Specify the first and last row numbers for the span of rows
+       you want to insert into an item in a model.
+
+    For example, as shown in the diagram, we insert three rows before
+    row 2, so \a first is 2 and \a last is 4:
+    \snippet doc/src/snippets/code/src_corelib_kernel_qabstractitemmodel.cpp 0
+    This inserts the three new rows as rows 2, 3, and 4.
+    \row
+    \o \inlineimage modelview-begin-append-rows.png Appending rows
+    \o To append rows, insert them after the last row.
+
+    For example, as shown in the diagram, we append two rows to a
+    collection of 4 existing rows (ending in row 3), so \a first is 4
+    and \a last is 5:
+    \snippet doc/src/snippets/code/src_corelib_kernel_qabstractitemmodel.cpp 1
+    This appends the two new rows as rows 4 and 5.
+    \endtable
+
+    \sa endInsertRows()
+*/
+void QAbstractItemModel::beginInsertRows(const QModelIndex &parent, int first, int last)
+{
+    Q_ASSERT(first >= 0);
+    Q_ASSERT(last >= first);
+    Q_D(QAbstractItemModel);
+    d->changes.push(QAbstractItemModelPrivate::Change(parent, first, last));
+    emit rowsAboutToBeInserted(parent, first, last);
+    d->rowsAboutToBeInserted(parent, first, last);
+}
+
+/*!
+    Ends a row insertion operation.
+
+    When reimplementing insertRows() in a subclass, you must call this
+    function \e after inserting data into the model's underlying data
+    store.
+
+    \sa beginInsertRows()
+*/
+void QAbstractItemModel::endInsertRows()
+{
+    Q_D(QAbstractItemModel);
+    QAbstractItemModelPrivate::Change change = d->changes.pop();
+    d->rowsInserted(change.parent, change.first, change.last);
+    emit rowsInserted(change.parent, change.first, change.last);
+}
+
+/*!
+    Begins a row removal operation.
+
+    When reimplementing removeRows() in a subclass, you must call this
+    function \e before removing data from the model's underlying data
+    store.
+
+    The \a parent index corresponds to the parent from which the new
+    rows are removed; \a first and \a last are the row numbers of the
+    rows to be removed.
+
+    \table 80%
+    \row \o \inlineimage modelview-begin-remove-rows.png Removing rows
+    \o Specify the first and last row numbers for the span of rows
+       you want to remove from an item in a model.
+
+    For example, as shown in the diagram, we remove the two rows from
+    row 2 to row 3, so \a first is 2 and \a last is 3:
+    \snippet doc/src/snippets/code/src_corelib_kernel_qabstractitemmodel.cpp 2
+    \endtable
+
+    \sa endRemoveRows()
+*/
+void QAbstractItemModel::beginRemoveRows(const QModelIndex &parent, int first, int last)
+{
+    Q_ASSERT(first >= 0);
+    Q_ASSERT(last >= first);
+    Q_D(QAbstractItemModel);
+    d->changes.push(QAbstractItemModelPrivate::Change(parent, first, last));
+    emit rowsAboutToBeRemoved(parent, first, last);
+    d->rowsAboutToBeRemoved(parent, first, last);
+}
+
+/*!
+    Ends a row removal operation.
+
+    When reimplementing removeRows() in a subclass, you must call this
+    function \e after removing data from the model's underlying data
+    store.
+
+    \sa beginRemoveRows()
+*/
+void QAbstractItemModel::endRemoveRows()
+{
+    Q_D(QAbstractItemModel);
+    QAbstractItemModelPrivate::Change change = d->changes.pop();
+    d->rowsRemoved(change.parent, change.first, change.last);
+    emit rowsRemoved(change.parent, change.first, change.last);
+}
+
+/*!
+    Begins a column insertion operation.
+
+    When reimplementing insertColumns() in a subclass, you must call this
+    function \e before inserting data into the model's underlying data
+    store.
+
+    The \a parent index corresponds to the parent into which the new
+    columns are inserted; \a first and \a last are the column numbers of
+    the new columns will have after they have been inserted.
+
+    \table 80%
+    \row \o \inlineimage modelview-begin-insert-columns.png Inserting columns
+    \o Specify the first and last column numbers for the span of columns
+       you want to insert into an item in a model.
+
+    For example, as shown in the diagram, we insert three columns before
+    column 4, so \a first is 4 and \a last is 6:
+    \snippet doc/src/snippets/code/src_corelib_kernel_qabstractitemmodel.cpp 3
+    This inserts the three new columns as columns 4, 5, and 6.
+    \row
+    \o \inlineimage modelview-begin-append-columns.png Appending columns
+    \o To append columns, insert them after the last column.
+
+    For example, as shown in the diagram, we append three columns to a
+    collection of six existing columns (ending in column 5), so \a first
+    is 6 and \a last is 8:
+    \snippet doc/src/snippets/code/src_corelib_kernel_qabstractitemmodel.cpp 4
+    This appends the two new columns as columns 6, 7, and 8.
+    \endtable
+
+    \sa endInsertColumns()
+*/
+void QAbstractItemModel::beginInsertColumns(const QModelIndex &parent, int first, int last)
+{
+    Q_ASSERT(first >= 0);
+    Q_ASSERT(last >= first);
+    Q_D(QAbstractItemModel);
+    d->changes.push(QAbstractItemModelPrivate::Change(parent, first, last));
+    emit columnsAboutToBeInserted(parent, first, last);
+    d->columnsAboutToBeInserted(parent, first, last);
+}
+
+/*!
+    Ends a column insertion operation.
+
+    When reimplementing insertColumns() in a subclass, you must call this
+    function \e after inserting data into the model's underlying data
+    store.
+
+    \sa beginInsertColumns()
+*/
+void QAbstractItemModel::endInsertColumns()
+{
+    Q_D(QAbstractItemModel);
+    QAbstractItemModelPrivate::Change change = d->changes.pop();
+    d->columnsInserted(change.parent, change.first, change.last);
+    emit columnsInserted(change.parent, change.first, change.last);
+}
+
+/*!
+    Begins a column removal operation.
+
+    When reimplementing removeColumns() in a subclass, you must call this
+    function \e before removing data from the model's underlying data
+    store.
+
+    The \a parent index corresponds to the parent from which the new
+    columns are removed; \a first and \a last are the column numbers of
+    the first and last columns to be removed.
+
+    \table 80%
+    \row \o \inlineimage modelview-begin-remove-columns.png Removing columns
+    \o Specify the first and last column numbers for the span of columns
+       you want to remove from an item in a model.
+
+    For example, as shown in the diagram, we remove the three columns
+    from column 4 to column 6, so \a first is 4 and \a last is 6:
+    \snippet doc/src/snippets/code/src_corelib_kernel_qabstractitemmodel.cpp 5
+    \endtable
+
+    \sa endRemoveColumns()
+*/
+void QAbstractItemModel::beginRemoveColumns(const QModelIndex &parent, int first, int last)
+{
+    Q_ASSERT(first >= 0);
+    Q_ASSERT(last >= first);
+    Q_D(QAbstractItemModel);
+    d->changes.push(QAbstractItemModelPrivate::Change(parent, first, last));
+    emit columnsAboutToBeRemoved(parent, first, last);
+    d->columnsAboutToBeRemoved(parent, first, last);
+}
+
+/*!
+    Ends a column removal operation.
+
+    When reimplementing removeColumns() in a subclass, you must call this
+    function \e after removing data from the model's underlying data
+    store.
+
+    \sa beginRemoveColumns()
+*/
+void QAbstractItemModel::endRemoveColumns()
+{
+    Q_D(QAbstractItemModel);
+    QAbstractItemModelPrivate::Change change = d->changes.pop();
+    d->columnsRemoved(change.parent, change.first, change.last);
+    emit columnsRemoved(change.parent, change.first, change.last);
+}
+
+/*!
+    Resets the model to its original state in any attached views.
+
+    \note The view to which the model is attached to will be reset as well.
+
+    When a model is reset it means that any previous data reported from the
+    model is now invalid and has to be queried for again.
+
+    When a model radically changes its data it can sometimes be easier to just
+    call this function rather than emit dataChanged() to inform other
+    components when the underlying data source, or its structure, has changed.
+
+    \sa modelAboutToBeReset(), modelReset()
+*/
+void QAbstractItemModel::reset()
+{
+    Q_D(QAbstractItemModel);
+    emit modelAboutToBeReset();
+    d->invalidatePersistentIndexes();
+    emit modelReset();
+}
+
+/*!
+  Changes the QPersistentModelIndex that is equal to the given \a from
+  model index to the given \a to model index.
+
+  If no persistent model index equal to the given \a from model index was
+  found, nothing is changed.
+
+  \sa persistentIndexList(), changePersistentIndexList()
+*/
+void QAbstractItemModel::changePersistentIndex(const QModelIndex &from, const QModelIndex &to)
+{
+    Q_D(QAbstractItemModel);
+    if (d->persistent.indexes.isEmpty())
+        return;
+    // find the data and reinsert it sorted
+    const QHash<QModelIndex, QPersistentModelIndexData *>::iterator it = d->persistent.indexes.find(from);
+    if (it != d->persistent.indexes.end()) {
+        QPersistentModelIndexData *data = *it;
+        d->persistent.indexes.erase(it);
+        data->index = to;
+        if (to.isValid())
+            d->persistent.insertMultiAtEnd(to, data);
+        else
+            data->model = 0;
+    }
+}
+
+/*!
+  \since 4.1
+
+  Changes the QPersistentModelIndexes that is equal to the indexes in the given \a from
+  model index list to the given \a to model index list.
+
+  If no persistent model indexes equal to the indexes in the given \a from model index list
+  was found, nothing is changed.
+
+  \sa persistentIndexList(), changePersistentIndex()
+*/
+void QAbstractItemModel::changePersistentIndexList(const QModelIndexList &from,
+                                                   const QModelIndexList &to)
+{
+    Q_D(QAbstractItemModel);
+    if (d->persistent.indexes.isEmpty())
+        return;
+    QVector<QPersistentModelIndexData *> toBeReinserted;
+    toBeReinserted.reserve(to.count());
+    for (int i = 0; i < from.count(); ++i) {
+        if (from.at(i) == to.at(i))
+            continue;
+        const QHash<QModelIndex, QPersistentModelIndexData *>::iterator it = d->persistent.indexes.find(from.at(i));
+        if (it != d->persistent.indexes.end()) {
+            QPersistentModelIndexData *data = *it;
+            d->persistent.indexes.erase(it);
+            data->index = to.at(i);
+            if (data->index.isValid())
+                toBeReinserted << data;
+            else
+                data->model = 0;
+        }
+    }
+
+    for (QVector<QPersistentModelIndexData *>::const_iterator it = toBeReinserted.constBegin();
+         it != toBeReinserted.constEnd() ; ++it) {
+        QPersistentModelIndexData *data = *it;
+        d->persistent.insertMultiAtEnd(data->index, data);
+    }
+}
+
+/*!
+  \since 4.2
+
+  Returns the list of indexes stored as persistent indexes in the model.
+*/
+QModelIndexList QAbstractItemModel::persistentIndexList() const
+{
+    Q_D(const QAbstractItemModel);
+    QModelIndexList result;
+    for (QHash<QModelIndex, QPersistentModelIndexData *>::const_iterator it = d->persistent.indexes.constBegin();
+         it != d->persistent.indexes.constEnd(); ++it) {
+        QPersistentModelIndexData *data = *it;
+        result.append(data->index);
+    }
+    return result;
+}
+
+
+/*!
+    \class QAbstractTableModel
+    \brief The QAbstractTableModel class provides an abstract model that can be
+    subclassed to create table models.
+
+    \ingroup model-view
+
+    QAbstractTableModel provides a standard interface for models that represent
+    their data as a two-dimensional array of items. It is not used directly,
+    but must be subclassed.
+
+    Since the model provides a more specialized interface than
+    QAbstractItemModel, it is not suitable for use with tree views, although
+    it can be used to provide data to a QListView. If you need to represent
+    a simple list of items, and only need a model to contain a single column
+    of data, subclassing the QAbstractListModel may be more appropriate.
+
+    The rowCount() and columnCount() functions return the dimensions of the
+    table. To retrieve a model index corresponding to an item in the model, use
+    index() and provide only the row and column numbers.
+
+    \section1 Subclassing
+
+    \bold{Note:} Some general guidelines for subclassing models are
+    available in the \l{Model Subclassing Reference}.
+
+    When subclassing QAbstractTableModel, you must implement rowCount(),
+    columnCount(), and data(). Default implementations of the index() and
+    parent() functions are provided by QAbstractTableModel.
+    Well behaved models will also implement headerData().
+
+    Editable models need to implement setData(), and implement flags() to
+    return a value containing
+    \l{Qt::ItemFlags}{Qt::ItemIsEditable}.
+
+    Models that provide interfaces to resizable data structures can
+    provide implementations of insertRows(), removeRows(), insertColumns(),
+    and removeColumns(). When implementing these functions, it is
+    important to call the appropriate functions so that all connected views
+    are aware of any changes:
+
+    \list
+    \o An insertRows() implementation must call beginInsertRows()
+       \e before inserting new rows into the data structure, and it must
+       call endInsertRows() \e{immediately afterwards}.
+    \o An insertColumns() implementation must call beginInsertColumns()
+       \e before inserting new columns into the data structure, and it must
+       call endInsertColumns() \e{immediately afterwards}.
+    \o A removeRows() implementation must call beginRemoveRows()
+       \e before the rows are removed from the data structure, and it must
+       call endRemoveRows() \e{immediately afterwards}.
+    \o A removeColumns() implementation must call beginRemoveColumns()
+       \e before the columns are removed from the data structure, and it must
+       call endRemoveColumns() \e{immediately afterwards}.
+    \endlist
+
+    \sa {Model Classes}, {Model Subclassing Reference}, QAbstractItemModel,
+        QAbstractListModel,
+        {Pixelator Example}
+*/
+
+/*!
+    Constructs an abstract table model for the given \a parent.
+*/
+
+QAbstractTableModel::QAbstractTableModel(QObject *parent)
+    : QAbstractItemModel(parent)
+{
+
+}
+
+/*!
+    \internal
+
+    Constructs an abstract table model with \a dd and the given \a parent.
+*/
+
+QAbstractTableModel::QAbstractTableModel(QAbstractItemModelPrivate &dd, QObject *parent)
+    : QAbstractItemModel(dd, parent)
+{
+
+}
+
+/*!
+    Destroys the abstract table model.
+*/
+
+QAbstractTableModel::~QAbstractTableModel()
+{
+
+}
+
+/*!
+    \fn QModelIndex QAbstractTableModel::index(int row, int column, const QModelIndex &parent = QModelIndex()) const
+
+    Returns the index of the data in \a row and \a column with \a parent.
+
+    \sa parent()
+*/
+
+QModelIndex QAbstractTableModel::index(int row, int column, const QModelIndex &parent) const
+{
+    return hasIndex(row, column, parent) ? createIndex(row, column, 0) : QModelIndex();
+}
+
+/*!
+    \fn QModelIndex QAbstractTableModel::parent(const QModelIndex &index) const
+
+    Returns the parent of the model item with the given \a index.
+
+    \sa index() hasChildren()
+*/
+
+QModelIndex QAbstractTableModel::parent(const QModelIndex &) const
+{
+    return QModelIndex();
+}
+
+bool QAbstractTableModel::hasChildren(const QModelIndex &parent) const
+{
+    if (parent.model() == this || !parent.isValid())
+        return rowCount(parent) > 0 && columnCount(parent) > 0;
+    return false;
+}
+
+/*!
+    \class QAbstractListModel
+    \brief The QAbstractListModel class provides an abstract model that can be
+    subclassed to create one-dimensional list models.
+
+    \ingroup model-view
+
+    QAbstractListModel provides a standard interface for models that represent
+    their data as a simple non-hierarchical sequence of items. It is not used
+    directly, but must be subclassed.
+
+    Since the model provides a more specialized interface than
+    QAbstractItemModel, it is not suitable for use with tree views; you will
+    need to subclass QAbstractItemModel if you want to provide a model for
+    that purpose. If you need to use a number of list models to manage data,
+    it may be more appropriate to subclass QAbstractTableModel class instead.
+
+    Simple models can be created by subclassing this class and implementing
+    the minimum number of required functions. For example, we could implement
+    a simple read-only QStringList-based model that provides a list of strings
+    to a QListView widget. In such a case, we only need to implement the
+    rowCount() function to return the number of items in the list, and the
+    data() function to retrieve items from the list.
+
+    Since the model represents a one-dimensional structure, the rowCount()
+    function returns the total number of items in the model. The columnCount()
+    function is implemented for interoperability with all kinds of views, but
+    by default informs views that the model contains only one column.
+
+    \section1 Subclassing
+
+    \bold{Note:} Some general guidelines for subclassing models are
+    available in the \l{Model Subclassing Reference}.
+
+    When subclassing QAbstractListModel, you must provide implementations
+    of the rowCount() and data() functions. Well behaved models also provide
+    a headerData() implementation.
+
+    For editable list models, you must also provide an implementation of
+    setData(), implement the flags() function so that it returns a value
+    containing \l{Qt::ItemFlags}{Qt::ItemIsEditable}.
+
+    Note that QAbstractListModel provides a default implementation of
+    columnCount() that informs views that there is only a single column
+    of items in this model.
+
+    Models that provide interfaces to resizable list-like data structures
+    can provide implementations of insertRows() and removeRows(). When
+    implementing these functions, it is important to call the appropriate
+    functions so that all connected views are aware of any changes:
+
+    \list
+    \o An insertRows() implementation must call beginInsertRows()
+       \e before inserting new rows into the data structure, and it must
+       call endInsertRows() \e{immediately afterwards}.
+    \o A removeRows() implementation must call beginRemoveRows()
+       \e before the rows are removed from the data structure, and it must
+       call endRemoveRows() \e{immediately afterwards}.
+    \endlist
+
+    \sa {Model Classes}, {Model Subclassing Reference}, QAbstractItemView,
+        QAbstractTableModel, {Item Views Puzzle Example}
+*/
+
+/*!
+    Constructs an abstract list model with the given \a parent.
+*/
+
+QAbstractListModel::QAbstractListModel(QObject *parent)
+    : QAbstractItemModel(parent)
+{
+
+}
+
+/*!
+    \internal
+
+    Constructs an abstract list model with \a dd and the given \a parent.
+*/
+
+QAbstractListModel::QAbstractListModel(QAbstractItemModelPrivate &dd, QObject *parent)
+    : QAbstractItemModel(dd, parent)
+{
+
+}
+
+/*!
+    Destroys the abstract list model.
+*/
+
+QAbstractListModel::~QAbstractListModel()
+{
+
+}
+
+/*!
+    \fn QModelIndex QAbstractListModel::index(int row, int column, const QModelIndex &parent = QModelIndex()) const
+
+    Returns the index of the data in \a row and \a column with \a parent.
+
+    \sa parent()
+*/
+
+QModelIndex QAbstractListModel::index(int row, int column, const QModelIndex &parent) const
+{
+    return hasIndex(row, column, parent) ? createIndex(row, column, 0) : QModelIndex();
+}
+
+/*!
+    Returns the parent of the model item with the given \a index.
+
+    \sa index() hasChildren()
+*/
+
+QModelIndex QAbstractListModel::parent(const QModelIndex & /* index */) const
+{
+    return QModelIndex();
+}
+
+/*!
+    \internal
+
+    Returns the number of columns in the list with the given \a parent.
+
+    \sa rowCount()
+*/
+
+int QAbstractListModel::columnCount(const QModelIndex &parent) const
+{
+    return parent.isValid() ? 0 : 1;
+}
+
+bool QAbstractListModel::hasChildren(const QModelIndex &parent) const
+{
+    return parent.isValid() ? false : (rowCount() > 0);
+}
+
+/*!
+    \typedef QModelIndexList
+    \relates QModelIndex
+
+    Synonym for QList<QModelIndex>.
+*/
+
+/*!
+  \reimp
+*/
+bool QAbstractTableModel::dropMimeData(const QMimeData *data, Qt::DropAction action,
+                                       int row, int column, const QModelIndex &parent)
+{
+    if (!data || !(action == Qt::CopyAction || action == Qt::MoveAction))
+        return false;
+
+    QStringList types = mimeTypes();
+    if (types.isEmpty())
+        return false;
+    QString format = types.at(0);
+    if (!data->hasFormat(format))
+        return false;
+
+    QByteArray encoded = data->data(format);
+    QDataStream stream(&encoded, QIODevice::ReadOnly);
+
+    // if the drop is on an item, replace the data in the items
+    if (parent.isValid() && row == -1 && column == -1) {
+        int top = INT_MAX;
+        int left = INT_MAX;
+        QVector<int> rows, columns;
+        QVector<QMap<int, QVariant> > data;
+
+        while (!stream.atEnd()) {
+            int r, c;
+            QMap<int, QVariant> v;
+            stream >> r >> c >> v;
+            rows.append(r);
+            columns.append(c);
+            data.append(v);
+            top = qMin(r, top);
+            left = qMin(c, left);
+        }
+
+        for (int i = 0; i < data.size(); ++i) {
+            int r = (rows.at(i) - top) + parent.row();
+            int c = (columns.at(i) - left) + parent.column();
+            if (hasIndex(r, c))
+                setItemData(index(r, c), data.at(i));
+        }
+
+        return true;
+    }
+
+    // otherwise insert new rows for the data
+    return decodeData(row, column, parent, stream);
+}
+
+/*!
+  \reimp
+*/
+bool QAbstractListModel::dropMimeData(const QMimeData *data, Qt::DropAction action,
+                                      int row, int column, const QModelIndex &parent)
+{
+    if (!data || !(action == Qt::CopyAction || action == Qt::MoveAction))
+        return false;
+
+    QStringList types = mimeTypes();
+    if (types.isEmpty())
+        return false;
+    QString format = types.at(0);
+    if (!data->hasFormat(format))
+        return false;
+
+    QByteArray encoded = data->data(format);
+    QDataStream stream(&encoded, QIODevice::ReadOnly);
+
+    // if the drop is on an item, replace the data in the items
+    if (parent.isValid() && row == -1 && column == -1) {
+        int top = INT_MAX;
+        int left = INT_MAX;
+        QVector<int> rows, columns;
+        QVector<QMap<int, QVariant> > data;
+
+        while (!stream.atEnd()) {
+            int r, c;
+            QMap<int, QVariant> v;
+            stream >> r >> c >> v;
+            rows.append(r);
+            columns.append(c);
+            data.append(v);
+            top = qMin(r, top);
+            left = qMin(c, left);
+        }
+
+        for (int i = 0; i < data.size(); ++i) {
+            int r = (rows.at(i) - top) + parent.row();
+            if (columns.at(i) == left && hasIndex(r, 0))
+                setItemData(index(r), data.at(i));
+        }
+
+        return true;
+    }
+
+    if (row == -1)
+        row = rowCount(parent);
+
+    // otherwise insert new rows for the data
+    return decodeData(row, column, parent, stream);
+}
+
+/*!
+    \fn QAbstractItemModel::modelAboutToBeReset()
+    \since 4.2
+
+    This signal is emitted when reset() is called, before the model's internal
+    state (e.g. persistent model indexes) has been invalidated.
+
+    \sa reset(), modelReset()
+*/
+
+/*!
+    \fn QAbstractItemModel::modelReset()
+    \since 4.1
+
+    This signal is emitted when reset() is called, after the model's internal
+    state (e.g. persistent model indexes) has been invalidated.
+
+    \sa reset(), modelAboutToBeReset()
+*/
+
+/*!
+    \fn bool QModelIndex::operator<(const QModelIndex &other) const
+    \since 4.1
+
+    Returns true if this model index is smaller than the \a other
+    model index; otherwise returns false.
+*/
+
+/*!
+    \fn uint qHash(const QPersistentModelIndex &index)
+    \since 4.5
+
+    Returns a hash of the QPersistentModelIndex
+ */
+
+
+/*!
+    \internal
+    QHash::insertMulti insert the value before the old value. and find() return the new value.
+    We need insertMultiAtEnd because we don't want to overwrite the old one, which should be removed later
+
+    There should be only one instance QPersistentModelIndexData per index, but in some intermediate state there may be
+    severals of PersistantModelIndex pointing to the same index, but one is already updated, and the other one is not.
+    This make sure than when updating the first one we don't overwrite the second one in the hash, and the second one
+    will be updated right later.
+ */
+void QAbstractItemModelPrivate::Persistent::insertMultiAtEnd(const QModelIndex& key, QPersistentModelIndexData *data)
+{
+    QHash<QModelIndex,QPersistentModelIndexData *>::iterator newIt =
+            indexes.insertMulti(key, data);
+    QHash<QModelIndex,QPersistentModelIndexData *>::iterator it = newIt + 1;
+    while (it != indexes.end() && it.key() == key) {
+        qSwap(*newIt,*it);
+        newIt = it;
+        ++it;
+    }
+}
+
+QT_END_NAMESPACE