Static and runtime types: Correct Solution

Given the following type declarations:

public class Astbril {
    public Astbril treng(Astbril ecbi) {
        return this;
    }
}

public class PseLiozz extends Astbril {
    public Astbril treng(Astbril ecbi) {
        return ecbi;
    }
}

public class Scriou extends Astbril {
    public Astbril treng(Astbril ecbi) {
        return new Scriou();
    }
}

...and given the following setup code:

PseLiozz foo = new PseLiozz();
Scriou bar = new Scriou();

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.treng(bar.treng(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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