Question

1. Given the following grammar, FIRST and FOLLOW sets and LL Parser table, trace the parse of the string “fd xcor + ycor rt ycor” and draw the parse tree.

FIRST(S) = FIRST(B) = FIRST(D) = { fd, rt }

FIRST(A) = { fd, rt, ε }

FIRST(E) = { xcor, ycor }

FIRST(F) = { +, -, ε }

FOLLOW(S) = { $ }                                      S --> BA

FOLLOW(A) = { $ }                                      A --> BA | ε

FOLLOW(B) = { fd, rt, $ }                            B --> D

FOLLOW(D) = { fd, rt, $ }                            D --> fd E | rt E

FOLLOW(E) = { fd, rt, $, +, - }                     E --> xcor F | ycor F

FOLLOW(F) = { fd, rt, $ }                            F --> + EF | - EF | ε

	fd	rt	xcor	ycor	+	-	$
S	BA	BA
A	BA	BA					ε
B	D	D
D	fd E	rt E
E			xcor F	ycor F
F	ε	ε			+ EF	- EF	ε

Stack                                             Input                               Production                  Derivation

Answer 1

Tracing The Parse of the String: