org.javimmutable.collections.array.TrieNode Maven / Gradle / Ivy

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// Burton Computer Corporation
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package org.javimmutable.collections.array;

import org.javimmutable.collections.Cursorable;
import org.javimmutable.collections.Holder;
import org.javimmutable.collections.Indexed;
import org.javimmutable.collections.InvariantCheckable;
import org.javimmutable.collections.JImmutableMap;
import org.javimmutable.collections.SplitableIterable;
import org.javimmutable.collections.common.MutableDelta;

import javax.annotation.concurrent.Immutable;

@Immutable
public abstract class TrieNode
    implements Cursorable>,
               SplitableIterable>,
               InvariantCheckable
{
    public static final int ROOT_SHIFT = 30;

    public abstract boolean isEmpty();

    public abstract T getValueOr(int shift,
                                 int index,
                                 T defaultValue);

    public abstract Holder find(int shift,
                                   int index);

    public abstract TrieNode assign(int shift,
                                       int index,
                                       T value,
                                       MutableDelta sizeDelta);

    public abstract TrieNode delete(int shift,
                                       int index,
                                       MutableDelta sizeDelta);

    public abstract int getShift();

    public abstract boolean isLeaf();

    public TrieNode trimmedToMinimumDepth()
    {
        return this;
    }

    public TrieNode paddedToMinimumDepthForShift(int shift)
    {
        TrieNode node = this;
        int nodeShift = node.getShift();
        while (nodeShift < shift) {
            nodeShift += 5;
            node = SingleBranchTrieNode.forBranchIndex(nodeShift, 0, node);
        }
        return node;
    }

    public static  TrieNode of()
    {
        return EmptyTrieNode.instance();
    }

    public static  TrieNode fromSource(int index,
                                             Indexed source,
                                             int offset,
                                             int limit)
    {
        final int size = Math.min(32, limit - offset);
        if (size < 0) {
            throw new IllegalArgumentException();
        }

        switch (size) {
            case 0:
                return of();

            case 1:
                return LeafTrieNode.of(index, source.get(offset));

            case 32:
                return FullBranchTrieNode.fromSource(index, source, offset);

            default:
                return MultiBranchTrieNode.forSource(index, size, source, offset);
        }
    }

    public static int shiftForIndex(int index)
    {
        switch (Integer.numberOfLeadingZeros(index)) {
            case 0:
            case 1:
                return 30;

            case 2:
            case 3:
            case 4:
            case 5:
            case 6:
                return 25;

            case 7:
            case 8:
            case 9:
            case 10:
            case 11:
                return 20;

            case 12:
            case 13:
            case 14:
            case 15:
            case 16:
                return 15;

            case 17:
            case 18:
            case 19:
            case 20:
            case 21:
                return 10;

            case 22:
            case 23:
            case 24:
            case 25:
            case 26:
                return 5;

            case 27:
            case 28:
            case 29:
            case 30:
            case 31:
            case 32:
                return 0;
        }
        throw new IllegalArgumentException();
    }
}