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1   /*
2    *
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *     http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing, software
14   * distributed under the License is distributed on an "AS IS" BASIS,
15   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16   * See the License for the specific language governing permissions and
17   * limitations under the License.
18   */
19  
20  package org.apache.hadoop.hbase.filter;
21  
22  import com.google.protobuf.InvalidProtocolBufferException;
23  import org.apache.hadoop.classification.InterfaceAudience;
24  import org.apache.hadoop.classification.InterfaceStability;
25  import org.apache.hadoop.hbase.exceptions.DeserializationException;
26  import org.apache.hadoop.hbase.protobuf.generated.ComparatorProtos;
27  import org.apache.hadoop.hbase.util.Bytes;
28  
29  /**
30   * A comparator which compares against a specified byte array, but only compares
31   * up to the length of this byte array. For the rest it is similar to
32   * {@link BinaryComparator}.
33   */
34  @InterfaceAudience.Public
35  @InterfaceStability.Stable
36  public class BinaryPrefixComparator extends ByteArrayComparable {
37  
38    /**
39     * Constructor
40     * @param value value
41     */
42    public BinaryPrefixComparator(byte[] value) {
43      super(value);
44    }
45  
46    @Override
47    public int compareTo(byte [] value, int offset, int length) {
48      return Bytes.compareTo(this.value, 0, this.value.length, value, offset,
49          this.value.length <= length ? this.value.length : length);
50    }
51  
52    /**
53     * @return The comparator serialized using pb
54     */
55    public byte [] toByteArray() {
56      ComparatorProtos.BinaryPrefixComparator.Builder builder =
57        ComparatorProtos.BinaryPrefixComparator.newBuilder();
58      builder.setComparable(super.convert());
59      return builder.build().toByteArray();
60    }
61  
62    /**
63     * @param pbBytes A pb serialized {@link BinaryPrefixComparator} instance
64     * @return An instance of {@link BinaryPrefixComparator} made from <code>bytes</code>
65     * @throws DeserializationException
66     * @see #toByteArray
67     */
68    public static BinaryPrefixComparator parseFrom(final byte [] pbBytes)
69    throws DeserializationException {
70      ComparatorProtos.BinaryPrefixComparator proto;
71      try {
72        proto = ComparatorProtos.BinaryPrefixComparator.parseFrom(pbBytes);
73      } catch (InvalidProtocolBufferException e) {
74        throw new DeserializationException(e);
75      }
76      return new BinaryPrefixComparator(proto.getComparable().getValue().toByteArray());
77    }
78  
79    /**
80     * @param other
81     * @return true if and only if the fields of the comparator that are serialized
82     * are equal to the corresponding fields in other.  Used for testing.
83     */
84    boolean areSerializedFieldsEqual(ByteArrayComparable other) {
85      if (other == this) return true;
86      if (!(other instanceof BinaryPrefixComparator)) return false;
87  
88      return super.areSerializedFieldsEqual(other);
89    }
90  }