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package jedi.either;

import java.io.Serializable;
import java.util.List;

import jedi.functional.Command;
import jedi.functional.Functor;
import jedi.functional.Functor0;

/**
 * The Either type represents a value of one of two possible types
 * (a disjoint union) and was Inspired by Scala's Either.
 */
public abstract class Either implements Serializable {
	private static final long serialVersionUID = 1L;

	/**
	 * If the condition satisfies, return the given A in Left,
	 * otherwise, return the given B in Right.
	 */
	public static  Either cond(boolean cond, A a, B b) {
		return cond ? new Left(a) : new Right(b);
	}

    /**
     * If the condition satisfies, return the result of executing a in Left,
	 * otherwise, return the result of executing b in Right.
     */
    public static  Either cond(boolean cond, Functor0 a, Functor0 b) {
		return cond ? new Left(a.execute()) : new Right(b.execute());
	}

	public boolean isLeft() {
		return false;
	}

	public boolean isRight() {
		return false;
	}

	public LeftProjection left() {
		return new LeftProjection(this);
	}

	public RightProjection right() {
		return new RightProjection(this);
	}

	/**
	 * Deconstruction of the type.
	 * 
	 * @param fa
	 *            the functor to apply if this is a Left
	 * @param fb
	 *            the functor to apply if this is a Left
	 * @return the result of applying the appropriate functor.
	 */
	public abstract  X fold(Functor fa, Functor fb);

	public abstract void execute(Command ca, Command cb);

	public abstract Either swap();

	/**
	 * @return Singleton list if Lift or empty list if Right.
	 */
	public abstract List asList();

	/**
	 * Maps the function argument through Left.
	 */
	public abstract  Either map(Functor f);

	public abstract  Either flatMap(Functor> f);
}