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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(final LeftType left, final RightType right) {
leftValue = left;
rightValue = right;
}
@Override
public <BoundLeft, BoundRight> IPair<BoundLeft, BoundRight> bind(
final 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(
final 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(
final 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(
final IPair<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 Pair<>(left, right);
});
}
@Override
public <NewLeft> IPair<NewLeft, RightType> mapLeft(final 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(final 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(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 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 Pair<?, ?>)) return false;
final 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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