001/* 
002    Licensed to the Apache Software Foundation (ASF) under one
003    or more contributor license agreements.  See the NOTICE file
004    distributed with this work for additional information
005    regarding copyright ownership.  The ASF licenses this file
006    to you under the Apache License, Version 2.0 (the
007    "License"); you may not use this file except in compliance
008    with the License.  You may obtain a copy of the License at
009
010       http://www.apache.org/licenses/LICENSE-2.0
011
012    Unless required by applicable law or agreed to in writing,
013    software distributed under the License is distributed on an
014    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015    KIND, either express or implied.  See the License for the
016    specific language governing permissions and limitations
017    under the License.  
018 */
019package org.apache.wiki.tags;
020
021import org.apache.log4j.Logger;
022import org.apache.wiki.api.core.Context;
023import org.apache.wiki.api.core.Page;
024
025import javax.servlet.jsp.JspWriter;
026import javax.servlet.jsp.PageContext;
027import javax.servlet.jsp.tagext.BodyTagSupport;
028import javax.servlet.jsp.tagext.TryCatchFinally;
029import java.io.IOException;
030import java.util.Arrays;
031import java.util.Collection;
032import java.util.Iterator;
033
034
035/**
036 *  Iterates through tags.
037 *
038 *  <P><B>Attributes</B></P>
039 *  <UL>
040 *    <LI>list - a collection.
041 *  </UL>
042 *
043 *  @since 2.0
044 */
045public abstract class IteratorTag extends BodyTagSupport implements TryCatchFinally {
046
047    private static final long serialVersionUID = 8945334759300595321L;
048    protected String m_pageName;
049    protected Iterator< ? > m_iterator;
050    protected Context m_wikiContext;
051
052    private static final Logger log = Logger.getLogger( IteratorTag.class );
053
054    /**
055     *  Sets the collection that is used to form the iteration.
056     *  
057     *  @param arg A Collection which will be iterated.
058     */
059    public void setList( final Collection< ? > arg ) {
060        if( arg != null ) {
061            m_iterator = arg.iterator();
062        }
063    }
064
065    /**
066     *  Sets the collection list, but using an array.
067     *
068     *  @param arg An array of objects which will be iterated.
069     */
070    public void setList( final Object[] arg ) {
071        if( arg != null ) {
072            m_iterator = Arrays.asList(arg).iterator();
073        }
074    }
075
076    /**
077     *  Clears the iterator away.  After calling this method doStartTag() will always return SKIP_BODY
078     */
079    public void clearList() {
080        m_iterator = null;
081    }
082    
083    /**
084     *  Override this method to reset your own iterator.
085     */
086    public void resetIterator() {
087        // No operation here
088    }
089    
090    /** {@inheritDoc} */
091    @Override
092    public int doStartTag() {
093        m_wikiContext = Context.findContext(pageContext);
094        resetIterator();
095        if( m_iterator == null ) {
096            return SKIP_BODY;
097        }
098        if( m_iterator.hasNext() ) {
099            buildContext();
100        }
101
102        return EVAL_BODY_BUFFERED;
103    }
104
105    /**
106     *  Arg, I hate globals.
107     */
108    private void buildContext() {
109        final Context context = m_wikiContext.clone();
110        final Object o = m_iterator.next();
111        if( o instanceof Page ) {
112            context.setPage( ( Page )o );
113        }
114
115        pageContext.setAttribute( Context.ATTR_CONTEXT, context, PageContext.REQUEST_SCOPE );
116        pageContext.setAttribute( getId(), o );
117    }
118
119    /** {@inheritDoc} */
120    @Override
121    public int doEndTag() {
122        // Return back to the original.
123        pageContext.setAttribute( Context.ATTR_CONTEXT, m_wikiContext, PageContext.REQUEST_SCOPE );
124
125        return EVAL_PAGE;
126    }
127
128    /** {@inheritDoc} */
129    @Override
130    public int doAfterBody() {
131        if( bodyContent != null ) {
132            try {
133                final JspWriter out = getPreviousOut();
134                out.print( bodyContent.getString() );
135                bodyContent.clearBody();
136            } catch( final IOException e ) {
137                log.error( "Unable to get inner tag text", e );
138                // FIXME: throw something?
139            }
140        }
141
142        if( m_iterator != null && m_iterator.hasNext() ) {
143            buildContext();
144            return EVAL_BODY_BUFFERED;
145        }
146
147        return SKIP_BODY;
148    }
149    
150    /**
151     *  In case your tag throws an exception at any point, you can override this method and implement a custom exception handler.
152     *  <p>
153     *  By default, this handler does nothing.
154     *  
155     *  @param arg0 The Throwable that the tag threw
156     *  @throws Throwable I have no idea why this would throw anything
157     */
158    @Override
159    public void doCatch( final Throwable arg0) throws Throwable {
160    }
161
162    /**
163     *  Executed after the tag has been finished.  This is a great place to put any cleanup code.  However you <b>must</b> call
164     *  super.doFinally() if you override this method, or else some of the things may not work as expected.
165     */
166    @Override
167    public void doFinally() {
168        resetIterator();
169        m_iterator = null;
170        m_pageName = null;
171        m_wikiContext = null;        
172    }
173
174}