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package bjc.utils.data.internals;
import java.util.function.Function;
import java.util.function.UnaryOperator;
import bjc.utils.data.IHolder;
import bjc.utils.data.Option;
/**
* A wrapped optional value.
*
* @author Ben Culkin.
* @param <ContainedType>
* The wrapped type.
*/
public class WrappedOption<ContainedType> implements IHolder<ContainedType> {
/* The held value. */
private final IHolder<IHolder<ContainedType>> held;
/**
* Create a new wrapped option.
*
* @param seedValue
* The value to wrap.
*/
public WrappedOption(final IHolder<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 IHolder<IHolder<ContainedType>> toHold,
@SuppressWarnings("unused") final boolean dummy) {
held = toHold;
}
@Override
public <BoundType> IHolder<BoundType> bind(final Function<ContainedType, IHolder<BoundType>> binder) {
final IHolder<IHolder<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, IHolder<NewType>> lift(final Function<ContainedType, NewType> func) {
return (val) -> {
return new Option<>(func.apply(val));
};
}
@Override
public <MappedType> IHolder<MappedType> map(final Function<ContainedType, MappedType> mapper) {
final IHolder<IHolder<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 IHolder<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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