GRAMMAR

compilation-unit ::= ( global-variable | function-definition | function-declaration )*
global-variable ::= type IDENTIFIER ( '=' expression )?

function-definition ::= function-prototype block
function-declaration ::= function-prototype ';'
function-prototype ::= type IDENTIFIER '(' ( type IDENTIFIER ( ',' type IDENTIFIER)* )? ')'

block ::= '{' local-variable* statement* '}'
local-variable ::= type IDENTIFIER ( '=' expression ) ( ',' IDENTIFIER ('=' expression )? )* ';'
statement ::=   expression ';' 
              | block
              | IF '(' expression ')' statement ( ELSE statement )?
              | FOR '(' expression ';' expression ';' expression ')' statement
              | WHILE '(' expression ')' statement
              | DO statement WHILE '(' expression ')' ';'

//TODO: boolean logic, relations, bitwise logic
expression ::= expression '*' factor | expression '/' factor | factor
factor ::= factor '+' addend | factor '-' addend | addend | '-' addend
addend ::= '(' expression ') | IDENTIFIER | FLOAT | INT


type ::= 'int' | 'float' | 'ptr'