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/**
 * Licensed under the Common Development and Distribution License,
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.sun.com/cddl/
 *   
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or 
 * implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

package com.sun.facelets.tag;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import com.sun.facelets.FaceletHandler;

/**
 * Foundation class for FaceletHandlers associated with markup in a Facelet
 * document.
 * 
 * @author Jacob Hookom
 * @version $Id: TagHandler.java,v 1.5 2005/09/02 19:25:57 jhook Exp $
 */
public abstract class TagHandler implements FaceletHandler {

    protected final String tagId;

    protected final Tag tag;

    protected final FaceletHandler nextHandler;

    public TagHandler(TagConfig config) {
        this.tagId = config.getTagId();
        this.tag = config.getTag();
        this.nextHandler = config.getNextHandler();
    }

    /**
     * Utility method for fetching the appropriate TagAttribute
     * 
     * @param localName
     *            name of attribute
     * @return TagAttribute if found, otherwise null
     */
    protected final TagAttribute getAttribute(String localName) {
        return this.tag.getAttributes().get(localName);
    }

    /**
     * Utility method for fetching a required TagAttribute
     * 
     * @param localName
     *            name of the attribute
     * @return TagAttribute if found, otherwise error
     * @throws TagException
     *             if the attribute was not found
     */
    protected final TagAttribute getRequiredAttribute(String localName)
            throws TagException {
        TagAttribute attr = this.getAttribute(localName);
        if (attr == null) {
            throw new TagException(this.tag, "Attribute '" + localName
                    + "' is required");
        }
        return attr;
    }
    
    /**
     * Searches child handlers, starting at the 'nextHandler' for all
     * instances of the passed type.  This process will stop searching
     * a branch if an instance is found.
     * 
     * @param type Class type to search for
     * @return iterator over instances of FaceletHandlers of the matching type
     */
    protected final Iterator findNextByType(Class type) {
        List found = new ArrayList();
        if (type.isAssignableFrom(this.nextHandler.getClass())) {
            found.add(this.nextHandler);
        } else if (this.nextHandler instanceof CompositeFaceletHandler) {
            FaceletHandler[] h = ((CompositeFaceletHandler) this.nextHandler).getHandlers();
            for (int i = 0; i < h.length; i++) {
                if (type.isAssignableFrom(h[i].getClass())) {
                    found.add(h[i]);
                }
            }
        }
        return found.iterator();
    }

    public String toString() {
        return this.tag.toString();
    }
}