org.spearce.jgit/src/org/spearce/jgit/lib/ObjectId.java

   1 /*
   2  *  Copyright (C) 2006  Shawn Pearce <spearce@spearce.org>
   3  *
   4  *  This library is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU General Public
   6  *  License, version 2, as published by the Free Software Foundation.
   7  *
   8  *  This library 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 GNU
  11  *  General Public License for more details.
  12  *
  13  *  You should have received a copy of the GNU General Public
  14  *  License along with this library; if not, write to the Free Software
  15  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
  16  */
  17 package org.spearce.jgit.lib;
  18
  19 import java.io.IOException;
  20 import java.io.OutputStream;
  21 import java.io.Writer;
  22
  23 public class ObjectId implements Comparable {
  24         private static final ObjectId ZEROID;
  25
  26         private static final String ZEROID_STR;
  27
  28         static {
  29                 ZEROID = new ObjectId(new byte[Constants.OBJECT_ID_LENGTH]);
  30                 ZEROID_STR = ZEROID.toString();
  31         }
  32
  33         public static ObjectId zeroId() {
  34                 return ZEROID;
  35         }
  36
  37         public static final boolean isId(final String id) {
  38                 if (id.length() != (2 * Constants.OBJECT_ID_LENGTH)) {
  39                         return false;
  40                 }
  41
  42                 for (int k = id.length() - 1; k >= 0; k--) {
  43                         final char c = id.charAt(k);
  44                         if ('0' <= c && c <= '9') {
  45                                 continue;
  46                         } else if ('a' <= c && c <= 'f') {
  47                                 continue;
  48                         } else {
  49                                 return false;
  50                         }
  51                 }
  52                 return true;
  53         }
  54
  55         public static String toString(final ObjectId i) {
  56                 return i != null ? i.toString() : ZEROID_STR;
  57         }
  58
  59         public static ObjectId fromString(final byte[] i, int offset) {
  60                 final byte[] id = new byte[Constants.OBJECT_ID_LENGTH];
  61                 for (int k = 0; k < Constants.OBJECT_ID_LENGTH; k++) {
  62                         final byte c1 = i[offset++];
  63                         final byte c2 = i[offset++];
  64                         int b;
  65
  66                         if ('0' <= c1 && c1 <= '9')
  67                                 b = c1 - '0';
  68                         else if ('a' <= c1 && c1 <= 'f')
  69                                 b = c1 - 'a' + 10;
  70                         else
  71                                 throw new IllegalArgumentException("Invalid id: " + (char) c1);
  72
  73                         b <<= 4;
  74
  75                         if ('0' <= c2 && c2 <= '9')
  76                                 b |= c2 - '0';
  77                         else if ('a' <= c2 && c2 <= 'f')
  78                                 b |= c2 - 'a' + 10;
  79                         else
  80                                 throw new IllegalArgumentException("Invalid id: " + (char) c2);
  81                         id[k] = (byte) b;
  82                 }
  83                 return new ObjectId(id);
  84         }
  85
  86         public int compareTo(byte[] b, long pos) {
  87                 for (int k = 0; k < Constants.OBJECT_ID_LENGTH; k++) {
  88                         final int ak = id[k] & 0xff;
  89                         final int bk = b[k + (int)pos] & 0xff;
  90                         if (ak < bk)
  91                                 return -1;
  92                         else if (ak > bk)
  93                                 return 1;
  94                 }
  95                 return 0;
  96         }
  97
  98         private static int compare(final byte[] a, final byte[] b) {
  99                 for (int k = 0 ; k < Constants.OBJECT_ID_LENGTH; k++) {
 100                         final int ak = a[k] & 0xff;
 101                         final int bk = b[k] & 0xff;
 102                         if (ak < bk)
 103                                 return -1;
 104                         else if (ak > bk)
 105                                 return 1;
 106                 }
 107                 if (a.length != Constants.OBJECT_ID_LENGTH)
 108                         throw new IllegalArgumentException("Looks like a bad object id");
 109                 if (b.length != Constants.OBJECT_ID_LENGTH)
 110                         throw new IllegalArgumentException("Looks like a bad object id");
 111                 return 0;
 112         }
 113
 114         private final byte[] id;
 115
 116         public ObjectId(final String i) {
 117                 if (i.length() != (2 * Constants.OBJECT_ID_LENGTH)) {
 118                         throw new IllegalArgumentException("Invalid id \"" + i
 119                                         + "\"; length = " + i.length());
 120                 }
 121
 122                 id = new byte[Constants.OBJECT_ID_LENGTH];
 123                 char[] bs = new char[Constants.OBJECT_ID_LENGTH*2];
 124                 i.getChars(0,Constants.OBJECT_ID_LENGTH*2,bs,0);
 125                 for (int j = 0, k = 0; k < Constants.OBJECT_ID_LENGTH; k++) {
 126                         final char c1 = bs[j++];
 127                         final char c2 = bs[j++];
 128                         int b;
 129
 130                         if ('0' <= c1 && c1 <= '9') {
 131                                 b = c1 - '0';
 132                         } else if ('a' <= c1 && c1 <= 'f') {
 133                                 b = c1 - 'a' + 10;
 134                         } else {
 135                                 throw new IllegalArgumentException("Invalid id: " + i);
 136                         }
 137
 138                         b <<= 4;
 139
 140                         if ('0' <= c2 && c2 <= '9') {
 141                                 b |= c2 - '0';
 142                         } else if ('a' <= c2 && c2 <= 'f') {
 143                                 b |= c2 - 'a' + 10;
 144                         } else {
 145                                 throw new IllegalArgumentException("Invalid id: " + i);
 146                         }
 147
 148                         id[k] = (byte) b;
 149                 }
 150         }
 151
 152         public ObjectId(final byte[] i) {
 153                 id = i;
 154         }
 155
 156         public int getFirstByte() {
 157                 return id[0] & 0xff;
 158         }
 159
 160         public byte[] getBytes() {
 161                 return id;
 162         }
 163
 164         public int compareTo(final byte[] b) {
 165                 return b != null ? compare(id, b) : 1;
 166         }
 167
 168         public int compareTo(final ObjectId b) {
 169                 return b != null ? compare(id, b.id) : 1;
 170         }
 171
 172         public int compareTo(final Object o) {
 173                 if (o instanceof ObjectId) {
 174                         return compare(id, ((ObjectId) o).id);
 175                 } else if (o instanceof byte[]) {
 176                         return compare(id, (byte[]) o);
 177                 }
 178                 return 1;
 179         }
 180
 181         public int hashCode() {
 182                 // Object Id' are well distributed so grab the first four bytes
 183                 int b0 = id[0] & 0xff;
 184                 int b1 = id[1] & 0xff;
 185                 int b2 = id[2] & 0xff;
 186                 int b3 = id[3] & 0xff;
 187                 int h = (b0 << 24) | (b1 << 16) | (b2 << 8) | b3;
 188                 return h;
 189         }
 190
 191         public boolean equals(final ObjectId o) {
 192                 return compareTo(o) == 0;
 193         }
 194
 195         public boolean equals(final Object o) {
 196                 return compareTo(o) == 0;
 197         }
 198
 199         public void copyTo(final OutputStream w) throws IOException {
 200                 for (int k = 0; k < Constants.OBJECT_ID_LENGTH; k++) {
 201                         final int b = id[k];
 202                         final int b1 = (b >> 4) & 0xf;
 203                         final int b2 = b & 0xf;
 204                         w.write(b1 < 10 ? (char) ('0' + b1) : (char) ('a' + b1 - 10));
 205                         w.write(b2 < 10 ? (char) ('0' + b2) : (char) ('a' + b2 - 10));
 206                 }
 207         }
 208
 209         public void copyTo(final Writer w) throws IOException {
 210                 for (int k = 0; k < Constants.OBJECT_ID_LENGTH; k++) {
 211                         final int b = id[k];
 212                         final int b1 = (b >> 4) & 0xf;
 213                         final int b2 = b & 0xf;
 214                         w.write(b1 < 10 ? (char) ('0' + b1) : (char) ('a' + b1 - 10));
 215                         w.write(b2 < 10 ? (char) ('0' + b2) : (char) ('a' + b2 - 10));
 216                 }
 217         }
 218
 219         public String toString() {
 220                 byte s[] = new byte[Constants.OBJECT_ID_LENGTH*2];
 221                 int i = 0;
 222                 for (int k = 0; k < Constants.OBJECT_ID_LENGTH; k++) {
 223                         final int b = id[k];
 224                         final int b1 = (b >> 4) & 0xf;
 225                         final int b2 = b & 0xf;
 226                         s[i++] = (b1 < 10 ? (byte) ('0' + b1) : (byte) ('a' + b1 - 10));
 227                         s[i++] = (b2 < 10 ? (byte) ('0' + b2) : (byte) ('a' + b2 - 10));
 228                 }
 229                 return new String(s,0);
 230         }
 231
 232 }