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/*
* esodata - data structures and other things, of varying utility
* Copyright 2022, Ben Culkin
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
package bjc.data;
import java.util.function.BiFunction;
import java.util.function.Function;
/**
* A pair of values, with nothing special about them.
*
* @author ben
*
* @param <LeftType>
* The type of the left value.
*
* @param <RightType>
* The type of the right value.
*/
public class SimplePair<LeftType, RightType> implements Pair<LeftType, RightType> {
/* The left value. */
private LeftType leftValue;
/* The right value. */
private RightType rightValue;
/** Create a new pair with both sides set to null. */
public SimplePair() {
// Do nothing :)
}
/**
* Create a new pair with both sides set to the specified values.
*
* @param left
* The value of the left side.
*
* @param right
* The value of the right side.
*/
public SimplePair(final LeftType left, final RightType right) {
leftValue = left;
rightValue = right;
}
@Override
public <BoundLeft, BoundRight> Pair<BoundLeft, BoundRight> bind(
final BiFunction<LeftType, RightType, Pair<BoundLeft, BoundRight>> binder) {
if (binder == null) throw new NullPointerException("Binder must not be null.");
return binder.apply(leftValue, rightValue);
}
@Override
public <BoundLeft> Pair<BoundLeft, RightType>
bindLeft(final Function<LeftType, Pair<BoundLeft, RightType>> leftBinder) {
if (leftBinder == null) throw new NullPointerException("Binder must not be null");
return leftBinder.apply(leftValue);
}
@Override
public <BoundRight> Pair<LeftType, BoundRight> bindRight(
final Function<RightType, Pair<LeftType, BoundRight>> rightBinder) {
if (rightBinder == null) throw new NullPointerException("Binder must not be null");
return rightBinder.apply(rightValue);
}
@Override
public <OtherLeft, OtherRight, CombinedLeft, CombinedRight>
Pair<CombinedLeft, CombinedRight>
combine(final Pair<OtherLeft, OtherRight> otherPair,
final BiFunction<LeftType, OtherLeft, CombinedLeft> leftCombiner,
final BiFunction<RightType, OtherRight,
CombinedRight> rightCombiner) {
return otherPair.bind((otherLeft, otherRight) -> {
final CombinedLeft left = leftCombiner.apply(leftValue, otherLeft);
final CombinedRight right = rightCombiner.apply(rightValue, otherRight);
return new SimplePair<>(left, right);
});
}
@Override
public <NewLeft> Pair<NewLeft, RightType>
mapLeft(final Function<LeftType, NewLeft> mapper) {
if (mapper == null) throw new NullPointerException("Mapper must not be null");
return new SimplePair<>(mapper.apply(leftValue), rightValue);
}
@Override
public <NewRight> Pair<LeftType, NewRight>
mapRight(final Function<RightType, NewRight> mapper) {
if (mapper == null) throw new NullPointerException("Mapper must not be null");
return new SimplePair<>(leftValue, mapper.apply(rightValue));
}
@Override
public <MergedType> MergedType
merge(final BiFunction<LeftType, RightType, MergedType> merger) {
if (merger == null) throw new NullPointerException("Merger must not be null");
return merger.apply(leftValue, rightValue);
}
@Override
public String toString() {
return String.format("Pair [leftValue='%s', rightValue='%s']", leftValue,
rightValue);
}
@Override
public LeftType getLeft() {
return leftValue;
}
@Override
public RightType getRight() {
return rightValue;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + (leftValue == null ? 0 : leftValue.hashCode());
result = prime * result + (rightValue == null ? 0 : rightValue.hashCode());
return result;
}
@Override
public boolean equals(final Object obj) {
if (this == obj) return true;
if (obj == null) return false;
if (!(obj instanceof SimplePair<?, ?>)) return false;
final SimplePair<?, ?> other = (SimplePair<?, ?>) obj;
if (leftValue == null) {
if (other.leftValue != null) return false;
} else if (!leftValue.equals(other.leftValue)) {
return false;
}
if (rightValue == null) {
if (other.rightValue != null) return false;
} else if (!rightValue.equals(other.rightValue)) {
return false;
}
return true;
}
}
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