org.infinispan.commons.util.SpliteratorMapper Maven / Gradle / Ivy
package org.infinispan.commons.util;
import java.util.Objects;
import java.util.Spliterator;
import java.util.function.Consumer;
import java.util.function.Function;
/**
* A spliterator that has been mapped from another spliterator. This is nice to only lazily convert these values, so
* that you can convert across multiple threads or if the entire spliterator is not consumed.
*
* This spliterator will always throw an {@link IllegalStateException} upon invocation of
* {@link Spliterator#getComparator()} since there is no trivial way of converting this with a mapper.
* @author wburns
* @since 9.0
*/
public class SpliteratorMapper implements CloseableSpliterator {
protected final Spliterator spliterator;
protected final Function mapper;
public SpliteratorMapper(Spliterator spliterator, Function mapper) {
this.spliterator = Objects.requireNonNull(spliterator);
this.mapper = Objects.requireNonNull(mapper);
}
@Override
public boolean tryAdvance(Consumer action) {
return spliterator.tryAdvance(e -> action.accept(mapper.apply(e)));
}
@Override
public Spliterator trySplit() {
Spliterator split = spliterator.trySplit();
if (split != null) {
return new SpliteratorMapper<>(split, mapper);
}
return null;
}
@Override
public long estimateSize() {
return spliterator.estimateSize();
}
@Override
public int characteristics() {
int characteristics = spliterator.characteristics();
if (mapper instanceof InjectiveFunction) {
return characteristics;
} else {
// Have to unset distinct if the function wasn't distinct
return characteristics & ~Spliterator.DISTINCT;
}
}
@Override
public void forEachRemaining(Consumer action) {
spliterator.forEachRemaining(e -> action.accept(mapper.apply(e)));
}
@Override
public long getExactSizeIfKnown() {
return spliterator.getExactSizeIfKnown();
}
@Override
public boolean hasCharacteristics(int characteristics) {
return spliterator.hasCharacteristics(characteristics);
}
@Override
public void close() {
if (spliterator instanceof CloseableSpliterator) {
((CloseableSpliterator) spliterator).close();
}
}
}