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//
// Burton Computer Corporation
// http://www.burton-computer.com
//
// Copyright (c) 2014, Burton Computer Corporation
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package org.javimmutable.collections.list;

import org.javimmutable.collections.Cursor;
import org.javimmutable.collections.cursors.StandardCursor;

import javax.annotation.Nonnull;
import javax.annotation.concurrent.Immutable;

/**
 * Node implementation containing no values.  Implemented as a singleton.
 *
 * @param 
 */
@Immutable
final class EmptyNode
        implements Node
{
    private static final EmptyNode INSTANCE = new EmptyNode();

    private EmptyNode()
    {
    }

    @SuppressWarnings("unchecked")
    static  EmptyNode of()
    {
        return (EmptyNode)INSTANCE;
    }

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

    @Override
    public boolean isFull()
    {
        return false;
    }

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

    @Override
    public int getDepth()
    {
        return 1;
    }

    @Override
    public Node deleteFirst()
    {
        throw new IllegalStateException();
    }

    @Override
    public Node deleteLast()
    {
        throw new IllegalStateException();
    }

    @Override
    public Node insertFirst(T value)
    {
        return new LeafNode(value);
    }

    @Override
    public Node insertLast(T value)
    {
        return new LeafNode(value);
    }

    @Override
    public boolean containsIndex(int index)
    {
        return false;
    }

    @Override
    public T get(int index)
    {
        throw new IndexOutOfBoundsException();
    }

    @Override
    public Node assign(int index,
                          T value)
    {
        throw new IndexOutOfBoundsException();
    }

    @Nonnull
    @Override
    public Cursor cursor()
    {
        return StandardCursor.of();
    }

    @Override
    public void checkInvariants()
    {
    }
}