Package org.spongepowered.api.data.value

Interface MergeFunction

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface MergeFunction

Represents a unique form of Function that attempts to merge two separate Values into a singular Value. A merge function is similar to a Function such that it can be reused for multiple purposes and should be "stateless" on its own.

Field Summary

Fields

Modifier and Type	Field	Description
static MergeFunction	ORIGINAL_PREFERRED	Represents a MergeFunction that will preferr the original's value if it is not null over the replacement.
static MergeFunction	REPLACEMENT_PREFERRED	Represents a MergeFunction that ignores all merges and uses the replacement, or the original if the replacement is null.

Method Summary

Modifier and Type	Method	Description
default MergeFunction	andThen(MergeFunction that)	Creates a new MergeFunction chaining this current merge function with the provided merge function.
<V extends Value<E>,E> V	merge(@Nullable V original, @Nullable V replacement)	Performs a merge of a type of Value such that a merge has been performed and the resulting merged Value is returned.

Field Detail

REPLACEMENT_PREFERRED

static final MergeFunction REPLACEMENT_PREFERRED

Represents a MergeFunction that ignores all merges and uses the replacement, or the original if the replacement is null.

ORIGINAL_PREFERRED

static final MergeFunction ORIGINAL_PREFERRED

Represents a MergeFunction that will preferr the original's value if it is not null over the replacement.

Method Detail

merge

<V extends Value<E>,E> V merge(@Nullable V original,
                                     @Nullable V replacement)

Performs a merge of a type of Value such that a merge has been performed and the resulting merged Value is returned. It is suffice to say that only one of the Values may be null, such that

 
 if (original == null) {
     return checkNotNull(replacement);
 } else if (replacement == null) {
     return original;
 } else {
     // do something merging the necessary values
 }
 

It can be therefor discerned that both values are passed in as copies and therefor either one can be modified and returned.

Type Parameters:

V - The type of Value being passed in

E - The type of value for the Value

Parameters:

original - The original Value from the value store

replacement - The replacing value container

Returns:

The "merged" Value

andThen

default MergeFunction andThen(MergeFunction that)

Creates a new MergeFunction chaining this current merge function with the provided merge function. The order of the merge is this performs merge(Value, Value) then, the provided MergeFunction merges the returned merged ValueContainer and the replacement. This can be used to apply a custom merge strategy after a pre-defined MergeFunction is applied.

Parameters:

that - The MergeFunction to chain

Returns:

The new MergeFunction