/*
* 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 opennlp.uima.chunker;
import org.apache.uima.UimaContext;
import org.apache.uima.analysis_component.CasAnnotator_ImplBase;
import org.apache.uima.analysis_engine.AnalysisEngineProcessException;
import org.apache.uima.cas.CAS;
import org.apache.uima.cas.FSIndex;
import org.apache.uima.cas.Feature;
import org.apache.uima.cas.Type;
import org.apache.uima.cas.TypeSystem;
import org.apache.uima.cas.text.AnnotationFS;
import org.apache.uima.resource.ResourceAccessException;
import org.apache.uima.resource.ResourceInitializationException;
import org.apache.uima.util.Level;
import org.apache.uima.util.Logger;
import opennlp.tools.chunker.ChunkerME;
import opennlp.tools.chunker.ChunkerModel;
import opennlp.uima.util.AnnotatorUtil;
import opennlp.uima.util.UimaUtil;
/**
* OpenNLP Chunker annotator.
* <p>
* Mandatory parameters
* <table border=1>
* <caption></caption>
* <tr><th>Type</th> <th>Name</th> <th>Description</th></tr>
* <tr><td>String</td> <td>opennlp.uima.ModelName</td> <td>The name of the model file</td></tr>
* <tr><td>String</td> <td>opennlp.uima.SentenceType</td> <td>The full name of the sentence type</td></tr>
* <tr><td>String</td> <td>opennlp.uima.TokenType</td> <td>The full name of the token type</td></tr>
* <tr><td>String</td> <td>opennlp.uima.POSFeature</td></tr>
* <tr><td>String</td> <td>opennlp.uima.ChunkType</td></tr>
* <tr><td>String</td> <td>opennlp.uima.ChunkTagFeature</td></tr>
* </table>
* <p>
* Optional parameters
* <table border=1>
* <caption></caption>
* <tr><th>Type</th> <th>Name</th> <th>Description</th></tr>
* <tr><td>Integer</td> <td>opennlp.uima.BeamSize</td></tr>
* </table>
*/
public final class Chunker extends CasAnnotator_ImplBase {
/**
* The chunk type parameter.
*/
public static final String CHUNK_TYPE_PARAMETER = "opennlp.uima.ChunkType";
/**
* The chunk tag feature parameter
*/
public static final String CHUNK_TAG_FEATURE_PARAMETER =
"opennlp.uima.ChunkTagFeature";
private Type mTokenType;
private Type mChunkType;
private Feature mPosFeature;
private ChunkerME mChunker;
private UimaContext context;
private Logger mLogger;
private Feature mChunkFeature;
/**
* Initializes a new instance.
* <p>
* Note: Use {@link #initialize(UimaContext) } to initialize
* this instance. Not use the constructor.
*/
public Chunker() {
// must not be implemented !
}
/**
* Initializes the current instance with the given context.
* <p>
* Note: Do all initialization in this method, do not use the constructor.
*/
public void initialize(UimaContext context)
throws ResourceInitializationException {
super.initialize(context);
this.context = context;
mLogger = context.getLogger();
if (mLogger.isLoggable(Level.INFO)) {
mLogger.log(Level.INFO, "Initializing the OpenNLP Chunker annotator.");
}
ChunkerModel model;
try {
ChunkerModelResource modelResource =
(ChunkerModelResource) context.getResourceObject(UimaUtil.MODEL_PARAMETER);
model = modelResource.getModel();
} catch (ResourceAccessException e) {
throw new ResourceInitializationException(e);
}
mChunker = new ChunkerME(model);
}
/**
* Initializes the type system.
*/
public void typeSystemInit(TypeSystem typeSystem)
throws AnalysisEngineProcessException {
// chunk type
mChunkType = AnnotatorUtil.getRequiredTypeParameter(context, typeSystem,
CHUNK_TYPE_PARAMETER);
// chunk feature
mChunkFeature = AnnotatorUtil.getRequiredFeatureParameter(context, mChunkType,
CHUNK_TAG_FEATURE_PARAMETER, CAS.TYPE_NAME_STRING);
// token type
mTokenType = AnnotatorUtil.getRequiredTypeParameter(context, typeSystem,
UimaUtil.TOKEN_TYPE_PARAMETER);
// pos feature
mPosFeature = AnnotatorUtil.getRequiredFeatureParameter(
context, mTokenType, UimaUtil.POS_FEATURE_PARAMETER, CAS.TYPE_NAME_STRING);
}
private void addChunkAnnotation(CAS tcas, AnnotationFS[] tokenAnnotations,
String tag, int start, int end) {
AnnotationFS chunk = tcas.createAnnotation(mChunkType,
tokenAnnotations[start].getBegin(), tokenAnnotations[end - 1].getEnd());
chunk.setStringValue(mChunkFeature, tag);
tcas.getIndexRepository().addFS(chunk);
}
/**
* Performs chunking on the given tcas object.
*/
public void process(CAS tcas) {
FSIndex<AnnotationFS> tokenAnnotationIndex = tcas.getAnnotationIndex(mTokenType);
String[] tokens = new String[tokenAnnotationIndex.size()];
String[] pos = new String[tokenAnnotationIndex.size()];
AnnotationFS[] tokenAnnotations = new AnnotationFS[tokenAnnotationIndex
.size()];
int index = 0;
for (AnnotationFS tokenAnnotation : tokenAnnotationIndex) {
tokenAnnotations[index] = tokenAnnotation;
tokens[index] = tokenAnnotation.getCoveredText();
pos[index++] = tokenAnnotation.getFeatureValueAsString(
mPosFeature);
}
String[] result = mChunker.chunk(tokens, pos);
int start = -1;
int end = -1;
for (int i = 0; i < result.length; i++) {
String chunkTag = result[i];
if (chunkTag.startsWith("B")) {
if (start != -1) {
addChunkAnnotation(tcas, tokenAnnotations, result[i - 1].substring(2),
start, end);
}
start = i;
end = i + 1;
} else if (chunkTag.startsWith("I")) {
end = i + 1;
} else if (chunkTag.startsWith("O")) {
if (start != -1) {
addChunkAnnotation(tcas, tokenAnnotations, result[i - 1].substring(2), start, end);
start = -1;
end = -1;
}
} else {
System.out.println("Unexpected tag: " + result[i]);
}
}
if (start != -1) {
addChunkAnnotation(tcas, tokenAnnotations, result[result.length - 1].substring(2), start, end);
}
}
/**
* Releases allocated resources.
*/
public void destroy() {
// dereference model to allow garbage collection
mChunker = null;
}
}