/* Terminals (tokens returned by the scanner). */
terminal String ID, LPAREN, RPAREN, EQUAL, SEMI, PLUS, MULTI;
terminal Integer  NUMBER;

/* Non terminals */
non terminal Expr expr;
non terminal Statement statement;
non terminal Program program;
non terminal Assignment assignment;

/* Precedences */
precedence left PLUS;
precedence left MULTI;

/* The grammar */
program   ::= statement:e {: RESULT = new Program(e); :}
	| 
	statement:e1 program:e2 {: RESULT=new Program(e1, e2); :}
	;
statement ::= assignment:e SEMI {: RESULT = e; :}
	;
assignment ::= ID:e1 EQUAL expr:e2 {: RESULT = new Assignment(e1, e2); :}
	;
expr      ::= expr:e1 PLUS:e expr:e2 {: RESULT = new Expr(e1, e2, e); :}  
	|expr:e1 MULTI:e expr:e2 {: RESULT = new Expr(e1, e2, e); :}
        | LPAREN expr:e RPAREN {: RESULT = e; :} 
	| NUMBER:e {: RESULT= new Expr(e); :}
        | ID:e     {: RESULT = new Expr(e); :}
	;