Q. Which one of the following kinds of derivation is used by LR parsers?
(A) Leftmost
(B) Leftmost in reverse
(C) Rightmost
(D) Rightmost in reverse
Ans: Rightmost in reverse
Solution:
Parsing is classified into two categories, i.e. Top Down Parsing and Bottom-Up Parsing. Top-Down Parsing is based on Left Most Derivation whereas Bottom Up Parsing is dependent on Reverse Right Most Derivation. A general shift reduce parsing is LR parsing is bottom-up parsing where L stands for scanning the input from left to right and R stands for constructing a rightmost derivation in reverse.
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