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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.Option;
/**
* A wrapped optional value.
*
* @author Ben Culkin.
* @param <ContainedType>
* The wrapped type.
*/
public class WrappedOption<ContainedType> implements Holder<ContainedType> {
/* The held value. */
private final Holder<Holder<ContainedType>> held;
/**
* Create a new wrapped option.
*
* @param seedValue
* The value to wrap.
*/
public WrappedOption(final Holder<ContainedType> seedValue) {
held = new Option<>(seedValue);
}
/*
* The dummy parameter is to ensure the compiler can pick the right method,
* because without this method erases to the same type as the public one.
*/
private WrappedOption(final Holder<Holder<ContainedType>> toHold,
@SuppressWarnings("unused") final boolean dummy) {
held = toHold;
}
@Override
public <BoundType> Holder<BoundType>
bind(final Function<ContainedType, Holder<BoundType>> binder) {
final Holder<Holder<BoundType>> newHolder = held.map(containedHolder -> {
return containedHolder.bind((containedValue) -> {
if (containedValue == null)
return new Option<>(null);
return binder.apply(containedValue);
});
});
return new WrappedOption<>(newHolder, false);
}
@Override
public <NewType> Function<ContainedType, Holder<NewType>>
lift(final Function<ContainedType, NewType> func) {
return val -> {
return new Option<>(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((containedValue) -> {
if (containedValue == null)
return null;
return mapper.apply(containedValue);
});
});
return new WrappedOption<>(newHolder, false);
}
@Override
public Holder<ContainedType>
transform(final UnaryOperator<ContainedType> transformer) {
held.transform(containedHolder -> {
return containedHolder.transform((containedValue) -> {
if (containedValue == null)
return null;
return transformer.apply(containedValue);
});
});
return this;
}
@Override
public <UnwrappedType> UnwrappedType
unwrap(final Function<ContainedType, UnwrappedType> unwrapper) {
return held.unwrap(containedHolder -> {
return containedHolder.unwrap((containedValue) -> {
if (containedValue == null)
return null;
return unwrapper.apply(containedValue);
});
});
}
}
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