1 Syntax trees

Consider the following grammar with terminals: number, +, , (, and ).

expr ::= expr + expr | expr expr | (expr ) | number

number = [0-9]+

1. We can derive the expression 78 20 + 5 39 as follows (among many other derivations).

expr expr expr expr + expr expr expr expr + expr expr number expr + expr expr 78 expr + expr expr 78 expr + number expr 78 expr + 5 expr 78 expr + 5 number 78 expr + 5 39 78 number + 5 39 78 20 + 5 39

. Give the corresponding AST for P1. Lets call this AST A1.