org.spongepowered.api.data.merge

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 ValueContainers into a singular ValueContainer. 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 and Description
static MergeFunction	FORCE_NOTHING Represents a MergeFunction that forces no merges and uses the original, or proposed replacement if the original is null.
static MergeFunction	IGNORE_ALL 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 and Description
default MergeFunction	andThen(MergeFunction that) Creates a new MergeFunction chaining this current merge function with the provided merge function.
<C extends ValueContainer<?>> C	merge(C original, C replacement) Performs a merge of a type of ValueContainer such that a merge of the contained BaseValues has been performed and the resulting merged ValueContainer is returned.

Field Detail

IGNORE_ALL

static final MergeFunction IGNORE_ALL

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

FORCE_NOTHING

static final MergeFunction FORCE_NOTHING

Represents a MergeFunction that forces no merges and uses the original, or proposed replacement if the original is null.

Method Detail

merge

<C extends ValueContainer<?>> C merge(@Nullable
                                      C original,
                                      @Nullable
                                      C replacement)

Performs a merge of a type of ValueContainer such that a merge of the contained BaseValues has been performed and the resulting merged ValueContainer is returned. It is suffice to say that only one of the ValueContainer containers 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.

Since CompositeValueStore.copyFrom(CompositeValueStore, MergeFunction) accepts only a single MergeFunction, and a CompositeValueStore may have multiple ValueContainers, as provided by CompositeValueStore.getContainers(), the merge function may be called for every single number of ValueContainer. This way, a MergeFunction can be fully customized to merge specific ValueContainers of matching types.

Type Parameters:

C - The type of ValueContainer

Parameters:

original - The original ValueContainer from the value store

replacement - The replacing value container

Returns:

The "merged" ValueContainer

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(ValueContainer, ValueContainer) 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