aggregate.h

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/* 
 * This program is free software; you can redistribute it and/or modify 
 * it under the terms of the GNU General Public License as published by 
 * the Free Software Foundation; either version 3 of the License, or 
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but 
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 
 * for more details.
 * 
 * You should have received a copy of the GNU General Public License along 
 * with this program; if not, see <http://www.gnu.org/licenses/>
 */

#ifndef QAGGREGATION_H
#define QAGGREGATION_H

#include "aggregation_global.h"

#include <QtCore/QObject>
#include <QtCore/QList>
#include <QtCore/QHash>
#include <QtCore/QReadWriteLock>
#include <QtCore/QReadLocker>

namespace Aggregation {

class AGGREGATION_EXPORT Aggregate : public QObject
{
    Q_OBJECT

public:
    Aggregate(QObject *parent = 0);
    virtual ~Aggregate();

    void add(QObject *component);
    void remove(QObject *component);

    template <typename T> T *component() {
        QReadLocker(&lock());
        foreach (QObject *component, m_components) {
            if (T *result = qobject_cast<T *>(component))
                return result;
        }
        return (T *)0;
    }

    template <typename T> QList<T *> components() {
        QReadLocker(&lock());
        QList<T *> results;
        foreach (QObject *component, m_components) {
            if (T *result = qobject_cast<T *>(component)) {
                results << result;
            }
        }
        return results;
    }

    static Aggregate *parentAggregate(QObject *obj);
    static QReadWriteLock &lock();

private slots:
    void deleteSelf(QObject *obj);

private:
    static QHash<QObject *, Aggregate *> &aggregateMap();

    QList<QObject *> m_components;
};

// get a component via global template function
template <typename T> T *query(Aggregate *obj)
{
    if (!obj)
        return (T *)0;
    return obj->template component<T>();
}

template <typename T> T *query(QObject *obj)
{
    if (!obj)
        return (T *)0;
    T *result = qobject_cast<T *>(obj);
    if (!result) {
        QReadLocker(&lock());
        Aggregate *parentAggregation = Aggregate::parentAggregate(obj);
        result = (parentAggregation ? query<T>(parentAggregation) : 0);
    }
    return result;
}

// get all components of a specific type via template function
template <typename T> QList<T *> query_all(Aggregate *obj)
{
    if (!obj)
        return QList<T *>();
    return obj->template components<T>();
}

template <typename T> QList<T *> query_all(QObject *obj)
{
    if (!obj)
        return QList<T *>();
    QReadLocker(&lock());
    Aggregate *parentAggregation = Aggregate::parentAggregate(obj);
    QList<T *> results;
    if (parentAggregation)
        results = query_all<T>(parentAggregation);
    else if (T *result = qobject_cast<T *>(obj))
        results.append(result);
    return results;
}

} // namespace Aggregation

#endif // QAGGREGATION_H