GATE CSE 2024 Set 2 Q29

Question

Which of the following statements is/are FALSE?
A) An attribute grammar is a syntax-directed definition (SDD) in which the functions in the semantic rules have no side effects
B) The attributes in a L-attributed definition cannot always be evaluated in a depth-first order
C) Synthesized attributes can be evaluated by a bottom-up parser as the input is parsed
D) All L-attributed definitions based on LR(1) grammar can be evaluated using a bottom-up parsing strategy

Accepted Answer

Official answer: B) The attributes in a L-attributed definition cannot always be evaluated in a depth-first order; D) All L-attributed definitions based on LR(1) grammar can be evaluated using a bottom-up parsing strategy. Explanation: - A is TRUE: An SDD without side effects in its semantic actions is known as an attribute grammar. - B is FALSE: By definition, attributes in any L-attributed definition can always be evaluated in a depth-first, left-to-right traversal. - C is TRUE: Synthesized attributes can be evaluated during bottom-up parsing alongside reductions. - D is FALSE: Not all L-attributed SDDs based on an LR(1) grammar can be evaluated during bottom-up parsing without grammar modification. Thus, the false statements are B and D.

Answer

A) An attribute grammar is a syntax-directed definition (SDD) in which the functions in the semantic rules have no side effects

Answer

B) The attributes in a L-attributed definition cannot always be evaluated in a depth-first order

Answer

C) Synthesized attributes can be evaluated by a bottom-up parser as the input is parsed

Answer

D) All L-attributed definitions based on LR(1) grammar can be evaluated using a bottom-up parsing strategy

Which of the following statements is/are FALSE?

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