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package bjc.utils.data;
import bjc.utils.data.internals.BoundListHolder;
import bjc.utils.data.internals.WrappedLazy;
import bjc.utils.data.internals.WrappedOption;
import bjc.utils.funcdata.FunctionalList;
import bjc.utils.funcdata.theory.Functor;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.UnaryOperator;
/**
* A holder of a single value.
*
* @author ben
*
* @param <ContainedType>
* The type of value held
*/
public interface IHolder<ContainedType> extends Functor<ContainedType> {
/**
* Bind a function across the value in this container
*
* @param <BoundType>
* The type of value in this container
* @param binder
* The function to bind to the value
* @return A holder from binding the value
*/
public <BoundType> IHolder<BoundType> bind(Function<ContainedType, IHolder<BoundType>> binder);
/**
* Apply an action to the value
*
* @param action
* The action to apply to the value
*/
public default void doWith(Consumer<? super ContainedType> action) {
transform(value -> {
action.accept(value);
return value;
});
}
@Override
default <ArgType, ReturnType> Function<Functor<ArgType>, Functor<ReturnType>> fmap(
Function<ArgType, ReturnType> func) {
return argumentFunctor -> {
if (!(argumentFunctor instanceof IHolder<?>)) {
String msg = "This functor only supports mapping over instances of IHolder";
throw new IllegalArgumentException(msg);
}
IHolder<ArgType> holder = (IHolder<ArgType>) argumentFunctor;
return holder.map(func);
};
}
@Override
public default ContainedType getValue() {
return unwrap(value -> value);
}
/**
* Lifts a function to bind over this holder
*
* @param <NewType>
* The type of the functions return
* @param func
* The function to lift over the holder
* @return The function lifted over the holder
*/
public <NewType> Function<ContainedType, IHolder<NewType>> lift(Function<ContainedType, NewType> func);
/**
* Make this holder lazy
*
* @return A lazy version of this holder
*/
public default IHolder<ContainedType> makeLazy() {
return new WrappedLazy<>(this);
}
/**
* Make this holder a list
*
* @return A list version of this holder
*/
public default IHolder<ContainedType> makeList() {
return new BoundListHolder<>(new FunctionalList<>(this));
}
/**
* Make this holder optional
*
* @return An optional version of this holder
*/
public default IHolder<ContainedType> makeOptional() {
return new WrappedOption<>(this);
}
/**
* Create a new holder with a mapped version of the value in this
* holder.
*
* Does not change the internal state of this holder
*
* @param <MappedType>
* The type of the mapped value
* @param mapper
* The function to do mapping with
* @return A holder with the mapped value
*/
public <MappedType> IHolder<MappedType> map(Function<ContainedType, MappedType> mapper);
/**
* Replace the held value with a new one
*
* @param newValue
* The value to hold instead
* @return The holder itself
*/
public default IHolder<ContainedType> replace(ContainedType newValue) {
return transform(oldValue -> {
return newValue;
});
}
/**
* Transform the value held in this holder
*
* @param transformer
* The function to transform the value with
* @return The holder itself, for easy chaining
*/
public IHolder<ContainedType> transform(UnaryOperator<ContainedType> transformer);
/**
* Unwrap the value contained in this holder so that it is no longer
* held
*
* @param <UnwrappedType>
* The type of the unwrapped value
* @param unwrapper
* The function to use to unwrap the value
* @return The unwrapped held value
*/
public <UnwrappedType> UnwrappedType unwrap(Function<ContainedType, UnwrappedType> unwrapper);
}
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