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package bjc.utils.data.internals;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Supplier;
import bjc.utils.data.IHolder;
import bjc.utils.data.IPair;
import bjc.utils.data.Identity;
import bjc.utils.data.LazyPair;
/*
* Implements a lazy pair that has been bound
*/
public class BoundLazyPair<OldLeft, OldRight, NewLeft, NewRight> implements IPair<NewLeft, NewRight> {
/*
* The supplier of the left value
*/
private final Supplier<OldLeft> leftSupplier;
/*
* The supplier of the right value
*/
private final Supplier<OldRight> rightSupplier;
/*
* The binder to transform values
*/
private final BiFunction<OldLeft, OldRight, IPair<NewLeft, NewRight>> binder;
/*
* The bound pair
*/
private IPair<NewLeft, NewRight> boundPair;
/*
* Whether the pair has been bound yet
*/
private boolean pairBound;
public BoundLazyPair(final Supplier<OldLeft> leftSupp, final Supplier<OldRight> rightSupp,
final BiFunction<OldLeft, OldRight, IPair<NewLeft, NewRight>> bindr) {
leftSupplier = leftSupp;
rightSupplier = rightSupp;
binder = bindr;
}
@Override
public <BoundLeft, BoundRight> IPair<BoundLeft, BoundRight> bind(
final BiFunction<NewLeft, NewRight, IPair<BoundLeft, BoundRight>> bindr) {
if (bindr == null) throw new NullPointerException("Binder must not be null");
final IHolder<IPair<NewLeft, NewRight>> newPair = new Identity<>(boundPair);
final IHolder<Boolean> newPairMade = new Identity<>(pairBound);
final Supplier<NewLeft> leftSupp = () -> {
if (!newPairMade.getValue()) {
newPair.replace(binder.apply(leftSupplier.get(), rightSupplier.get()));
newPairMade.replace(true);
}
return newPair.unwrap((pair) -> pair.getLeft());
};
final Supplier<NewRight> rightSupp = () -> {
if (!newPairMade.getValue()) {
newPair.replace(binder.apply(leftSupplier.get(), rightSupplier.get()));
newPairMade.replace(true);
}
return newPair.unwrap((pair) -> pair.getRight());
};
return new BoundLazyPair<>(leftSupp, rightSupp, bindr);
}
@Override
public <BoundLeft> IPair<BoundLeft, NewRight> bindLeft(
final Function<NewLeft, IPair<BoundLeft, NewRight>> leftBinder) {
if (leftBinder == null) throw new NullPointerException("Left binder must not be null");
final Supplier<NewLeft> leftSupp = () -> {
IPair<NewLeft, NewRight> newPair = boundPair;
if (!pairBound) {
newPair = binder.apply(leftSupplier.get(), rightSupplier.get());
}
return newPair.getLeft();
};
return new HalfBoundLazyPair<>(leftSupp, leftBinder);
}
@Override
public <BoundRight> IPair<NewLeft, BoundRight> bindRight(
final Function<NewRight, IPair<NewLeft, BoundRight>> rightBinder) {
if (rightBinder == null) throw new NullPointerException("Right binder must not be null");
final Supplier<NewRight> rightSupp = () -> {
IPair<NewLeft, NewRight> newPair = boundPair;
if (!pairBound) {
newPair = binder.apply(leftSupplier.get(), rightSupplier.get());
}
return newPair.getRight();
};
return new HalfBoundLazyPair<>(rightSupp, rightBinder);
}
@Override
public <OtherLeft, OtherRight, CombinedLeft, CombinedRight> IPair<CombinedLeft, CombinedRight> combine(
final IPair<OtherLeft, OtherRight> otherPair,
final BiFunction<NewLeft, OtherLeft, CombinedLeft> leftCombiner,
final BiFunction<NewRight, OtherRight, CombinedRight> rightCombiner) {
if (otherPair == null)
throw new NullPointerException("Other pair must not be null");
else if (leftCombiner == null)
throw new NullPointerException("Left combiner must not be null");
else if (rightCombiner == null) throw new NullPointerException("Right combiner must not be null");
return otherPair.bind((otherLeft, otherRight) -> {
return bind((leftVal, rightVal) -> {
return new LazyPair<>(leftCombiner.apply(leftVal, otherLeft),
rightCombiner.apply(rightVal, otherRight));
});
});
}
@Override
public <NewLeftType> IPair<NewLeftType, NewRight> mapLeft(final Function<NewLeft, NewLeftType> mapper) {
if (mapper == null) throw new NullPointerException("Mapper must not be null");
final Supplier<NewLeftType> leftSupp = () -> {
if (!pairBound) {
final NewLeft leftVal = binder.apply(leftSupplier.get(), rightSupplier.get()).getLeft();
return mapper.apply(leftVal);
}
return mapper.apply(boundPair.getLeft());
};
final Supplier<NewRight> rightSupp = () -> {
if (!pairBound) return binder.apply(leftSupplier.get(), rightSupplier.get()).getRight();
return boundPair.getRight();
};
return new LazyPair<>(leftSupp, rightSupp);
}
@Override
public <NewRightType> IPair<NewLeft, NewRightType> mapRight(final Function<NewRight, NewRightType> mapper) {
if (mapper == null) throw new NullPointerException("Mapper must not be null");
final Supplier<NewLeft> leftSupp = () -> {
if (!pairBound) return binder.apply(leftSupplier.get(), rightSupplier.get()).getLeft();
return boundPair.getLeft();
};
final Supplier<NewRightType> rightSupp = () -> {
if (!pairBound) {
final NewRight rightVal = binder.apply(leftSupplier.get(), rightSupplier.get())
.getRight();
return mapper.apply(rightVal);
}
return mapper.apply(boundPair.getRight());
};
return new LazyPair<>(leftSupp, rightSupp);
}
@Override
public <MergedType> MergedType merge(final BiFunction<NewLeft, NewRight, MergedType> merger) {
if (merger == null) throw new NullPointerException("Merger must not be null");
if (!pairBound) {
boundPair = binder.apply(leftSupplier.get(), rightSupplier.get());
pairBound = true;
}
return boundPair.merge(merger);
}
@Override
public String toString() {
if (pairBound) return boundPair.toString();
return "(un-materialized)";
}
}
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