3460:430/530 Theory of Programming Languages Summer 2004

Dr. C.-C. Chan Due: 6/7/04

Project #2 (30 pts)

Problem: Based on Project 1, extend the language to allow the following features:

1. Use semicolon instead of newline to separate input expressions.

2. Allow assignment operator, =, has the lowest priority and is right associative.

3. Allow an input expression to across multiple lines. e.g.,

x =

1 + 3

+ 4;

should be treated as a valid input.

4. Variables may be declared as int, char, or float. The syntax for declaring variables is

<var declaration> ::= <type name> <var name> {, <var name>}⁺ ;

Variables must be declared before they are referenced.

Variable names may be of 32 characters long and consist of letters of upper or lower cases. They are case-insensitive.

5. Operations of char include assignment.

6. Add a built-in function printVars that prints out values of variables defined in the symbol table.

Implementation:

1. Add new token types for built-in functions and type names.

2. Add new rules and corresponding actions to reflect the new features.

3. Extend yylex function to recognize new features.

4. You must create a symbol.c source file to implement the symbol table.

Error Checking:

1. References to undefined variables should cause errors.

2. Each variable can only be defined once.

Submissions:

1. Name your source files as "p2.y". "p2.h", and "symbol.c".

2. Send the source file by e-mail to chan@cs.uakron.edu

3. The project is due by midnight of the due day.