/*
* 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;
import java.io.File;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.beanutils.ConvertUtils;
import org.apache.commons.beanutils.Converter;
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.TagFactory;
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: 155420 $
*/
public abstract class TagLibrary {
private Map tags = new HashMap();
static {
// register standard converters
ConvertUtils.register(
new Converter() {
public Object convert(Class type, Object value) {
if ( value instanceof File ) {
return (File) value;
}
else if ( value != null ) {
String text = value.toString();
return new File( text );
}
return null;
}
},
File.class
);
}
public TagLibrary() {
}
/** Creates a new script to execute the given tag name and attributes */
public TagScript createTagScript(String name, Attributes attributes)
throws JellyException {
Object value = tags.get(name);
if (value instanceof Class) {
Class type = (Class) value;
return TagScript.newInstance(type);
}
else if (value instanceof TagFactory) {
return new TagScript( (TagFactory) value );
}
return null;
}
/** Creates a new Tag for the given tag name and attributes */
public Tag createTag(String name, Attributes attributes)
throws JellyException {
Object value = tags.get(name);
if (value instanceof Class) {
Class type = (Class) value;
try {
return (Tag) type.newInstance();
} catch (InstantiationException e) {
throw new JellyException(e.toString());
} catch (IllegalAccessException e) {
throw new JellyException(e.toString());
}
}
else if (value instanceof TagFactory) {
TagFactory factory = (TagFactory) value;
return factory.createTag(name, attributes);
}
return null;
}
/** Allows taglibs to use their own expression evaluation mechanism */
public Expression createExpression(
ExpressionFactory factory,
TagScript tagScript,
String attributeName,
String attributeValue)
throws JellyException {
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 implementation Class for a given tag name
*/
protected void registerTag(String name, Class type) {
tags.put(name, type);
}
/**
* Registers a tag factory for a given tag name
*/
protected void registerTagFactory(String name, TagFactory tagFactory) {
tags.put(name, tagFactory);
}
/** Allows derived tag libraries to use their own factory */
protected ExpressionFactory getExpressionFactory() {
return null;
}
protected Map getTagClasses() {
return tags;
}
}