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 java.io.IOException;
/** Abstract base class providing a mechanism to restrict searches to a subset
of an index and also maintains and returns position information.
This is useful if you want to compare the positions from a SpanQuery with the positions of items in
a filter. For instance, if you had a SpanFilter that marked all the occurrences of the word "foo" in documents,
and then you entered a new SpanQuery containing bar, you could not only filter by the word foo, but you could
then compare position information for post processing.
*/
public abstract class SpanFilter extends Filter{
/** Returns a SpanFilterResult with true for documents which should be permitted in
search results, and false for those that should not and Spans for where the true docs match.
* @param reader The {@link org.apache.lucene.index.IndexReader} to load position and DocIdSet information from
* @return A {@link SpanFilterResult}
* @throws java.io.IOException if there was an issue accessing the necessary information
* */
public abstract SpanFilterResult bitSpans(IndexReader reader) throws IOException;
}