/*
* Redberry: symbolic tensor computations.
*
* Copyright (c) 2010-2012:
* Stanislav Poslavsky <stvlpos@mail.ru>
* Bolotin Dmitriy <bolotin.dmitriy@gmail.com>
*
* This file is part of Redberry.
*
* Redberry is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Redberry 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Redberry. If not, see <http://www.gnu.org/licenses/>.
*/
package cc.redberry.transformation.collect;
import cc.redberry.core.indices.EmptyIndices;
import cc.redberry.core.tensor.AbstractScalarFunction;
import cc.redberry.core.tensor.Product;
import cc.redberry.core.tensor.SimpleTensor;
import cc.redberry.core.tensor.Tensor;
import cc.redberry.core.tensor.TensorIterator;
import cc.redberry.transformation.Transformation;
/**
*
* @author Dmitry Bolotin
* @author Stanislav Poslavsky
*/
public class CollectPowers implements Transformation {
public static final CollectPowers INSTANCE = new CollectPowers();
private CollectPowers() {
}
@Override
public Tensor transform(Tensor tensor) {
if (!(tensor instanceof Product))
return tensor;
CollectPowersInputPort port = new CollectPowersInputPort();
TensorIterator iterator = tensor.iterator();
Tensor current;
while (iterator.hasNext()) {
current = iterator.next();
if ((current instanceof SimpleTensor && current.getIndices() instanceof EmptyIndices)
|| current instanceof AbstractScalarFunction) {
port.put(current);
iterator.remove();
}
}
if (port.isEmpty())
return tensor;
((Product) tensor).addFirst(port.getResult());
return tensor.equivalent();
}
}