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comparison src/org/tmatesoft/hg/core/Nodeid.java @ 74:6f1b88693d48

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Complete refactoring to org.tmatesoft
author Artem Tikhomirov <tikhomirov.artem@gmail.com>
date Mon, 24 Jan 2011 03:14:45 +0100
parents src/com/tmate/hgkit/ll/Nodeid.java@4022c34a4804
children c25c5c348d1b
comparison
equal deleted inserted replaced
73:0d279bcc4442 74:6f1b88693d48
1 /*
2 * Copyright (c) 2010-2011 TMate Software Ltd
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; version 2 of the License.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * For information on how to redistribute this software under
14 * the terms of a license other than GNU General Public License
15 * contact TMate Software at support@svnkit.com
16 */
17 package org.tmatesoft.hg.core;
18
19 import static org.tmatesoft.hg.internal.DigestHelper.toHexString;
20
21 import java.util.Arrays;
22
23
24
25 /**
26 * A 20-bytes (40 characters) long hash value to identify a revision.
27 * @see http://mercurial.selenic.com/wiki/Nodeid
28 *
29 * @author Artem Tikhomirov
30 * @author TMate Software Ltd.
31 *
32 */
33 public final class Nodeid {
34
35 /**
36 * <b>nullid</b>, empty root revision.
37 */
38 public static final Nodeid NULL = new Nodeid(new byte[20], false);
39
40 private final byte[] binaryData;
41
42 /**
43 * @param binaryRepresentation - array of exactly 20 bytes
44 * @param shallClone - true if array is subject to future modification and shall be copied, not referenced
45 */
46 public Nodeid(byte[] binaryRepresentation, boolean shallClone) {
47 // 5 int fields => 32 bytes
48 // byte[20] => 48 bytes
49 if (binaryRepresentation == null || binaryRepresentation.length != 20) {
50 throw new IllegalArgumentException();
51 }
52 this.binaryData = shallClone ? binaryRepresentation.clone() : binaryRepresentation;
53 }
54
55 @Override
56 public int hashCode() {
57 // digest (part thereof) seems to be nice candidate for the hashCode
58 byte[] b = binaryData;
59 return b[0] << 24 | (b[1] & 0xFF) << 16 | (b[2] & 0xFF) << 8 | (b[3] & 0xFF);
60 }
61
62 @Override
63 public boolean equals(Object o) {
64 if (o instanceof Nodeid) {
65 return Arrays.equals(this.binaryData, ((Nodeid) o).binaryData);
66 }
67 return false;
68 }
69
70 public boolean equalsTo(byte[] buf) {
71 return Arrays.equals(this.binaryData, buf);
72 }
73
74 @Override
75 public String toString() {
76 // XXX may want to output just single 0 for the NULL id?
77 return toHexString(binaryData, 0, binaryData.length);
78 }
79
80 public String shortNotation() {
81 return toHexString(binaryData, 0, 6);
82 }
83
84 public boolean isNull() {
85 if (this == NULL) {
86 return true;
87 }
88 for (int i = 0; i < 20; i++) {
89 if (this.binaryData[i] != 0) {
90 return false;
91 }
92 }
93 return true;
94 }
95
96 // copy
97 public byte[] toByteArray() {
98 return binaryData.clone();
99 }
100
101 // primary difference with cons is handling of NULL id (this method returns constant)
102 // always makes a copy of an array passed
103 public static Nodeid fromBinary(byte[] binaryRepresentation, int offset) {
104 if (binaryRepresentation == null || binaryRepresentation.length - offset < 20) {
105 throw new IllegalArgumentException();
106 }
107 int i = 0;
108 while (i < 20 && binaryRepresentation[offset+i] == 0) i++;
109 if (i == 20) {
110 return NULL;
111 }
112 if (offset == 0 && binaryRepresentation.length == 20) {
113 return new Nodeid(binaryRepresentation, true);
114 }
115 byte[] b = new byte[20]; // create new instance if no other reasonable guesses possible
116 System.arraycopy(binaryRepresentation, offset, b, 0, 20);
117 return new Nodeid(b, false);
118 }
119
120 public static Nodeid fromAscii(byte[] asciiRepresentation, int offset, int length) {
121 if (length != 40) {
122 throw new IllegalArgumentException();
123 }
124 byte[] data = new byte[20];
125 boolean zeroBytes = true;
126 for (int i = 0, j = offset; i < data.length; i++) {
127 int hiNibble = Character.digit(asciiRepresentation[j++], 16);
128 int lowNibble = Character.digit(asciiRepresentation[j++], 16);
129 byte b = (byte) (((hiNibble << 4) | lowNibble) & 0xFF);
130 data[i] = b;
131 zeroBytes = zeroBytes && b == 0;
132 }
133 if (zeroBytes) {
134 return NULL;
135 }
136 return new Nodeid(data, false);
137 }
138 }