model.h Example File
demos/interview/model.h

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 #ifndef MODEL_H
 #define MODEL_H

 #include <QAbstractItemModel>
 #include <QFileIconProvider>
 #include <QVector>

 class Model : public QAbstractItemModel
 {
     Q_OBJECT

 public:
     Model(int rows, int columns, QObject *parent = 0);
     ~Model();

     QModelIndex index(int row, int column, const QModelIndex &parent) const;
     QModelIndex parent(const QModelIndex &child) const;

     int rowCount(const QModelIndex &parent) const;
     int columnCount(const QModelIndex &parent) const;

     QVariant data(const QModelIndex &index, int role) const;
     QVariant headerData(int section, Qt::Orientation orientation, int role) const;

     bool hasChildren(const QModelIndex &parent) const;
     Qt::ItemFlags flags(const QModelIndex &index) const;

 private:

     struct Node
     {
         Node(Node *parent = 0) : parent(parent), children(0) {}
         ~Node() { delete children; }
         Node *parent;
         QVector<Node> *children;
     };

     Node *node(int row, Node *parent) const;
     Node *parent(Node *child) const;
     int row(Node *node) const;

     int rc, cc;
     QVector<Node> *tree;
     QFileIconProvider iconProvider;
 };

 #endif