cc.redberry.transformation.collect.ScalarsSplitCriteria 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.collect;

import cc.redberry.core.context.CC;
import cc.redberry.core.tensor.*;

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

    private ScalarsSplitCriteria() {
    }

    @Override
    public boolean factorOut(Tensor tensor) {
        return (tensor instanceof TensorNumber);
    }

    @Override
    public ScalarsSplit split(Tensor tensor) {
        if (tensor instanceof Product) {
            TensorIterator it = tensor.iterator();
            Tensor current;
            TensorNumber factored = TensorNumber.createONE();
            while (it.hasNext()) {
                current = it.next();
                if (factorOut(current)) {
                    factored.multiply((TensorNumber) current);
                    it.remove();
                }
            }
            if (((Product) tensor).isEmpty())
                return new ScalarsSplit(factored);
            Tensor term = tensor.equivalent();
            term.setParent(CC.getRootParentTensor());
            return new ScalarsSplit(factored, term);
        }
        if (tensor instanceof SimpleTensor || tensor instanceof AbstractScalarFunction) {
            Tensor term = tensor.equivalent();
            term.setParent(CC.getRootParentTensor());
            return new ScalarsSplit(TensorNumber.createONE(), term);
        }
        if (tensor instanceof TensorNumber)
            return new ScalarsSplit((TensorNumber) tensor.clone());
        throw new UnsupportedOperationException("Not supported yet.");
    }
}