cc.redberry.transformation.fraction.ReduceFraction 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 ReduceFraction implements Transformation {
    @Override
    public Tensor transform(Tensor tensor) {
        if (!(tensor instanceof Fraction))
            return tensor;
        
        Fraction fraction = (Fraction) tensor;  
        TensorIterator iterator = fraction.iterator();
        Tensor current;
        while (iterator.hasNext()) {
            current = iterator.next();
            
            if (current instanceof Fraction) {
                Fraction temp = (Fraction) current;
                if (Fraction.onDenominatorIndicator.is(iterator))
                    return new Fraction(new Product(fraction.getNumerator(), temp.getDenominator()), temp.getNumerator());
                else
                    return new Fraction(temp.getNumerator(), new Product(fraction.getDenominator(), temp.getDenominator()));
            }
            if (current instanceof Product) {
                List multiplicands = new ArrayList<>();
                TensorIterator it = current.iterator();
                Tensor current1;
                while (it.hasNext()) {
                    current1 = it.next();
                    if (current1 instanceof Fraction) {
                        Fraction currentFraction = (Fraction) current1;
                        multiplicands.add(currentFraction.getDenominator());
                        it.set(currentFraction.getNumerator());
                    }
                }
                if (multiplicands.isEmpty())
                    return tensor;
                Product newNumerator = new Product();
                if (Fraction.onDenominatorIndicator.is(iterator)) {
                    newNumerator.add(fraction.getNumerator());
                    newNumerator.add(multiplicands);
                    return new Fraction(newNumerator, fraction.getDenominator());
                } else {
                    newNumerator.add(fraction.getDenominator());
                    newNumerator.add(multiplicands);
                    return new Fraction(fraction.getNumerator(), newNumerator);
                }
            }
        }
        return tensor;
    }
}