| package org.apache.lucene.search; |
| |
| /** |
| * Copyright 2004 The Apache Software Foundation |
| * |
| * Licensed 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; |
| |
| /** A Query that matches documents containing terms with a specified prefix. */ |
| 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(); |
| 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) { |
| TermQuery tq = new TermQuery(term); // found a match |
| tq.setBoost(getBoost()); // set the boost |
| query.add(tq, false, false); // add to query |
| //System.out.println("added " + term); |
| } else { |
| break; |
| } |
| } while (enumerator.next()); |
| } finally { |
| enumerator.close(); |
| } |
| return query; |
| } |
| |
| public Query combine(Query[] queries) { |
| return Query.mergeBooleanQueries(queries); |
| } |
| |
| /** 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('*'); |
| if (getBoost() != 1.0f) { |
| buffer.append("^"); |
| buffer.append(Float.toString(getBoost())); |
| } |
| return buffer.toString(); |
| } |
| |
| } |