Syntax-Directed-Translation
Question 1 |
Consider the following grammar (that admits a series of declarations, followed by expressions) and the associated syntax directed translation (SDT) actions, given as pseudo-code:
P ⟶ D* E*
D ⟶ int ID {record that ID.lexeme is of type int}
D ⟶ bool ID {record that ID.lexeme is of type bool}
E ⟶ E1 + E2 {check that E1.type = E2.type = int; set E.type := int}
E ⟶ !E1 {check that E1.type = bool; set E.type := bool}
E ⟶ ID {set E.type := int}
With respect to the above grammar, which one of the following choices is correct?
P ⟶ D* E*
D ⟶ int ID {record that ID.lexeme is of type int}
D ⟶ bool ID {record that ID.lexeme is of type bool}
E ⟶ E1 + E2 {check that E1.type = E2.type = int; set E.type := int}
E ⟶ !E1 {check that E1.type = bool; set E.type := bool}
E ⟶ ID {set E.type := int}
With respect to the above grammar, which one of the following choices is correct?
The actions can be used to type-check syntactically correct integer variable declarations and integer expressions. | |
The actions will lead to an infinite loop. | |
The actions can be used to type-check syntactically correct boolean variable declarations and boolean expressions. | |
The actions can be used to correctly type-check any syntactically correct program. |
Question 1 Explanation:
This SDT will never lead to infinite loop so option 2 is false. This SDT is type checking for bool as well as integer variables, hence this SDT can be used to correctly type-check any syntactically correct program involving boolean and integer variables.
Question 2 |
Suppose we have a computer with a single register and only three instructions given below:
LOAD addren ; load register
; from addren
STORE addren ; store register
; at addren
ADD addren ; add register to
; contents of addren
; and place the result
; in the register
Consider the following grammar:
A → id :=E E → E + T|T T → (E)|id
Write a syntax directed translation to generate code using this grammar for the computer described above.
Theory Explanation. |
Question 3 |
Consider the syntax-directed translation schema (SDTS) shown below:
E → E + E {print “+”}
E → E ∗ E {print “.”}
E → id {print id.name}
E → (E)
An LR-parser executes the actions associated with the productions immediately after a reduction by the corresponding production. Draw the parse tree and write the translation for the sentence.
(a+b)∗(c+d), using the SDTS given above.
Theory Explanation. |
There are 3 questions to complete.