/*
* 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.integral;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import cc.redberry.core.tensor.Integral;
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;
import cc.redberry.core.utils.TensorUtils;
/**
*
* @author Dmitry Bolotin
* @author Stanislav Poslavsky
*/
public class UnderIntegral implements Transformation {
public static final UnderIntegral INSTANCE = new UnderIntegral();
private UnderIntegral() {
}
@Override
public Tensor transform(Tensor tensor) {
if (!(tensor instanceof Product))
return tensor;
//remember integrals
final List<Integral> integrals = new ArrayList<>();
TensorIterator iterator = tensor.iterator();
Tensor current;
while (iterator.hasNext()) {
current = iterator.next();
if (current instanceof Integral) {
integrals.add((Integral) current);
iterator.remove();
}
}
//no any integrals in the expression
if (integrals.isEmpty())
return tensor;
//only integrals
if (((Product) tensor).isEmpty())
return new Product(integrals);
//remember integration vars for each integral
final List<Map<Integer, SimpleTensor>> vars = new ArrayList<>();
for (final Integral i : integrals) {
final Map<Integer, SimpleTensor> map = new HashMap<>();
for (final SimpleTensor s : i.vars())
map.put(s.getName(), s);
vars.add(map);
}
//main routine
iterator = tensor.iterator();
Collection<SimpleTensor> tempVars;
while (iterator.hasNext()) {
current = iterator.next();
//vars in current
tempVars = TensorUtils.getDiffSimpleTensorContent(current);
out_for:
for (int i = 0; i < integrals.size(); ++i) {
final Map<Integer, SimpleTensor> map = vars.get(i);
for (SimpleTensor st : tempVars)
if (map.containsKey(st.getName()))
continue out_for;
//current can be placed under current integral
final Integral integral = integrals.get(i);
integrals.set(i, new Integral(new Product(current, integral.target()), integral.vars()));
iterator.remove();
}
}
Product result = new Product();
result.add(tensor);
result.add(integrals);
return result.equivalent();
}
}