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Data types package for Neo4j Procedures
package apoc.util.collection;
import java.util.Iterator;
import java.util.NoSuchElementException;
import org.neo4j.graphdb.Resource;
import org.neo4j.graphdb.ResourceIterable;
import org.neo4j.graphdb.ResourceIterator;
import org.neo4j.graphdb.ResourceUtils;
public abstract class ResourceClosingIterator implements ResourceIterator {
public static ResourceIterator newResourceIterator(Iterator iterator, Resource... resources) {
return new ResourceClosingIterator<>(iterator, resources) {
@Override
public R map(R elem) {
return elem;
}
};
}
/**
* Return a {@link ResourceIterator} for the provided {@code iterable} that will also close
* this {@code iterable} when the returned iterator is itself closed. Please note, it is
* much preferred to explicitly close the {@link ResourceIterable} but this utility
* provides a way of cleaning up resources when the {@code iterable} is never exposed to
* client code; for example when the {@link ResourceIterator} is the return-type of a method
* call.
*
* @param iterable the iterable to provider the iterator
* @param the type of elements in the given iterable
* @return the iterator for the provided {@code iterable}
*/
public static ResourceIterator fromResourceIterable(ResourceIterable iterable) {
ResourceIterator iterator = iterable.iterator();
return newResourceIterator(iterator, iterator, iterable);
}
private Resource[] resources;
private final Iterator iterator;
ResourceClosingIterator(Iterator iterator, Resource... resources) {
this.resources = resources;
this.iterator = iterator;
}
@Override
public void close() {
if (resources != null) {
ResourceUtils.closeAll(resources);
resources = null;
}
}
@Override
public boolean hasNext() {
boolean hasNext = iterator.hasNext();
if (!hasNext) {
close();
}
return hasNext;
}
public abstract V map(T elem);
@Override
public V next() {
try {
return map(iterator.next());
} catch (NoSuchElementException e) {
close();
throw e;
}
}
@Override
public void remove() {
iterator.remove();
}
}
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