CompositeTagDecorator.java

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package com.sun.faces.facelets.tag;

import com.sun.faces.util.Util;

import javax.faces.view.facelets.Tag;
import javax.faces.view.facelets.TagDecorator;

/**
 * A TagDecorator that is composed of 1 or more TagDecorator instances. It uses
 * the chain of responsibility pattern to stop processing if any of the
 * TagDecorators return a value other than null.
 * 
 * @author Jacob Hookom
 * @version $Id$
 */
public final class CompositeTagDecorator implements TagDecorator {

    private final TagDecorator[] decorators;

    private final DefaultTagDecorator defaultTagDecorator;

    public CompositeTagDecorator(TagDecorator[] decorators) {
        Util.notNull("decorators", decorators);
        this.decorators = decorators;
        this.defaultTagDecorator = new DefaultTagDecorator();
    }

    /**
     * Uses the chain of responsibility pattern to stop processing if any of
     * the TagDecorators return a value other than null.
     */
    @Override
    public Tag decorate(Tag tag) {
        // eliminate the jsf: attributes
        Tag noJsfAttributes = defaultTagDecorator.decorate(tag);
        if(noJsfAttributes != null) {
            // pass the converted tag to the other decorators
            tag = noJsfAttributes;
        }

        Tag t = null;
        for (int i = 0; i < this.decorators.length; i++) {
            t = this.decorators[i].decorate(tag);
            if (t != null) {
                return t;
            }
        }
        return tag;
    }

}