https://lucene.apache.org/lucene-parent/lucene-core: Apache Lucene Java Core (The Apache Software Foundation) 
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 * 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,
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package org.apache.lucene.search;


import org.apache.lucene.util.Attribute;
import org.apache.lucene.util.AttributeSource; // javadocs only
import org.apache.lucene.index.TermsEnum; // javadocs only
import org.apache.lucene.index.Terms; // javadocs only


Add this Attribute to a TermsEnum returned by MultiTermQuery.getTermsEnum(Terms, AttributeSource) and update the boost on each returned term. This enables to control the boost factor for each matching term in MultiTermQuery.SCORING_BOOLEAN_REWRITE or TopTermsRewrite mode. FuzzyQuery is using this to take the edit distance into account. 
Please note: This attribute is intended to be added only by the TermsEnum to itself in its constructor and consumed by the RewriteMethod. 
@lucene.internal
/** Add this {@link Attribute} to a {@link TermsEnum} returned by {@link MultiTermQuery#getTermsEnum(Terms,AttributeSource)}
 * and update the boost on each returned term. This enables to control the boost factor
 * for each matching term in {@link MultiTermQuery#SCORING_BOOLEAN_REWRITE} or
 * {@link TopTermsRewrite} mode.
 * {@link FuzzyQuery} is using this to take the edit distance into account.
 * <p><b>Please note:</b> This attribute is intended to be added only by the TermsEnum
 * to itself in its constructor and consumed by the {@link MultiTermQuery.RewriteMethod}.
 * @lucene.internal
 */
public interface BoostAttribute extends Attribute {
  float DEFAULT_BOOST = 1.0f;
  
Sets the boost in this attribute 
/** Sets the boost in this attribute */
  public void setBoost(float boost);
  
Retrieves the boost, default is 1.0f. 
/** Retrieves the boost, default is {@code 1.0f}. */
  public float getBoost();
}