Package cc.redberry.transformation.collect.old

Source Code of cc.redberry.transformation.collect.old.CollectScalars$SplitNumber

/*
* 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.old;

import java.util.ArrayList;
import java.util.List;
import cc.redberry.core.tensor.Product;
import cc.redberry.core.tensor.SimpleTensor;
import cc.redberry.core.tensor.Sum;
import cc.redberry.core.tensor.Tensor;
import cc.redberry.core.tensor.TensorIterator;
import cc.redberry.core.tensor.TensorNumber;
import cc.redberry.core.tensor.testing.TTest;
import cc.redberry.transformation.Transformation;

/**
*
* @author Dmitry Bolotin
* @author Stanislav Poslavsky
*/
public class CollectScalars implements Transformation {
    public static final CollectScalars INSTANCE = new CollectScalars();

    private CollectScalars() {
    }

    public Tensor transform(Tensor tensor) {
        if (!(tensor instanceof Sum))
            return tensor;
        if (!TTest.testIsScalar(tensor))
            return tensor;
        List<SplitNumber> result = new ArrayList<>();
        OUT_FOR:
        for (Tensor current : tensor) {
            SplitNumber split = splitNumber(current);
            for (SplitNumber r : result)
                if (TTest.testParity(r.nonNumber, split.nonNumber)) {
                    r.number.add(split.number);
                    continue OUT_FOR;
                }
            result.add(splitNumber(current));
        }
        Sum sum = new Sum();
        for (SplitNumber split : result)
            if (split.number.isOne())
                sum.add(split.nonNumber);
            else
                sum.add(new Product(split.number, split.nonNumber));
        return sum.equivalent();
    }

    private SplitNumber splitNumber(Tensor tensor) {
        if (tensor instanceof SimpleTensor)
            return new SplitNumber(TensorNumber.createONE(), tensor);
        if (tensor instanceof TensorNumber)
            return new SplitNumber(TensorNumber.createONE(), tensor);
        if (tensor instanceof Product) {
            TensorNumber number = TensorNumber.createONE();
            TensorIterator iterator = tensor.iterator();
            Tensor current;
            while (iterator.hasNext()) {
                current = iterator.next();
                if (current instanceof TensorNumber) {
                    number.multiply((TensorNumber) current);
                    iterator.remove();
                }
            }
            return new SplitNumber(number, tensor.equivalent());
        }
        throw new UnsupportedOperationException();
    }

    private static class SplitNumber {
        TensorNumber number;
        Tensor nonNumber;

        SplitNumber(TensorNumber number, Tensor nonNumber) {
            this.number = number;
            this.nonNumber = nonNumber;
        }
    }
}
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