/*
* Redberry: symbolic tensor computations.
*
* Copyright (c) 2010-2013:
* 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.physics.oneloopdiv;
import cc.redberry.core.indexmapping.IndexMappingBuffer;
import cc.redberry.core.indexmapping.IndexMappings;
import cc.redberry.core.tensor.Tensor;
import cc.redberry.core.tensor.iterator.TraverseState;
import cc.redberry.core.tensor.iterator.TreeTraverseIterator;
import cc.redberry.core.tensor.ApplyIndexMapping;
import cc.redberry.core.transformations.Transformation;
/**
*
* @author Dmitry Bolotin
* @author Stanislav Poslavsky
*/
final class NaiveSubstitution implements Transformation {
private final Tensor from, to;
NaiveSubstitution(Tensor from, Tensor to) {
this.from = from;
this.to = to;
}
@Override
public Tensor transform(Tensor tensor) {
TreeTraverseIterator iterator = new TreeTraverseIterator(tensor);
TraverseState state;
Tensor current;
while ((state = iterator.next()) != null) {
if (state != TraverseState.Leaving)
continue;
current = iterator.current();
IndexMappingBuffer buffer = IndexMappings.getFirst(from, current);
if (buffer != null) {
Tensor newFrom = ApplyIndexMapping.applyIndexMapping(to, buffer);
iterator.set(newFrom);
}
}
return iterator.result();
}
}