com.github.f4b6a3.uuid.codec.base

Class BaseN

java.lang.Object

com.github.f4b6a3.uuid.codec.base.BaseN

public final class BaseN
extends Object

Class that represents the base-n encodings.

Field Summary

Fields

Modifier and Type	Field and Description
protected static String	ALPHABET_36 The default alphabet for case-insensitive base-n.
protected static String	ALPHABET_64 The default alphabet for case-sensitive base-n.
protected static int	RADIX_MAX The maximum radix: 64.
protected static int	RADIX_MIN The minimum radix: 2.

Constructor Summary

Constructors

Constructor and Description
BaseN(int radix) Public constructor for the base-n object.
BaseN(String alphabet) Public constructor for the base-n object.

Method Summary

Modifier and Type	Method and Description
protected static char[]	expand(char a, char b) Expands a character sequence similar to 0-9, a-z and A-Z.
protected static String	expand(String string) Expands character sequences similar to 0-9, a-z and A-Z.
CharArray	getAlphabet() Returns the alphabet of the base-n.
int	getLength() Returns the length of encoded UUIDs.
ByteArray	getMap() Returns the map of the base-n.
char	getPadding() Return the padding character.
int	getRadix() Returns the radix of the base-n.
boolean	isSensitive() Informs if the base-n is case-sensitive.
boolean	isValid(String uuid) Checks if the UUID string is valid.
void	validate(String uuid) Checks if the UUID string is a valid.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

RADIX_MIN

protected static final int RADIX_MIN

The minimum radix: 2.

See Also:

Constant Field Values

RADIX_MAX

protected static final int RADIX_MAX

The maximum radix: 64.

See Also:

Constant Field Values

ALPHABET_36

protected static final String ALPHABET_36

The default alphabet for case-insensitive base-n.

See Also:

Constant Field Values

ALPHABET_64

protected static final String ALPHABET_64

The default alphabet for case-sensitive base-n.

See Also:

Constant Field Values

Constructor Detail

BaseN

public BaseN(int radix)

Public constructor for the base-n object.

The radix is the alphabet size.

The supported alphabet sizes are from 2 to 64.

If there are mixed cases in the alphabet, the base-n is case SENSITIVE.

The encoded string length is equal to `CEIL(128 / LOG2(n))`, where n is the radix. The encoded string is padded to fit the expected length.

The padding character is the first character of the string. For example, the padding character for the alphabet "abcdef0123456" is 'a'.

The example below shows how to create a BaseN for an hypothetical base-26 encoding that contains only letters. You only need to pass a number 40.

 String radix = 40;
 BaseN base = new BaseN(radix);
 

If radix is greater than 36, the alphabet generated is a subset of the character sequence "0-9A-Za-z-_". Otherwise it is a subset of "0-9a-z". In the example above the resulting alphabet is "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcd" (0-9A-Za-d).

Parameters:

radix - the radix to be used

BaseN

public BaseN(String alphabet)

Public constructor for the base-n object.

The radix is the alphabet size.

The supported alphabet sizes are from 2 to 64.

If there are mixed cases in the alphabet, the base-n is case SENSITIVE.

The encoded string length is equal to `CEIL(128 / LOG2(n))`, where n is the radix. The encoded string is padded to fit the expected length.

The padding character is the first character of the string. For example, the padding character for the alphabet "abcdef0123456" is 'a'.

The example below shows how to create a BaseN for an hypothetical base-26 encoding that contains only letters. You only need to pass a string with 26 characters.

 String alphabet = "abcdefghijklmnopqrstuvwxyz";
 BaseN base = new BaseN(alphabet);
 

Alphabet strings similar to "a-f0-9" are expanded to "abcdef0123456789". The same example using the string "a-z" instead of "abcdefghijklmnopqrstuvwxyz":

 String alphabet = "a-z";
 BaseN base = new BaseN(alphabet);
 

Parameters:

alphabet - the alphabet to be used

Method Detail

getRadix

public int getRadix()

Returns the radix of the base-n.

Returns:

the radix

getLength

public int getLength()

Returns the length of encoded UUIDs.

Returns:

the length

getPadding

public char getPadding()

Return the padding character.

Returns:

a character

isSensitive

public boolean isSensitive()

Informs if the base-n is case-sensitive.

Returns:

true if it is case-sensitive

getAlphabet

public CharArray getAlphabet()

Returns the alphabet of the base-n.

Returns:

the alphabet

getMap

public ByteArray getMap()

Returns the map of the base-n.

Returns:

a map

isValid

public boolean isValid(String uuid)

Checks if the UUID string is valid.

Parameters:

uuid - a UUID string

Returns:

true if valid, false if invalid

validate

public void validate(String uuid)

Checks if the UUID string is a valid.

Parameters:

uuid - a UUID string

Throws:

InvalidUuidException - if the argument is invalid

expand

protected static String expand(String string)

Expands character sequences similar to 0-9, a-z and A-Z.

Parameters:

string - a string to be expanded

Returns:

a string

expand

protected static char[] expand(char a,
                               char b)

Expands a character sequence similar to 0-9, a-z and A-Z.

Parameters:

a - the first character of the sequence

b - the last character of the sequence

Returns:

an expanded sequence of characters