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package bjc.utils.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 Pair<LeftType, RightType> implements IPair<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 Pair() {
}
/**
* 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 Pair(LeftType left, RightType right) {
leftValue = left;
rightValue = right;
}
@Override
public <BoundLeft, BoundRight> IPair<BoundLeft, BoundRight> bind(
BiFunction<LeftType, RightType, IPair<BoundLeft, BoundRight>> binder) {
if (binder == null)
throw new NullPointerException("Binder must not be null.");
return binder.apply(leftValue, rightValue);
}
@Override
public <BoundLeft> IPair<BoundLeft, RightType> bindLeft(
Function<LeftType, IPair<BoundLeft, RightType>> leftBinder) {
if (leftBinder == null)
throw new NullPointerException("Binder must not be null");
return leftBinder.apply(leftValue);
}
@Override
public <BoundRight> IPair<LeftType, BoundRight> bindRight(
Function<RightType, IPair<LeftType, BoundRight>> rightBinder) {
if (rightBinder == null)
throw new NullPointerException("Binder must not be null");
return rightBinder.apply(rightValue);
}
@Override
public <OtherLeft, OtherRight, CombinedLeft, CombinedRight> IPair<CombinedLeft, CombinedRight> combine(
IPair<OtherLeft, OtherRight> otherPair,
BiFunction<LeftType, OtherLeft, CombinedLeft> leftCombiner,
BiFunction<RightType, OtherRight, CombinedRight> rightCombiner) {
return otherPair.bind((otherLeft, otherRight) -> {
CombinedLeft left = leftCombiner.apply(leftValue, otherLeft);
CombinedRight right = rightCombiner.apply(rightValue, otherRight);
return new Pair<>(left, right);
});
}
@Override
public <NewLeft> IPair<NewLeft, RightType> mapLeft(Function<LeftType, NewLeft> mapper) {
if (mapper == null)
throw new NullPointerException("Mapper must not be null");
return new Pair<>(mapper.apply(leftValue), rightValue);
}
@Override
public <NewRight> IPair<LeftType, NewRight> mapRight(Function<RightType, NewRight> mapper) {
if (mapper == null)
throw new NullPointerException("Mapper must not be null");
return new Pair<>(leftValue, mapper.apply(rightValue));
}
@Override
public <MergedType> MergedType merge(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 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(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (!(obj instanceof Pair<?, ?>))
return false;
Pair<?, ?> other = (Pair<?, ?>) 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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