package jmultimethod;

public class DispatchTest {
    static class Asteroid {
        String id;
        public Asteroid(String id) {this.id = id;}
        public String id() {return id;}
    }
    static class Spaceship {
        String name;
        public Spaceship(String name) {this.name = name;}
        public String name() {return name;}
    }
    static class Static {
        static void colide(Asteroid x, Asteroid y) {
            System.out.println("AA colide " + x.id() + " with " + y.id());
        }
        static void colide(Asteroid x, Spaceship y) {
            System.out.println("AS colide " + x.id() + " with " + y.name());
        }
        static void colide(Spaceship x, Asteroid y) {
            System.out.println("SA colide " + x.name() + " with " + y.id());
        }
        static void colide(Spaceship x, Spaceship y) {
            System.out.println("SS colide " + x.name() + " with " + y.name());
        }
        static void colide(Object x, Object y) {
            System.out.println("OO colide " + x + " with " + y);
        }
        static void run() {
            run1();
            run2();
        }
        static void run1() {
            System.out.println("-- Static: explicitly typed");
            Asteroid a1 = new Asteroid("A1");
            Asteroid a2 = new Asteroid("A2");
            Spaceship s1 = new Spaceship("S1");
            Spaceship s2 = new Spaceship("S2");
            colide(a1, a2);
            colide(a1, s1);
            colide(s1, a1);
            colide(s1, s2);
        }
        static void run2() {
            System.out.println("-- Static: superclass typed");
            // here is the problem: the declared variable type is used
            // but it should be infered by the compiler instead
            Object a1 = new Asteroid("A1");
            Object a2 = new Asteroid("A2");
            Object s1 = new Spaceship("S1");
            Object s2 = new Spaceship("S2");
            colide(a1, a2);
            colide(a1, s1);
            colide(s1, a1);
            colide(s1, s2);
        }
    }
    static class Dynamic {
        void colide(Asteroid x, Asteroid y) {
            System.out.println("AA colide " + x.id() + " with " + y.id());
        }
        void colide(Asteroid x, Spaceship y) {
            System.out.println("AS colide " + x.id() + " with " + y.name());
        }
        void colide(Spaceship x, Asteroid y) {
            System.out.println("SA colide " + x.name() + " with " + y.id());
        }
        void colide(Spaceship x, Spaceship y) {
            System.out.println("SS colide " + x.name() + " with " + y.name());
        }
        void colide(Object x, Object y) {
            System.out.println("OO colide " + x + " with " + y);
        }
        void run() {
            run1();
            run2();
        }
        void run1() {
            System.out.println("-- Dynamic: explicitly typed");
            Asteroid a1 = new Asteroid("A1");
            Asteroid a2 = new Asteroid("A2");
            Spaceship s1 = new Spaceship("S1");
            Spaceship s2 = new Spaceship("S2");
            colide(a1, a2);
            colide(a1, s1);
            colide(s1, a1);
            colide(s1, s2);
        }
        void run2() {
            System.out.println("-- Dynamic: superclass typed");
            // here is the problem: dispatch is on the declared
            // variable type instead of the run-time value type
            Object a1 = new Asteroid("A1");
            Object a2 = new Asteroid("A2");
            Object s1 = new Spaceship("S1");
            Object s2 = new Spaceship("S2");
            colide(a1, a2);
            colide(a1, s1);
            colide(s1, a1);
            colide(s1, s2);
        }
    }
    public static void main(String args[]) {
        Static.run();
        new Dynamic().run();
    }
}