xtc.parser
Class Simplifier

java.lang.Object
  xtc.tree.Visitor
      xtc.parser.GrammarVisitor
          xtc.parser.Simplifier

public class Simplifier
extends GrammarVisitor

Visitor to simplify a grammar. This visitor folds nested choices and sequences into the embedding choice or sequence, eliminates choices and sequences with only one alternative or element (with the exception of the top-level choice of a production), and reduces repetitions and options to their simplest form. It also reduces trivial character classes and string literals to character literals. Note that the resulting grammar may violate the requirements of code generation.

Version:

$Revision: 1.54 $

Author:

Robert Grimm

Field Summary

Fields inherited from class xtc.parser.GrammarVisitor

analyzer, isBound, isLastElement, isPredicate, isRepeatedOnce, isTopLevel, isVoided, needsSequence, runtime, transformInPlace

Constructor Summary

Simplifier(Runtime runtime, Analyzer analyzer)
Create a new simplifier.

Method Summary

Element	visit(Binding b) Visit the specified binding.
Element	visit(CharClass c) Visit the specified character class.
Element	visit(Option o) Visit the specified option.
Element	visit(OrderedChoice c) Visit the specified ordered choice.
Element	visit(Repetition r) Visit the specified repetition.
Element	visit(Sequence s) Visit the specified sequence.
Element	visit(StringMatch m) Visit the specified string match.
Element	visit(VoidedElement v) Visit the specified voided element.

Methods inherited from class xtc.parser.GrammarVisitor

visit, visit, visit, visit, visit, visit, visit, visit, visit

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

Constructor Detail

Simplifier

public Simplifier(Runtime runtime,
                  Analyzer analyzer)

Create a new simplifier.

Parameters:

runtime - The runtime.

analyzer - The analyzer utility.

Method Detail

visit

public Element visit(OrderedChoice c)

Visit the specified ordered choice.

Overrides:

visit in class GrammarVisitor

visit

public Element visit(Repetition r)

Visit the specified repetition.

Overrides:

visit in class GrammarVisitor

visit

public Element visit(Option o)

Visit the specified option.

Overrides:

visit in class GrammarVisitor

visit

public Element visit(Sequence s)

Visit the specified sequence.

Overrides:

visit in class GrammarVisitor

visit

public Element visit(VoidedElement v)

Visit the specified voided element.

Overrides:

visit in class GrammarVisitor

visit

public Element visit(Binding b)

Visit the specified binding.

Overrides:

visit in class GrammarVisitor

visit

public Element visit(StringMatch m)

Visit the specified string match.

Overrides:

visit in class GrammarVisitor

visit

public Element visit(CharClass c)

Visit the specified character class.