UPPCL AE 2018:17

Question

Which of the following statements are $\text{TRUE}$?

1. Top-down parsers are equipped to handle left recursive grammar.
2. $\text{LALR}$ parser is more powerful than an $\text{SLR}$ parser
3. Recursive descent parsing is an example of top-down parsing.

• A. $\text{III}$ only
• B. $\text{I}$ only
• C. $\text{II}$ only
• D. $\text{II}$ and $\text{III}$

Answer 1

I. Non Recursive descentparser(LL(1)) fails with Left recursive as it might lead to infinite loop,So False.

 

II.Parser according to power: CLR  > LALR > SLR  So True.

 

III.Recursive descent parsing is an example of Top Down parser. True.

 

Hence D is correct option.

Answer 2

LALR parser is more powerful than SLR(1).

Recursive Descent Parser is top down parsing which uses backtracking and uses os stack instead of parser stack

Top down parsers doesn't handle left recursion because there is a problem of halting (may go to infinite loop)