add clearData() methods

svn path=/trunk/KDE/kdebase/workspace/libs/plasma/; revision=685602

dataengine.cpp

@@ -225,6 +225,15 @@ void DataEngine::setData(const QString& source, const QString& key, const QVaria
     d->queueUpdate();
 }
 
+void DataEngine::clearData(const QString& source)
+{
+    DataSource* s = d->source(source, false);
+    if (s) {
+        s->clearData();
+        d->queueUpdate();
+    }
+}
+
 void DataEngine::removeData(const QString& source, const QString& key)
 {
     DataSource* s = d->source(source, false);

dataengine.h

@@ -210,6 +210,13 @@ class PLASMA_EXPORT DataEngine : public QObject
          **/
         void setData(const QString& source, const QString& key, const QVariant& value);
 
+        /**
+         * Clears all the data associated with a data source.
+         *
+         * @param source the name of the data source
+         **/
+        void clearData(const QString& source);
+
         /**
          * Removes a data entry from a source
          *

datasource.cpp

@@ -69,6 +69,17 @@ void DataSource::setData(const QString& key, const QVariant& value)
     d->dirty = true;
 }
 
+void DataSource::clearData()
+{
+    if (d->data.count() < 1) {
+        // avoid an update if we don't have any data anyways
+        return;
+    }
+
+    d->data.clear();
+    d->dirty = true;
+}
+
 void DataSource::checkForUpdate()
 {
     if (d->dirty) {

datasource.h

@@ -69,6 +69,11 @@ class PLASMA_EXPORT DataSource : public QObject
          **/
         void setData(const QString& key, const QVariant& value);
 
+        /**
+         * Clears all data currently associated with this source
+         **/
+        void clearData();
+
         /**
          * Checks for whether the data has changed and therefore an update
          * signal needs to be emitted.