001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019package org.apache.hadoop.io;
020
021import org.apache.hadoop.classification.InterfaceAudience;
022import org.apache.hadoop.classification.InterfaceStability;
023
024/**
025 * Interface supported by {@link org.apache.hadoop.io.WritableComparable}
026 * types supporting ordering/permutation by a representative set of bytes.
027 */
028@InterfaceAudience.Public
029@InterfaceStability.Stable
030public abstract class BinaryComparable implements Comparable<BinaryComparable> {
031
032  /**
033   * Return n st bytes 0..n-1 from {#getBytes()} are valid.
034   */
035  public abstract int getLength();
036
037  /**
038   * Return representative byte array for this instance.
039   */
040  public abstract byte[] getBytes();
041
042  /**
043   * Compare bytes from {#getBytes()}.
044   * @see org.apache.hadoop.io.WritableComparator#compareBytes(byte[],int,int,byte[],int,int)
045   */
046  @Override
047  public int compareTo(BinaryComparable other) {
048    if (this == other)
049      return 0;
050    return WritableComparator.compareBytes(getBytes(), 0, getLength(),
051             other.getBytes(), 0, other.getLength());
052  }
053
054  /**
055   * Compare bytes from {#getBytes()} to those provided.
056   */
057  public int compareTo(byte[] other, int off, int len) {
058    return WritableComparator.compareBytes(getBytes(), 0, getLength(),
059             other, off, len);
060  }
061
062  /**
063   * Return true if bytes from {#getBytes()} match.
064   */
065  @Override
066  public boolean equals(Object other) {
067    if (!(other instanceof BinaryComparable))
068      return false;
069    BinaryComparable that = (BinaryComparable)other;
070    if (this.getLength() != that.getLength())
071      return false;
072    return this.compareTo(that) == 0;
073  }
074
075  /**
076   * Return a hash of the bytes returned from {#getBytes()}.
077   * @see org.apache.hadoop.io.WritableComparator#hashBytes(byte[],int)
078   */
079  @Override
080  public int hashCode() {
081    return WritableComparator.hashBytes(getBytes(), getLength());
082  }
083
084}