Question

7. Find the FIRST and FOLLOW sets for the grammar
S --> ABC
A --> a | Cb | ε
B --> c | dA | ε
C --> e | f

Construct LL(1) parsing table from grammar

Answer 1

Note:

• First of any character is defined as set of terminals that begin , in the strings derived from that character.
• Follow of any character is defined as a set of terminals that appear immediately to the right of that character.

--->ANSWER:

1.FIRST:-

• First(S)={First(A)-} U {First(B)-} U {First(C)} = { a,c,d,e,f }
• First(A)={a} U {First(C)} U ={ a,e,f,}
• First(B) = {c} U {d} U {} ={c,d,}
• First(C)={e,f}

2.FOLLOW:-

• Follow(S)={ $ }
• Follow(A) ={First(B)-} U {First(C)}= { c,d,e,f }
• Follow(B) = {First(C)} ={e,f}
• Follow(C) ={b}

LL(1) PARSING TABLE:

• For productions involving non-epsilon First , the production is written in the cells in the column of the first values.
• For epsilon productions, the production is written in the cells of the columns of follow of the character deriving that production.

	a	b	c	d	e	f	$
S	S->ABC		S->ABC	S->ABC	S->ABC	S->ABC
A	A->a		A->	A->	A->Cb , A->	A->Cb
B			B->c	B->dA	B->	B->
C					C->e	C->f

Hope it helps, for any queries feel free to ask...

Thanks!