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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2017 Mike Becker, Olaf Wintermann All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */


/**
 * @file avl.h
 * 
 * AVL tree implementation.
 * 
 * This binary search tree implementation allows average O(1) insertion and
 * removal of elements (excluding binary search time).
 * 
 * @author Mike Becker
 * @author Olaf Wintermann
 */

#ifndef UCX_AVL_H
#define UCX_AVL_H

#include "ucx.h"
#include "allocator.h"
#include <inttypes.h>

#ifdef	__cplusplus
extern "C" {
#endif

/**
 * UCX AVL Node type.
 * 
 * @see UcxAVLNode
 */
typedef struct UcxAVLNode UcxAVLNode;

/**
 * UCX AVL Node.
 */
struct UcxAVLNode {
    /**
     * The key for this node.
     */
    intptr_t key;
    /**
     * Data contained by this node.
     */
    void *value;
    /**
     * The height of this (sub)-tree.
     */
    size_t height;
    /**
     * Parent node.
     */
    UcxAVLNode *parent;
    /**
     * Root node of left subtree.
     */
    UcxAVLNode *left;
    /**
     * Root node of right subtree.
     */
    UcxAVLNode *right;
};

/**
 * UCX AVL Tree.
 */
typedef struct {
    /**
     * The UcxAllocator that shall be used to manage the memory for node data.
     */
    UcxAllocator *allocator;
    /**
     * Root node of the tree.
     */
    UcxAVLNode *root;
    /**
     * Compare function that shall be used to compare the UcxAVLNode keys.
     * @see UcxAVLNode.key
     */
    cmp_func cmpfunc;
    /**
     * Custom user data.
     * This data will also be provided to the cmpfunc.
     */
    void *userdata;
} UcxAVLTree;

/**
 * Initializes a new UcxAVLTree with a default allocator.
 * 
 * @param cmpfunc the compare function that shall be used
 * @return a new UcxAVLTree object
 * @see ucx_avl_new_a()
 */
UcxAVLTree *ucx_avl_new(cmp_func cmpfunc);

/**
 * Initializes a new UcxAVLTree with the specified allocator.
 * 
 * The cmpfunc should be capable of comparing two keys within this AVL tree.
 * So if you want to use null terminated strings as keys, you could use the
 * ucx_strcmp() function here.
 * 
 * @param cmpfunc the compare function that shall be used
 * @param allocator the UcxAllocator that shall be used
 * @return a new UcxAVLTree object
 */
UcxAVLTree *ucx_avl_new_a(cmp_func cmpfunc, UcxAllocator *allocator);

/**
 * Destroys a UcxAVLTree.
 * @param tree the tree to destroy
 */
void ucx_avl_free(UcxAVLTree *tree);

/**
 * Macro for initializing a new UcxAVLTree with the default allocator and a
 * ucx_ptrcmp() compare function.
 * 
 * @return a new default UcxAVLTree object
 */
#define ucx_avl_default_new() ucx_avl_new_a(ucx_ptrcmp, ucx_default_allocator())

/**
 * Gets the node from the tree, that is associated with the specified key.
 * @param tree the UcxAVLTree
 * @param key the key
 * @return the node (or <code>NULL</code>, if the key is not present)
 */
UcxAVLNode *ucx_avl_get_node(UcxAVLTree *tree, intptr_t key);

/**
 * Gets the value from the tree, that is associated with the specified key.
 * @param tree the UcxAVLTree
 * @param key the key
 * @return the value (or <code>NULL</code>, if the key is not present)
 */
void *ucx_avl_get(UcxAVLTree *tree, intptr_t key);

/**
 * A mode for #ucx_avl_find_node() with the same behavior as
 * #ucx_avl_get_node().
 */
#define UCX_AVL_FIND_EXACT         0
/**
 * A mode for #ucx_avl_find_node() finding the node whose key is at least
 * as large as the specified key.
 */
#define UCX_AVL_FIND_LOWER_BOUNDED 1
/**
 * A mode for #ucx_avl_find_node() finding the node whose key is at most
 * as large as the specified key.
 */
#define UCX_AVL_FIND_UPPER_BOUNDED 2
/**
 * A mode for #ucx_avl_find_node() finding the node with a key that is as close
 * to the specified key as possible. If the key is present, the behavior is
 * like #ucx_avl_get_node(). This mode only returns <code>NULL</code> on
 * empty trees.
 */
#define UCX_AVL_FIND_CLOSEST       3

/**
 * Finds a node within the tree. The following modes are supported:
 * <ul>
 * <li>#UCX_AVL_FIND_EXACT: the same behavior as #ucx_avl_get_node()</li>
 * <li>#UCX_AVL_FIND_LOWER_BOUNDED: finds the node whose key is at least
 * as large as the specified key</li>
 * <li>#UCX_AVL_FIND_UPPER_BOUNDED: finds the node whose key is at most
 * as large as the specified key</li>
 * <li>#UCX_AVL_FIND_CLOSEST: finds the node with a key that is as close to
 * the specified key as possible. If the key is present, the behavior is
 * like #ucx_avl_get_node(). This mode only returns <code>NULL</code> on
 * empty trees.</li> 
 * </ul>
 * 
 * The distance function provided MUST agree with the compare function of
 * the AVL tree.
 * 
 * @param tree the UcxAVLTree
 * @param key the key
 * @param dfnc the distance function
 * @param mode the find mode
 * @return the node (or <code>NULL</code>, if no node can be found)
 */
UcxAVLNode *ucx_avl_find_node(UcxAVLTree *tree, intptr_t key,
        distance_func dfnc, int mode);

/**
 * Finds a value within the tree.
 * See #ucx_avl_find_node() for details.
 * 
 * @param tree the UcxAVLTree
 * @param key the key
 * @param dfnc the distance function
 * @param mode the find mode
 * @return the value (or <code>NULL</code>, if no value can be found)
 */
void *ucx_avl_find(UcxAVLTree *tree, intptr_t key,
        distance_func dfnc, int mode);

/**
 * Puts a key/value pair into the tree.
 * 
 * Attention: use this function only, if a possible old value does not need
 * to be preserved.
 * 
 * @param tree the UcxAVLTree
 * @param key the key
 * @param value the new value
 * @return zero, if and only if the operation succeeded
 */
int ucx_avl_put(UcxAVLTree *tree, intptr_t key, void *value);

/**
 * Puts a key/value pair into the tree.
 * 
 * This is a secure function which saves the old value to the variable pointed
 * at by oldvalue.
 * 
 * @param tree the UcxAVLTree
 * @param key the key
 * @param value the new value
 * @param oldvalue optional: a pointer to the location where a possible old
 * value shall be stored
 * @return zero, if and only if the operation succeeded
 */
int ucx_avl_put_s(UcxAVLTree *tree, intptr_t key, void *value, void **oldvalue);

/**
 * Removes a node from the AVL tree.
 * 
 * Note: the specified node is logically removed. The tree implementation
 * decides which memory area is freed. In most cases the here provided node
 * is freed, so its further use is generally undefined.
 * 
 * @param tree the UcxAVLTree
 * @param node the node to remove
 * @return zero, if and only if an element has been removed
 */
int ucx_avl_remove_node(UcxAVLTree *tree, UcxAVLNode *node);

/**
 * Removes an element from the AVL tree.
 * 
 * @param tree the UcxAVLTree
 * @param key the key
 * @return zero, if and only if an element has been removed
 */
int ucx_avl_remove(UcxAVLTree *tree, intptr_t key);

/**
 * Removes an element from the AVL tree.
 * 
 * This is a secure function which saves the old key and value data from node
 * to the variables at the location of oldkey and oldvalue (if specified), so
 * they can be freed afterwards (if necessary).
 * 
 * Note: the returned key in oldkey is possibly not the same as the provided
 * key for the lookup (in terms of memory location).
 * 
 * @param tree the UcxAVLTree
 * @param key the key of the element to remove
 * @param oldkey optional: a pointer to the location where the old key shall be
 * stored
 * @param oldvalue optional: a pointer to the location where the old value
 * shall be stored
 * @return zero, if and only if an element has been removed
 */
int ucx_avl_remove_s(UcxAVLTree *tree, intptr_t key,
        intptr_t *oldkey, void **oldvalue);

/**
 * Counts the nodes in the specified UcxAVLTree.
 * @param tree the AVL tree
 * @return the node count
 */
size_t ucx_avl_count(UcxAVLTree *tree);

/**
 * Finds the in-order predecessor of the given node.
 * @param node an AVL node
 * @return the in-order predecessor of the given node, or <code>NULL</code> if
 * the given node is the in-order minimum
 */
UcxAVLNode* ucx_avl_pred(UcxAVLNode* node);

/**
 * Finds the in-order successor of the given node.
 * @param node an AVL node
 * @return the in-order successor of the given node, or <code>NULL</code> if
 * the given node is the in-order maximum
 */
UcxAVLNode* ucx_avl_succ(UcxAVLNode* node);

#ifdef	__cplusplus
}
#endif

#endif	/* UCX_AVL_H */