/*
* $Header: /home/cvs/jakarta-commons-sandbox/jelly/src/java/org/apache/commons/jelly/TagLibrary.java,v 1.11 2002/06/07 11:56:29 dion Exp $
* $Revision: 1.11 $
* $Date: 2002/06/07 11:56:29 $
*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999-2002 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowlegement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The Jakarta Project", "Commons", and "Apache Software
* Foundation" must not be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache"
* nor may "Apache" appear in their names without prior written
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*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
* $Id: TagLibrary.java,v 1.11 2002/06/07 11:56:29 dion Exp $
*/
package org.apache.commons.jelly;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.jelly.expression.CompositeExpression;
import org.apache.commons.jelly.expression.ConstantExpression;
import org.apache.commons.jelly.expression.Expression;
import org.apache.commons.jelly.expression.ExpressionFactory;
import org.apache.commons.jelly.impl.TagScript;
import org.xml.sax.Attributes;
/** <p><code>Taglib</code> represents the metadata for a Jelly custom tag library.</p>
*
* @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
* @version $Revision: 1.11 $
*/
public abstract class TagLibrary {
private Map tags = new HashMap();
public TagLibrary() {
}
/** Creates a new script to execute the given tag name and attributes */
public TagScript createTagScript(String name, Attributes attributes)
throws Exception {
Class type = (Class) tags.get(name);
if ( type != null ) {
Tag tag = (Tag) type.newInstance();
return TagScript.newInstance(tag);
}
return null;
}
/** Allows taglibs to use their own expression evaluation mechanism */
public Expression createExpression(
ExpressionFactory factory,
String tagName,
String attributeName,
String attributeValue)
throws Exception {
ExpressionFactory myFactory = getExpressionFactory();
if (myFactory == null) {
myFactory = factory;
}
if (myFactory != null) {
return CompositeExpression.parse(attributeValue, myFactory);
}
// will use a constant expression instead
return new ConstantExpression(attributeValue);
}
// Implementation methods
//-------------------------------------------------------------------------
/** Registers a tag class for a given tag name */
protected void registerTag(String name, Class type) {
tags.put(name, type);
}
/** Allows derived tag libraries to use their own factory */
protected ExpressionFactory getExpressionFactory() {
return null;
}
protected Map getTagClasses() {
return tags;
}
}