Parsing and Syntax directed translation

Question 41

Which one of the following grammars is free from left recursion?

• A
• B
• C
• D

Question 42

Which of the following is the most powerful parsing method?

• LL(1)
• Canonical LR
• SLR
• LALR

Question 43

Which of the following statement is true?

• SLR parser is more powerful than LALR.
• LALR parser is more powerful than Canonical LR parser.
• Canonical LR parser is more powerful than LALR parser.
• The parsers SLR, Canonical LR, and LALR have the same power.

Question 44

Type checking is normally done during

• Lexical analysis
• Syntax analysis
• Syntax directed translation
• Code optimization

Question 45

Consider the grammar

S →  Aa | b
A → Ac | Sd | ε

Construct an equivalent grammar with no left recursion and with minimum number of production rules.

Question 46

Answer the following: a.  Let G1 = (N, T, P, S1) be a CFG where, N= {S1A, B}, T= {a,b} and P is given by

         S1 → aS1b             S1 → aBb
         S1 → aAb              B → Bb
         A → aA                B → b
         A → a

What is L(G₁)? b. Use the grammar in part(a) to give a CFG for L₂ = {aⁱ b^j a^k b^l | i, j, k, l ≥ 1, i= j or k=l} by adding not more than 5 production rule. c.  Is L₂ inherently ambiguous?

Question 47

[5 Marks question] Answer the following: a. An identifier in a programming language consists of upto six letters and digits of which the first character must be a letter. Derive a regular expression for the identifier. b. Build an LL(1) parsing table for the language defined by the LL(1) grammar with productions

Program → begin d semi X end
X → d semi X | s Y
Y → semi s Y | ε

Question 48

Let the attribute \'val\' give the value of a binary number generated by S in the following grammar: S → L.L | L L→ LB | B B → 0 | 1 For example, an input 101.101 gives S.val = 5.625 Construct a syntax directed translation scheme using only synthesized attributes, to determine S.val.

Question 49

In the following grammar

X :: = X ⊕ Y / Y
Y :: = Z * Y / Z
Z :: = id

Which of the following is true? a. \'⊕\' is left associative while \'*\' is right associative b. Both \'⊕\' and \'*\' are left associative c. \'⊕\' is right associative while \'*\' is left associative d. None of the above

• a
• b
• c
• d

Question 50

Which of the following is essential for converting an infix expression to the postfix from efficiently ?

• An operator stack
• An operand stack
• An operand stack and an operator stack
• A parse tree