CollectionDifferIndexStrategy.java

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

import java.util.Collection;

import com.google.common.collect.ContiguousSet;
import com.google.common.collect.DiscreteDomain;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Range;

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

public final class CollectionDifferIndexStrategy<T> extends AbstractCollectionDifferStrategy<T, Integer> {
	public CollectionDifferIndexStrategy(ItemContentComparisonStrategy itemContentComparisonStrategy) {
		super(itemContentComparisonStrategy);
	}

	@Override
	protected Accessor createItemAccessor(Integer key) {
		return new CollectionItemByIndexAccessor<T>(key);
	}
	
	@Override
	public Iterable<Integer> difference(Collection<T> source, Collection<T> filter) {
		int sourceSize = source == null ? 0 : Iterables.size(source);
		int filterSize = filter == null ? 0 : Iterables.size(filter);
		if (sourceSize > filterSize) {
			return ContiguousSet.create(Range.closedOpen(filterSize, sourceSize), DiscreteDomain.integers());
		} else {
			return ImmutableList.of();
		}
	}

	@Override
	public Iterable<Integer> intersection(Collection<T> source, Collection<T> filter) {
		int sourceSize = source == null ? 0 : Iterables.size(source);
		int filterSize = filter == null ? 0 : Iterables.size(filter);
		return ContiguousSet.create(Range.closedOpen(0, Math.min(sourceSize, filterSize)), DiscreteDomain.integers());
	}
}