I have following grammar
E -> TX
X -> +E
|epsilon
T -> intY
| (E)
Y -> *T
| epsilon
Is the below Follow set is correct for above grammar?
E = {$, )}
X = {$, )}
T = {int, (, $}
Y = {int, (, $}
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2 Answers
First
First(E) -> {int, (}
First(X) -> {+, epl}
First(T) -> {int, (}
First(Y) -> {*, epl}
Follow
Follow(E) -> {$, )}
Follow(X) -> {Follow(E)}
Follow(T) -> {First(X) - epl, Follow(E)} -> {+, $, )}
Follow(Y) -> {Follow(T)}
Why Follow(E) in Follow(T)? because First(X) has epsilon ->which give us E -> T production
Comments
For the following grammar:
E -> TX
X -> +E |epsilon
T -> intY| (E)
Y -> *T| epsilon
Calculating the First of the set
FIRST(E) = FIRST(T) - epsilon U FIRST(X)
={int, (, +, epsilon }
FIRST(X) = FIRST(+E) - epsilon U epsilon
={+, epsilon}
FIRST(T) = FIRST(intY) - epsilon U FIRST( (E) )
={int, ( }
FIRST(Y) = FIRST(*T) - epsilon U epsilon
={*, epsilon}
Calculating of FOLLOW set
Follow(E) -> {$,)}
Follow(X) -> {$,)}
Follow(T) -> {+,$,)}
Follow(Y) -> {+,$,)}
