content: package org.apache.lucene.search;
  
  /**
   * 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.
   */
  
  import java.io.IOException;
  
  import org.apache.lucene.index.IndexReader;
  import org.apache.lucene.index.Term;
  
  /**
   * Subclass of FilteredTermEnum for enumerating a single term.
   * <p>
   * This can be used by {@link MultiTermQuery}s that need only visit one term,
   * but want to preserve MultiTermQuery semantics such as
   * {@link MultiTermQuery#rewriteMethod}.
   */
  public class SingleTermEnum extends FilteredTermEnum {
    private Term singleTerm;
    private boolean endEnum = false;
    
    /**
     * Creates a new <code>SingleTermEnum</code>.
     * <p>
     * After calling the constructor the enumeration is already pointing to the term,
     * if it exists.
     */
    public SingleTermEnum(IndexReader reader, Term singleTerm) throws IOException {
      super();
      this.singleTerm = singleTerm;
      setEnum(reader.terms(singleTerm));
    }
  
    @Override
    public float difference() {
      return 1.0F;
    }
  
    @Override
    protected boolean endEnum() {
      return endEnum;
    }
  
    @Override
    protected boolean termCompare(Term term) {
      if (term.equals(singleTerm)) {
        return true;
      } else {
        endEnum = true;
        return false;
      }
    }
  }
  