step.encoding
Class IdentifierStrategy

java.lang.Object
  |
  +--step.encoding.Encoder
        |
        +--step.encoding.Strategy
              |
              +--step.encoding.RegularValueStrategy
                    |
                    +--step.encoding.IdentifierStrategy

Direct Known Subclasses:

PIdentifierStrategy

public class IdentifierStrategy

extends RegularValueStrategy

Assume that values derive from a relatively small, fixed distribution. Instead of encoding the full value, use a small integer ID in its place.

NOTE: The ID values are encoded with a CreepIntEncoder, thus the strategy is optimized for distributions with < 128 distinct values.

Field Summary

static String

STRATEGY_NAME

Fields inherited from class step.encoding.RegularValueStrategy

_nextIsRegular

Fields inherited from class step.encoding.Strategy

_baseEncoder

Constructor Summary

IdentifierStrategy(Encoder baseEncoder)
Create a new "identifier" strategy.

Method Summary

protected void	add(StepObject value) Pre-map a value in the expected distribution.
StepObject	decode(DecodeContext context) Decode an ID, map it to a value.
void	dump(int level)
void	encode(StepObject o, EncodeContext context) Encode a value as an ID.
protected Object	idToValue(StepObject id) Get the current value for this ID.
protected Object	valueToId(StepObject value) Get the current ID for this value.

Methods inherited from class step.encoding.RegularValueStrategy

setNextIsRegular

Methods inherited from class step.encoding.Strategy

baseDecode, baseEncode, eventMessage

Methods inherited from class step.encoding.Encoder

getFactory, getName, indent, makeFieldName

Methods inherited from class java.lang.Object

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

Field Detail

STRATEGY_NAME

public static final String STRATEGY_NAME

See Also:

Constant Field Values

Constructor Detail

IdentifierStrategy

public IdentifierStrategy(Encoder baseEncoder)

Create a new "identifier" strategy.

Parameters:

baseEncoder - the encoder to defer to when writing previously unmapped values.

Method Detail

encode

public void encode(StepObject o,
                   EncodeContext context)
            throws EncoderException,
                   IOException

Encode a value as an ID.

Specified by:

encode in class Encoder

Throws:

IOException - if the encode operation encountered an I/O failure.

EncoderException - if the encode operation encountered an error.

decode

public StepObject decode(DecodeContext context)
                  throws EncoderException,
                         IOException

Decode an ID, map it to a value.

Specified by:

decode in class Encoder

Throws:

IOException - if the decode operation encountered an I/O failure.

EncoderException - if the decode operation encountered an error.

valueToId

protected Object valueToId(StepObject value)

Get the current ID for this value.

Returns:

the current ID (as a StepInt) or null if no ID is defined for the value.

idToValue

protected Object idToValue(StepObject id)

Get the current value for this ID.

Returns:

the current value associated with the ID or null if no value is defined for the ID.

add

protected void add(StepObject value)

Pre-map a value in the expected distribution.

WARNING: This method is provided for bootstrapping purposes. Don't use it unless you understand the consequences.

Throws:

IllegalArgumentException - if a mapping already exists for the value.

dump

public void dump(int level)

Specified by:

dump in class Encoder