The George Washington University
School of Engineering and Applied Science
Department of Computer Science
CSci 169 – Software Paradigms – Fall 2007
Programming Assignment # 3: A Static Type Checker
Due Date: Wednesday, November 14, 2007
Instructor: A. Bellaachia
Send the electronic version of your assignment to: [email protected]
The following represents the EBNF grammar for a very simple language, called C--:
program ----> {stmt}
stmt ----> var_dec ";" | assign ";" | read_stat ";" |
write_stat ";" | if_stmt ";" | while_stmt ";"
var_dec ----> type var
assign ----> var "=" expr
expr ----> add_expr
add_expr ----> mul_expr {("+"|"-") mul_expr}
mul_expr ----> simple_expr {("*"|"/"|"%") simple_expr }
simple_expr ----> id | var | "(" expr ")"
read_stat ----> "READ" "(" expr ")"
write_stat ----> "PRINT" "(" expr ")"
type ----> "int" | "float" | "boolean"
id ----> Digit | Digit id
Digit ----> [0-9]+
boolean ----> "0" | "1";
var ----> [A-Z, a-z]+
block ----> program [ block ]
if_stmt ----> "if" bool_stmt ":" [block] [ "else:" [block] ] "end if"
while_stmt ----> "while" bool_stmt "do" [block] "end while"
bool_stmt ----> and_stmt | rel_stmt |boolean
and_stmt ----> bool_stmt {("and"|"or") bool_stmt}
rel_stmt ----> simple_expr (">"|"<"|">="|"==") simple_expr
In this project, you would like to implement, in C++, a strict static type checker, we call
TCC for C--. Remember, you only need to check the types of all statements. TCC
reads a C--program and should:
• You can use the lexical analyzer you developed in assignment 2.
• Print “Your program is type error free”, if there are no type errors in the program,
or Print a brief, accurate description (including line numbers) of each error, if
there are any type errors in the program.
