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# treemodel.cpp Example File
itemviews/simpletreemodel/treemodel.cpp

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     /*
         treemodel.cpp

         Provides a simple tree model to show how to create and use hierarchical
         models.
     */

     #include <QtGui>

     #include "treeitem.h"
     #include "treemodel.h"

     TreeModel::TreeModel(const QString &data, QObject *parent)
         : QAbstractItemModel(parent)
     {
         QList<QVariant> rootData;
         rootData << "Title" << "Summary";
         rootItem = new TreeItem(rootData);
         setupModelData(data.split(QString("\n")), rootItem);
     }

     TreeModel::~TreeModel()
     {
         delete rootItem;
     }

     int TreeModel::columnCount(const QModelIndex &parent) const
     {
         if (parent.isValid())
             return static_cast<TreeItem*>(parent.internalPointer())->columnCount();
         else
             return rootItem->columnCount();
     }

     QVariant TreeModel::data(const QModelIndex &index, int role) const
     {
         if (!index.isValid())
             return QVariant();

         if (role != Qt::DisplayRole)
             return QVariant();

         TreeItem *item = static_cast<TreeItem*>(index.internalPointer());

         return item->data(index.column());
     }

     Qt::ItemFlags TreeModel::flags(const QModelIndex &index) const
     {
         if (!index.isValid())
             return 0;

         return Qt::ItemIsEnabled | Qt::ItemIsSelectable;
     }

     QVariant TreeModel::headerData(int section, Qt::Orientation orientation,
                                    int role) const
     {
         if (orientation == Qt::Horizontal && role == Qt::DisplayRole)
             return rootItem->data(section);

         return QVariant();
     }

     QModelIndex TreeModel::index(int row, int column, const QModelIndex &parent)
                 const
     {
         if (!hasIndex(row, column, parent))
             return QModelIndex();

         TreeItem *parentItem;

         if (!parent.isValid())
             parentItem = rootItem;
         else
             parentItem = static_cast<TreeItem*>(parent.internalPointer());

         TreeItem *childItem = parentItem->child(row);
         if (childItem)
             return createIndex(row, column, childItem);
         else
             return QModelIndex();
     }

     QModelIndex TreeModel::parent(const QModelIndex &index) const
     {
         if (!index.isValid())
             return QModelIndex();

         TreeItem *childItem = static_cast<TreeItem*>(index.internalPointer());
         TreeItem *parentItem = childItem->parent();

         if (parentItem == rootItem)
             return QModelIndex();

         return createIndex(parentItem->row(), 0, parentItem);
     }

     int TreeModel::rowCount(const QModelIndex &parent) const
     {
         TreeItem *parentItem;
         if (parent.column() > 0)
             return 0;

         if (!parent.isValid())
             parentItem = rootItem;
         else
             parentItem = static_cast<TreeItem*>(parent.internalPointer());

         return parentItem->childCount();
     }

     void TreeModel::setupModelData(const QStringList &lines, TreeItem *parent)
     {
         QList<TreeItem*> parents;
         QList<int> indentations;
         parents << parent;
         indentations << 0;

         int number = 0;

         while (number < lines.count()) {
             int position = 0;
             while (position < lines[number].length()) {
                 if (lines[number].mid(position, 1) != " ")
                     break;
                 position++;
             }

             QString lineData = lines[number].mid(position).trimmed();

             if (!lineData.isEmpty()) {
                 // Read the column data from the rest of the line.
                 QStringList columnStrings = lineData.split("\t", QString::SkipEmptyParts);
                 QList<QVariant> columnData;
                 for (int column = 0; column < columnStrings.count(); ++column)
                     columnData << columnStrings[column];

                 if (position > indentations.last()) {
                     // The last child of the current parent is now the new parent
                     // unless the current parent has no children.

                     if (parents.last()->childCount() > 0) {
                         parents << parents.last()->child(parents.last()->childCount()-1);
                         indentations << position;
                     }
                 } else {
                     while (position < indentations.last() && parents.count() > 0) {
                         parents.pop_back();
                         indentations.pop_back();
                     }
                 }

                 // Append a new item to the current parent's list of children.
                 parents.last()->appendChild(new TreeItem(columnData, parents.last()));
             }

             number++;
         }
     }