MultimapDifferAsMapStrategy.java

package fr.openwide.core.jpa.more.business.difference.differ.strategy;

import java.util.Collection;
import java.util.Map;
import java.util.Set;

import com.google.common.collect.Multimap;
import com.google.common.collect.Sets;

import de.danielbechler.diff.access.Accessor;
import fr.openwide.core.jpa.more.business.difference.access.MultimapValueByKeyAccessor;

public class MultimapDifferAsMapStrategy<K, V> extends AbstractContainerDifferStrategy<Map<K, Collection<V>>, K> {

	public MultimapDifferAsMapStrategy(ItemContentComparisonStrategy itemContentComparisonStrategy) {
		super(itemContentComparisonStrategy);
	}

	@Override
	protected Accessor createItemAccessor(K key) {
		return new MultimapValueByKeyAccessor<K>(key);
	}

	@SuppressWarnings({ "rawtypes", "unchecked" })
	@Override
	public Map<K, Collection<V>> toContainer(Object object) {
		if (object == null) {
			return null;
		} else if (object instanceof Multimap) {
			return ((Multimap)object).asMap();
		} else {
			throw new IllegalArgumentException("This differ only supports Maps and Multimaps.");
		}
	}
	
	@Override
	public Set<K> difference(Map<K, Collection<V>> source, Map<K, Collection<V>> filter) {
		final Set<K> copy = Sets.newLinkedHashSet();
		if (source != null) {
			if (filter != null) {
				copy.addAll(Sets.difference(source.keySet(), filter.keySet()));
			} else {
				copy.addAll(source.keySet());
			}
		}
		return copy;
	}
	
	@Override
	public Set<K> intersection(Map<K, Collection<V>> source, Map<K, Collection<V>> filter) {
		final Set<K> copy = Sets.newLinkedHashSet();
		if (source != null && filter != null) {
			copy.addAll(Sets.intersection(source.keySet(), filter.keySet()));
		}
		return copy;
	}

}