| /* |
| * 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: 1.25 $ |
| */ |
| |
| 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; |
| } |
| |
| } |