Question

Consider the following grammar: (//some alternative rules are listed on separate lines without using symbol |):

stmt −> assignment

−> subr call

assignment −> id := expr

subr call −> id ( arg list )

expr −> primary expr tail

expr tail −> op expr

−> ε

primary −> id

−> subr call

−> ( expr )

op −> + | - | * | /

arg list −> expr args tail

args tail −> , arg list

−> ε

(a) Construct a parse tree for the input string foo(a,b).

(b) Give a canonical (right-most) derivation of this same string.

(c) Prove that the grammar is not LL(1). (//hint: find an example that LL(1) does not work).

(d) Modify the grammar so that it is LL(1). (//hint: use left factoring)

Answer 1

)Ubi > foo (a ,b SVb-all bte

6) Kit most derivahion ブrm i d nge-2- ︵伊

C) for 65) then First (a) n follow(A): stntid B