/*
 * Copyright 2002,2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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 org.apache.commons.jelly.tags.define;

import org.apache.commons.jelly.JellyTagException;
import org.apache.commons.jelly.TagSupport;
import org.apache.commons.jelly.impl.DynamicTagLibrary;

/**
 * An abstract base class useful for implementation inheritence.
 *
 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
 * @version $Revision: 1.5 $
 */
public abstract class DefineTagSupport extends TagSupport {

    // Implementation methods
    //-------------------------------------------------------------------------

    /**
     * @return the current dynamic tag library instance or throws a JellyException
     * if one is not available
     */
    protected DynamicTagLibrary getTagLibrary() throws JellyTagException {
        TaglibTag tag
            = (TaglibTag) findAncestorWithClass(TaglibTag.class);
        if ( tag == null ) {
            throw new JellyTagException( "<define:tag> must be inside <define:taglib>" );
        }
        return tag.getTagLibrary();
    }

}