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Added more functions to Either and make it right-biased
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src/main/java/de/tototec/utils/functional/Either.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,153 +1,192 @@ | ||
| package de.tototec.utils.functional; | ||
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| import java.io.Serializable; | ||
| import java.util.Collections; | ||
| import java.util.List; | ||
| import java.util.NoSuchElementException; | ||
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| /** | ||
| * Value class representing exactly one of two options, left or right. | ||
| * | ||
| * <p> | ||
| * This class is immutable and thus threadsafe. | ||
| * | ||
| * @param <L> | ||
| * The type of the left option. | ||
| * @param <R> | ||
| * The type of the right option. | ||
| * @param <L> The type of the left option. | ||
| * @param <R> The type of the right option. | ||
| */ | ||
| public final class Either<L, R> implements Serializable { | ||
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| private static final long serialVersionUID = 1L; | ||
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| private final L left; | ||
| private final R right; | ||
| private final boolean isRight; | ||
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| public static <L, R> Either<L, R> left(final L left) { | ||
| return new Either<L, R>(left, null, false); | ||
| } | ||
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| public static <L, R> Either<L, R> right(final R right) { | ||
| return new Either<L, R>(null, right, true); | ||
| } | ||
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| /* package private */ Either(final L left, final R right, final boolean isRight) { | ||
| this.left = left; | ||
| this.right = right; | ||
| this.isRight = isRight; | ||
| if (isRight && left != null) { | ||
| throw new IllegalArgumentException("Left value must be null"); | ||
| } else if (!isRight && right != null) { | ||
| throw new IllegalArgumentException("Right value must be null"); | ||
| } | ||
| } | ||
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| public L left() { | ||
| if (!isRight) { | ||
| return left; | ||
| } else { | ||
| throw new NoSuchElementException("Left value not defined."); | ||
| } | ||
| } | ||
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| public Optional<L> leftOption() { | ||
| if (!isRight) { | ||
| return Optional.some(left); | ||
| } else { | ||
| return Optional.none(); | ||
| } | ||
| } | ||
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| public Try<L> leftTry() { | ||
| if (!isRight) { | ||
| return Try.success(left); | ||
| } else { | ||
| return Try.failure(new NoSuchElementException("Either.left.value on Right")); | ||
| } | ||
| } | ||
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| public R right() { | ||
| if (isRight) { | ||
| return right; | ||
| } else { | ||
| throw new NoSuchElementException("Right value not defined."); | ||
| } | ||
| } | ||
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| public Optional<R> rightOption() { | ||
| if (isRight) { | ||
| return Optional.some(right); | ||
| } else { | ||
| return Optional.none(); | ||
| } | ||
| } | ||
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| public Try<R> rightTry() { | ||
| if (isRight) { | ||
| return Try.success(right); | ||
| } else { | ||
| return Try.failure(new NoSuchElementException("Either.right.value on Left")); | ||
| } | ||
| } | ||
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| public boolean isLeft() { | ||
| return !isRight; | ||
| } | ||
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| public boolean isRight() { | ||
| return isRight; | ||
| } | ||
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| @Override | ||
| public String toString() { | ||
| return isRight ? ("Right(" + right + ")") : ("Left(" + left + ")"); | ||
| } | ||
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| @Override | ||
| public int hashCode() { | ||
| final int prime = 31; | ||
| int result = 1; | ||
| result = prime * result + (isRight ? 1231 : 1237); | ||
| result = prime * result + ((left == null) ? 0 : left.hashCode()); | ||
| result = prime * result + ((right == null) ? 0 : right.hashCode()); | ||
| return result; | ||
| } | ||
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| @Override | ||
| public boolean equals(final Object obj) { | ||
| if (this == obj) { | ||
| return true; | ||
| } | ||
| if (obj == null) { | ||
| return false; | ||
| } | ||
| if (getClass() != obj.getClass()) { | ||
| return false; | ||
| } | ||
| final Either<?, ?> other = (Either<?, ?>) obj; | ||
| if (isRight != other.isRight) { | ||
| return false; | ||
| } | ||
| if (isRight) { | ||
| if (right == null) { | ||
| if (other.right != null) { | ||
| return false; | ||
| } | ||
| } else if (!right.equals(other.right)) { | ||
| return false; | ||
| } | ||
| } else { | ||
| if (left == null) { | ||
| if (other.left != null) { | ||
| return false; | ||
| } | ||
| } else if (!left.equals(other.left)) { | ||
| return false; | ||
| } | ||
| } | ||
| return true; | ||
| } | ||
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| public Either<R, L> swap() { | ||
| return new Either<R, L>(right, left, !isRight); | ||
| } | ||
| private static final long serialVersionUID = 1L; | ||
|
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| private final L left; | ||
| private final R right; | ||
| private final boolean isRight; | ||
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| public static <L, R> Either<L, R> left(final L left) { | ||
| return new Either<L, R>(left, null, false); | ||
| } | ||
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| public static <L, R> Either<L, R> right(final R right) { | ||
| return new Either<L, R>(null, right, true); | ||
| } | ||
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| /* package private */ Either(final L left, final R right, final boolean isRight) { | ||
| this.left = left; | ||
| this.right = right; | ||
| this.isRight = isRight; | ||
| if (isRight && left != null) { | ||
| throw new IllegalArgumentException("Left value must be null"); | ||
| } else if (!isRight && right != null) { | ||
| throw new IllegalArgumentException("Right value must be null"); | ||
| } | ||
| } | ||
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| public L left() { | ||
| if (!isRight) { | ||
| return left; | ||
| } else { | ||
| throw new NoSuchElementException("Left value not defined."); | ||
| } | ||
| } | ||
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| public Optional<L> leftOption() { | ||
| if (!isRight) { | ||
| return Optional.some(left); | ||
| } else { | ||
| return Optional.none(); | ||
| } | ||
| } | ||
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| public Try<L> leftTry() { | ||
| if (!isRight) { | ||
| return Try.success(left); | ||
| } else { | ||
| return Try.failure(new NoSuchElementException("Either.left.value on Right")); | ||
| } | ||
| } | ||
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| public R right() { | ||
| if (isRight) { | ||
| return right; | ||
| } else { | ||
| throw new NoSuchElementException("Right value not defined."); | ||
| } | ||
| } | ||
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| public Optional<R> rightOption() { | ||
| if (isRight) { | ||
| return Optional.some(right); | ||
| } else { | ||
| return Optional.none(); | ||
| } | ||
| } | ||
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| public Try<R> rightTry() { | ||
| if (isRight) { | ||
| return Try.success(right); | ||
| } else { | ||
| return Try.failure(new NoSuchElementException("Either.right.value on Left")); | ||
| } | ||
| } | ||
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| public boolean isLeft() { | ||
| return !isRight; | ||
| } | ||
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| public boolean isRight() { | ||
| return isRight; | ||
| } | ||
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| @Override | ||
| public String toString() { | ||
| return isRight ? ("Right(" + right + ")") : ("Left(" + left + ")"); | ||
| } | ||
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| @Override | ||
| public int hashCode() { | ||
| final int prime = 31; | ||
| int result = 1; | ||
| result = prime * result + (isRight ? 1231 : 1237); | ||
| result = prime * result + ((left == null) ? 0 : left.hashCode()); | ||
| result = prime * result + ((right == null) ? 0 : right.hashCode()); | ||
| return result; | ||
| } | ||
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| @Override | ||
| public boolean equals(final Object obj) { | ||
| if (this == obj) { | ||
| return true; | ||
| } | ||
| if (obj == null) { | ||
| return false; | ||
| } | ||
| if (getClass() != obj.getClass()) { | ||
| return false; | ||
| } | ||
| final Either<?, ?> other = (Either<?, ?>) obj; | ||
| if (isRight != other.isRight) { | ||
| return false; | ||
| } | ||
| if (isRight) { | ||
| if (right == null) { | ||
| if (other.right != null) { | ||
| return false; | ||
| } | ||
| } else if (!right.equals(other.right)) { | ||
| return false; | ||
| } | ||
| } else { | ||
| if (left == null) { | ||
| if (other.left != null) { | ||
| return false; | ||
| } | ||
| } else if (!left.equals(other.left)) { | ||
| return false; | ||
| } | ||
| } | ||
| return true; | ||
| } | ||
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| public Either<R, L> swap() { | ||
| return new Either<R, L>(right, left, !isRight); | ||
| } | ||
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| public <C> C fold(F1<L, C> l, F1<R, C> r) { | ||
| return isRight ? r.apply(right) : l.apply(left); | ||
| } | ||
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| public <R1> Either<L, R1> map(F1<R, R1> f) { | ||
| return isRight ? Either.<L, R1>right(f.apply(right)) : (Either<L, R1>) left; | ||
| } | ||
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| public <R1> Either<L, R1> flatMap(F1<R, Either<L, R1>> f) { | ||
| return isRight ? f.apply(right) : (Either<L, R1>) left; | ||
| } | ||
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| public void foreach(final Procedure1<? super R> f) { | ||
| if (isRight) { | ||
| f.apply(right); | ||
| } | ||
| } | ||
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| public R getOrElse(final R t) { | ||
| return isRight ? right : t; | ||
| } | ||
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| public R getOrElseF(final F0<R> f) { | ||
| return isRight ? right : f.apply(); | ||
| } | ||
|
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| public Either<L, R> orElse(Either<L, R> or) { | ||
| return isRight ? this : or; | ||
| } | ||
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| public Either<L, R> orElseF(F0<Either<L, R>> or) { | ||
| return isRight ? this : or.apply(); | ||
| } | ||
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| public List<R> toList() { | ||
| return isRight ? Collections.singletonList(right) : Collections.<R>emptyList(); | ||
| } | ||
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| } |