package org.apache.lucene.search;
/**
* Copyright 2007 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 org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.spans.SpanQuery;
import org.apache.lucene.search.spans.Spans;
import java.io.IOException;
import java.util.ArrayList;
import java.util.BitSet;
import java.util.List;
/**
* Constrains search results to only match those which also match a provided
* query. Also provides position information about where each document matches
* at the cost of extra space compared with the QueryWrapperFilter.
* There is an added cost to this above what is stored in a {@link QueryWrapperFilter}. Namely,
* the position information for each matching document is stored.
* <p/>
* This filter does not cache. See the {@link org.apache.lucene.search.CachingSpanFilter} for a wrapper that
* caches.
*
*
* @version $Id:$
*/
public class SpanQueryFilter extends SpanFilter {
protected SpanQuery query;
protected SpanQueryFilter()
{
}
/** Constructs a filter which only matches documents matching
* <code>query</code>.
* @param query The {@link org.apache.lucene.search.spans.SpanQuery} to use as the basis for the Filter.
*/
public SpanQueryFilter(SpanQuery query) {
this.query = query;
}
public BitSet bits(IndexReader reader) throws IOException {
SpanFilterResult result = bitSpans(reader);
return result.getBits();
}
public SpanFilterResult bitSpans(IndexReader reader) throws IOException {
final BitSet bits = new BitSet(reader.maxDoc());
Spans spans = query.getSpans(reader);
List tmp = new ArrayList(20);
int currentDoc = -1;
SpanFilterResult.PositionInfo currentInfo = null;
while (spans.next())
{
int doc = spans.doc();
bits.set(doc);
if (currentDoc != doc)
{
currentInfo = new SpanFilterResult.PositionInfo(doc);
tmp.add(currentInfo);
currentDoc = doc;
}
currentInfo.addPosition(spans.start(), spans.end());
}
return new SpanFilterResult(bits, tmp);
}
public SpanQuery getQuery() {
return query;
}
public String toString() {
return "QueryWrapperFilter(" + query + ")";
}
public boolean equals(Object o) {
return o instanceof SpanQueryFilter && this.query.equals(((SpanQueryFilter) o).query);
}
public int hashCode() {
return query.hashCode() ^ 0x923F64B9;
}
}