Q. Consider the following translation scheme. S → ER R → *E{print("*");}R | ε E → F + E {print("+");} | F F → (S) | id {print(id.value);} Here id is a token that represents an integer and id.value represents the corresponding integer value. For an input '2 * 3 + 4', this translation scheme prints

View solution

Q. The grammar A → AA | (A) | ε is not suitable for predictive-parsing because the grammar is

View solution

Q. Consider the grammar

E → E + n | E × n | n

For a sentence n + n × n, the handles in the right-sentential form of the reduction are

View solution

Q. Consider the grammar

S → (S) | a

Let the number of states in SLR(1), LR(1) and LALR(1) parsers for the grammar be n1, n2 and n3 respectively. The following relationship holds good

View solution

Q. 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

The above grammar and the semantic rules are fed to a yacc tool (which is an LALR (1) parser generator) for parsing and evaluating arithmetic expressions. Which one of the following is true about the action of yacc for the given grammar?

View solution

Q. 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?

View solution

Q. Which of the following grammar rules violate the requirements of an operator grammar ? P, Q, R are nonterminals, and r, s, t are terminals.

1. P → Q R
2. P → Q s R
3. P → ε
4. P → Q t R r

View solution

Q. Consider the grammar with the following translation rules and E as the start symbol.

E → E1 # T { E.value = E1.value * T.value }
| T{ E.value = T.value }
T → T1 & F { T.value = T1.value + F.value }
| F{ T.value = F.value }
F → num { F.value = num.value }

Compute E.value for the root of the parse tree for the expression: 2 # 3 & 5 # 6 & 4.

View solution

Q. Which of the following suffices to convert an arbitrary CFG to an LL(1) grammar?

View solution

Q. Assume that the SLR parser for a grammar G has n1 states and the LALR parser for G has n2 states. The relationship between n1 and n2 is:

View solution

Q. In a bottom-up evaluation of a syntax directed definition, inherited attributes can

View solution

Q. Consider the grammar shown below S → i E t S S' | a S' → e S | ε E → b In the predictive parse table. M, of this grammar, the entries M[S', e] and M[S', $] respectively are

View solution

Q. Consider the grammar shown below.

S → C C
C → c C | d

The grammar is

View solution

Q. Consider the translation scheme shown below

S → T R
R → + T {print ('+');} R | ε
T → num {print (num.val);}

Here num is a token that represents an integer and num.val represents the corresponding integer value. For an input string '9 + 5 + 2', this translation scheme will print

View solution

Q. Consider the syntax directed definition shown below.

S → id : = E {gen (id.place = E.place;);}
E → E1 + E2 {t = newtemp ( ); gen (t = El.place + E2.place;); E.place = t}
E → id {E.place = id.place;}

Here, gen is a function that generates the output code, and newtemp is a function that returns the name of a new temporary variable on every call. Assume that ti's are the temporary variable names generated by newtemp. For the statement 'X: = Y + Z', the 3-address code sequence generated by this definition is

View solution

Q. Which of the following statements is false?

View solution

Q. Which of the following derivations does a top-down parser use while parsing an input string? The input is assumed to be scanned in left to right order.

View solution

Q. Given the following expression grammar:

E -> E * F | F + E | F
F -> F - F | id

which of the following is true?

View solution

Q. Which one of the following is True at any valid state in shift-reduce parsing?

View solution

Q. In the context of abstract-syntax-tree (AST) and control-flow-graph (CFG), which one of the following is True?

View solution