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

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// Burton Computer Corporation
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package org.javimmutable.collections.tree;

import org.javimmutable.collections.Cursor;
import org.javimmutable.collections.Cursorable;
import org.javimmutable.collections.Holder;
import org.javimmutable.collections.JImmutableMap;
import org.javimmutable.collections.common.MutableDelta;

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

/**
 * Abstract base class for 2-3 tree nodes.  Provides public methods for searching and modifying
 * the tree and package private methods used to implement the public methods.
 *
 * @param 
 * @param 
 */
@Immutable
public abstract class TreeNode
        implements Cursorable>
{
    public static  TreeNode of()
    {
        return EmptyNode.of();
    }

    /**
     * Return the value matching key or defaultValue if no match is found.  Searches this node
     * and its appropriate children.
     *
     * @param comparator
     * @param key
     * @param defaultValue
     * @return
     */
    public abstract V getValueOr(Comparator comparator,
                                 K key,
                                 V defaultValue);

    /**
     * Return a (possibly empty) Holder containing the value matching key.  Searches this node
     * and its appropriate children.
     *
     * @param comparator
     * @param key
     * @return
     */
    public abstract Holder find(Comparator comparator,
                                   K key);

    /**
     * Return a (possibly empty) Holder containing the an Entry matching key.  Searches this node
     * and its appropriate children.
     *
     * @param comparator
     * @param key
     * @return
     */
    public abstract Holder> findEntry(Comparator comparator,
                                                                K key);

    /**
     * Adds this node's value and all of its children's value to the collection.
     *
     * @param collection
     */
    public abstract void addEntriesTo(Collection> collection);

    /**
     * Returns a Cursor visiting all entries in sorted order.
     *
     * @return
     */
    @Nonnull
    public abstract Cursor> cursor();

    /**
     * Assign the specified value to the specified key.  Returns a node (possibly this same node)
     * reflecting the assignment and updates sizeDelta with the change in size (if any).
     *
     * @param comparator
     * @param key
     * @param value
     * @param sizeDelta
     * @return
     */
    public TreeNode assign(Comparator comparator,
                                 K key,
                                 V value,
                                 MutableDelta sizeDelta)
    {
        UpdateResult result = assignImpl(comparator, key, value);
        switch (result.type) {
        case UNCHANGED:
            return this;

        case INPLACE:
            sizeDelta.add(result.sizeDelta);
            return result.newNode;

        case SPLIT:
            sizeDelta.add(result.sizeDelta);
            return new TwoNode(result.newNode,
                                     result.extraNode,
                                     result.newNode.getMaxKey(),
                                     result.extraNode.getMaxKey());
        }
        throw new RuntimeException();
    }

    /**
     * Deletes the specified key.  Returns a node (possibly this same node)
     * reflecting the deletion and updates sizeDelta with the change in size (if any).
     *
     * @param comparator
     * @param key
     * @param sizeDelta
     * @return
     */
    public TreeNode delete(Comparator comparator,
                                 K key,
                                 MutableDelta sizeDelta)
    {
        DeleteResult result = deleteImpl(comparator, key);
        switch (result.type) {
        case UNCHANGED:
            return this;

        default:
            sizeDelta.subtract(1);
            return result.node;
        }
    }

    /**
     * Return true if this node contains no children or value.
     *
     * @return
     */
    public boolean isEmpty()
    {
        return false;
    }

    abstract int verifyDepthsMatch();

    abstract K getMaxKey();

    abstract UpdateResult assignImpl(Comparator comparator,
                                           K key,
                                           V value);

    abstract DeleteResult deleteImpl(Comparator comparator,
                                           K key);

    abstract DeleteMergeResult leftDeleteMerge(TreeNode node);

    abstract DeleteMergeResult rightDeleteMerge(TreeNode node);
}