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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.

  * 

  * Note, that the contents are not automatically freed.

  * Use may use #ucx_avl_free_content() before calling this function.

  * 

  * @param tree the tree to destroy

  * @see ucx_avl_free_content()

  */

 void ucx_avl_free(UcxAVLTree *tree);

 /**

  * Frees the contents of a UcxAVLTree.

  * 

  * This is a convenience function that iterates over the tree and passes all

  * values to the specified destructor function.

  * 

  * If no destructor is specified (<code>NULL</code>), the free() function of

  * the tree's own allocator is used.

  * 

  * You must ensure, that it is valid to pass each value in the map to the same

  * destructor function.

  * 

  * You should free the entire tree afterwards, as the contents will be invalid.

  * 

  * @param tree for which the contents shall be freed

  * @param destr optional pointer to a destructor function

  * @see ucx_avl_free()

  */

 void ucx_avl_free_content(UcxAVLTree *tree, ucx_destructor destr);

 /**

  * 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 */