CS 234	Lab 3 Parsing arithmetic expressions	design due Wed. 12 Oct. 1 PM

The purpose of this lab is to give you additional experience with design
and experience with the use of stacks needed to parse and evaluate 
arithmetic expressions.  In particular, you will base your work on some of 
the authors' work in chapter 5.  Lab 3 is an expression manager.  Project 3 
on page 300 of the text serves as its base.  The 4 main parts of the 
project are to 

    check for balanced symbols in an infix expression, 
    convert an infix expression to its equivalent postfix form
    evaluate a postfix expression and
    convert a postfix expression to its equivalent infix form.

The authors' class ParenChecker does almost all of part 1.
Their class InfixToPostfixParens does some of part 2.
Their class PostfixEvaluator does some of part 3.
You must design a class to do part 4.

My specification for lab 3 makes some additions and changes to that on
page 300.

You must use the authors' generic class LinkedStack< E > and their interface 
StackInt< E > in each of the classes of lab 3 that use a stack.

You must include the binary operator ^ for exponentiation among the operators 
in parts 2, 3 and 4.
    
A class called ClientIO manages all input and output from the client.

You must design a class to convert a postfix expression to its equivalent
infix form.  The class name should probably be PostfixToInfix.  Your design 
should be detailed and use an essay format.  You should explain the 
development of your conversion algorithm in detail.  This algorithm must 
use a stack.  You must include a simulation of your conversion algorithm 
for a non trivial postfix expression.  You should list the attributes, 
constructors and methods for this class.  You should describe an algorithm 
for each non-trivial method.  

In particular your design must have the following parts.

0. Write an essay that describes the design for the class PostFixToInfix.
1. Document in detail the changes that you make to other classes to
   accommodate the use of the class LinkedStack< E >.
2. Document in detail the changes that you make to other classes to
   accommodate the use of the operator ^.
3. Design the class ClientIO.  
4. A UML diagram for your software system.

To ease the work for part 3, I suggest use of the following scenario.
Task: Parse an arithmetic expression.
1. The system asks the client for an
   arithmetic expression.
2.                                     The client enters a valid expression.
3. The system classifies it as 
   infix or postfix.
4. The system converts it to the other form.
5. If the postfix expression is numeric,
   the system evaluates it.
6. The system displays a message with two 
   expressions and possibly an integer.

Part 3 of your design must contain a detailed design scenario for the above 
task.  Most of its steps identify a class and a method with parameters.

Feel free to see me in Science 103g or send me email for assistance
with your design.