+/*
+ This file is part of the Nepomuk KDE project.
+ Copyright (C) 2011 Vishesh Handa <handa.vish@gmail.com>
+ Copyright (C) 2011 Sebastian Trueg <trueg@kde.org>
+
+ This library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ This library 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with this library; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+*/
+
+
+#ifndef RESOURCEWATCHER_H
+#define RESOURCEWATCHER_H
+
+#include <Nepomuk/Types/Class>
+#include <Nepomuk/Types/Property>
+#include <Nepomuk/Resource>
+
+#include <QtDBus/QDBusVariant>
+#include <QtCore/QVariant>
+
+#include "knepomukdatamanagement_export_p.h"
+
+namespace Nepomuk {
+
+ /**
+ * \class ResourceWatcher resourcewatcher.h
+ *
+ * \brief Selectively monitor the nepomuk repository for changes.
+ *
+ * Resources may be monitored on the basis of types, properties, and uris.
+ *
+ * Changes may be monitored in one of the following ways:
+ * -# By resources -
+ * Specify the exact resources that should be watched. Any changes made to the specified resources
+ * (Excluding \ref nepomuk_dms_metadata) will be notified through the propertyAdded() and propertyRemoved()
+ * signals. Notifications will also be sent if any of the watched resources is deleted.
+ * -# By resources and properties -
+ * Specify the exact resources and their properties. Any changes made to the specified resources
+ * which touch one of the specified properties will be notified through the propertyAdded() and propertyRemoved()
+ * signals.
+ * -# By types -
+ * Specific types may be specified via add/setType. If types are set, then notifications will be
+ * sent for all new resources of that type. This includes property changes and resource creation and removal.
+ * TODO: add flags that allow to only watch for resource creation and removal.
+ * -# By types and properties -
+ * Both the types and properties may be specified. Notifications will be sent for property changes
+ * in resource with the specified types.
+ *
+ * \section nepomuk_rw_examples Resource Watcher Usage Example
+ *
+ * The following code creates a new ResourceWatcher, configures it to listen to changes on the \c nmm:performer
+ * property on one specific resource \c res.
+ *
+ * \code
+ * Nepomuk::ResourceWatcher* watcher = new Nepomuk::ResourceWatcher(this);
+ * watcher->addResource(res);
+ * watcher->addProperty(NMM:performer());
+ * connect(watcher, SIGNAL(propertyAdded(Nepomuk::Resource, Nepomuk::Types::Property, QVariant)),
+ * this, SLOT(slotPropertyChanged()));
+ * connect(watcher, SIGNAL(propertyRemoved(Nepomuk::Resource, Nepomuk::Types::Property, QVariant)),
+ * this, SLOT(slotPropertyChanged()));
+ * rwatcher->start();
+ * \endcode
+ *
+ * \author Vishesh Handa <handa.vish@gmail.com>, Sebastian Trueg <trueg@kde.org>
+ *
+ * \ingroup nepomuk_datamanagement
+ */
+ class NEPOMUK_DATA_MANAGEMENT_EXPORT ResourceWatcher : public QObject
+ {
+ Q_OBJECT
+
+ public:
+ /**
+ * \brief Create a new %ResourceWatcher instance.
+ *
+ * This instance will not emit any signals before it has been configured
+ * and started.
+ */
+ ResourceWatcher( QObject* parent = 0 );
+
+ /**
+ * \brief Destructor.
+ */
+ virtual ~ResourceWatcher();
+
+ /**
+ * \brief Add a type to be watched.
+ *
+ * Every resource of this type will be watched for changes.
+ *
+ * \sa setTypes()
+ */
+ void addType( const Types::Class & type );
+
+ /**
+ * \brief Add a resource to be watched.
+ *
+ * Every change to this resource will be
+ * signalled, depending on the configured properties().
+ *
+ * \sa setResources()
+ */
+ void addResource( const Nepomuk::Resource & res );
+
+ /**
+ * \brief Add a property to be watched.
+ *
+ * Every change to a value of this property
+ * will be signalled, depending on the configured resources() or types().
+ *
+ * \sa setProperties()
+ */
+ void addProperty( const Types::Property & property );
+
+ /**
+ * \brief Set the types to be watched.
+ *
+ * Every resource having one of these types will be watched for changes.
+ *
+ * \sa addType()
+ */
+ void setTypes( const QList<Types::Class> & types_ );
+
+ /**
+ * \brief Set the resources to be watched.
+ *
+ * Every change to one of these resources will be
+ * signalled, depending on the configured properties().
+ *
+ * \sa addResource()
+ */
+ void setResources( const QList<Nepomuk::Resource> & resources_ );
+
+ /**
+ * \brief Set the properties to be watched.
+ *
+ * Every change to a value of any of these properties
+ * will be signalled, depending on the configured resources() or types().
+ *
+ * \sa addProperty()
+ */
+ void setProperties( const QList<Types::Property> & properties_ );
+
+ /**
+ * \brief The types that have been configured via addType() and setTypes().
+ *
+ * Every resource having one of these types will be watched
+ * for changes.
+ */
+ QList<Types::Class> types() const;
+
+ /**
+ * \brief The resources that have been configured via addResource() and setResources().
+ *
+ * Every change to one of these resources will be
+ * signalled, depending on the configured properties().
+ */
+ QList<Nepomuk::Resource> resources() const;
+
+ /**
+ * \brief The properties that have been configured via addProperty() and setProperties().
+ *
+ * Every change to a value of any of these properties
+ * will be signalled, depending on the configured resources() or types().
+ */
+ QList<Types::Property> properties() const;
+
+ public Q_SLOTS:
+ /**
+ * \brief Start the signalling of changes.
+ *
+ * Before calling this method no signal will be emitted. In
+ * combination with stop() this allows to suspend the watching.
+ * Calling start() multiple times has no effect.
+ */
+ bool start();
+
+ /**
+ * \brief Stop the signalling of changes.
+ *
+ * Allows to stop the watcher which has been started
+ * via start(). Calling stop() multiple times has no effect.
+ */
+ void stop();
+
+ Q_SIGNALS:
+ /**
+ * \brief This signal is emitted when a new resource is created.
+ * \param resource The newly created resource.
+ * \param types The types the new resource has. If types() have been configured this list will always
+ * contain one of the configured types.
+ */
+ void resourceCreated( const Nepomuk::Resource & resource, const QList<QUrl>& types ); //FIXME: Use either Resource or uri, not a mix
+
+ /**
+ * \brief This signal is emitted when a resource is deleted.
+ * \param uri The resource URI of the removed resource.
+ * \param types The types the removed resource had. If types() have been configured this list will always
+ * contain one of the configured types.
+ */
+ void resourceRemoved( const QUrl & uri, const QList<QUrl>& types );
+
+ /**
+ * \brief This signal is emitted when a type has been added to a resource. This does not include creation which
+ * is signalled via resourceCreated(). It only applies to changes in a resource's types.
+ * \param res The changed resource.
+ * \param type The newly added type. If types() have been configured it will be one of them.
+ */
+ void resourceTypeAdded( const Nepomuk::Resource & res, const Types::Class & type );
+
+ /**
+ * \brief This signal is emitted when a type has been removed from a resource.
+ *
+ * This does not include removal of entire resources which is signalled via resourceRemoved().
+ * It only applies to changes in a resource's types.
+ * \param res The changed resource.
+ * \param type The removed type. If types() have been configured it will be one of them.
+ */
+ void resourceTypeRemoved( const Nepomuk::Resource & res, const Types::Class & type );
+
+ /**
+ * \brief This signal is emitted when a property value is added.
+ * \param resource The changed resource.
+ * \param property The property which has a new value.
+ * \param value The newly added property value.
+ */
+ void propertyAdded( const Nepomuk::Resource & resource,
+ const Nepomuk::Types::Property & property,
+ const QVariant & value );
+
+ /**
+ * \brief This signal is emitted when a property value is removed.
+ * \param resource The changed resource.
+ * \param property The property which was changed.
+ * \param value The removed property value.
+ */
+ void propertyRemoved( const Nepomuk::Resource & resource,
+ const Nepomuk::Types::Property & property,
+ const QVariant & value );
+
+ /**
+ * \brief This signal is emitted when a property value is changed.
+ *
+ * This signal cannot be emitted for all changes. It doesn't work if a property is first
+ * removed and then set, cause the Data Mangement Service does not maintain an internal
+ * cache for the purpose of emitting the propertyChanged signal.
+ *
+ * Specially, since one could theoretically take forever between the removal and the
+ * setting of the property.
+ *
+ * \param resource The changed resource.
+ * \param property The property which was changed.
+ * \param oldValue The removed property value.
+ */
+ void propertyChanged( const Nepomuk::Resource & resource,
+ const Nepomuk::Types::Property & property,
+ const QVariantList & oldValue,
+ const QVariantList & newValue );
+
+ private Q_SLOTS:
+ void slotResourceCreated(const QString& res, const QStringList& types);
+ void slotResourceRemoved(const QString& res, const QStringList& types);
+ void slotResourceTypeAdded(const QString& res, const QString& type);
+ void slotResourceTypeRemoved(const QString& res, const QString& type);
+ void slotPropertyAdded(const QString& res, const QString& prop, const QDBusVariant& object);
+ void slotPropertyRemoved(const QString& res, const QString& prop, const QDBusVariant& object);
+ void slotPropertyChanged(const QString& res, const QString& prop,
+ const QVariantList & oldObjs,
+ const QVariantList & newObjs);
+ private:
+ class Private;
+ Private * d;
+ };
+}
+
+#endif // RESOURCEWATCHER_H
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