Gate CS-2005 Question Paper With Solutions

Q. 86 Consider the following expression grammar. The seman­tic rules for expression calculation are stated next to each grammar production.

 E → number 	 E.val = number. val
    | E '+' E 	 E(1).val = E(2).val + E(3).val
    | E '×' E	 E(1).val = E(2).val × E(3).val

Assume the conflicts in Part (a) of this question are resolved and an LALR(1) parser is generated for parsing arithmetic expressions as per the given grammar. Consider an expression 3 × 2 + 1. What precedence and associativity properties does the generated parser realize?

(A) Equal precedence and left associativity; ex­pression is evaluated to 7

(B) Equal precedence and right associativity; ex­pression is evaluated to 9

(C) Precedence of ‘×’ is higher than that of ‘+’, and both operators are left associative; expression is evaluated to 7

(D) Precedence of ‘+’ is higher than that of ‘×’, and both operators are left associative; expression is evaluated to 9

Answer: (B)

Explanation:

Gate CS-2005 Question Paper With Solutions

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