phrasepositions.java

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package org.apache.lucene.search;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache Lucene" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
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 * 5. Products derived from this software may not be called "Apache",
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import java.io.IOException;
import org.apache.lucene.index.*;

final class PhrasePositions {
  int doc;					  // current doc
  int position;					  // position in doc
  int count;					  // remaining pos in this doc
  int offset;					  // position in phrase
  TermPositions tp;				  // stream of positions
  PhrasePositions next;				  // used to make lists

  PhrasePositions(TermPositions t, int o) throws IOException {
    tp = t;
    offset = o;
    next();
  }

  final void next() throws IOException {	  // increments to next doc
    if (!tp.next()) {
      tp.close();				  // close stream
      doc = Integer.MAX_VALUE;			  // sentinel value
      return;
    }
    doc = tp.doc();
    position = 0;
  }

  final void firstPosition() throws IOException {
    count = tp.freq();				  // read first pos
    nextPosition();
  }

  final boolean nextPosition() throws IOException {
    if (count-- > 0) {				  // read subsequent pos's
      position = tp.nextPosition() - offset;
      return true;
    } else
      return false;
  }
}