LongBitmapReverseIterator.java

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// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
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package org.apache.doris.nereids.jobs.joinorder.hypergraph.bitmap;

import org.jetbrains.annotations.NotNull;

import java.util.Iterator;

/**
 * This is an Iterator for iterating bitmap descending
 */
public class LongBitmapReverseIterator implements Iterable<Integer> {
    private int lastIndex = 0;
    private long bitmap;

    LongBitmapReverseIterator(long bitmap) {
        this.bitmap = bitmap;
        lastIndex = 63;
    }

    @NotNull
    @Override
    public Iterator<Integer> iterator() {
        class Iter implements Iterator<Integer> {
            @Override
            public boolean hasNext() {
                return bitmap != 0;
            }

            @Override
            public Integer next() {
                lastIndex = LongBitmap.previousSetBit(bitmap, lastIndex);
                bitmap = LongBitmap.unset(bitmap, lastIndex);
                return lastIndex;
            }

            @Override
            public void remove() {
            }
        }

        return new Iter();
    }
}