PositionIncrementAttribute.java

package com.antbrains.wordseg.luceneanalyzer;

/**
 * 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.
 */

/**
 * The positionIncrement determines the position of this token relative to the previous Token in a
 * TokenStream, used in phrase searching.
 *
 * <p>
 * The default value is one.
 *
 * <p>
 * Some common uses for this are:
 * <ul>
 *
 * <li>Set it to zero to put multiple terms in the same position. This is useful if, e.g., a word
 * has multiple stems. Searches for phrases including either stem will match. In this case, all but
 * the first stem's increment should be set to zero: the increment of the first instance should be
 * one. Repeating a token with an increment of zero can also be used to boost the scores of matches
 * on that token.
 *
 * <li>Set it to values greater than one to inhibit exact phrase matches. If, for example, one does
 * not want phrases to match across removed stop words, then one could build a stop word filter that
 * removes stop words and also sets the increment to the number of stop words removed before each
 * non-stop word. Then exact phrase queries will only match when the terms occur with no intervening
 * stop words.
 *
 * </ul>
 * 
 * @see org.apache.lucene.index.DocsAndPositionsEnum
 */
public interface PositionIncrementAttribute extends Attribute {
  /**
   * Set the position increment. The default value is one.
   *
   * @param positionIncrement
   *          the distance from the prior term
   */
  public void setPositionIncrement(int positionIncrement);

  /**
   * Returns the position increment of this Token.
   * 
   * @see #setPositionIncrement
   */
  public int getPositionIncrement();
}