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Datastructures and utility classes for non-negative integers

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/*
 * Copyright (C) 2017 Tobias Meggendorfer
 *
 * This program 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.
 *
 * This program 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 this program.  If not, see .
 */

package de.tum.in.naturals.bitset;

import java.util.BitSet;
import java.util.Iterator;
import java.util.NoSuchElementException;

final class PowerBitSetSimpleIterator implements Iterator {
    private final BitSet iteration;
    private final int size;
    private int numSetBits = -1;

    PowerBitSetSimpleIterator(int size) {
        this.size = size;
        this.iteration = new BitSet(size);
    }

    @Override
    public boolean hasNext() {
        return numSetBits < size;
    }

    @Override
    public BitSet next() {
        if (numSetBits == -1) {
            numSetBits = 0;
            return iteration;
        }

        if (numSetBits == size) {
            throw new NoSuchElementException("No next element");
        }

        for (int index = 0; index < size; index++) {
            if (iteration.get(index)) {
                iteration.clear(index);
                numSetBits -= 1;
            } else {
                iteration.set(index);
                numSetBits += 1;
                break;
            }
        }

        return iteration;
    }
}