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

   1 /*
   2  * Copyright (C) 2008, Robin Rosenberg <robin.rosenberg@dewire.com>
   3  * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
   4  *
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or
   8  * without modification, are permitted provided that the following
   9  * conditions are met:
  10  *
  11  * - Redistributions of source code must retain the above copyright
  12  *   notice, this list of conditions and the following disclaimer.
  13  *
  14  * - Redistributions in binary form must reproduce the above
  15  *   copyright notice, this list of conditions and the following
  16  *   disclaimer in the documentation and/or other materials provided
  17  *   with the distribution.
  18  *
  19  * - Neither the name of the Git Development Community nor the
  20  *   names of its contributors may be used to endorse or promote
  21  *   products derived from this software without specific prior
  22  *   written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  25  * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  26  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  27  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  29  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  30  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  31  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  32  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  33  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  34  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  36  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  37  */
  38
  39 package org.spearce.jgit.lib;
  40
  41 import java.io.UnsupportedEncodingException;
  42
  43 import org.spearce.jgit.util.NB;
  44
  45 /**
  46  * A SHA-1 abstraction.
  47  */
  48 public class ObjectId extends AnyObjectId {
  49         private static final ObjectId ZEROID;
  50
  51         private static final String ZEROID_STR;
  52
  53         static {
  54                 ZEROID = new ObjectId(0, 0, 0, 0, 0);
  55                 ZEROID_STR = ZEROID.name();
  56         }
  57
  58         /**
  59          * Get the special all-null ObjectId.
  60          *
  61          * @return the all-null ObjectId, often used to stand-in for no object.
  62          */
  63         public static final ObjectId zeroId() {
  64                 return ZEROID;
  65         }
  66
  67         /**
  68          * Test a string of characters to verify it is a hex format.
  69          * <p>
  70          * If true the string can be parsed with {@link #fromString(String)}.
  71          *
  72          * @param id
  73          *            the string to test.
  74          * @return true if the string can converted into an ObjectId.
  75          */
  76         public static final boolean isId(final String id) {
  77                 if (id.length() != 2 * Constants.OBJECT_ID_LENGTH)
  78                         return false;
  79                 try {
  80                         for (int k = id.length() - 1; k >= 0; k--)
  81                                 if (fromhex[id.charAt(k)] < 0)
  82                                         return false;
  83                         return true;
  84                 } catch (ArrayIndexOutOfBoundsException e) {
  85                         return false;
  86                 }
  87         }
  88
  89         /**
  90          * Convert an ObjectId into a hex string representation.
  91          *
  92          * @param i
  93          *            the id to convert. May be null.
  94          * @return the hex string conversion of this id's content.
  95          */
  96         public static final String toString(final ObjectId i) {
  97                 return i != null ? i.name() : ZEROID_STR;
  98         }
  99
 100         /**
 101          * Compare to object identifier byte sequences for equality.
 102          *
 103          * @param firstBuffer
 104          *            the first buffer to compare against. Must have at least 20
 105          *            bytes from position ai through the end of the buffer.
 106          * @param fi
 107          *            first offset within firstBuffer to begin testing.
 108          * @param secondBuffer
 109          *            the second buffer to compare against. Must have at least 2
 110          *            bytes from position bi through the end of the buffer.
 111          * @param si
 112          *            first offset within secondBuffer to begin testing.
 113          * @return true if the two identifiers are the same.
 114          */
 115         public static boolean equals(final byte[] firstBuffer, final int fi,
 116                         final byte[] secondBuffer, final int si) {
 117                 return firstBuffer[fi] == secondBuffer[si]
 118                                 && firstBuffer[fi + 1] == secondBuffer[si + 1]
 119                                 && firstBuffer[fi + 2] == secondBuffer[si + 2]
 120                                 && firstBuffer[fi + 3] == secondBuffer[si + 3]
 121                                 && firstBuffer[fi + 4] == secondBuffer[si + 4]
 122                                 && firstBuffer[fi + 5] == secondBuffer[si + 5]
 123                                 && firstBuffer[fi + 6] == secondBuffer[si + 6]
 124                                 && firstBuffer[fi + 7] == secondBuffer[si + 7]
 125                                 && firstBuffer[fi + 8] == secondBuffer[si + 8]
 126                                 && firstBuffer[fi + 9] == secondBuffer[si + 9]
 127                                 && firstBuffer[fi + 10] == secondBuffer[si + 10]
 128                                 && firstBuffer[fi + 11] == secondBuffer[si + 11]
 129                                 && firstBuffer[fi + 12] == secondBuffer[si + 12]
 130                                 && firstBuffer[fi + 13] == secondBuffer[si + 13]
 131                                 && firstBuffer[fi + 14] == secondBuffer[si + 14]
 132                                 && firstBuffer[fi + 15] == secondBuffer[si + 15]
 133                                 && firstBuffer[fi + 16] == secondBuffer[si + 16]
 134                                 && firstBuffer[fi + 17] == secondBuffer[si + 17]
 135                                 && firstBuffer[fi + 18] == secondBuffer[si + 18]
 136                                 && firstBuffer[fi + 19] == secondBuffer[si + 19];
 137         }
 138
 139         /**
 140          * Convert an ObjectId from raw binary representation.
 141          *
 142          * @param bs
 143          *            the raw byte buffer to read from. At least 20 bytes must be
 144          *            available within this byte array.
 145          * @return the converted object id.
 146          */
 147         public static final ObjectId fromRaw(final byte[] bs) {
 148                 return fromRaw(bs, 0);
 149         }
 150
 151         /**
 152          * Convert an ObjectId from raw binary representation.
 153          *
 154          * @param bs
 155          *            the raw byte buffer to read from. At least 20 bytes after p
 156          *            must be available within this byte array.
 157          * @param p
 158          *            position to read the first byte of data from.
 159          * @return the converted object id.
 160          */
 161         public static final ObjectId fromRaw(final byte[] bs, final int p) {
 162                 final int a = NB.decodeInt32(bs, p);
 163                 final int b = NB.decodeInt32(bs, p + 4);
 164                 final int c = NB.decodeInt32(bs, p + 8);
 165                 final int d = NB.decodeInt32(bs, p + 12);
 166                 final int e = NB.decodeInt32(bs, p + 16);
 167                 return new ObjectId(a, b, c, d, e);
 168         }
 169
 170         /**
 171          * Convert an ObjectId from raw binary representation.
 172          *
 173          * @param is
 174          *            the raw integers buffer to read from. At least 5 integers must
 175          *            be available within this int array.
 176          * @return the converted object id.
 177          */
 178         public static final ObjectId fromRaw(final int[] is) {
 179                 return fromRaw(is, 0);
 180         }
 181
 182         /**
 183          * Convert an ObjectId from raw binary representation.
 184          *
 185          * @param is
 186          *            the raw integers buffer to read from. At least 5 integers
 187          *            after p must be available within this int array.
 188          * @param p
 189          *            position to read the first integer of data from.
 190          * @return the converted object id.
 191          */
 192         public static final ObjectId fromRaw(final int[] is, final int p) {
 193                 return new ObjectId(is[p], is[p + 1], is[p + 2], is[p + 3], is[p + 4]);
 194         }
 195
 196         /**
 197          * Convert an ObjectId from hex characters (US-ASCII).
 198          *
 199          * @param buf
 200          *            the US-ASCII buffer to read from. At least 40 bytes after
 201          *            offset must be available within this byte array.
 202          * @param offset
 203          *            position to read the first character from.
 204          * @return the converted object id.
 205          */
 206         public static final ObjectId fromString(final byte[] buf, final int offset) {
 207                 return fromHexString(buf, offset);
 208         }
 209
 210         /**
 211          * Convert an ObjectId from hex characters.
 212          *
 213          * @param str
 214          *            the string to read from. Must be 40 characters long.
 215          * @return the converted object id.
 216          */
 217         public static final ObjectId fromString(final String str) {
 218                 if (str.length() != STR_LEN)
 219                         throw new IllegalArgumentException("Invalid id: " + str);
 220                 return fromHexString(Constants.encodeASCII(str), 0);
 221         }
 222
 223         private static final ObjectId fromHexString(final byte[] bs, int p) {
 224                 try {
 225                         final int a = hexUInt32(bs, p);
 226                         final int b = hexUInt32(bs, p + 8);
 227                         final int c = hexUInt32(bs, p + 16);
 228                         final int d = hexUInt32(bs, p + 24);
 229                         final int e = hexUInt32(bs, p + 32);
 230                         return new ObjectId(a, b, c, d, e);
 231                 } catch (ArrayIndexOutOfBoundsException e1) {
 232                         try {
 233                                 final String str = new String(bs, p, STR_LEN, "US-ASCII");
 234                                 throw new IllegalArgumentException("Invalid id: " + str);
 235                         } catch (UnsupportedEncodingException e2) {
 236                                 throw new IllegalArgumentException("Invalid id");
 237                         }
 238                 }
 239         }
 240
 241         ObjectId(final int new_1, final int new_2, final int new_3,
 242                         final int new_4, final int new_5) {
 243                 w1 = new_1;
 244                 w2 = new_2;
 245                 w3 = new_3;
 246                 w4 = new_4;
 247                 w5 = new_5;
 248         }
 249
 250         /**
 251          * Initialize this instance by copying another existing ObjectId.
 252          * <p>
 253          * This constructor is mostly useful for subclasses who want to extend an
 254          * ObjectId with more properties, but initialize from an existing ObjectId
 255          * instance acquired by other means.
 256          *
 257          * @param src
 258          *            another already parsed ObjectId to copy the value out of.
 259          */
 260         protected ObjectId(final AnyObjectId src) {
 261                 w1 = src.w1;
 262                 w2 = src.w2;
 263                 w3 = src.w3;
 264                 w4 = src.w4;
 265                 w5 = src.w5;
 266         }
 267
 268         @Override
 269         public ObjectId toObjectId() {
 270                 return this;
 271         }
 272 }