content: 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.index.IndexReader;
  
  /** 
   * Constrains search results to only match those which also match a provided
   * query.  
   *
   * <p> This could be used, for example, with a {@link TermRangeQuery} on a suitably
   * formatted date field to implement date filtering.  One could re-use a single
   * QueryFilter that matches, e.g., only documents modified within the last
   * week.  The QueryFilter and TermRangeQuery would only need to be reconstructed
   * once per day.
   */
  public class QueryWrapperFilter extends Filter {
    private Query query;
  
    /** Constructs a filter which only matches documents matching
     * <code>query</code>.
     */
    public QueryWrapperFilter(Query query) {
      this.query = query;
    }
  
    @Override
    public DocIdSet getDocIdSet(final IndexReader reader) throws IOException {
      final Weight weight = new IndexSearcher(reader).createNormalizedWeight(query);
      return new DocIdSet() {
        @Override
        public DocIdSetIterator iterator() throws IOException {
          return weight.scorer(reader, true, false);
        }
        @Override
        public boolean isCacheable() { return false; }
      };
    }
  
    @Override
    public String toString() {
      return "QueryWrapperFilter(" + query + ")";
    }
  
    @Override
    public boolean equals(Object o) {
      if (!(o instanceof QueryWrapperFilter))
        return false;
      return this.query.equals(((QueryWrapperFilter)o).query);
    }
  
    @Override
    public int hashCode() {
      return query.hashCode() ^ 0x923F64B9;
    }
  }
  