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package dev.marksman.collectionviews;
import com.jnape.palatable.lambda.adt.Maybe;
import dev.marksman.enhancediterables.ImmutableNonEmptyFiniteIterable;
import static com.jnape.palatable.lambda.adt.Maybe.just;
/**
* A {@code Set} that is guaranteed at compile-time to be non-empty and safe from mutation anywhere.
* In other words, it owns the sole reference to the underlying collection.
*
* Provides all the guarantees of {@link Set}, {@link NonEmptySet}, and {@link ImmutableSet}.
*
* @param the element type
*/
public interface ImmutableNonEmptySet extends NonEmptySet, ImmutableSet, ImmutableNonEmptyFiniteIterable {
/**
* Returns an {@code ImmutableNonEmptySet} containing the same elements as this one.
*
* Since this is an {@link ImmutableNonEmptySet} already, this method simply returns
* itself.
*
* @return itself
*/
@Override
default ImmutableNonEmptySet toImmutable() {
return this;
}
/**
* Attempts to convert this {@code ImmutableSet} to an {@code ImmutableNonEmptySet}.
*
* Since this will always be successful for {@link ImmutableNonEmptySet}s,
* this method always returns itself wrapped in a {@link Maybe#just}.
*
* Does not make copies of any underlying data structures.
*
* @return this {@code ImmutableNonEmptySet} wrapped in a {@link Maybe#just}
*/
@Override
default Maybe> toNonEmpty() {
return just(this);
}
/**
* Attempts to convert this {@code ImmutableSet} to a {@code ImmutableNonEmptySet}.
*
* Since this will always be successful for {@link ImmutableNonEmptySet}s,
* this method always returns itself.
*
* Does not make copies of any underlying data structures.
*
* @return this {@code ImmutableNonEmptySet}
*/
@Override
default ImmutableNonEmptySet toNonEmptyOrThrow() {
return this;
}
/**
* Creates a {@code ImmutableNonEmptySet} with the given elements.
*
* @param first the first element
* @param more the remaining elements
* @param the element type
* @return an {@code ImmutableNonEmptySet}
*/
@SuppressWarnings("varargs")
@SafeVarargs
static ImmutableNonEmptySet of(A first, A... more) {
return Sets.nonEmptySetOf(first, more);
}
}