| package org.apache.lucene.search; |
| |
| /* ==================================================================== |
| * The Apache Software License, Version 1.1 |
| * |
| * Copyright (c) 2001 The Apache Software Foundation. All rights |
| * reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in |
| * the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * 3. The end-user documentation included with the redistribution, |
| * if any, must include the following acknowledgment: |
| * "This product includes software developed by the |
| * Apache Software Foundation (http://www.apache.org/)." |
| * Alternately, this acknowledgment may appear in the software itself, |
| * if and wherever such third-party acknowledgments normally appear. |
| * |
| * 4. The names "Apache" and "Apache Software Foundation" and |
| * "Apache Lucene" must not be used to endorse or promote products |
| * derived from this software without prior written permission. For |
| * written permission, please contact apache@apache.org. |
| * |
| * 5. Products derived from this software may not be called "Apache", |
| * "Apache Lucene", nor may "Apache" appear in their name, without |
| * prior written permission of the Apache Software Foundation. |
| * |
| * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED |
| * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
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| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
| * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
| * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| * ==================================================================== |
| * |
| * This software consists of voluntary contributions made by many |
| * individuals on behalf of the Apache Software Foundation. For more |
| * information on the Apache Software Foundation, please see |
| * <http://www.apache.org/>. |
| */ |
| |
| import java.io.IOException; |
| import java.util.Hashtable; |
| import org.apache.lucene.document.Document; |
| import org.apache.lucene.index.IndexReader; |
| |
| /** The abstract base class for queries. |
| <p>Instantiable subclasses are: |
| <ul> |
| <li> {@link TermQuery} |
| <li> {@link PhraseQuery} |
| <li> {@link BooleanQuery} |
| </ul> |
| <p>A parser for queries is contained in: |
| <ul> |
| <li><a href="doc/lucene.queryParser.QueryParser.html">QueryParser</a> |
| </ul> |
| */ |
| abstract public class Query { |
| |
| // query weighting |
| abstract float sumOfSquaredWeights(Searcher searcher) throws IOException; |
| abstract void normalize(float norm); |
| |
| // query evaluation |
| abstract Scorer scorer(IndexReader reader) throws IOException; |
| |
| void prepare(IndexReader reader) {} |
| |
| static Scorer scorer(Query query, Searcher searcher, IndexReader reader) |
| throws IOException { |
| query.prepare(reader); |
| float sum = query.sumOfSquaredWeights(searcher); |
| float norm = 1.0f / (float)Math.sqrt(sum); |
| query.normalize(norm); |
| return query.scorer(reader); |
| } |
| |
| /** Prints a query to a string, with <code>field</code> as the default field |
| for terms. |
| <p>The representation used is one that is readable by |
| <a href="doc/lucene.queryParser.QueryParser.html">QueryParser</a> |
| (although, if the query was created by the parser, the printed |
| representation may not be exactly what was parsed). */ |
| abstract public String toString(String field); |
| } |