/*
* Copyright 2010 The Apache Software Foundation
*
* 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.
*/
package org.apache.hadoop.hbase.filter;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
/**
* A bit comparator which performs the specified bitwise operation on each of the bytes
* with the specified byte array. Then returns whether the result is non-zero.
*/
public class BitComparator extends WritableByteArrayComparable {
/** Nullary constructor for Writable, do not use */
public BitComparator() {}
/** Bit operators. */
public enum BitwiseOp {
/** and */
AND,
/** or */
OR,
/** xor */
XOR
}
protected BitwiseOp bitOperator;
/**
* Constructor
* @param value value
* @param bitOperator operator to use on the bit comparison
*/
public BitComparator(byte[] value, BitwiseOp bitOperator) {
super(value);
this.bitOperator = bitOperator;
}
/**
* @return the bitwise operator
*/
public BitwiseOp getOperator() {
return bitOperator;
}
@Override
public void readFields(DataInput in) throws IOException {
super.readFields(in);
bitOperator = BitwiseOp.valueOf(in.readUTF());
}
@Override
public void write(DataOutput out) throws IOException {
super.write(out);
out.writeUTF(bitOperator.name());
}
@Override
public int compareTo(byte[] value, int offset, int length) {
if (length != this.value.length) {
return 1;
}
int b = 0;
//Iterating backwards is faster because we can quit after one non-zero byte.
for (int i = length - 1; i >= 0 && b == 0; i--) {
switch (bitOperator) {
case AND:
b = (this.value[i] & value[i+offset]) & 0xff;
break;
case OR:
b = (this.value[i] | value[i+offset]) & 0xff;
break;
case XOR:
b = (this.value[i] ^ value[i+offset]) & 0xff;
break;
}
}
return b == 0 ? 1 : 0;
}
}