Which one of the following is a top-down parser?

2015

Which one of the following is a top-down parser?

  1. A.

    Recursive descent parser

  2. B.

    Shift left associative parser

  3. C.

    SLR(k) parser

  4. D.

    LR(k) parser

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Correct answer: A

A recursive descent parser is a top-down parsing technique that builds the parse tree starting from the root node and working down to the leaves. It uses a set of mutually recursive procedures, where each procedure corresponds to one non-terminal symbol in the grammar. This approach attempts to predict which production rule to apply based on the current input token, making it inherently top-down.\nIn contrast, SLR(k) and LR(k) parsers are bottom-up parsing methods. They construct the parse tree from the leaves up to the root by shifting input symbols onto a stack and reducing them according to grammar rules. These parsers analyze the input from left to right but build the tree in reverse order.\

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