org.metawidget.widgetprocessor.iface.WidgetProcessor 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.widgetprocessor.iface;
import java.util.Map;
import org.metawidget.iface.Immutable;
/**
* Common interface implemented by all WidgetProcessors. WidgetProcessors allow arbitrary processing
* of a widget following its building by the WidgetBuilder and before adding to the Layout.
*
* WidgetProcessors must be immutable (or, at least, appear that way to clients. They can have
* caches or configuration settings internally, as long as they are threadsafe). If they need to
* store state, they should use the Metawidget passed to each method.
*
* Note: WidgetProcessors are an example of the Strategy design pattern.
*
* @param
* base class of widgets that this WidgetProcessor processes
* @param
* Metawidget that supports this WidgetProcessor
* @author Richard Kennard
*/
public interface WidgetProcessor
extends Immutable {
//
// Methods
//
/**
* Process the given widget. Called after a widget has been built by the
* WidgetBuilder, and before it is added to the Layout.
*
* @param widget
* the widget to process. Never null
* @param elementName
* XML node name of the business field. Typically 'entity', 'property' or 'action'.
* Never null
* @param attributes
* attributes of the widget to process. Never null. This Map is modifiable - changes
* will be passed to subsequent WidgetProcessors and Layouts
* @param metawidget
* the parent Metawidget. Never null
* @return generally the original widget (as passed in to the first argument). Can be a
* different widget if the WidgetProcessor wishes to substitute the original widget for
* another. Can be null if the WidgetProcessor wishes to cancel all further processing
* of this widget (including laying out)
*/
W processWidget( W widget, String elementName, Map attributes, M metawidget );
}