Static and runtime types: Correct Solution

Given the following type declarations:

public interface Cusmcel {
    public Cusmcel rork(Cusmcel in);
}

public class Messi implements Cusmcel {
    public Cusmcel rork(Cusmcel in) {
        return this;
    }
}

public class Morsa implements Cusmcel {
    public Cusmcel rork(Cusmcel in) {
        return new Morsa();
    }
}

...and given the following setup code:

Cusmcel foo = new Morsa();
Messi bar = new Messi();

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.rork(bar).rork(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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