Parsing Questions

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1.

In how many types parsing is divided?

A

2

B

3

C

4

D

5

Correct Answer: A

Syntax analyzers follow production rules defined by means of context-free grammar. The way the production rules are implemented (derivation) divides parsing into two types : top-down parsing and bottom-up parsing.

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2.

When the parser starts constructing the parse tree from the start symbol and then tries to transform the start symbol to the input, it is called?

A

bottom-up parsing

B

top-down parsing

C

Both A and B

D

None of the above

Correct Answer: B

When the parser starts constructing the parse tree from the start symbol and then tries to transform the start symbol to the input, it is called top-down parsing.

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3.

 In ___________________, if one derivation of a production fails, the syntax analyzer restarts the process using different rules of same production

A

Bottom-up Parsing

B

Recursive descent parsing

C

Backtracking

D

All of the above

Correct Answer: C

Backtracking : It means, if one derivation of a production fails, the syntax analyzer restarts the process using different rules of same production. This technique may process the input string more than once to determine the right production.

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4.

A form of recursive-descent parsing that does not require any back-tracking is known as?

A

predictive parsing

B

non-predictive parsing

C

recursive parsing

D

non-recursive parsing

Correct Answer: A

A form of recursive-descent parsing that does not require any back-tracking is known as predictive parsing.

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5.

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

A

40

B

80

C

120

D

160

Correct Answer: D

Higher precedence operator will never produce an expression with operator with lower precedence.&># in terms of precedence order.

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6.

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

A

40

B

80

C

120

D

160

Correct Answer: D

Higher precedence operator will never produce an expression with operator with lower precedence.&># in terms of precedence order.

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7.

Assume that the SLR parser for a grammar G has n1 states and the LALR parser for G has n2 states.n1 is necessarily less than n2

A

n1 is necessarily less than n2

B

n1 is necessarily equal to n2

C

n1 is necessarily greater than n2

D

None of the above

Correct Answer: B

SLR parser has less range of context free languages than LALR but still both n1 & n2 are same for SLR & LALR respectively.

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8.

the predictive parser puts some constraints on the grammar and accepts only a class of grammar known as LL(k) grammar.

A

TRUE

B

FALSE

C

Can be true or false

D

Can not say

Correct Answer: A

To accomplish its tasks, the predictive parser uses a look-ahead pointer, which points to the next input symbols. To make the parser back-tracking free, the predictive parser puts some constraints on the grammar and accepts only a class of grammar known as LL(k) grammar.

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9.

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

A

Removing left recursion only

B

Factoring the grammar alone

C

Factoring & left recursion removal

D

None of the above

Correct Answer: D

Factoring as well as left recursion removal do not suffice to convert an arbitrary CFG to LL(1) grammar.

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10.

Which of the following derivations does a top-down parser use while parsing an input string?

A

Leftmost derivation

B

Leftmost derivation in reverse

C

Rightmost derivation

D

Rightmost derivation in reverse

Correct Answer: A

In top down parser takes input from Left to right constructing leftmost derivation of the sentence.

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