de.ls5.jlearn.oracles
Class PrefixClosureFilter

java.lang.Object
  de.ls5.jlearn.oracles.PrefixClosureFilter

All Implemented Interfaces:

Oracle, Serializable

public class PrefixClosureFilter
extends Object
implements Oracle

A prefix closure filter answers known prefixes that ends up with some specific output (contained in rejectedSymbols) with a special defines output. The special output futureError should not be contained within the output alphabet.

Author:

Oliver Bauer

See Also:

Serialized Form

Nested Class Summary

static class

PrefixClosureFilter.AppliedAction For unit testing purposes.

Constructor Summary

PrefixClosureFilter(Oracle delegate, Symbol futureOutput)
Default constructor.

Method Summary

void	addRejectedSymbol(Symbol symbol) Adds a rejecting symbol.
Word	addToFilter(Word trace, Word result) Adds the trace with the result to rejected prefixes if the trace contains a symbol that should be rejected.
PrefixClosureFilter.AppliedAction	getLastAppliedAction() For unit testing.
Word	lookupWord(Word trace) If there exists a prefix that already known and that ends up with some symbol in rejectedSymbols an answer is constructed.
Word	processQuery(Word trace) Process an incoming sequence (word) of input symbols and return a sequence (word) of output symbols produced as reacion to the input symbols.

Methods inherited from class java.lang.Object

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

Constructor Detail

PrefixClosureFilter

public PrefixClosureFilter(Oracle delegate,
                           Symbol futureOutput)

Default constructor.

Parameters:

delegate - The Oracle to delegate queries to, if this filter can't answer received queries.

futureOutput - The symbol that act as a placeholder for suffix answers if the corresponding prefix ends with an rejected symbol.

See Also:

addRejectedSymbol(Symbol)

Method Detail

addRejectedSymbol

public void addRejectedSymbol(Symbol symbol)

Adds a rejecting symbol.

Parameters:

symbol -

lookupWord

public Word lookupWord(Word trace)

If there exists a prefix that already known and that ends up with some symbol in rejectedSymbols an answer is constructed. Otherwise this method returns null

Parameters:

trace -

Returns:

addToFilter

public Word addToFilter(Word trace,
                        Word result)

Adds the trace with the result to rejected prefixes if the trace contains a symbol that should be rejected.

Parameters:

trace -

result -

processQuery

public Word processQuery(Word trace)
                  throws LearningException

Process an incoming sequence (word) of input symbols and return a sequence (word) of output symbols produced as reacion to the input symbols..

Specified by:

processQuery in interface Oracle

Parameters:

trace - Word object respresenting the query the system is supposed to process

Returns:

Word object with the system's response to the provide query

Throws:

LearningException

getLastAppliedAction

public PrefixClosureFilter.AppliedAction getLastAppliedAction()

For unit testing. Returns the last applied action this filter had used on the last received query.

Returns: