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.Term;import org.apache.lucene.index.TermEnum;import org.apache.lucene.index.IndexReader;import org.apache.lucene.util.ToStringUtils;/** A Query that matches documents containing terms with a specified prefix. A PrefixQuery * is built by QueryParser for input like <code>app*</code>. */public class PrefixQuery extends Query {  private Term prefix;  /** Constructs a query for terms starting with <code>prefix</code>. */  public PrefixQuery(Term prefix) {    this.prefix = prefix;  }  /** Returns the prefix of this query. */  public Term getPrefix() { return prefix; }  public Query rewrite(IndexReader reader) throws IOException {    BooleanQuery query = new BooleanQuery(true);    TermEnum enumerator = reader.terms(prefix);    try {      String prefixText = prefix.text();      String prefixField = prefix.field();      do {        Term term = enumerator.term();        if (term != null &&            term.text().startsWith(prefixText) &&            term.field() == prefixField) // interned comparison         {          TermQuery tq = new TermQuery(term);	  // found a match          tq.setBoost(getBoost());                // set the boost          query.add(tq, BooleanClause.Occur.SHOULD);		  // add to query          //System.out.println("added " + term);        } else {          break;        }      } while (enumerator.next());    } finally {      enumerator.close();    }    return query;  }  /** Prints a user-readable version of this query. */  public String toString(String field) {    StringBuffer buffer = new StringBuffer();    if (!prefix.field().equals(field)) {      buffer.append(prefix.field());      buffer.append(":");    }    buffer.append(prefix.text());    buffer.append('*');    buffer.append(ToStringUtils.boost(getBoost()));    return buffer.toString();  }  /** Returns true iff <code>o</code> is equal to this. */  public boolean equals(Object o) {    if (!(o instanceof PrefixQuery))      return false;    PrefixQuery other = (PrefixQuery)o;    return (this.getBoost() == other.getBoost())      && this.prefix.equals(other.prefix);  }  /** Returns a hash code value for this object.*/  public int hashCode() {    return Float.floatToIntBits(getBoost()) ^ prefix.hashCode() ^ 0x6634D93C;  }}