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.document.Document;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.index.Term;
import org.apache.lucene.document.FieldSelector;
/**
* An abstract base class for search implementations. Implements the main search
* methods.
*
* <p>
* Note that you can only access hits from a Searcher as long as it is not yet
* closed, otherwise an IOException will be thrown.
*/
public abstract class Searcher implements Searchable {
/** Search implementation with arbitrary sorting. Finds
* the top <code>n</code> hits for <code>query</code>, applying
* <code>filter</code> if non-null, and sorting the hits by the criteria in
* <code>sort</code>.
*
* <p>NOTE: this does not compute scores by default; use
* {@link IndexSearcher#setDefaultFieldSortScoring} to
* enable scoring.
*
* @throws BooleanQuery.TooManyClauses
*/
public TopFieldDocs search(Query query, Filter filter, int n,
Sort sort) throws IOException {
return search(createWeight(query), filter, n, sort);
}
/** Lower-level search API.
*
* <p>{@link Collector#collect(int)} is called for every matching document.
*
* <p>Applications should only use this if they need <i>all</i> of the
* matching documents. The high-level search API ({@link
* Searcher#search(Query, int)}) is usually more efficient, as it skips
* non-high-scoring hits.
* <p>Note: The <code>score</code> passed to this method is a raw score.
* In other words, the score will not necessarily be a float whose value is
* between 0 and 1.
* @throws BooleanQuery.TooManyClauses
*/
public void search(Query query, Collector results)
throws IOException {
search(createWeight(query), null, results);
}
/** Lower-level search API.
*
* <p>{@link Collector#collect(int)} is called for every matching
* document.
* <br>Collector-based access to remote indexes is discouraged.
*
* <p>Applications should only use this if they need <i>all</i> of the
* matching documents. The high-level search API ({@link
* Searcher#search(Query, Filter, int)}) is usually more efficient, as it skips
* non-high-scoring hits.
*
* @param query to match documents
* @param filter if non-null, used to permit documents to be collected.
* @param results to receive hits
* @throws BooleanQuery.TooManyClauses
*/
public void search(Query query, Filter filter, Collector results)
throws IOException {
search(createWeight(query), filter, results);
}
/** Finds the top <code>n</code>
* hits for <code>query</code>, applying <code>filter</code> if non-null.
*
* @throws BooleanQuery.TooManyClauses
*/
public TopDocs search(Query query, Filter filter, int n)
throws IOException {
return search(createWeight(query), filter, n);
}
/** Finds the top <code>n</code>
* hits for <code>query</code>.
*
* @throws BooleanQuery.TooManyClauses
*/
public TopDocs search(Query query, int n)
throws IOException {
return search(query, null, n);
}
/** Returns an Explanation that describes how <code>doc</code> scored against
* <code>query</code>.
*
* <p>This is intended to be used in developing Similarity implementations,
* and, for good performance, should not be displayed with every hit.
* Computing an explanation is as expensive as executing the query over the
* entire index.
*/
public Explanation explain(Query query, int doc) throws IOException {
return explain(createWeight(query), doc);
}
/** The Similarity implementation used by this searcher. */
private Similarity similarity = Similarity.getDefault();
/** Expert: Set the Similarity implementation used by this Searcher.
*
* @see Similarity#setDefault(Similarity)
*/
public void setSimilarity(Similarity similarity) {
this.similarity = similarity;
}
/** Expert: Return the Similarity implementation used by this Searcher.
*
* <p>This defaults to the current value of {@link Similarity#getDefault()}.
*/
public Similarity getSimilarity() {
return this.similarity;
}
/**
* creates a weight for <code>query</code>
* @return new weight
*/
protected Weight createWeight(Query query) throws IOException {
return query.weight(this);
}
// inherit javadoc
public int[] docFreqs(Term[] terms) throws IOException {
int[] result = new int[terms.length];
for (int i = 0; i < terms.length; i++) {
result[i] = docFreq(terms[i]);
}
return result;
}
abstract public void search(Weight weight, Filter filter, Collector results) throws IOException;
abstract public void close() throws IOException;
abstract public int docFreq(Term term) throws IOException;
abstract public int maxDoc() throws IOException;
abstract public TopDocs search(Weight weight, Filter filter, int n) throws IOException;
abstract public Document doc(int i) throws CorruptIndexException, IOException;
abstract public Document doc(int docid, FieldSelector fieldSelector) throws CorruptIndexException, IOException;
abstract public Query rewrite(Query query) throws IOException;
abstract public Explanation explain(Weight weight, int doc) throws IOException;
abstract public TopFieldDocs search(Weight weight, Filter filter, int n, Sort sort) throws IOException;
/* End patch for GCJ bug #15411. */
}