Sr Parsers

1. Consider the grammar

   S -> A

   A -> $B$ | id

   B -> B,A | A

   If I₀ = CLOSURE[S -> .A] then how many items be in the set for GOTO(I₀, $)

• 3

• 4

• 5

• 6

Which of the following kind of derivation is used by LR parsers?

• Leftmost

• Leftmost in reverse

• Rightmost

• Rightmost in reverse

Which of the following statemnets about parser is/are correct?

I. Canonical LR is more powerful than SLR

II. SLR is more powerful than LALR

III. SLR is more powerful than Canonical LR

• I only

• II only

• III only

• II and III only

Assume that the SLR parser for a grammar G has n1 states and the LALR parser for G has n2 states. The relationship between n1 and n2 is:

• n1 is necessarily less than n2

• n1 is necessarily equal to n2

• n1 is necessarily greater than n2

• none of the options

Which of the following is true for shift reduce parsers?

• Scans and parses the input in one forward pass over the text, without any backup

• A shift command advances in the input stream by one symbol

• LALR parser

• all of the mentioned

Which of the following can be a LALR parser generator?

• YACC

• GNU Bison

• YACC and GNU Bison

• None of the mentioned

Consider the following 2 sets of LR(1) items of an LR(1) grammar.

X -> c.X, c|d X -> c.X, $

X->.cX, c|d X->.cX, $

X->.x, c|d X->.d, $

Which of the following statements related to merging of the 2 sets in the corresponding LALR parser is/are FALSE?

1. Cannot be merged since lookaheads are different

2. Can be merged but will result in SR conflict

3. Can be merged but will result in RR conflict

4. Cannot be merged since GOTO on c will lead to two different sets

• 1 only

• 2 only

• 1 and 4 only

• 1,2,3 and 4

Consider the following grammar

S -> aMd | bNd | aNe | bMe

M -> c

N -> c

Which of the following is the correct option?

• LALR(1) but not SLR(1)

• LR(1) but not LALR(1)

• SLR(1) but not LR(1)

• LALR(1)

In LR(k) parsing, when the value of k is omitted, it is assumed to be _______

• 1

• 2

• 3

• 8

Which of the following statements is/are FALSE?

S1: LR(0) grammar and SLR(1) grammar are equivalent.

S2: LR(1) gammar are subset of LALR(1) grammars

• S1 only

• S1 and S2 both

• S2 only

• None of the options