com.swoval.functional

Class Either<L,R>

java.lang.Object

com.swoval.functional.Either<L,R>

Type Parameters:

L - The left value

R - The right value

Direct Known Subclasses:

Either.Left, Either.Right

public abstract class Either<L,R>
extends java.lang.Object

Represents a value that can be one of two types. Inspired by Either, it is right biased, but does not define all of the combinators that the scala version does.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Either.Left<L,R> A left projected Either.
static class	Either.NotLeftException An error that is thrown if an attempt is made to project an Either to Either.Left when the object is actually an instance of Either.Right.
static class	Either.NotRightException An error that is thrown if an attempt is made to project an Either to Either.Right when the object is actually an instance of Either.Left.
static class	Either.Right<L,R> A right projected Either.

Method Summary

Modifier and Type	Method and Description
abstract boolean	equals(java.lang.Object other)
R	get() Get the right projected value of the either.
static <T> T	getOrElse(Either<?,? extends T> either, T t) Get the right projected value of the either or a provided default value.
abstract int	hashCode()
abstract boolean	isLeft() Check whether this is a Left projection.
abstract boolean	isRight() Check whether this is a Right projection.
static <L,R,T extends L> Either<L,R>	left(T value) Returns a left projected either.
static <L,R> Either.Left<L,R>	leftProjection(Either<L,R> either) Returns the Left projection for the provided Either or throws an exception if the Either is actually an instance of Either.Right.
static <L,R,T extends R> Either<L,R>	right(T value) Returns a right projected either.
static <L,R> Either.Right<L,R>	rightProjection(Either<L,R> either) Returns the Right projection for the provided Either or throws an exception if the Either is actually an instance of Either.Left.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Method Detail

leftProjection

public static <L,R> Either.Left<L,R> leftProjection(Either<L,R> either)
                                             throws Either.NotLeftException

Returns the Left projection for the provided Either or throws an exception if the Either is actually an instance of Either.Right.

Type Parameters:

L - the left type of the either.

R - the right type of the either.

Parameters:

either - the either, assumed to be an instance of left, that will

Returns:

a Left projection.

Throws:

Either.NotLeftException - if the value is a Either.Right.

rightProjection

public static <L,R> Either.Right<L,R> rightProjection(Either<L,R> either)
                                               throws Either.NotRightException

Returns the Right projection for the provided Either or throws an exception if the Either is actually an instance of Either.Left.

Type Parameters:

L - the left type of the either.

R - the right type of the either.

Parameters:

either - the either, assumed to be an instance of left, that will

Returns:

a Right projection.

Throws:

Either.NotRightException - if the value is a Either.Left.

isLeft

public abstract boolean isLeft()

Check whether this is a Left projection.

Returns:

true if this is a Reft projection

isRight

public abstract boolean isRight()

Check whether this is a Right projection.

Returns:

true if this is a Right projection

get

public R get()

Get the right projected value of the either. This is unsafe to call without checking whether the value is a right first.

Returns:

the wrapped value if is a right projection

Throws:

Either.NotRightException - if this is a left projection

getOrElse

public static <T> T getOrElse(Either<?,? extends T> either,
                              T t)

Get the right projected value of the either or a provided default value.

Type Parameters:

T - the default type

Parameters:

either - the either from which the method extracts the result if it is a Either.Right.

t - the default value

Returns:

the wrapped value if this is a right projection, otherwise the default

hashCode

public abstract int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public abstract boolean equals(java.lang.Object other)

Overrides:

equals in class java.lang.Object

left

public static <L,R,T extends L> Either<L,R> left(T value)

Returns a left projected either.

Type Parameters:

L - the type of the left parameter of the result

R - the type of the right parameter of the result

T - a refinement type that allows us to wrap subtypes of L

Parameters:

value - the value to wrap

Returns:

A left projected either

right

public static <L,R,T extends R> Either<L,R> right(T value)

Returns a right projected either.

Type Parameters:

L - the type of the left parameter of the result

R - the type of the right parameter of the result

T - a refinement type that allows us to wrap subtypes of R

Parameters:

value - the value to wrap

Returns:

a right projected either.