pkg15.pkg121project1

Class RPNParser

java.lang.Object

pkg15.pkg121project1.RPNParser

public class RPNParser
extends java.lang.Object

Constructor Summary

Constructors

Constructor and Description
RPNParser()

Method Summary

Modifier and Type	Method and Description
static void	doOperation(RPNCalc the_calc, java.lang.String token) Given a token, determines what operation the token represents and calls the appropriate method of the RPNCalc object.
static boolean	isOper(java.lang.String tok) pre: none post: returns true if and only if tok is a legal operation.
static void	main(java.lang.String[] argv) Continuously reads a well formed post fix expression.

Methods inherited from class java.lang.Object

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

Constructor Detail

RPNParser

public RPNParser()

Method Detail

doOperation

public static void doOperation(RPNCalc the_calc,
                               java.lang.String token)

Given a token, determines what operation the token represents and calls the appropriate method of the RPNCalc object. If the token does not represent a valid operation, prints an error message. pre:

Parameters:

the_calc - An initialized RPNCalc object which will perform the given operation.

token - A token representing an operation to be performed. Legal tokens are "=", "+", "-", "/", "*", "^". post: appropriate calls are made to the calculator's operations.

isOper

public static boolean isOper(java.lang.String tok)

pre: none post: returns true if and only if tok is a legal operation.

main

public static void main(java.lang.String[] argv)
                 throws java.io.IOException

Continuously reads a well formed post fix expression. Valid tokens for use in an expression are: any floating point number, a legal variable name, +, -, *, /, ^. If no string is entered the application terminates. pre: All tokens are separated by a single space and the expression is well formed postfix. post: The user had a wonderful time with the calculator.

Throws:

java.io.IOException