CompilerDesign
October 7, 2023CompilerDesign
October 7, 2023CompilerDesign
Question 25

Consider the syntax directed translation scheme (SDTS) given in the following.
Assume attribute evaluation with bottomup parsing, i.e., attributes are evaluated immediately after a reduction.
E → E_{1} * T {E.val = E_{1}.val * T.val} E → T {E.val = T.val} T → F – T_{1}{T.val = F.val – T_{1}.val} T → F {T.val = F.val} F → 2 {F.val = 2} F → 4 {F.val = 4}
(a) Using this SDTS, construct a parse tree for the expression
4 – 2 – 4 * 2
and also compute its E.val.
(b) It is required to compute the total number of reductions performed to parse a given input. Using synthesized attributes only, modify the SDTS given, without changing the grammar, to find E.red, the number of reductions performed while reducing an input to E.
Theory Explanation is given below.

Correct Answer: A
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