org.javimmutable.collections.list.ListHelper Maven / Gradle / Ivy

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//
// Burton Computer Corporation
// http://www.burton-computer.com
//
// Copyright (c) 2018, Burton Computer Corporation
// All rights reserved.
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package org.javimmutable.collections.list;

import org.javimmutable.collections.Indexed;

import javax.annotation.Nonnull;

final class ListHelper
{
    private static final Object[] EMPTY_VALUES = new Object[0];
    private static final Node[] EMPTY_NODES = new Node[0];

    @SuppressWarnings("unchecked")
    static  Node[] allocateNodes(int size)
    {
        return (Node[])((size == 0) ? EMPTY_NODES : new Node[size]);
    }

    static  Node[] allocateNodes(@Nonnull Indexed> source,
                                       int offset,
                                       int limit)
    {
        assert source.size() >= (limit - offset);

        final int size = limit - offset;
        final Node[] nodes = allocateNodes(size);
        for (int i = 0; i < size; ++i) {
            nodes[i] = source.get(offset + i);
        }
        return nodes;
    }

    @SuppressWarnings("unchecked")
    static  T[] allocateValues(int size)
    {
        return (T[])((size == 0) ? EMPTY_VALUES : new Object[size]);
    }

    static  Node[] allocateSingleNode(Node node)
    {
        Node[] answer = allocateNodes(1);
        answer[0] = node;
        return answer;
    }

    static int sizeForDepth(int depth)
    {
        return 1 << (5 * depth);
    }

    static  boolean allNodesFull(int depth,
                                    @Nonnull Indexed> nodes,
                                    int offset,
                                    int limit)
    {
        for (int i = offset; i < limit; ++i) {
            Node node = nodes.get(i);
            if (node.getDepth() != depth - 1) {
                return false;
            }
            if (!node.isFull()) {
                return false;
            }
        }
        return true;
    }
}