cc.redberry.transformation.fraction.MultiplyFractions Maven / Gradle / Ivy

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/*
 * Redberry: symbolic tensor computations.
 *
 * Copyright (c) 2010-2012:
 *   Stanislav Poslavsky   
 *   Bolotin Dmitriy       
 *
 * 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 .
 */
package cc.redberry.transformation.fraction;

import java.util.ArrayList;
import java.util.List;
import cc.redberry.core.tensor.Fraction;
import cc.redberry.core.tensor.Product;
import cc.redberry.core.tensor.Tensor;
import cc.redberry.core.tensor.TensorIterator;
import cc.redberry.transformation.Transformation;

/**
 *
 * @author Dmitry Bolotin
 * @author Stanislav Poslavsky
 * @author Konstantin Kiselev
 */
public class MultiplyFractions implements Transformation {
    @Override
    public Tensor transform(Tensor tensor) {
        if (!(tensor instanceof Product))
            return tensor;
        List denominators = new ArrayList<>();
        TensorIterator iterator = tensor.iterator();
        Tensor current;
        while (iterator.hasNext()) {
            current = iterator.next();
            if (current instanceof Fraction) {
                Fraction frac = (Fraction) current;
                iterator.set(frac.getNumerator());
                denominators.add(frac.getDenominator());
            }
        }
        if (denominators.isEmpty())
            return tensor;
        //TODO run with RemmoveOneFromProduct transformation
        return new Fraction(tensor, denominators.size() == 1 ? denominators.get(0) : new Product(denominators));

    }
}