FilteredDocIdSet.cs

Go to the documentation of this file.

/* 
 * 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.
 */

using System;

namespace Lucene.Net.Search
{
    
    /// <summary> Abstract decorator class for a DocIdSet implementation
    /// that provides on-demand filtering/validation
    /// mechanism on a given DocIdSet.
    /// 
    /// <p/>
    /// 
    /// Technically, this same functionality could be achieved
    /// with ChainedFilter (under contrib/misc), however the
    /// benefit of this class is it never materializes the full
    /// bitset for the filter.  Instead, the <see cref="Match" />
    /// method is invoked on-demand, per docID visited during
    /// searching.  If you know few docIDs will be visited, and
    /// the logic behind <see cref="Match" /> is relatively costly,
    /// this may be a better way to filter than ChainedFilter.
    /// 
    /// </summary>
    /// <seealso cref="DocIdSet">
    /// </seealso>
    
    public abstract class FilteredDocIdSet:DocIdSet
    {
        private class AnonymousClassFilteredDocIdSetIterator:FilteredDocIdSetIterator
        {
            public AnonymousClassFilteredDocIdSetIterator(FilteredDocIdSet enclosingInstance) : base(null)
            {
                System.Diagnostics.Debug.Fail("Port issue:", "Lets see if we need this"); // {{Aroush-2.9}}
                InitBlock(enclosingInstance);
            }
            private void InitBlock(FilteredDocIdSet enclosingInstance)
            {
                this.enclosingInstance = enclosingInstance;
            }
            private FilteredDocIdSet enclosingInstance;
            public FilteredDocIdSet Enclosing_Instance
            {
                get
                {
                    return enclosingInstance;
                }
                
            }
            internal AnonymousClassFilteredDocIdSetIterator(FilteredDocIdSet enclosingInstance, Lucene.Net.Search.DocIdSetIterator Param1):base(Param1)
            {
                InitBlock(enclosingInstance);
            }
            public /*protected internal*/ override bool Match(int docid)
            {
                return Enclosing_Instance.Match(docid);
            }
        }
        private DocIdSet _innerSet;
        
        /// <summary> Constructor.</summary>
        /// <param name="innerSet">Underlying DocIdSet
        /// </param>
        protected FilteredDocIdSet(DocIdSet innerSet)
        {
            _innerSet = innerSet;
        }

        /// <summary>This DocIdSet implementation is cacheable if the inner set is cacheable. </summary>
        public override bool IsCacheable
        {
            get { return _innerSet.IsCacheable; }
        }

        /// <summary> Validation method to determine whether a docid should be in the result set.</summary>
        /// <param name="docid">docid to be tested
        /// </param>
        /// <returns> true if input docid should be in the result set, false otherwise.
        /// </returns>
        public /*protected internal*/ abstract bool Match(int docid);
        
        /// <summary> Implementation of the contract to build a DocIdSetIterator.</summary>
        /// <seealso cref="DocIdSetIterator">
        /// </seealso>
        /// <seealso cref="FilteredDocIdSetIterator">
        /// </seealso>
        // @Override
        public override DocIdSetIterator Iterator()
        {
            return new AnonymousClassFilteredDocIdSetIterator(this, _innerSet.Iterator());
        }
    }
}