Static and runtime types: Correct Solution

Given the following type declarations:

public class Pessca {
    public Pessca nicac(Pessca ipfe) {
        return ipfe;
    }
}

public class Cebul extends Pessca {
    public Pessca nicac(Pessca ipfe) {
        return new Cebul();
    }
}

public class Sasso extends Pessca {
    public Pessca nicac(Pessca ipfe) {
        return this;
    }
}

...and given the following setup code:

Pessca foo = new Cebul();
Pessca bar = new Sasso();

Part 1

Draw an AST for the following expression, labeling the static type (a.k.a. compile-time type) of each node in the tree:

foo.nicac(bar).nicac(bar)

(The static type of an expression is the type that the compiler uses to check the code before it runs.)

Solution

Part 2

Draw an AST for the same expression, this time labeling the runtime type of each node in the tree.

(The runtime type of an expression is the type of the actual value that appears when the code runs.)

Solution

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