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Library providing immutable/persistent collection classes for Java. While collections are immutable they provide methods for adding and removing values by creating new modified copies of themselves. Each copy shares almost all of its structure with other copies to minimize memory consumption.

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///###////////////////////////////////////////////////////////////////////////
//
// Burton Computer Corporation
// http://www.burton-computer.com
//
// Copyright (c) 2019, Burton Computer Corporation
// All rights reserved.
//
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//
//     Redistributions in binary form must reproduce the above copyright
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package org.javimmutable.collections.array;

import org.javimmutable.collections.Holder;
import org.javimmutable.collections.Holders;
import org.javimmutable.collections.JImmutableMap;
import org.javimmutable.collections.iterators.GenericIterator;

import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;

@Immutable
class EmptyTrieNode
    extends TrieNode
{
    private static final EmptyTrieNode EMPTY = new EmptyTrieNode();

    @SuppressWarnings("unchecked")
    static  EmptyTrieNode instance()
    {
        return EMPTY;
    }

    @Override
    public int valueCount()
    {
        return 0;
    }

    @Override
    public boolean isEmpty()
    {
        return true;
    }

    @Override
    public T getValueOr(int shift,
                        int index,
                        T defaultValue)
    {
        return defaultValue;
    }

    @Override
    public Holder find(int shift,
                          int index)
    {
        return Holders.of();
    }

    @Override
    public TrieNode assign(int shift,
                              int index,
                              T value)
    {
        return LeafTrieNode.of(index, value);
    }

    @Override
    public TrieNode delete(int shift,
                              int index)
    {
        return this;
    }

    @Override
    public int getShift()
    {
        return 0;
    }

    @Override
    public boolean isLeaf()
    {
        return true;
    }

    @Override
    public TrieNode paddedToMinimumDepthForShift(int shift)
    {
        return this;
    }

    @Nullable
    @Override
    public GenericIterator.State> iterateOverRange(@Nullable GenericIterator.State> parent,
                                                                                   int offset,
                                                                                   int limit)
    {
        return parent;
    }

    @Override
    public void checkInvariants()
    {
    }
}