elan.parser
Class ExpressionParser

java.lang.Object
  |
  +--elan.parser.ExpressionParser

All Implemented Interfaces:

Parser

public class ExpressionParser

extends java.lang.Object

implements Parser

This is a recursive descent parser for parsing expressions using the standard grammar for expressions

 expression ::= term
            ::= term + expression
            ::= term - expression

 term       ::= factor
            ::= factor * term
            ::= factor / term

 factor     ::= number
            ::= - factor
            ::= ( expression )
 

Method Summary

static ExpressionParser	getInstance() Retuns the initialized instance of this class.
GrammarElement	parse(ElanParser ep)
protected Expression	parseExpression()
protected Expression	parseFactor() Determines the nature of the current token on the StreamTokenizer.
protected Expression	parseTerm()

Methods inherited from class java.lang.Object

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

Method Detail

getInstance

public static ExpressionParser getInstance()

Retuns the initialized instance of this class.

parse

public GrammarElement parse(ElanParser ep)

Specified by:

parse in interface Parser

parseExpression

protected Expression parseExpression()

parseTerm

protected Expression parseTerm()

parseFactor

protected Expression parseFactor()

Determines the nature of the current token on the StreamTokenizer.