001/** 
002 * Copyright (c) 2007-2008, Regents of the University of Colorado 
003 * All rights reserved.
004 * 
005 * Redistribution and use in source and binary forms, with or without
006 * modification, are permitted provided that the following conditions are met:
007 * 
008 * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 
009 * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 
010 * Neither the name of the University of Colorado at Boulder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. 
011 * 
012 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
013 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
014 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
015 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
016 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
017 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
018 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
019 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
020 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
021 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
022 * POSSIBILITY OF SUCH DAMAGE. 
023 */
024package org.cleartk.ml.feature.extractor;
025
026import java.util.ArrayList;
027import java.util.List;
028import java.util.regex.Pattern;
029
030import org.apache.uima.jcas.JCas;
031import org.apache.uima.jcas.tcas.Annotation;
032import org.cleartk.ml.Feature;
033
034/**
035 * <br>
036 * Copyright (c) 2007-2008, Regents of the University of Colorado <br>
037 * All rights reserved.
038 */
039
040public class WhiteSpaceExtractor<T extends Annotation> implements NamedFeatureExtractor1<T> {
041
042  private static final String FEATURE_NAME = "whitespace";
043
044  public static final String WhiteSpaceRegex = "\\s";
045
046  public static final Pattern WhiteSpacePattern = Pattern.compile(WhiteSpaceRegex);
047
048  public static final String ORIENTATION_LEFT = "L";
049
050  public static final String ORIENTATION_RIGHT = "R";
051
052  @Override
053  public String getFeatureName() {
054    return FEATURE_NAME;
055  }
056
057  public List<Feature> extract(JCas view, Annotation focusAnnotation)
058      throws CleartkExtractorException {
059    List<Feature> features = new ArrayList<Feature>();
060
061    String text = view.getDocumentText();
062    int begin = focusAnnotation.getBegin();
063    int end = focusAnnotation.getEnd();
064
065    // white space to the left of the focusAnnotation
066    if (begin == 0) {
067      Feature feature = new Feature(FEATURE_NAME, ORIENTATION_LEFT);
068      features.add(feature);
069    } else {
070      char leftChar = text.charAt(begin - 1);
071      if (Character.isWhitespace(leftChar)) {
072        Feature feature = new Feature(FEATURE_NAME, ORIENTATION_LEFT);
073        features.add(feature);
074      }
075    }
076
077    // white space to the right of the focusAnnotation
078    if (end == text.length()) {
079      Feature feature = new Feature(FEATURE_NAME, ORIENTATION_RIGHT);
080      features.add(feature);
081    } else {
082      char rightChar = text.charAt(end);
083      if (Character.isWhitespace(rightChar)) {
084        Feature feature = new Feature(FEATURE_NAME, ORIENTATION_RIGHT);
085        features.add(feature);
086      }
087    }
088    return features;
089  }
090
091}