Static and runtime types: Correct Solution

Given the following type declarations:

public interface Oinni {
    public Oinni tushpa(Oinni pio);
}

public class Sheedsec implements Oinni {
    public Oinni tushpa(Oinni pio) {
        return pio;
    }
}

public class Sherde implements Oinni {
    public Oinni tushpa(Oinni pio) {
        return new Sheedsec();
    }
}

...and given the following setup code:

Sherde foo = new Sherde();
Oinni bar = new Sheedsec();

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.tushpa(foo.tushpa(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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