dk.brics.grammar.ambiguity
Class TerminalApproximation

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

public class TerminalApproximation
extends ApproximationStrategy

Terminal approximation, using terminals, nullables, and FIRST/LAST sets.

Field Summary

Fields inherited from class dk.brics.grammar.ambiguity.ApproximationStrategy

debug, g, HORIZONTAL_NOT_APPLICABLE, out, VERTICAL_NOT_APPLICABLE

Constructor Summary

TerminalApproximation()
Constructs a new approximator.

Method Summary

HorizontalOverlapString	checkHorizontalOverlap(Production p, int index) Conservatively checks horizontal overlap in a production.
VerticalOverlapString	checkVerticalOverlap(Production p1, Production p2) Conservatively checks vertical overlap of two productions of the same nonterminal.
String	getName() Returns the name "terminal".
void	horizontalDone() Invoked once per production when all its horizontal checks are done.
void	init() Initializes for the current grammar.
void	verticalDone() Invoked once per nonterminal when all its vertical checks are done (in the outer loop).

Methods inherited from class dk.brics.grammar.ambiguity.ApproximationStrategy

horizontalCheck, init, printStatistics, verticalCheck

Methods inherited from class java.lang.Object

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

Constructor Detail

TerminalApproximation

public TerminalApproximation()

Constructs a new approximator.

Method Detail

checkHorizontalOverlap

public HorizontalOverlapString checkHorizontalOverlap(Production p,
                                                      int index)

Description copied from class: ApproximationStrategy

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

Overrides:

checkHorizontalOverlap in class ApproximationStrategy

Parameters:

p - a production

index - division point

Returns:

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

checkVerticalOverlap

public VerticalOverlapString checkVerticalOverlap(Production p1,
                                                  Production p2)

Description copied from class: ApproximationStrategy

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

Overrides:

checkVerticalOverlap in class ApproximationStrategy

Parameters:

p1 - one production

p2 - another production

Returns:

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

getName

public String getName()

Returns the name "terminal".

Returns:

approximation strategy name

horizontalDone

public void horizontalDone()

Description copied from class: ApproximationStrategy

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

Overrides:

horizontalDone in class ApproximationStrategy

init

public void init()

Description copied from class: ApproximationStrategy

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

Overrides:

init in class ApproximationStrategy

verticalDone

public void verticalDone()

Description copied from class: ApproximationStrategy

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

Overrides:

verticalDone in class ApproximationStrategy