DocIdBitSet.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;
using System.Collections;
using Lucene.Net.Support;
using DocIdSet = Lucene.Net.Search.DocIdSet;
using DocIdSetIterator = Lucene.Net.Search.DocIdSetIterator;

namespace Lucene.Net.Util
{
    /// <summary>Simple DocIdSet and DocIdSetIterator backed by a BitSet </summary>
    public class DocIdBitSet:DocIdSet
    {
        private System.Collections.BitArray bitSet;
        
        public DocIdBitSet(System.Collections.BitArray bitSet)
        {
            this.bitSet = bitSet;
        }
        
        public override DocIdSetIterator Iterator()
        {
            return new DocIdBitSetIterator(bitSet);
        }

        /// <summary>This DocIdSet implementation is cacheable.</summary>
        public override bool IsCacheable
        {
            get { return true; }
        }

        /// <summary> Returns the underlying BitSet. </summary>
        public virtual BitArray BitSet
        {
            get { return this.bitSet; }
        }

        private class DocIdBitSetIterator:DocIdSetIterator
        {
            private int docId;
            private System.Collections.BitArray bitSet;
            
            internal DocIdBitSetIterator(System.Collections.BitArray bitSet)
            {
                this.bitSet = bitSet;
                this.docId = - 1;
            }
            
            public override int DocID()
            {
                return docId;
            }
            
            public override int NextDoc()
            {
                // (docId + 1) on next line requires -1 initial value for docNr:
                int d = BitSetSupport.NextSetBit(bitSet, docId + 1);
                // -1 returned by BitSet.nextSetBit() when exhausted
                docId = d == - 1?NO_MORE_DOCS:d;
                return docId;
            }
            
            public override int Advance(int target)
            {
                int d = BitSetSupport.NextSetBit(bitSet, target);
                // -1 returned by BitSet.nextSetBit() when exhausted
                docId = d == - 1?NO_MORE_DOCS:d;
                return docId;
            }
        }
    }
}