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package org.apache.lucene.search;
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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import java.io.IOException;
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import org.apache.lucene.index.IndexReader;
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import org.apache.lucene.util.DocIdBitSet;
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* Abstract base class for restricting which documents may
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* be returned during searching.
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public abstract class Filter implements java.io.Serializable {
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* Creates a {@link DocIdSet} enumerating the documents that should be
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* permitted in search results. <b>NOTE:</b> null can be
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* returned if no documents are accepted by this Filter.
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* Note: This method will be called once per segment in
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* the index during searching. The returned {@link DocIdSet}
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* must refer to document IDs for that segment, not for
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* the top-level reader.
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* @param reader a {@link IndexReader} instance opened on the index currently
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* searched on. Note, it is likely that the provided reader does not
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* represent the whole underlying index i.e. if the index has more than
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* one segment the given reader only represents a single segment.
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* @return a DocIdSet that provides the documents which should be permitted or
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* prohibited in search results. <b>NOTE:</b> null can be returned if
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* no documents will be accepted by this Filter.
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public abstract DocIdSet getDocIdSet(IndexReader reader) throws IOException;