Package gw.util.fingerprint

Class FP64

java.lang.Object

gw.util.fingerprint.FP64

public final class FP64
extends Object

Field Summary

Fields

Modifier and Type	Field	Description
private long	_fp
private static long[]	ByteModTable
private static final long	IrredPoly
private static final String	LEADING_ZEROS
private static final long	One
private static final long	X63
private static final long	Zero

Constructor Summary

Constructors

Constructor	Description
FP64()	Initializes this object to the fingerprint of the empty string.
FP64(byte[] bytes)	Initializes this object to the fingerprint of the byte array bytes, which must be non-null.
FP64(byte[] bytes, int start, int length)	Initializes this object to the fingerprint of the bytes bytes[start]..bytes[start+length-1].
FP64(char[] chars)	Initializes this object to the fingerprint of the character array chars, which must be non-null.
FP64(char[] chars, int start, int length)	Initializes this object to the fingerprint of the characters chars[start]..chars[start+length-1].
FP64(FP64 fp)	Initializes this fingerprint to a copy of fp, which must be non-null.
FP64(InputStream stream)	Initializes this object to the fingerprint of the bytes in stream, which must be non-null.
FP64(String s)	Initializes this object to the fingerprint of the String s, which must be non-null.
FP64(ByteBuffer buffer)	Initializes this object to the fingerprint of the bytes in buffer, which must be non-null.

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object obj)
FP64	extend(byte b)	Extends this fingerprint by the byte b.
FP64	extend(byte[] bytes)	Extends this fingerprint by the bytes
FP64	extend(byte[] bytes, int start, int len)	Extends this fingerprint by the bytes bytes[offset]..bytes[offset+length-1].
FP64	extend(char c)	Extends this fingerprint by the character c.
FP64	extend(char[] chars)	Extends this fingerprint by the characters chars[start]..chars[start+length-1].
FP64	extend(char[] chars, int start, int len)	Extends this fingerprint by the characters chars[start]..chars[start+length-1].
FP64	extend(int i)	Extends this fingerprint by the integer i.
FP64	extend(long i)	Extends this fingerprint by the integer i.
FP64	extend(InputStream stream)	Extends this fingerprint by the bytes of the stream stream, which must be non-null.
FP64	extend(String s)	Extends this fingerprint by the characters of the String s, which must be non-null.
FP64	extend(ByteBuffer buffer)
long	getRawFingerprint()
int	hashCode()
byte[]	toBytes()	Returns the value of this fingerprint as a newly-allocated array of 8 bytes.
byte[]	toBytes(byte[] buff)	Returns the value of this fingerprint as an 8-byte array.
String	toHexString()	Returns the value of this fingerprint as an unsigned integer encoded in base 16 (hexideicmal), padded with leading zeros to a total length of 16 characters.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Details

_fp

private long _fp

LEADING_ZEROS

private static final String LEADING_ZEROS

See Also:

• Constant Field Values

Zero

private static final long Zero

See Also:

• Constant Field Values

One

private static final long One

See Also:

• Constant Field Values

IrredPoly

private static final long IrredPoly

See Also:

• Constant Field Values

X63

private static final long X63

See Also:

• Constant Field Values

ByteModTable

private static long[] ByteModTable

Constructor Details

FP64

public FP64()

Initializes this object to the fingerprint of the empty string.

FP64

public FP64(FP64 fp)

Initializes this fingerprint to a copy of fp, which must be non-null.

FP64

public FP64(String s)

Initializes this object to the fingerprint of the String s, which must be non-null.

FP64

public FP64(char[] chars)

Initializes this object to the fingerprint of the character array chars, which must be non-null.

FP64

public FP64(char[] chars,
 int start,
 int length)

Initializes this object to the fingerprint of the characters chars[start]..chars[start+length-1].

FP64

public FP64(byte[] bytes)

Initializes this object to the fingerprint of the byte array bytes, which must be non-null.

FP64

public FP64(byte[] bytes,
 int start,
 int length)

Initializes this object to the fingerprint of the bytes bytes[start]..bytes[start+length-1].

FP64

public FP64(InputStream stream)
     throws IOException

Initializes this object to the fingerprint of the bytes in stream, which must be non-null.

Throws:

IOException - if an error is encountered reading stream.

FP64

public FP64(ByteBuffer buffer)
     throws IOException

Initializes this object to the fingerprint of the bytes in buffer, which must be non-null.

Throws:

IOException - if an error is encountered reading stream.

Method Details

toBytes

public byte[] toBytes()

Returns the value of this fingerprint as a newly-allocated array of 8 bytes.

Important: If the output of this function is subsequently fingerprinted, the probabilistic guarantee is lost. That is, there is a much higher liklihood of fingerprint collisions if fingerprint values are themselves fingerprinted in any way.

toBytes

public byte[] toBytes(byte[] buff)

Returns the value of this fingerprint as an 8-byte array. Unlike toBytes(), this variant does not perform an allocation. Instead, the client passes in a buffer into which the fingerprint value is written. This can be used to get the values of a set of fingerprints without having to perform an allocation for each one.

Parameters:

buff - The buffer into which the bytes will be written. This array is required to be non-null and exactly 8 bytes in length. This buffer is returned.

toHexString

public String toHexString()

Returns the value of this fingerprint as an unsigned integer encoded in base 16 (hexideicmal), padded with leading zeros to a total length of 16 characters.

Important: If the output of this function is subsequently fingerprinted, the probabilistic guarantee is lost. That is, there is a much higher liklihood of fingerprint collisions if fingerprint values are themselves fingerprinted in any way.

extend

public FP64 extend(String s)

Extends this fingerprint by the characters of the String s, which must be non-null.

Returns:

the resulting fingerprint.

extend

public FP64 extend(char[] chars)

Extends this fingerprint by the characters chars[start]..chars[start+length-1].

Returns:

the resulting fingerprint.

extend

public FP64 extend(char[] chars,
 int start,
 int len)

Extends this fingerprint by the characters chars[start]..chars[start+length-1].

Returns:

the resulting fingerprint.

extend

public FP64 extend(byte[] bytes,
 int start,
 int len)

Extends this fingerprint by the bytes bytes[offset]..bytes[offset+length-1].

Returns:

the resulting fingerprint.

extend

public FP64 extend(byte[] bytes)

Extends this fingerprint by the bytes

Returns:

the resulting fingerprint.

extend

public FP64 extend(int i)

Extends this fingerprint by the integer i.

Returns:

the resulting fingerprint.

extend

public FP64 extend(long i)

Extends this fingerprint by the integer i.

Returns:

the resulting fingerprint.

extend

public FP64 extend(char c)

Extends this fingerprint by the character c.

Returns:

the resulting fingerprint.

extend

public FP64 extend(byte b)

Extends this fingerprint by the byte b.

Returns:

the resulting fingerprint.

extend

public FP64 extend(InputStream stream)
            throws IOException

Extends this fingerprint by the bytes of the stream stream, which must be non-null.

Returns:

the resulting fingerprint.

Throws:

IOException - if an error is encountered reading stream.

extend

public FP64 extend(ByteBuffer buffer)
            throws IOException

Throws:

IOException

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

getRawFingerprint

public long getRawFingerprint()

toString

public String toString()

Overrides:

toString in class Object