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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
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// Copyright (c) 2019, Burton Computer Corporation
// All rights reserved.
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package org.javimmutable.collections.hash.hamt;

import org.javimmutable.collections.Func1;
import org.javimmutable.collections.Holder;
import org.javimmutable.collections.Holders;
import org.javimmutable.collections.JImmutableMap;
import org.javimmutable.collections.Proc2;
import org.javimmutable.collections.Proc2Throws;
import org.javimmutable.collections.Sum2;
import org.javimmutable.collections.Sum2Throws;
import org.javimmutable.collections.common.CollisionMap;
import org.javimmutable.collections.iterators.GenericIterator;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

public class HamtEmptyNode
    implements HamtNode
{
    private static final HamtEmptyNode EMPTY = new HamtEmptyNode();


    @SuppressWarnings("unchecked")
    public static  HamtNode of()
    {
        return EMPTY;
    }

    @Override
    public Holder find(@Nonnull CollisionMap collisionMap,
                          int hashCode,
                          @Nonnull K hashKey)
    {
        return Holders.of();
    }

    @Override
    public V getValueOr(@Nonnull CollisionMap collisionMap,
                        int hashCode,
                        @Nonnull K hashKey,
                        V defaultValue)
    {
        return defaultValue;
    }

    @Nonnull
    @Override
    public HamtNode assign(@Nonnull CollisionMap collisionMap,
                                 int hashCode,
                                 @Nonnull K hashKey,
                                 @Nullable V value)
    {
        return new HamtLeafNode<>(hashCode, collisionMap.update(collisionMap.emptyNode(), hashKey, value));
    }

    @Nonnull
    @Override
    public HamtNode update(@Nonnull CollisionMap collisionMap,
                                 int hashCode,
                                 @Nonnull K hashKey,
                                 @Nonnull Func1, V> generator)
    {
        return new HamtLeafNode<>(hashCode, collisionMap.update(collisionMap.emptyNode(), hashKey, generator));
    }

    @Nonnull
    @Override
    public HamtNode delete(@Nonnull CollisionMap collisionMap,
                                 int hashCode,
                                 @Nonnull K hashKey)
    {
        return this;
    }

    @Override
    public int size(@Nonnull CollisionMap collisionMap)
    {
        return 0;
    }

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

    @Nullable
    @Override
    public GenericIterator.State> iterateOverRange(@Nonnull CollisionMap collisionMap,
                                                                             @Nullable GenericIterator.State> parent,
                                                                             int offset,
                                                                             int limit)
    {
        assert offset == 0 && limit == 0;
        return parent;
    }

    @Override
    public void forEach(@Nonnull CollisionMap collisionMap,
                        @Nonnull Proc2 proc)
    {
    }

    @Override
    public  void forEachThrows(@Nonnull CollisionMap collisionMap,
                                                    @Nonnull Proc2Throws proc)
        throws E
    {
    }

    @Override
    public  R reduce(@Nonnull CollisionMap collisionMap,
                        R sum,
                        @Nonnull Sum2 proc)
    {
        return sum;
    }

    @Override
    public  R reduceThrows(@Nonnull CollisionMap collisionMap,
                                                   R sum,
                                                   @Nonnull Sum2Throws proc)
        throws E
    {
        return sum;
    }
}