org.apache.solr.handler.tagger.XmlOffsetCorrector Maven / Gradle / Ivy
/*
* This software was produced for the U. S. Government
* under Contract No. W15P7T-11-C-F600, and is
* subject to the Rights in Noncommercial Computer Software
* and Noncommercial Computer Software Documentation
* Clause 252.227-7014 (JUN 1995)
*
* Copyright 2013 The MITRE Corporation. All Rights Reserved.
*
* 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.solr.handler.tagger;
import javax.xml.stream.XMLResolver;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.events.XMLEvent;
import java.io.InputStream;
import java.io.StringReader;
import com.ctc.wstx.stax.WstxInputFactory;
import org.apache.commons.io.input.ClosedInputStream;
import org.codehaus.stax2.LocationInfo;
import org.codehaus.stax2.XMLInputFactory2;
import org.codehaus.stax2.XMLStreamReader2;
/**
* Corrects offsets to adjust for XML formatted data. The goal is such that the caller should be
* able to insert a start XML tag at the start offset and a corresponding end XML tag at the end
* offset of the tagger, and have it be valid XML. See {@link #correctPair(int, int)}.
*
* This will not work on invalid XML.
*
* Not thread-safe.
*/
public class XmlOffsetCorrector extends OffsetCorrector {
//TODO use StAX without hard requirement on woodstox. xmlStreamReader.getLocation().getCharacterOffset()
private static final XMLInputFactory2 XML_INPUT_FACTORY;
static {
// note: similar code in Solr's EmptyEntityResolver
XML_INPUT_FACTORY = new WstxInputFactory();
XML_INPUT_FACTORY.setXMLResolver(new XMLResolver() {
@Override
public InputStream resolveEntity(String publicId, String systemId, String baseURI, String namespace) {
return ClosedInputStream.CLOSED_INPUT_STREAM;
}
});
// TODO disable DTD?
// XML_INPUT_FACTORY.setProperty(XMLInputFactory.IS_VALIDATING, Boolean.FALSE)
XML_INPUT_FACTORY.configureForSpeed();
}
/**
* Initialize based on the document text.
* @param docText non-null XML content.
* @throws XMLStreamException If there's a problem parsing the XML.
*/
public XmlOffsetCorrector(String docText) throws XMLStreamException {
super(docText, false);
int tagCounter = 0;
int thisTag = -1;
//note: we *could* add a virtual outer tag to guarantee all text is in the context of a tag,
// but we shouldn't need to because there is no findable text outside the top element.
final XMLStreamReader2 xmlStreamReader =
(XMLStreamReader2) XML_INPUT_FACTORY.createXMLStreamReader(new StringReader(docText));
while (xmlStreamReader.hasNext()) {
int eventType = xmlStreamReader.next();
switch (eventType) {
case XMLEvent.START_ELEMENT: {
tagInfo.ensureCapacity(tagInfo.size() + 5);
final int parentTag = thisTag;
final LocationInfo info = xmlStreamReader.getLocationInfo();
tagInfo.add(parentTag);
tagInfo.add((int) info.getStartingCharOffset(), (int) info.getEndingCharOffset());
tagInfo.add(-1, -1);//these 2 will be populated when we get to the close tag
thisTag = tagCounter++;
parentChangeOffsets.add((int) info.getStartingCharOffset());
parentChangeIds.add(thisTag);
break;
}
case XMLEvent.END_ELEMENT: {
final LocationInfo info = xmlStreamReader.getLocationInfo();
tagInfo.set(5 * thisTag + 3, (int) info.getStartingCharOffset());
tagInfo.set(5 * thisTag + 4, (int) info.getEndingCharOffset());
thisTag = getParentTag(thisTag);
parentChangeOffsets.add((int) info.getEndingCharOffset());
parentChangeIds.add(thisTag);
break;
}
default: //do nothing
}
}
}
}