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package bjc.data.internals;
import java.util.function.Function;
import java.util.function.UnaryOperator;
import bjc.data.Holder;
import bjc.data.Lazy;
/**
* A wrapped lazy value.
*
* @author Ben Culkin
* @param <ContainedType>
* The type of the wrapped value.
*/
public class WrappedLazy<ContainedType> implements Holder<ContainedType> {
/* Held value. */
private final Holder<Holder<ContainedType>> held;
/**
* Create a new wrapped lazy value.
*
* @param wrappedHolder
* The holder to make lazy.
*/
public WrappedLazy(final Holder<ContainedType> wrappedHolder) {
held = new Lazy<>(wrappedHolder);
}
/*
* This has an extra parameter, because otherwise it erases to the same as the
* public one.
*
* This is a case where reified generics would be useful, because then the
* compiler could know which one we meant without the dummy parameter.
*/
private WrappedLazy(final Holder<Holder<ContainedType>> wrappedHolder,
@SuppressWarnings("unused") final boolean dummy) {
held = wrappedHolder;
}
@Override
public <BoundType> Holder<BoundType>
bind(final Function<ContainedType, Holder<BoundType>> binder) {
final Holder<Holder<BoundType>> newHolder = held.map(containedHolder -> {
return containedHolder.bind(binder);
});
return new WrappedLazy<>(newHolder, false);
}
@Override
public <NewType> Function<ContainedType, Holder<NewType>>
lift(final Function<ContainedType, NewType> func) {
return val -> {
return new Lazy<>(func.apply(val));
};
}
@Override
public <MappedType> Holder<MappedType>
map(final Function<ContainedType, MappedType> mapper) {
final Holder<Holder<MappedType>> newHolder = held.map(containedHolder -> {
return containedHolder.map(mapper);
});
return new WrappedLazy<>(newHolder, false);
}
@Override
public Holder<ContainedType>
transform(final UnaryOperator<ContainedType> transformer) {
held.transform(containedHolder -> {
return containedHolder.transform(transformer);
});
return this;
}
@Override
public <UnwrappedType> UnwrappedType
unwrap(final Function<ContainedType, UnwrappedType> unwrapper) {
return held.unwrap(containedHolder -> {
return containedHolder.unwrap(unwrapper);
});
}
}
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