SBVTailIndex.java

/*
 * Copyright 2012 Takao Nakaguchi
 *
 * 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.
 */
package org.trie4j.tail.index;

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;

import org.trie4j.bv.BytesSuccinctBitVector;
import org.trie4j.bv.SuccinctBitVector;

public class SBVTailIndex
implements Externalizable, TailIndex{
	public SBVTailIndex() {
		sbv = new BytesSuccinctBitVector();
	}

	public SBVTailIndex(SuccinctBitVector sbv, int size) {
		this.sbv = sbv;
		this.size = size;
	}
	public SBVTailIndex(byte[] bits, int bitSize, int size) {
		this.sbv = new BytesSuccinctBitVector(bits, bitSize);
		this.size = size;
	}

	public SuccinctBitVector getSbv(){
		return sbv;
	}

	@Override
	public int size() {
		return size;
	}

	@Override
	public int get(int nodeId) {
		if(nodeId == 0){
			if(sbv.isZero(0)) return -1;
			else return 0;
		}
		int s = sbv.select0(nodeId);
		if(sbv.isZero(s + 1)) return -1;
		return sbv.rank1(s);
	}

	@Override
	public void readExternal(ObjectInput in)
	throws ClassNotFoundException, IOException{
		sbv = (SuccinctBitVector)in.readObject();
		size = in.readInt();
	}

	@Override
	public void writeExternal(ObjectOutput out) throws IOException{
		out.writeObject(sbv);
		out.writeInt(size);
	}

	private SuccinctBitVector sbv;
	private int size;
	private static final long serialVersionUID = 8843853578097509573L;
}