Index: src/main/java/org/apache/hadoop/hbase/filter/BitComparator.java =================================================================== --- src/main/java/org/apache/hadoop/hbase/filter/BitComparator.java (revision 0) +++ src/main/java/org/apache/hadoop/hbase/filter/BitComparator.java (revision 0) @@ -0,0 +1,92 @@ +/* + * 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 BitwiseOp bitOperator - the operator to use on the bit comparison + */ + public BitComparator(byte[] value, BitwiseOp bitOperator) { + super(value); + this.bitOperator = 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) { + if (value.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 = value.length - 1; i > 0 && b == 0; i--) { + switch (bitOperator) { + case AND: + b = (this.value[i] & value[i]) & 0xff; + break; + case OR: + b = (this.value[i] | value[i]) & 0xff; + break; + case XOR: + b = (this.value[i] ^ value[i]) & 0xff; + break; + } + } + return b == 0 ? 1 : 0; + } +} +