GATE CS 2024 Set 1 Q.26: Parsing and Syntax Analysis (LL and LR)

Which of the following is/are Bottom-Up Parser(s)?

Shift-reduce Parser

Predictive Parser

LL(1) Parser

LR Parser

Official answer and solution

Solution

Classify standard compiler parsers into Top-Down (LL / Predictive) vs. Bottom-Up (Shift-Reduce / LR).

(A) Shift-reduce Parser and (D) LR Parser build the parse tree from the leaves (input tokens) up toward the start symbol (root) by reducing handles, so both are Bottom-Up Parsers.
(B) Predictive Parser and (C) LL(1) Parser expand non-terminals from the start symbol down to the leaves, so both are Top-Down Parsers.

Final answer

Options (A), (D)

The answer is the one in the official GATE answer key. The solution is this site's own explanation.

GATE questions are the work of the organising institutes. This site is independent and is not affiliated with them.