XtfSpanRangeQuery.java

package org.cdlib.xtf.textEngine;


/*
 * Copyright (c) 2006, Regents of the University of California
 * All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
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 *   this list of conditions and the following disclaimer.
 * - 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.
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 *   contributors may be used to endorse or promote products derived from this
 *   software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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import org.apache.lucene.bigram.BigramSpanRangeQuery;
import org.apache.lucene.index.Term;

/**
 * Matches spans containing terms within a specified range. Performs extra
 * filtering to make sure bi-grams are not matched, and that start/end of
 * field marks are not matched.
 */
public class XtfSpanRangeQuery extends BigramSpanRangeQuery 
{
  public XtfSpanRangeQuery(Term lowerTerm, Term upperTerm, boolean inclusive,
                           int termLimit) 
  {
    super(lowerTerm, upperTerm, inclusive, termLimit);
  }

  protected boolean shouldSkipTerm(Term term) 
  {
    // Skip the special start-of-field and end-of-field terms.
    String word = term.text();
    if (word.length() > 1) {
      if (word.charAt(0) == Constants.FIELD_START_MARKER)
        return true;
      if (word.charAt(word.length() - 1) == Constants.FIELD_END_MARKER)
        return true;
    }

    // Do the normal thing.
    return super.shouldSkipTerm(term);
  }
} // class XtfSpanRangeQuery