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package jedi.functors;

import jedi.functional.Functor;
import jedi.functional.Functor0;
import jedi.functional.Functor2;

/**
 * A functor that can be composed with other Functors.
 * For example, given:
 *  * Functor f that takes T and returns R
 * Functor g that takes R and returns NEW_R
 * new ComposeableFunctor(f).andThen(g).execute(x) == g(f(x))
 *
 * or with static imports:
 * composeable(f).andThen(g)
 * or
 * composeable(f).o(g)
 * or
 * c(f).o(g)
 * 
 * @param 
 * @param 
 */
public class ComposeableFunctor implements Functor {

    private final Functor functor;

    public ComposeableFunctor(final Functor functor) {
        this.functor = functor;
    }

    public R execute(final T value) {
        return functor.execute(value);
    }

    /**
     * Function composition: this.andThen(g) applied to x == g(this.execute(value))
     */
    public  ComposeableFunctor andThen(final Functor g) {
        return new ComposeableFunctor(new Functor() {
            public NEW_R execute(T value) {
                return g.execute(functor.execute(value));
            }
        });
    }

    /**
     * Like the Haskell dot operator, this.o(g).execute(x) = this.execute(g.execute(x))
     */
    public  ComposeableFunctor o(Functor g) {
        return composeable(g).andThen(functor);
    }

    public ComposeableFunctor0 o(Functor0 g) {
        return composeable(g).andThen(functor);
    }

    public static  ComposeableFunctor composeable(Functor functor) {
        return new ComposeableFunctor(functor);
    }

    public static  ComposeableFunctor c(Functor functor) {
        return composeable(functor);
    }

    public static  ComposeableFunctor0 composeable(Functor0 functor) {
        return new ComposeableFunctor0(functor);
    }

    public static  ComposeableFunctor0 c(Functor0 functor) {
        return composeable(functor);
    }

    public static  ComposeableFunctor2 composeable(Functor2 functor) {
        return new ComposeableFunctor2(functor);
    }

    public static  ComposeableFunctor2 c(Functor2 functor) {
        return composeable(functor);
    }
}