/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.cocoon.transformation;
import org.apache.avalon.framework.parameters.Parameters;
import org.apache.cocoon.ProcessingException;
import org.apache.cocoon.caching.CacheableProcessingComponent;
import org.apache.cocoon.environment.SourceResolver;
import org.apache.excalibur.source.SourceValidity;
import org.apache.excalibur.source.impl.validity.NOPValidity;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.AttributesImpl;
import java.io.IOException;
import java.util.Map;
/**
* @cocoon.sitemap.component.documentation
* The filter transformer can be used to let only an amount of elements through in
* a given block.
*
* @cocoon.sitemap.component.name filter
* @cocoon.sitemap.component.documentation.caching TBD
* @cocoon.sitemap.component.logger sitemap.transformer.filter
*
*
* The filter transformer can be used to let only an amount of elements through in
* a given block.
*
* <p>Usage in the sitemap:
* <map:transform type="filter">
* <map:parameter name="element-name" value="row"/>
* <map:parameter name="count" value="5"/>
* <map:parameter name="blocknr" value="3"/>
* </map:transform>
*
* <p>Only the 3rd block will be shown, containing only 5 row elements.
*
* <p><b>Known limitation: behaviour of transformer when trigger elements are nested
* is not predictable.</b>
*
* @author <a href="mailto:sven.beauprez@the-ecorp.com">Sven Beauprez</a>
* @author <a href="mailto:cziegeler@apache.org">Carsten Ziegeler</a>
* @version CVS $Id$
*/
public class FilterTransformer
extends AbstractTransformer
implements CacheableProcessingComponent {
private static final String ELEMENT = "element-name";
private static final String COUNT = "count";
private static final String BLOCKNR = "blocknr";
private static final String BLOCK = "block";
private static final String BLOCKID = "id";
private static final int DEFAULT_COUNT = 10;
private static final int DEFAULT_BLOCK = 1;
protected int counter;
protected int count;
protected int blocknr;
protected int currentBlocknr;
protected String elementName;
protected String parentName;
protected boolean skip;
protected boolean foundIt;
/** BEGIN SitemapComponent methods **/
public void setup(SourceResolver resolver,
Map objectModel,
String source,
Parameters parameters)
throws ProcessingException, SAXException, IOException {
this.counter=0;
this.currentBlocknr=0;
this.skip=false;
this.foundIt=false;
this.parentName=null;
this.elementName = parameters.getParameter(ELEMENT, "");
this.count = parameters.getParameterAsInteger(COUNT, DEFAULT_COUNT);
this.blocknr = parameters.getParameterAsInteger(BLOCKNR, DEFAULT_BLOCK);
if (this.elementName == null || this.elementName.length() == 0 || this.count == 0) {
throw new ProcessingException("FilterTransformer: both "+ ELEMENT + " and " +
COUNT + " parameters need to be specified");
}
}
/**
* Generate the unique key.
* This key must be unique inside the space of this component.
* This method must be invoked before the generateValidity() method.
*
* @return The generated key or <code>0</code> if the component
* is currently not cacheable.
*/
public java.io.Serializable getKey() {
return this.elementName + '<' + this.count + '>' + this.blocknr;
}
/**
* Generate the validity object.
* Before this method can be invoked the generateKey() method
* must be invoked.
*
* @return The generated validity object or <code>null</code> if the
* component is currently not cacheable.
*/
public SourceValidity getValidity() {
return NOPValidity.SHARED_INSTANCE;
}
/** BEGIN SAX ContentHandler handlers **/
public void startElement(String uri, String name, String raw, Attributes attributes)
throws SAXException {
if (name.equalsIgnoreCase(elementName)) {
this.foundIt = true;
this.counter++;
if (this.counter <= (this.count*(this.blocknr)) && this.counter > (this.count*(this.blocknr-1))) {
this.skip = false;
} else {
this.skip = true;
}
if (this.currentBlocknr != (int)Math.ceil((float)this.counter/this.count)) {
this.currentBlocknr = (int)Math.ceil((float)this.counter/this.count);
AttributesImpl attr = new AttributesImpl();
attr.addAttribute("", BLOCKID, BLOCKID, "CDATA", String.valueOf(this.currentBlocknr));
if (this.counter < this.count) {
super.contentHandler.startElement("", BLOCK, BLOCK, attr);
} else {
// fix Bugzilla Bug 13904, check if counter == 1
// in this case there is no startElement("", BLOCK, BLOCK)
// written, yet
if (this.counter > 1) {
super.contentHandler.endElement("", BLOCK, BLOCK);
}
super.contentHandler.startElement("", BLOCK, BLOCK, attr);
}
}
} else if (!this.foundIt) {
this.parentName = name;
}
if (!this.skip) {
super.contentHandler.startElement(uri,name,raw,attributes);
}
}
public void endElement(String uri,String name,String raw)
throws SAXException {
if (this.foundIt && name.equals(this.parentName)) {
// FIXME: VG: This will fail on XML like:
// <parent>
// <element>
// <parent>
super.contentHandler.endElement("", BLOCK, BLOCK);
super.contentHandler.endElement(uri, name, raw);
this.foundIt = false;
this.skip = false;
} else if (!this.skip) {
super.contentHandler.endElement(uri,name,raw);
}
}
public void characters(char c[], int start, int len)
throws SAXException {
if (!this.skip) {
super.contentHandler.characters(c,start,len);
}
}
public void processingInstruction(String target, String data)
throws SAXException {
if (!this.skip) {
super.contentHandler.processingInstruction(target, data);
}
}
public void startEntity(String name)
throws SAXException {
if (!this.skip) {
super.lexicalHandler.startEntity(name);
}
}
public void endEntity(String name)
throws SAXException {
if (!this.skip) {
super.lexicalHandler.endEntity( name);
}
}
public void startCDATA()
throws SAXException {
if (!this.skip) {
super.lexicalHandler.startCDATA();
}
}
public void endCDATA()
throws SAXException {
if (!this.skip) {
super.lexicalHandler.endCDATA();
}
}
public void comment(char ch[], int start, int len)
throws SAXException {
if (!this.skip) {
super.lexicalHandler.comment(ch, start, len);
}
}
}