Consider the following grammar: stmt −→ assignment −→ subr call assignment −→ id := expr subr call −→ id ( arg list ) expr −→ primary expr tail expr tail −→ op expr −→ primary −→ id −→ subr call −→ (...

Consider the following grammar:

stmt −→ assignment

−→ subr call

assignment −→ id := expr

subr call −→ id ( arg list )

expr −→ primary expr tail

expr tail −→ op expr

−→

primary −→ id

−→ subr call

−→ ( expr )

op −→ + | - | * | /

arg list −→ expr args tail

args tail −→ , arg list

−→

(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).

(d) Modify the grammar so that it is LL(1).