com.facebook.presto.common.type.encoding

Class BaseNCodec

java.lang.Object

com.facebook.presto.common.type.encoding.BaseNCodec

Direct Known Subclasses:

Base32

public abstract class BaseNCodec
extends Object

Abstract superclass for Base-N encoders and decoders.

This class is thread-safe.

Version:

$Id: BaseNCodec.java 1634404 2014-10-26 23:06:10Z ggregory $

Field Summary

Fields

Modifier and Type	Field and Description
protected int	lineLength Chunksize for encoding.
protected static int	MASK_8BITS Mask used to extract 8 bits, used in decoding bytes
protected byte	pad
protected static byte	PAD_DEFAULT Byte used to pad output.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	BaseNCodec(int unencodedBlockSize, int encodedBlockSize, int lineLength, int chunkSeparatorLength) Note lineLength is rounded down to the nearest multiple of encodedBlockSize If chunkSeparatorLength is zero, then chunking is disabled.

Method Summary

Modifier and Type	Method and Description
byte[]	decode(byte[] pArray) Decodes a byte[] containing characters in the Base-N alphabet.
byte[]	decode(String pArray) Decodes a String containing characters in the Base-N alphabet.
byte[]	encode(byte[] pArray) Encodes a byte[] containing binary data, into a byte[] containing characters in the alphabet.
String	encodeAsString(byte[] pArray) Encodes a byte[] containing binary data, into a String containing characters in the appropriate alphabet.
protected abstract boolean	isInAlphabet(byte value) Returns whether or not the octet is in the current alphabet.
protected static boolean	isWhiteSpace(byte byteToCheck) Checks if a byte value is whitespace or not.

Methods inherited from class java.lang.Object

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

Field Detail

MASK_8BITS

protected static final int MASK_8BITS

Mask used to extract 8 bits, used in decoding bytes

See Also:

Constant Field Values

PAD_DEFAULT

protected static final byte PAD_DEFAULT

Byte used to pad output.

See Also:

Constant Field Values

pad

protected final byte pad

lineLength

protected final int lineLength

Chunksize for encoding. Not used when decoding. A value of zero or less implies no chunking of the encoded data. Rounded down to nearest multiple of encodedBlockSize.

Constructor Detail

BaseNCodec

protected BaseNCodec(int unencodedBlockSize,
                     int encodedBlockSize,
                     int lineLength,
                     int chunkSeparatorLength)

Note lineLength is rounded down to the nearest multiple of encodedBlockSize If chunkSeparatorLength is zero, then chunking is disabled.

Parameters:

unencodedBlockSize - the size of an unencoded block (e.g. Base64 = 3)

encodedBlockSize - the size of an encoded block (e.g. Base64 = 4)

lineLength - if > 0, use chunking with a length lineLength

chunkSeparatorLength - the chunk separator length, if relevant

Method Detail

isWhiteSpace

protected static boolean isWhiteSpace(byte byteToCheck)

Checks if a byte value is whitespace or not. Whitespace is taken to mean: space, tab, CR, LF

Parameters:

byteToCheck - the byte to check

Returns:

true if byte is whitespace, false otherwise

encodeAsString

public String encodeAsString(byte[] pArray)

Encodes a byte[] containing binary data, into a String containing characters in the appropriate alphabet. Uses UTF8 encoding.

Parameters:

pArray - a byte array containing binary data

Returns:

String containing only character data in the appropriate alphabet.

decode

public byte[] decode(String pArray)

Decodes a String containing characters in the Base-N alphabet.

Parameters:

pArray - A String containing Base-N character data

Returns:

a byte array containing binary data

decode

public byte[] decode(byte[] pArray)

Decodes a byte[] containing characters in the Base-N alphabet.

Parameters:

pArray - A byte array containing Base-N character data

Returns:

a byte array containing binary data

encode

public byte[] encode(byte[] pArray)

Encodes a byte[] containing binary data, into a byte[] containing characters in the alphabet.

Parameters:

pArray - a byte array containing binary data

Returns:

A byte array containing only the base-n alphabetic character data

isInAlphabet

protected abstract boolean isInAlphabet(byte value)

Returns whether or not the octet is in the current alphabet. Does not allow whitespace or pad.

Parameters:

value - The value to test

Returns:

true if the value is defined in the current alphabet, false otherwise.