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package bjc.utils.data;
import java.util.function.Function;
import java.util.function.UnaryOperator;
/**
* A holder that may or may not contain a value
*
* @author ben
*
* @param <ContainedType>
* The type of the value that may or may not be held
*/
public class Option<ContainedType> implements IHolder<ContainedType> {
private ContainedType held;
/**
* Create a new optional, using the given initial value
*
* @param seedValue
* The initial value for the optional
*/
public Option(ContainedType seedValue) {
held = seedValue;
}
@Override
public <BoundType> IHolder<BoundType> bind(
Function<ContainedType, IHolder<BoundType>> binder) {
if (held == null) {
return new Option<>(null);
}
return binder.apply(held);
}
@Override
public <NewType> Function<ContainedType, IHolder<NewType>> lift(
Function<ContainedType, NewType> func) {
return (val) -> {
return new Option<>(func.apply(val));
};
}
@Override
public <MappedType> IHolder<MappedType> map(
Function<ContainedType, MappedType> mapper) {
if (held == null) {
return new Option<>(null);
}
return new Option<>(mapper.apply(held));
}
@Override
public IHolder<ContainedType> transform(
UnaryOperator<ContainedType> transformer) {
if (held != null) {
held = transformer.apply(held);
}
return this;
}
@Override
public <UnwrappedType> UnwrappedType unwrap(
Function<ContainedType, UnwrappedType> unwrapper) {
if (held == null) {
return null;
}
return unwrapper.apply(held);
}
}
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