// This software is released into the Public Domain. See copying.txt for details.
package org.openstreetmap.osmosis.pgsnapshot.v0_6.impl;
import java.util.List;
import java.util.NoSuchElementException;
import org.openstreetmap.osmosis.core.database.FeaturePopulator;
import org.openstreetmap.osmosis.core.domain.v0_6.Entity;
import org.openstreetmap.osmosis.core.lifecycle.ReleasableContainer;
import org.openstreetmap.osmosis.core.lifecycle.ReleasableIterator;
/**
* Provides a single iterator based on data provided by underlying iterators from each of the
* underlying entity and feature iterators. Each underlying iterator provides one component of the
* overall entity.
*
* @param <T>
* The type of entity provided by this iterator.
*/
public class EntityReader<T extends Entity> implements ReleasableIterator<T> {
private boolean nextValueLoaded;
private ReleasableContainer releasableContainer;
private ReleasableIterator<T> entityIterator;
private List<FeaturePopulator<T>> featurePopulators;
private T nextValue;
/**
* Creates a new instance.
*
* @param entityIterator
* The entity source.
* @param featurePopulators
* Populators to add entity specific features to the generated entities.
*/
public EntityReader(ReleasableIterator<T> entityIterator, List<FeaturePopulator<T>> featurePopulators) {
releasableContainer = new ReleasableContainer();
this.entityIterator = releasableContainer.add(entityIterator);
for (FeaturePopulator<T> featurePopulator : featurePopulators) {
releasableContainer.add(featurePopulator);
}
this.featurePopulators = featurePopulators;
}
/**
* Consolidates the output of all readers so that entities are fully
* populated.
*
* @return An entity record where the entity is fully populated.
*/
private T readNextEntity() {
T entity;
entity = entityIterator.next();
// Add entity type specific features to the entity.
for (FeaturePopulator<T> populator : featurePopulators) {
populator.populateFeatures(entity);
}
return entity;
}
/**
* {@inheritDoc}
*/
public boolean hasNext() {
if (!nextValueLoaded && entityIterator.hasNext()) {
nextValue = readNextEntity();
nextValueLoaded = true;
}
return nextValueLoaded;
}
/**
* {@inheritDoc}
*/
public T next() {
T result;
if (!hasNext()) {
throw new NoSuchElementException();
}
result = nextValue;
nextValueLoaded = false;
return result;
}
/**
* {@inheritDoc}
*/
public void remove() {
throw new UnsupportedOperationException();
}
/**
* {@inheritDoc}
*/
public void release() {
releasableContainer.release();
}
}