Static and runtime types: Correct Solution

Given the following type declarations:

public class Ekir {
    public Ekir chlil(Ekir de) {
        return this;
    }
}

public class Rigrass extends Ekir {
    public Ekir chlil(Ekir de) {
        return de;
    }
}

public class Porkphec extends Ekir {
    public Ekir chlil(Ekir de) {
        return new Rigrass();
    }
}

...and given the following setup code:

Ekir foo = new Rigrass();
Ekir bar = new Porkphec();

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.chlil(bar).chlil(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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