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/*
* 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.
*/
/* $Id$ */
package org.apache.fop.accessibility;
import java.io.StringWriter;
import java.io.Writer;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMResult;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.sax.SAXTransformerFactory;
import javax.xml.transform.sax.TransformerHandler;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.NodeList;
import org.xml.sax.ContentHandler;
import org.xml.sax.SAXException;
import org.apache.fop.util.DelegatingContentHandler;
/**
* A StructureTree implementation re-created from the structure stored in an IF
* XML document.
*/
public class ParsedStructureTree implements StructureTree {
private SAXTransformerFactory factory;
private List pageSequenceStructures = new ArrayList();
/**
* Creates a new instance.
*
* @param factory a factory internally used to build the structures of page
* sequences
*/
public ParsedStructureTree(SAXTransformerFactory factory) {
this.factory = factory;
}
/**
* Returns a ContenHandler for parsing the structure of a new page sequence.
* It is assumed that page sequences are being parsed in the document order.
* This class will automatically number the structure trees.
*
* @return a handler for parsing the <structure-tree> element and its
* descendants
* @throws SAXException if there is an error when creating the handler
*/
public ContentHandler getHandlerForNextPageSequence() throws SAXException {
TransformerHandler structureTreeBuilder;
try {
structureTreeBuilder = factory.newTransformerHandler();
} catch (TransformerConfigurationException e) {
throw new SAXException(e);
}
final DOMResult domResult = new DOMResult();
structureTreeBuilder.setResult(domResult);
return new DelegatingContentHandler(structureTreeBuilder) {
public void characters(char[] ch, int start, int length) throws SAXException {
/*
* There's no text node in the structure tree. This is just
* whitespace => ignore
*/
}
public void endDocument() throws SAXException {
super.endDocument();
pageSequenceStructures.add(domResult.getNode().getFirstChild().getChildNodes());
}
};
}
/** {@inheritDoc} */
public NodeList getPageSequence(int number) {
return (NodeList) pageSequenceStructures.get(number - 1);
}
/**
* Returns an XML-like representation of the structure trees.
* <p>
* <strong>Note:</strong> use only for debugging purpose, as this method
* performs non-trivial operations.
* </p>
* @return a string representation of this object
*/
public String toString() {
try {
Transformer t = TransformerFactory.newInstance().newTransformer();
Writer str = new StringWriter();
for (Iterator iter = pageSequenceStructures.iterator(); iter.hasNext();) {
NodeList nodes = (NodeList) iter.next();
for (int i = 0, c = nodes.getLength(); i < c; i++) {
t.transform(new DOMSource(nodes.item(i)), new StreamResult(str));
}
}
return str.toString();
} catch (Exception e) {
return e.toString();
}
}
}
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