xtc.parser
Class ElementVoider

java.lang.Object
  xtc.tree.Visitor
      xtc.parser.ElementVoider

public class ElementVoider
extends Visitor

Visitor to void ordered choices, repetitions, and options. This visitor voids ordered choices, repetitions, and options, if all expressions appearing in such an expression are either void nonterminals or explicitly voided. It requires that a grammar has been resolved into a single module, that text-only productions have been marked as such, and that all expressions have been simplified.

Version:

$Revision: 1.15 $

Author:

Robert Grimm

Field Summary

protected Analyzer	analyzer The analyzer utility.
protected boolean	hasValue The flag for potentially having a value.
protected boolean	isLastElement The flag for the last element.
protected boolean	isTopLevel The flag for the top-level element.
protected Runtime	runtime The runtime.
protected boolean	suppressVoided The flag for suppressing the insertion of voided elements.

Constructor Summary

ElementVoider(Runtime runtime, Analyzer analyzer)
Create a new element voider.

Method Summary

Action	visit(Action a) Visit the specified action.
Binding	visit(Binding b) Visit the specified binding.
Element	visit(Element e) Visit the specified element.
void	visit(FullProduction p) Visit the specified full production.
void	visit(Module m) Visit the specified self-contained module.
NonTerminal	visit(NonTerminal nt) Visit the specified nonterminal.
Element	visit(OrderedChoice c) Visit the specified ordered choice.
ParserAction	visit(ParserAction pa) Visit the specified parser action.
Element	visit(Predicate p) Visit the specified predicate.
Element	visit(Quantification q) Visit the specified quantification.
Element	visit(Sequence s) Visit the specified sequence.
StringMatch	visit(StringMatch m) Visit the specified string match.
VoidedElement	visit(VoidedElement v) Visit the specified voided element.
protected Element	wrap(Element el) Wrap the specified element in a voiding operator.

Methods inherited from class xtc.tree.Visitor

dispatch, equals, hashCode, iterate, map, mapInPlace, unableToVisit, visit

Methods inherited from class java.lang.Object

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

Field Detail

runtime

protected final Runtime runtime

The runtime.

analyzer

protected final Analyzer analyzer

The analyzer utility.

isTopLevel

protected boolean isTopLevel

The flag for the top-level element.

isLastElement

protected boolean isLastElement

The flag for the last element.

suppressVoided

protected boolean suppressVoided

The flag for suppressing the insertion of voided elements.

hasValue

protected boolean hasValue

The flag for potentially having a value.

Constructor Detail

ElementVoider

public ElementVoider(Runtime runtime,
                     Analyzer analyzer)

Create a new element voider.

Parameters:

runtime - The runtime.

analyzer - The analyzer.

Method Detail

wrap

protected Element wrap(Element el)

Wrap the specified element in a voiding operator.

Parameters:

el - The element to wrap.

Returns:

The wrapped element.

visit

public void visit(Module m)

Visit the specified self-contained module.

visit

public void visit(FullProduction p)

Visit the specified full production.

visit

public Element visit(OrderedChoice c)

Visit the specified ordered choice.

visit

public Element visit(Quantification q)

Visit the specified quantification.

visit

public Element visit(Sequence s)

Visit the specified sequence.

visit

public Element visit(Predicate p)

Visit the specified predicate.

visit

public VoidedElement visit(VoidedElement v)

Visit the specified voided element.

visit

public Binding visit(Binding b)

Visit the specified binding.

visit

public StringMatch visit(StringMatch m)

Visit the specified string match.

visit

public ParserAction visit(ParserAction pa)

Visit the specified parser action.

visit

public Action visit(Action a)

Visit the specified action.

visit

public NonTerminal visit(NonTerminal nt)

Visit the specified nonterminal.

visit

public Element visit(Element e)

Visit the specified element. This method provides the default implementation for terminals, parse tree nodes, null literals, node markers, and value elements.