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 all terms that match the
   * specified prefix filter term.
   * <p>
   * Term enumerations are always ordered by Term.compareTo().  Each term in
   * the enumeration is greater than all that precede it.
   *
   */
  public class PrefixTermEnum extends FilteredTermEnum {
  
    private final Term prefix;
    private boolean endEnum = false;
  
    public PrefixTermEnum(IndexReader reader, Term prefix) throws IOException {
      this.prefix = prefix;
  
      setEnum(reader.terms(new Term(prefix.field(), prefix.text())));
    }
  
    @Override
    public float difference() {
      return 1.0f;
    }
  
    @Override
    protected boolean endEnum() {
      return endEnum;
    }
    
    protected Term getPrefixTerm() {
        return prefix;
    }
  
    @Override
    protected boolean termCompare(Term term) {
      if (term.field() == prefix.field() && term.text().startsWith(prefix.text())) {                                                                              
        return true;
      }
      endEnum = true;
      return false;
    }
  }
  