dk.brics.grammar.ambiguity
Class ApproximationStrategy

java.lang.Object
  dk.brics.grammar.ambiguity.ApproximationStrategy

Direct Known Subclasses:

RegularApproximation, TerminalApproximation

public abstract class ApproximationStrategy
extends Object

Abstract base class for approximation strategies.

Field Summary

protected boolean	debug Verbose flag.
protected Grammar	g Current grammar.
static HorizontalOverlapString	HORIZONTAL_NOT_APPLICABLE Value used by checkHorizontalOverlap(Production, int) for "not applicable" responses.
protected PrintWriter	out Print stream for messages.
static VerticalOverlapString	VERTICAL_NOT_APPLICABLE Value used by checkVerticalOverlap(Production, Production) for "not applicable" responses.

Constructor Summary

protected

ApproximationStrategy() Abstract constructor.

Method Summary

protected HorizontalOverlapString	checkHorizontalOverlap(Production p, int index) Conservatively checks horizontal overlap in a production.
protected VerticalOverlapString	checkVerticalOverlap(Production p1, Production p2) Conservatively checks vertical overlap of two productions of the same nonterminal.
HorizontalOverlapString	horizontalCheck(Production p, int index) Conservatively checks horizontal overlap in a production.
protected void	horizontalDone() Invoked once per production when all its horizontal checks are done.
protected void	init() Initializes for the current grammar.
void	init(Grammar g, PrintWriter out, boolean debug) Initializes for the given grammar.
void	printStatistics(PrintWriter out) Prints statistics from the last analysis.
VerticalOverlapString	verticalCheck(Production p1, Production p2) Conservatively checks vertical overlap of two productions of the same nonterminal.
protected void	verticalDone() Invoked once per nonterminal when all its vertical checks are done (in the outer loop).

Methods inherited from class java.lang.Object

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

Field Detail

debug

protected boolean debug

Verbose flag.

g

protected Grammar g

Current grammar.

HORIZONTAL_NOT_APPLICABLE

public static final HorizontalOverlapString HORIZONTAL_NOT_APPLICABLE

Value used by checkHorizontalOverlap(Production, int) for "not applicable" responses.

out

protected PrintWriter out

Print stream for messages.

VERTICAL_NOT_APPLICABLE

public static final VerticalOverlapString VERTICAL_NOT_APPLICABLE

Value used by checkVerticalOverlap(Production, Production) for "not applicable" responses.

Constructor Detail

ApproximationStrategy

protected ApproximationStrategy()

Abstract constructor.

Method Detail

checkHorizontalOverlap

protected HorizontalOverlapString checkHorizontalOverlap(Production p,
                                                         int index)

Conservatively checks horizontal overlap in a production. This method is typically implemented in a subclass. The default implementation returns HORIZONTAL_NOT_APPLICABLE.

Parameters:

p - a production

index - division point

Returns:

potential example string in overlap, null if definitely no overlap, HORIZONTAL_NOT_APPLICABLE can be used as a "don't know" value

checkVerticalOverlap

protected VerticalOverlapString checkVerticalOverlap(Production p1,
                                                     Production p2)

Conservatively checks vertical overlap of two productions of the same nonterminal. This method is typically implemented in a subclass. The default implementation returns VERTICAL_NOT_APPLICABLE.

Parameters:

p1 - one production

p2 - another production

Returns:

potential example string in overlap, null if definitely no overlap, VERTICAL_NOT_APPLICABLE can be used as a "don't know" value

horizontalCheck

public final HorizontalOverlapString horizontalCheck(Production p,
                                                     int index)

Conservatively checks horizontal overlap in a production. This method is invoked by AmbiguityAnalyzer.

Parameters:

p - a production

index - division point

Returns:

potential example string in overlap, null if definitely no overlap, HORIZONTAL_NOT_APPLICABLE can be used as a "don't know" value

horizontalDone

protected void horizontalDone()

Invoked once per production when all its horizontal checks are done. Default implementation does nothing.

init

protected void init()

Initializes for the current grammar. This method is typically implemented in a subclass. The default implementation does nothing. The grammar is available as g.

init

public final void init(Grammar g,
                       PrintWriter out,
                       boolean debug)

Initializes for the given grammar. This method is invoked by AmbiguityAnalyzer.

Parameters:

g - current grammar

out - print writer for messages

debug - debug flag

printStatistics

public void printStatistics(PrintWriter out)

Prints statistics from the last analysis.

Parameters:

out - print writer for output

verticalCheck

public final VerticalOverlapString verticalCheck(Production p1,
                                                 Production p2)

Conservatively checks vertical overlap of two productions of the same nonterminal. This method is invoked by AmbiguityAnalyzer.

Parameters:

p1 - one production

p2 - another production

Returns:

potential example string in overlap, null if definitely no overlap, VERTICAL_NOT_APPLICABLE can be used as a "don't know" value

verticalDone

protected void verticalDone()

Invoked once per nonterminal when all its vertical checks are done (in the outer loop). Default implementation does nothing.