Assignment 2: Language Processing in Java, Now with Visitors! Solution

In our last assignment, we focused on transforming function-oriented
language processors in Racket into object-oriented language processors
in Java. In this assignment, you will produce a function-oriented
language processor in Java, using the Visitor pattern, which will be a
recurring theme in this course.

Your mission is to transform the ABE interpreter and type checker to Java,
this time using the Visitor pattern.


Particulars:
- All of your Java code should be placed in the package
ca.ubc.cs411.assignment2.
- When translating a Racket function to a Visitor, you will use the
Java Class convention and affix Visitor to it, e.g., the 'type-of'
function becomes the 'TypeOfVisitor'.
- Other conventions from last assignment carry over:
+ Class names must be written in UpperCamelCase (e.g. Add);
+ Method names must be written in lowerCamelCase (e.g. typeOf);
+ Enumeration type names must be written in UpperCamelCase (e.g. Type);
+ Enumeration elements must be written in UPPERCASE (e.g. INT).
- You should still use the object-oriented presentation of Values.
Only the functions on ABE abstract syntax are to be transformed to
Visitors.
- You should still use the enumeration-based representation of types.
- Runtime errors are still translated by throwing Error().