org.javimmutable.collections.hash.collision_map.TreeCollisionMap Maven / Gradle / Ivy

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package org.javimmutable.collections.hash.collision_map;

import org.javimmutable.collections.Cursor;
import org.javimmutable.collections.Func1;
import org.javimmutable.collections.Holder;
import org.javimmutable.collections.Holders;
import org.javimmutable.collections.JImmutableMap;
import org.javimmutable.collections.SplitableIterator;
import org.javimmutable.collections.common.MutableDelta;
import org.javimmutable.collections.tree.BranchNode;
import org.javimmutable.collections.tree.ComparableComparator;
import org.javimmutable.collections.tree.LeafNode;
import org.javimmutable.collections.tree.Node;
import org.javimmutable.collections.tree.UpdateResult;

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

/**
 * Transforms implementation that stores values in Node objects (b-trees trees).
 * Usable with keys that implement Comparable.  Will fail with any other
 * type of key.
 */
@Immutable
public class TreeCollisionMap, V>
    implements CollisionMap, K, V>
{
    private final Comparator comparator = ComparableComparator.of();

    @Nonnull
    @Override
    public Node update(Node leaf,
                             @Nonnull K key,
                             V value,
                             @Nonnull MutableDelta delta)
    {
        if (leaf == null) {
            delta.add(1);
            return new LeafNode<>(key, value);
        } else {
            return resultForUpdate(leaf, delta, leaf.assign(comparator, key, value));
        }
    }

    @Nonnull
    @Override
    public Node update(@Nullable Node leaf,
                             @Nonnull K key,
                             @Nonnull Func1, V> generator,
                             @Nonnull MutableDelta delta)
    {
        if (leaf == null) {
            delta.add(1);
            return new LeafNode<>(key, generator.apply(Holders.of()));
        } else {
            return resultForUpdate(leaf, delta, leaf.update(comparator, key, generator));
        }
    }

    @Override
    public Node delete(@Nonnull Node leaf,
                             @Nonnull K key,
                             @Nonnull MutableDelta delta)
    {
        final Node newLeaf = leaf.delete(comparator, key);
        if (newLeaf == leaf) {
            return leaf;
        } else {
            delta.add(-1);
            return newLeaf.isEmpty() ? null : newLeaf.compress();
        }
    }

    @Override
    public V getValueOr(@Nonnull Node leaf,
                        @Nonnull K key,
                        V defaultValue)
    {
        return leaf.getValueOr(comparator, key, defaultValue);
    }

    @Override
    public Holder findValue(@Nonnull Node leaf,
                               @Nonnull K key)
    {
        return leaf.find(comparator, key);
    }

    @Override
    public Holder> findEntry(@Nonnull Node leaf,
                                                       @Nonnull K key)
    {
        return leaf.findEntry(comparator, key);
    }

    @Override
    public Cursor> cursor(@Nonnull Node leaf)
    {
        return leaf.cursor();
    }

    @Override
    public SplitableIterator> iterator(@Nonnull Node leaf)
    {
        return leaf.iterator();
    }

    private Node resultForUpdate(Node leaf,
                                       @Nonnull MutableDelta delta,
                                       UpdateResult result)
    {
        switch (result.type) {
            case UNCHANGED:
                return leaf;
            case INPLACE:
                delta.add(result.sizeDelta);
                return result.newNode;
            case SPLIT:
                delta.add(result.sizeDelta);
                return new BranchNode<>(result.newNode, result.extraNode);
            default:
                throw new IllegalStateException("unknown UpdateResult.Type value");
        }
    }
}