/*
 * Redberry: symbolic tensor computations.
 *
 * Copyright (c) 2010-2015:
 *   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.core.transformations;

import cc.redberry.core.tensor.Sum;
import cc.redberry.core.tensor.SumBuilderSplitingScalars;
import cc.redberry.core.tensor.Tensor;
import cc.redberry.core.tensor.iterator.FromChildToParentIterator;

/**
 * @author Dmitry Bolotin
 * @author Stanislav Poslavsky
 * @since 1.1
 */
public final class CollectNonScalarsTransformation implements Transformation {
    public static final CollectNonScalarsTransformation COLLECT_NON_SCALARS
            = new CollectNonScalarsTransformation();

    private CollectNonScalarsTransformation() {
    }

    @Override
    public Tensor transform(Tensor t) {
        return collectNonScalars(t);
    }

    public static Tensor collectNonScalars(Tensor t) {
        FromChildToParentIterator iterator = new FromChildToParentIterator(t);
        Tensor c;
        while ((c = iterator.next()) != null)
            if (c instanceof Sum) {
                //TODO add check whether we need to do this transformation
                SumBuilderSplitingScalars sbss = new SumBuilderSplitingScalars(c.size());
                for (Tensor tt : c)
                    sbss.put(tt);
                iterator.set(sbss.build());
            }
        return iterator.result();
    }
}