Static and runtime types: Correct Solution

Given the following type declarations:

public class Sosm {
    public Sosm truFing(Sosm po) {
        return this;
    }
}

public class Irne extends Sosm {
    public Sosm truFing(Sosm po) {
        return new Irne();
    }
}

public class Speintgeel extends Sosm {
    public Sosm truFing(Sosm po) {
        return po;
    }
}

...and given the following setup code:

Sosm foo = new Speintgeel();
Sosm bar = new Irne();

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.truFing(bar).truFing(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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