Question

C and Java allows loop exits using the "break" and "continue" statements. A "break" statement leaves the current loop entirely, and a "continue" statement jumps to the end of the current loop. A break statement can only appear inside a loop or a switch statement, and a continue can only appear inside a loop. If we add "break" and "continue" to VSL, what changes would have to be made to the semantic analyzer to ensure that these statements only appear within loops? What changes would be needed for the abstract stack machine to implement break and "continue"?

Answer 1

Generally break and continue alwyas oposite to each other.

When you used both in one stack them the stack might cause stuck with the oposite condition

1 The semantics and the intended meaning of statements

We show that the transition rules of the semantics of statements continue

,

break and

goto

follow their intended meaning. The meaning of continue If continue

is inside an active while-loop has a counter of the form s(n)

Here the code for semnatic anyasler as ---

continue,s(m), y, (S, s(n)) : E, ρ, γ, s →
continue, s(m), y, E, ρ, γ, s
γ m = true ∧ n = m

and for Break

If break is inside an active while-loop, has a counter of the form s(n) where
γ n = true. We have to skip all the sentences in the environment until
finding the corresponding while sentence.

break,s(m), y, (S, s(n)) : E, ρ, γ, s →
break, s(m), y, E, ρ, γ, s
γ m = true ∧ n = m