ObjectId.java

  1. /*
  2.  * Copyright (C) 2008, Robin Rosenberg <robin.rosenberg@dewire.com>
  3.  * Copyright (C) 2006-2008, Shawn O. Pearce <spearce@spearce.org>
  4.  * and other copyright owners as documented in the project's IP log.
  5.  *
  6.  * This program and the accompanying materials are made available
  7.  * under the terms of the Eclipse Distribution License v1.0 which
  8.  * accompanies this distribution, is reproduced below, and is
  9.  * available at http://www.eclipse.org/org/documents/edl-v10.php
  10.  *
  11.  * All rights reserved.
  12.  *
  13.  * Redistribution and use in source and binary forms, with or
  14.  * without modification, are permitted provided that the following
  15.  * conditions are met:
  16.  *
  17.  * - Redistributions of source code must retain the above copyright
  18.  *   notice, this list of conditions and the following disclaimer.
  19.  *
  20.  * - Redistributions in binary form must reproduce the above
  21.  *   copyright notice, this list of conditions and the following
  22.  *   disclaimer in the documentation and/or other materials provided
  23.  *   with the distribution.
  24.  *
  25.  * - Neither the name of the Eclipse Foundation, Inc. nor the
  26.  *   names of its contributors may be used to endorse or promote
  27.  *   products derived from this software without specific prior
  28.  *   written permission.
  29.  *
  30.  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  31.  * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  32.  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  33.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  34.  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  35.  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  36.  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  37.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  38.  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  39.  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  40.  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  41.  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  42.  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  43.  */

  45. package org.eclipse.jgit.lib;

  47. import java.io.IOException;
  48. import java.io.ObjectInputStream;
  49. import java.io.ObjectOutputStream;
  50. import java.io.Serializable;

  52. import org.eclipse.jgit.annotations.Nullable;
  53. import org.eclipse.jgit.errors.InvalidObjectIdException;
  54. import org.eclipse.jgit.util.NB;
  55. import org.eclipse.jgit.util.RawParseUtils;

  57. /**
  58.  * A SHA-1 abstraction.
  59.  */
  60. public class ObjectId extends AnyObjectId implements Serializable {
  61.     private static final long serialVersionUID = 1L;

  63.     private static final ObjectId ZEROID;

  65.     private static final String ZEROID_STR;

  67.     static {
  68.         ZEROID = new ObjectId(0, 0, 0, 0, 0);
  69.         ZEROID_STR = ZEROID.name();
  70.     }

  72.     /**
  73.      * Get the special all-null ObjectId.
  74.      *
  75.      * @return the all-null ObjectId, often used to stand-in for no object.
  76.      */
  77.     public static final ObjectId zeroId() {
  78.         return ZEROID;
  79.     }

  81.     /**
  82.      * Test a string of characters to verify it is a hex format.
  83.      * <p>
  84.      * If true the string can be parsed with {@link #fromString(String)}.
  85.      *
  86.      * @param id
  87.      *            the string to test.
  88.      * @return true if the string can converted into an ObjectId.
  89.      */
  90.     public static final boolean isId(@Nullable String id) {
  91.         if (id == null) {
  92.             return false;
  93.         }
  94.         if (id.length() != Constants.OBJECT_ID_STRING_LENGTH)
  95.             return false;
  96.         try {
  97.             for (int i = 0; i < Constants.OBJECT_ID_STRING_LENGTH; i++) {
  98.                 RawParseUtils.parseHexInt4((byte) id.charAt(i));
  99.             }
  100.             return true;
  101.         } catch (ArrayIndexOutOfBoundsException e) {
  102.             return false;
  103.         }
  104.     }

  106.     /**
  107.      * Convert an ObjectId into a hex string representation.
  108.      *
  109.      * @param i
  110.      *            the id to convert. May be null.
  111.      * @return the hex string conversion of this id's content.
  112.      */
  113.     public static final String toString(ObjectId i) {
  114.         return i != null ? i.name() : ZEROID_STR;
  115.     }

  117.     /**
  118.      * Compare two object identifier byte sequences for equality.
  119.      *
  120.      * @param firstBuffer
  121.      *            the first buffer to compare against. Must have at least 20
  122.      *            bytes from position fi through the end of the buffer.
  123.      * @param fi
  124.      *            first offset within firstBuffer to begin testing.
  125.      * @param secondBuffer
  126.      *            the second buffer to compare against. Must have at least 20
  127.      *            bytes from position si through the end of the buffer.
  128.      * @param si
  129.      *            first offset within secondBuffer to begin testing.
  130.      * @return true if the two identifiers are the same.
  131.      */
  132.     public static boolean equals(final byte[] firstBuffer, final int fi,
  133.             final byte[] secondBuffer, final int si) {
  134.         return firstBuffer[fi] == secondBuffer[si]
  135.                 && firstBuffer[fi + 1] == secondBuffer[si + 1]
  136.                 && firstBuffer[fi + 2] == secondBuffer[si + 2]
  137.                 && firstBuffer[fi + 3] == secondBuffer[si + 3]
  138.                 && firstBuffer[fi + 4] == secondBuffer[si + 4]
  139.                 && firstBuffer[fi + 5] == secondBuffer[si + 5]
  140.                 && firstBuffer[fi + 6] == secondBuffer[si + 6]
  141.                 && firstBuffer[fi + 7] == secondBuffer[si + 7]
  142.                 && firstBuffer[fi + 8] == secondBuffer[si + 8]
  143.                 && firstBuffer[fi + 9] == secondBuffer[si + 9]
  144.                 && firstBuffer[fi + 10] == secondBuffer[si + 10]
  145.                 && firstBuffer[fi + 11] == secondBuffer[si + 11]
  146.                 && firstBuffer[fi + 12] == secondBuffer[si + 12]
  147.                 && firstBuffer[fi + 13] == secondBuffer[si + 13]
  148.                 && firstBuffer[fi + 14] == secondBuffer[si + 14]
  149.                 && firstBuffer[fi + 15] == secondBuffer[si + 15]
  150.                 && firstBuffer[fi + 16] == secondBuffer[si + 16]
  151.                 && firstBuffer[fi + 17] == secondBuffer[si + 17]
  152.                 && firstBuffer[fi + 18] == secondBuffer[si + 18]
  153.                 && firstBuffer[fi + 19] == secondBuffer[si + 19];
  154.     }

  156.     /**
  157.      * Convert an ObjectId from raw binary representation.
  158.      *
  159.      * @param bs
  160.      *            the raw byte buffer to read from. At least 20 bytes must be
  161.      *            available within this byte array.
  162.      * @return the converted object id.
  163.      */
  164.     public static final ObjectId fromRaw(byte[] bs) {
  165.         return fromRaw(bs, 0);
  166.     }

  168.     /**
  169.      * Convert an ObjectId from raw binary representation.
  170.      *
  171.      * @param bs
  172.      *            the raw byte buffer to read from. At least 20 bytes after p
  173.      *            must be available within this byte array.
  174.      * @param p
  175.      *            position to read the first byte of data from.
  176.      * @return the converted object id.
  177.      */
  178.     public static final ObjectId fromRaw(byte[] bs, int p) {
  179.         final int a = NB.decodeInt32(bs, p);
  180.         final int b = NB.decodeInt32(bs, p + 4);
  181.         final int c = NB.decodeInt32(bs, p + 8);
  182.         final int d = NB.decodeInt32(bs, p + 12);
  183.         final int e = NB.decodeInt32(bs, p + 16);
  184.         return new ObjectId(a, b, c, d, e);
  185.     }

  187.     /**
  188.      * Convert an ObjectId from raw binary representation.
  189.      *
  190.      * @param is
  191.      *            the raw integers buffer to read from. At least 5 integers must
  192.      *            be available within this int array.
  193.      * @return the converted object id.
  194.      */
  195.     public static final ObjectId fromRaw(int[] is) {
  196.         return fromRaw(is, 0);
  197.     }

  199.     /**
  200.      * Convert an ObjectId from raw binary representation.
  201.      *
  202.      * @param is
  203.      *            the raw integers buffer to read from. At least 5 integers
  204.      *            after p must be available within this int array.
  205.      * @param p
  206.      *            position to read the first integer of data from.
  207.      * @return the converted object id.
  208.      */
  209.     public static final ObjectId fromRaw(int[] is, int p) {
  210.         return new ObjectId(is[p], is[p + 1], is[p + 2], is[p + 3], is[p + 4]);
  211.     }

  213.     /**
  214.      * Convert an ObjectId from hex characters (US-ASCII).
  215.      *
  216.      * @param buf
  217.      *            the US-ASCII buffer to read from. At least 40 bytes after
  218.      *            offset must be available within this byte array.
  219.      * @param offset
  220.      *            position to read the first character from.
  221.      * @return the converted object id.
  222.      */
  223.     public static final ObjectId fromString(byte[] buf, int offset) {
  224.         return fromHexString(buf, offset);
  225.     }

  227.     /**
  228.      * Convert an ObjectId from hex characters.
  229.      *
  230.      * @param str
  231.      *            the string to read from. Must be 40 characters long.
  232.      * @return the converted object id.
  233.      */
  234.     public static ObjectId fromString(String str) {
  235.         if (str.length() != Constants.OBJECT_ID_STRING_LENGTH) {
  236.             throw new InvalidObjectIdException(str);
  237.         }
  238.         return fromHexString(Constants.encodeASCII(str), 0);
  239.     }

  241.     private static final ObjectId fromHexString(byte[] bs, int p) {
  242.         try {
  243.             final int a = RawParseUtils.parseHexInt32(bs, p);
  244.             final int b = RawParseUtils.parseHexInt32(bs, p + 8);
  245.             final int c = RawParseUtils.parseHexInt32(bs, p + 16);
  246.             final int d = RawParseUtils.parseHexInt32(bs, p + 24);
  247.             final int e = RawParseUtils.parseHexInt32(bs, p + 32);
  248.             return new ObjectId(a, b, c, d, e);
  249.         } catch (ArrayIndexOutOfBoundsException e1) {
  250.             throw new InvalidObjectIdException(bs, p,
  251.                     Constants.OBJECT_ID_STRING_LENGTH);
  252.         }
  253.     }

  255.     /**
  256.      * Construct an ObjectId from 160 bits provided in 5 words.
  257.      *
  258.      * @param new_1
  259.      *            an int
  260.      * @param new_2
  261.      *            an int
  262.      * @param new_3
  263.      *            an int
  264.      * @param new_4
  265.      *            an int
  266.      * @param new_5
  267.      *            an int
  268.      * @since 4.7
  269.      */
  270.     public ObjectId(int new_1, int new_2, int new_3, int new_4, int new_5) {
  271.         w1 = new_1;
  272.         w2 = new_2;
  273.         w3 = new_3;
  274.         w4 = new_4;
  275.         w5 = new_5;
  276.     }

  278.     /**
  279.      * Initialize this instance by copying another existing ObjectId.
  280.      * <p>
  281.      * This constructor is mostly useful for subclasses who want to extend an
  282.      * ObjectId with more properties, but initialize from an existing ObjectId
  283.      * instance acquired by other means.
  284.      *
  285.      * @param src
  286.      *            another already parsed ObjectId to copy the value out of.
  287.      */
  288.     protected ObjectId(AnyObjectId src) {
  289.         w1 = src.w1;
  290.         w2 = src.w2;
  291.         w3 = src.w3;
  292.         w4 = src.w4;
  293.         w5 = src.w5;
  294.     }

  296.     /** {@inheritDoc} */
  297.     @Override
  298.     public ObjectId toObjectId() {
  299.         return this;
  300.     }

  302.     private void writeObject(ObjectOutputStream os) throws IOException {
  303.         os.writeInt(w1);
  304.         os.writeInt(w2);
  305.         os.writeInt(w3);
  306.         os.writeInt(w4);
  307.         os.writeInt(w5);
  308.     }

  310.     private void readObject(ObjectInputStream ois) throws IOException {
  311.         w1 = ois.readInt();
  312.         w2 = ois.readInt();
  313.         w3 = ois.readInt();
  314.         w4 = ois.readInt();
  315.         w5 = ois.readInt();
  316.     }
  317. }
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