Update items if a Nepomuk property has been changed

If a Nepomuk property has been changed (e.g. by changing the rating
in the Information Panel) the corresponding item in the view must
be updated.

1 files changed, 288 insertions, 0 deletions

diff --git a/src/kitemviews/knepomukresourcewatcher_p.h b/src/kitemviews/knepomukresourcewatcher_p.h
new file mode 100644
index 000000000..9b4b8b71d
--- /dev/null
+++ b/src/kitemviews/knepomukresourcewatcher_p.h
@@ -0,0 +1,288 @@
+/*
+    This file is part of the Nepomuk KDE project.
+    Copyright (C) 2011  Vishesh Handa <[email protected]>
+    Copyright (C) 2011 Sebastian Trueg <[email protected]>
+
+    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 <[email protected]>, Sebastian Trueg <[email protected]>
+     *
+     * \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