/**
 * Copyright 2004-2016 Riccardo Solmi. All rights reserved.
 * This file is part of the Whole Platform.
 *
 * The Whole Platform is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * The Whole Platform is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with the Whole Platform. If not, see <http://www.gnu.org/licenses/>.
 */
package org.whole.lang.queries.iterators;

import org.whole.lang.bindings.BindingManagerFactory;
import org.whole.lang.commons.factories.CommonsEntityFactory;
import org.whole.lang.iterators.AbstractProductIterator;
import org.whole.lang.iterators.IEntityIterator;
import org.whole.lang.model.IEntity;

/**
 * @author Riccardo Solmi
 */
public abstract class AbstractTupleProductIterator extends AbstractProductIterator<IEntity> {
	protected AbstractTupleProductIterator(IEntityIterator<? extends IEntity>... iterators) {
		super(iterators);
	}

	public IEntity lookahead() {
		IEntity[] tupleChildren = lookaheadTuple();
		if (tupleChildren == null)
			return null;

		IEntity tuple = BindingManagerFactory.instance.createTuple();
		for (IEntity child : tupleChildren)
			if (child != null)
				tuple.wAdd(child);
			else
				tuple.wAdd(CommonsEntityFactory.instance.createResolver());

		return tuple; //TODO cache result for next()
	}

	public IEntity next() {
		IEntity[] tupleChildren = nextTuple();

		IEntity tuple = BindingManagerFactory.instance.createTuple();
		for (IEntity child : tupleChildren)
			if (child != null)
				tuple.wAdd(child);
			else
				tuple.wAdd(CommonsEntityFactory.instance.createResolver());

		return tuple;
	}

	public void add(IEntity entity) {
		throw new UnsupportedOperationException();
	}
	public void set(IEntity entity) {
		throw new UnsupportedOperationException();
	}
}