org.javimmutable.collections.tree.FringeNode Maven / Gradle / Ivy

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// Burton Computer Corporation
// http://www.burton-computer.com
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// Copyright (c) 2019, Burton Computer Corporation
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package org.javimmutable.collections.tree;

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

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
import java.util.Comparator;

/**
 * Node with no value and no children.  Used as the terminating node at the bottom
 * of every tree or the root of an empty tree.  Only one instance exists and is
 * reused everywhere.
 */
@Immutable
class FringeNode
    extends AbstractNode
{
    @SuppressWarnings("rawtypes")
    private static final FringeNode INSTANCE = new FringeNode();

    private FringeNode()
    {
    }

    @SuppressWarnings("unchecked")
    static  AbstractNode instance()
    {
        return INSTANCE;
    }

    @Nonnull
    @Override
    public AbstractNode assign(@Nonnull Comparator comp,
                                     @Nonnull K key,
                                     @Nullable V value)
    {
        return ValueNode.instance(key, value);
    }

    @Nonnull
    @Override
    public AbstractNode update(@Nonnull Comparator comp,
                                     @Nonnull K key,
                                     @Nonnull Func1, V> generator)
    {
        return ValueNode.instance(key, generator.apply(Holders.of()));
    }

    @Nonnull
    @Override
    public AbstractNode delete(@Nonnull Comparator comp,
                                     @Nonnull K key)
    {
        return this;
    }

    @Nonnull
    @Override
    DeleteResult deleteLeftmost()
    {
        throw new UnsupportedOperationException();
    }

    @Nonnull
    @Override
    DeleteResult deleteRightmost()
    {
        throw new UnsupportedOperationException();
    }

    @Override
    boolean containsKey(@Nonnull Comparator comp,
                        @Nonnull K key)
    {
        return false;
    }

    @Nullable
    @Override
    public V get(@Nonnull Comparator comp,
                 @Nonnull K key,
                 V defaultValue)
    {
        return defaultValue;
    }

    @Nonnull
    @Override
    public Holder find(@Nonnull Comparator comp,
                          @Nonnull K key)
    {
        return Holders.of();
    }

    @Nonnull
    @Override
    public Holder> findEntry(@Nonnull Comparator comp,
                                         @Nonnull K key)
    {
        return Holders.of();
    }

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

    @Override
    int depth()
    {
        return 0;
    }

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

    @Nonnull
    @Override
    K key()
    {
        throw new UnsupportedOperationException();
    }

    @Nullable
    @Override
    V value()
    {
        throw new UnsupportedOperationException();
    }

    @Nonnull
    @Override
    AbstractNode left()
    {
        throw new UnsupportedOperationException();
    }

    @Nonnull
    @Override
    AbstractNode right()
    {
        throw new UnsupportedOperationException();
    }

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

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

    @Override
    void forEach(@Nonnull Proc2 proc)
    {
    }

    @Override
     void forEachThrows(@Nonnull Proc2Throws proc)
        throws E
    {
    }

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

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

    @Override
    public void checkInvariants(@Nonnull Comparator comp)
    {
    }
}