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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.set;

import it.unimi.dsi.fastutil.ints.IntIterator;
import java.util.Iterator;
import java.util.NoSuchElementException;

final class PowerNatBitSetIterator implements Iterator {
    private final NatBitSet baseSet;
    private boolean hasNext = true;
    private final NatBitSet current;

    @SuppressWarnings("AssignmentOrReturnOfFieldWithMutableType")
    PowerNatBitSetIterator(NatBitSet baseSet) {
        assert !baseSet.isEmpty();
        this.baseSet = baseSet;
        this.current = NatBitSets.setWithMaximalLength(baseSet.lastInt());
    }

    @Override
    public boolean hasNext() {
        return hasNext;
    }

    @SuppressWarnings("AssignmentOrReturnOfFieldWithMutableType")
    @Override
    public NatBitSet next() {
        if (!hasNext) {
            throw new NoSuchElementException("No next element");
        }

        hasNext = false;
        IntIterator iterator = baseSet.iterator();
        while (iterator.hasNext()) {
            int index = iterator.nextInt();
            if (current.contains(index)) {
                current.clear(index);
            } else {
                hasNext = true;
                current.set(index);
                break;
            }
        }

        return current;
    }
}