org.metawidget.widgetbuilder.composite.CompositeWidgetBuilder Maven / Gradle / Ivy
// Metawidget
//
// This file is dual licensed under both the LGPL
// (http://www.gnu.org/licenses/lgpl-2.1.html) and the EPL
// (http://www.eclipse.org/org/documents/epl-v10.php). As a
// recipient of Metawidget, you may choose to receive it under either
// the LGPL or the EPL.
//
// Commercial licenses are also available. See http://metawidget.org
// for details.
package org.metawidget.widgetbuilder.composite;
import java.util.Map;
import org.metawidget.widgetbuilder.iface.AdvancedWidgetBuilder;
import org.metawidget.widgetbuilder.iface.WidgetBuilder;
import org.metawidget.widgetbuilder.iface.WidgetBuilderException;
/**
* Delegates widget building to one or more sub-WidgetBuilders.
*
* Each sub-WidgetBuilder in the list is invoked, in order, calling its buildWidget
* method. The first non-null result is returned. If all sub-WidgetBuilders return null, null is
* returned (the parent Metawidget will generally instantiate a nested Metawidget in this case).
*
* Note: the name CompositeWidgetBuilder refers to the Composite design pattern.
*
* @author Richard Kennard
*/
public class CompositeWidgetBuilder
implements AdvancedWidgetBuilder {
//
// Private members
//
/* package private */final WidgetBuilder[] mWidgetBuilders;
//
// Constructor
//
@SuppressWarnings( "unchecked" )
public CompositeWidgetBuilder( CompositeWidgetBuilderConfig config ) {
WidgetBuilder[] widgetBuilders = config.getWidgetBuilders();
// Must have at least two WidgetBuilders
if ( widgetBuilders == null || widgetBuilders.length < 2 ) {
throw WidgetBuilderException.newException( "CompositeWidgetBuilder needs at least two WidgetBuilders" );
}
// Defensive copy
mWidgetBuilders = new WidgetBuilder[widgetBuilders.length];
for ( int loop = 0, length = widgetBuilders.length; loop < length; loop++ ) {
WidgetBuilder widgetBuilder = widgetBuilders[loop];
for ( int checkDuplicates = 0; checkDuplicates < loop; checkDuplicates++ ) {
if ( mWidgetBuilders[checkDuplicates].equals( widgetBuilder ) ) {
throw WidgetBuilderException.newException( "CompositeWidgetBuilder's list of WidgetBuilders contains two of the same " + widgetBuilder.getClass().getName() );
}
}
mWidgetBuilders[loop] = widgetBuilder;
}
}
//
// Public methods
//
public void onStartBuild( M metawidget ) {
for ( WidgetBuilder widgetBuilder : mWidgetBuilders ) {
if ( widgetBuilder instanceof AdvancedWidgetBuilder ) {
((AdvancedWidgetBuilder) widgetBuilder).onStartBuild( metawidget );
}
}
}
public W buildWidget( String elementName, Map attributes, M metawidget ) {
for ( WidgetBuilder widgetBuilder : mWidgetBuilders ) {
W widget = widgetBuilder.buildWidget( elementName, attributes, metawidget );
if ( widget != null ) {
return widget;
}
}
return null;
}
public void onEndBuild( M metawidget ) {
for ( WidgetBuilder widgetBuilder : mWidgetBuilders ) {
if ( widgetBuilder instanceof AdvancedWidgetBuilder ) {
((AdvancedWidgetBuilder) widgetBuilder).onEndBuild( metawidget );
}
}
}
/**
* Exposed for getValue calls.
*/
public WidgetBuilder[] getWidgetBuilders() {
// Defensive copy
@SuppressWarnings( "unchecked" )
WidgetBuilder[] widgetBuilders = new WidgetBuilder[mWidgetBuilders.length];
System.arraycopy( mWidgetBuilders, 0, widgetBuilders, 0, mWidgetBuilders.length );
return widgetBuilders;
}
}