Class AbbreviatedLongObjectId

  • All Implemented Interfaces:
    java.io.Serializable

    public final class AbbreviatedLongObjectId
    extends java.lang.Object
    implements java.io.Serializable
    A prefix abbreviation of an LongObjectId.

    Enable abbreviating SHA-256 strings used by Git LFS, using sufficient leading digits from the LongObjectId name to still be unique within the repository the string was generated from. These ids are likely to be unique for a useful period of time, especially if they contain at least 6-10 hex digits.

    This class converts the hex string into a binary form, to make it more efficient for matching against an object. Ported to SHA-256 from AbbreviatedObjectId

    Since:
    4.3
    See Also:
    Serialized Form
    • Field Detail

      • nibbles

        final int nibbles
        Number of half-bytes used by this id.
      • w1

        final long w1
      • w2

        final long w2
      • w3

        final long w3
      • w4

        final long w4
    • Constructor Detail

      • AbbreviatedLongObjectId

        AbbreviatedLongObjectId​(int n,
                                long new_1,
                                long new_2,
                                long new_3,
                                long new_4)
    • Method Detail

      • isId

        public static final boolean isId​(java.lang.String id)
        Test a string of characters to verify it is a hex format.

        If true the string can be parsed with fromString(String).

        Parameters:
        id - the string to test.
        Returns:
        true if the string can converted into an AbbreviatedObjectId.
      • fromString

        public static final AbbreviatedLongObjectId fromString​(byte[] buf,
                                                               int offset,
                                                               int end)
        Convert an AbbreviatedObjectId from hex characters (US-ASCII).
        Parameters:
        buf - the US-ASCII buffer to read from.
        offset - position to read the first character from.
        end - one past the last position to read (end-offset is the length of the string).
        Returns:
        the converted object id.
      • fromString

        public static final AbbreviatedLongObjectId fromString​(java.lang.String str)
        Convert an AbbreviatedLongObjectId from hex characters.
        Parameters:
        str - the string to read from. Must be <= 64 characters.
        Returns:
        the converted object id.
      • hexUInt64

        private static final long hexUInt64​(byte[] bs,
                                            int p,
                                            int end)
      • mask

        static long mask​(int nibbles,
                         long word,
                         long v)
      • length

        public int length()
        Get length
        Returns:
        number of hex digits appearing in this id.
      • isComplete

        public boolean isComplete()
        Check if this id is complete
        Returns:
        true if this ObjectId is actually a complete id.
      • toLongObjectId

        public LongObjectId toLongObjectId()
        Convert to LongObjectId
        Returns:
        a complete ObjectId; null if isComplete() is false.
      • prefixCompare

        public final int prefixCompare​(AnyLongObjectId other)
        Compares this abbreviation to a full object id.
        Parameters:
        other - the other object id.
        Returns:
        <0 if this abbreviation names an object that is less than other; 0 if this abbreviation exactly matches the first length() digits of other.name(); >0 if this abbreviation names an object that is after other.
      • prefixCompare

        public final int prefixCompare​(byte[] bs,
                                       int p)
        Compare this abbreviation to a network-byte-order LongObjectId.
        Parameters:
        bs - array containing the other LongObjectId in network byte order.
        p - position within bs to start the compare at. At least 32 bytes, starting at this position are required.
        Returns:
        <0 if this abbreviation names an object that is less than other; 0 if this abbreviation exactly matches the first length() digits of other.name(); >0 if this abbreviation names an object that is after other.
      • prefixCompare

        public final int prefixCompare​(long[] bs,
                                       int p)
        Compare this abbreviation to a network-byte-order LongObjectId.
        Parameters:
        bs - array containing the other LongObjectId in network byte order.
        p - position within bs to start the compare at. At least 4 longs, starting at this position are required.
        Returns:
        <0 if this abbreviation names an object that is less than other; 0 if this abbreviation exactly matches the first length() digits of other.name(); >0 if this abbreviation names an object that is after other.
      • getFirstByte

        public final int getFirstByte()
        Get the first byte of this id
        Returns:
        value for a fan-out style map, only valid of length >= 2.
      • mask

        private long mask​(long word,
                          long v)
      • hashCode

        public int hashCode()
        Overrides:
        hashCode in class java.lang.Object
      • equals

        public boolean equals​(java.lang.Object o)
        Overrides:
        equals in class java.lang.Object
      • name

        public final java.lang.String name()

        name.

        Returns:
        string form of the abbreviation, in lower case hexadecimal.
      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object