com.trassare.calculator.engine
Class ExpressionScanner

java.lang.Object
  com.trassare.calculator.engine.ExpressionScanner

public class ExpressionScanner
extends Object

A scanner class used for arithmetic expressions.
CS 152, Fall, 2005
Programming Assignment #1

Version:

10 September 2006

Author:

Kenneth Louden, Samuel T Trassare

Nested Class Summary

static class

ExpressionScanner.ScanException An exception to indicate an IO error in the scanner. Useful to avoid the checked exception IOException. CS 152, Fall, 2005 Programming Assignment #1

Constructor Summary

ExpressionScanner(PushbackReader stream)
Constructs an ExpressionScanner object and reads a line of input.

Method Summary

Token	getToken() Recognize and return the next token in the input, be it an operator, variable, or number.
void	resetScanner(PushbackReader stream) Supply the calculator with a new input stream.

Methods inherited from class java.lang.Object

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

Constructor Detail

ExpressionScanner

public ExpressionScanner(PushbackReader stream)

Constructs an ExpressionScanner object and reads a line of input.

Parameters:

stream - the stream from which to read the input

Method Detail

getToken

public final Token getToken()

Recognize and return the next token in the input, be it an operator, variable, or number.

Returns:

the next token in the input

resetScanner

public final void resetScanner(PushbackReader stream)

Supply the calculator with a new input stream. This function is necessary if input is delivered via a StringReader wrapped in the PushbackReader. Unfortunately StringReaders don't have a "rewind" capability so instead, supply a new input.

Parameters:

stream - the stream from which to read the input