#ifndef ubi_AVLtree_H #define ubi_AVLtree_H /* ========================================================================== ** * ubi_AVLtree.h * * Copyright (C) 1991-1997 by Christopher R. Hertel * * Email: crh@ubiqx.mn.org * -------------------------------------------------------------------------- ** * * This module provides an implementation of AVL height balanced binary * trees. (Adelson-Velskii, Landis 1962) * * This header file contains the basic AVL structure and pointer typedefs * as well as the prototypes needed to access the functions in the AVL * module ubi_AVLtree. The .c file implements the low-level height balancing * routines that manage the AVL tree, plus all of the basic primops for * adding, searching for, and deleting nodes. * * -------------------------------------------------------------------------- ** * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Library General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Library General Public License for more details. * * You should have received a copy of the GNU Library General Public * License along with this library; if not, write to the Free * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * * -------------------------------------------------------------------------- ** * * Revision 2.4 1997/07/26 04:36:23 crh * Andrew Leppard, aka "Grazgur", discovered that I still had my brains tied * on backwards with respect to node deletion. I did some more digging and * discovered that I was not changing the balance values correctly in the * single rotation functions. Double rotation was working correctly because * the formula for changing the balance values is the same for insertion or * deletion. Not so for single rotation. * * I have tested the fix by loading the tree with over 44 thousand names, * deleting 2,629 of them (all those in which the second character is 'u') * and then walking the tree recursively to verify that the balance factor of * each node is correct. Passed. * * Thanks Andrew! * * Also: * + Changed ubi_TRUE and ubi_FALSE to ubi_trTRUE and ubi_trFALSE. * + Rewrote the ubi_tr<func> macros because they weren't doing what I'd * hoped they would do (see the bottom of the header file). They work now. * * Revision 2.3 1997/06/03 05:22:07 crh * Changed TRUE and FALSE to ubi_TRUE and ubi_FALSE to avoid causing * problems. * * Revision 2.2 1995/10/03 22:15:47 CRH * Ubisized! * * Revision 2.1 95/03/09 23:46:44 CRH * Added the ModuleID static string and function. These modules are now * self-identifying. * * Revision 2.0 95/03/05 14:11:22 CRH * This revision of ubi_AVLtree coincides with revision 2.0 of ubi_BinTree, * and so includes all of the changes to that module. In addition, a bug in * the node deletion process has been fixed. * * After rewriting the Locate() function in ubi_BinTree, I decided that it was * time to overhaul this module. In the process, I discovered a bug related * to node deletion. To fix the bug, I wrote function Debalance(). A quick * glance will show that it is very similar to the Rebalance() function. In * previous versions of this module, I tried to include the functionality of * Debalance() within Rebalance(), with poor results. * * Revision 1.0 93/10/15 22:58:48 CRH * With this revision, I have added a set of #define's that provide a single, * standard API to all existing tree modules. Until now, each of the three * existing modules had a different function and typedef prefix, as follows: * * Module Prefix * ubi_BinTree ubi_bt * ubi_AVLtree ubi_avl * ubi_SplayTree ubi_spt * * To further complicate matters, only those portions of the base module * (ubi_BinTree) that were superceeded in the new module had the new names. * For example, if you were using ubi_AVLtree, the AVL node structure was * named "ubi_avlNode", but the root structure was still "ubi_btRoot". Using * SplayTree, the locate function was called "ubi_sptLocate", but the next * and previous functions remained "ubi_btNext" and "ubi_btPrev". * * This was not too terrible if you were familiar with the modules and knew * exactly which tree model you wanted to use. If you wanted to be able to * change modules (for speed comparisons, etc), things could get messy very * quickly. * * So, I have added a set of defined names that get redefined in any of the * descendant modules. To use this standardized interface in your code, * simply replace all occurances of "ubi_bt", "ubi_avl", and "ubi_spt" with * "ubi_tr". The "ubi_tr" names will resolve to the correct function or * datatype names for the module that you are using. Just remember to * include the header for that module in your program file. Because these * names are handled by the preprocessor, there is no added run-time * overhead. * * Note that the original names do still exist, and can be used if you wish * to write code directly to a specific module. This should probably only be * done if you are planning to implement a new descendant type, such as * red/black trees. CRH * * V0.0 - May, 1990 - Written by Christopher R. Hertel (CRH). * * ========================================================================= ** */ #include "ubi_BinTree.h" /* Base erg binary tree support. */ /* ------------------------------------------------------------------------- ** * AVL Tree Node Structure: This structure defines the basic elements of * the AVL tree nodes. In general you *SHOULD NOT PLAY WITH THESE * FIELDS*! But, of course, I have to put the structure into this * header so that you can use the structure as a building block. * * The fields are as follows: * Link - An array of pointers. These pointers are manipulated by the * BT and AVL routines, and indicate the left and right child * nodes, plus the parent node. By keeping track of the parent * pointer, we avoid the need for recursive routines or hand- * tooled stacks to keep track of our path back to the root. * The use of these pointers is subject to change without * notice. * gender - For tree rebalancing purposes, it is necessary that each node * know whether it is the left or right child of its parent, or * if it is the root. This information is stored in this field. * balance - This field is also needed for AVL balancing purposes. It * indicates which subtree of the current node is longer, or if * the subtrees are, in fact, balanced with respect to each * other. * ------------------------------------------------------------------------- ** */ typedef struct ubi_avlNodeStruct { struct ubi_avlNodeStruct *Link[3]; /* Normal Binary Tree Node type. */ char gender; /* The node is either the RIGHT or LEFT child of its */ /* parent, or is the root node. */ char balance; /* In an AVL tree, each node is the root of a subtree */ /* that may be balanced, or be one node longer to the */ /* right or left. This field keeps track of the */ /* balance value of each node. */ } ubi_avlNode; /* Typedef'd name for an avl tree node. */ typedef ubi_avlNode *ubi_avlNodePtr; /* a Pointer to an AVL node */ /* -------------------------------------------------------------------------- ** * Function prototypes. * -------------------------------------------------------------------------- ** */ ubi_avlNodePtr ubi_avlInitNode( ubi_avlNodePtr NodePtr ); /* ------------------------------------------------------------------------ ** * Initialize a tree node. * * Input: NodePtr - a pointer to a ubi_btNode structure to be * initialized. * Output: a pointer to the initialized ubi_avlNode structure (ie. the * same as the input pointer). * ------------------------------------------------------------------------ ** */ ubi_trBool ubi_avlInsert( ubi_btRootPtr RootPtr, ubi_avlNodePtr NewNode, ubi_btItemPtr ItemPtr, ubi_avlNodePtr *OldNode ); /* ------------------------------------------------------------------------ ** * This function uses a non-recursive algorithm to add a new element to * the tree. * * Input: RootPtr - a pointer to the ubi_btRoot structure that indicates * the root of the tree to which NewNode is to be added. * NewNode - a pointer to an ubi_avlNode structure that is NOT * part of any tree. * ItemPtr - A pointer to the sort key that is stored within * *NewNode. ItemPtr MUST point to information stored * in *NewNode or an EXACT DUPLICATE. The key data * indicated by ItemPtr is used to place the new node * into the tree. * OldNode - a pointer to an ubi_btNodePtr. When searching * the tree, a duplicate node may be found. If * duplicates are allowed, then the new node will * be simply placed into the tree. If duplicates * are not allowed, however, then one of two things * may happen. * 1) if overwritting *is not* allowed, this * function will return FALSE (indicating that * the new node could not be inserted), and * *OldNode will point to the duplicate that is * still in the tree. * 2) if overwritting *is* allowed, then this * function will swap **OldNode for *NewNode. * In this case, *OldNode will point to the node * that was removed (thus allowing you to free * the node). * ** If you are using overwrite mode, ALWAYS ** * ** check the return value of this parameter! ** * Note: You may pass NULL in this parameter, the * function knows how to cope. If you do this, * however, there will be no way to return a * pointer to an old (ie. replaced) node (which is * a problem if you are using overwrite mode). * * Output: a boolean value indicating success or failure. The function * will return FALSE if the node could not be added to the tree. * Such failure will only occur if duplicates are not allowed, * nodes cannot be overwritten, AND a duplicate key was found * within the tree. * ------------------------------------------------------------------------ ** */ ubi_avlNodePtr ubi_avlRemove( ubi_btRootPtr RootPtr, ubi_avlNodePtr DeadNode ); /* ------------------------------------------------------------------------ ** * This function removes the indicated node from the tree, after which the * tree is rebalanced. * * Input: RootPtr - A pointer to the header of the tree that contains * the node to be removed. * DeadNode - A pointer to the node that will be removed. * * Output: This function returns a pointer to the node that was removed * from the tree (ie. the same as DeadNode). * * Note: The node MUST be in the tree indicated by RootPtr. If not, * strange and evil things will happen to your trees. * ------------------------------------------------------------------------ ** */ int ubi_avlModuleID( int size, char *list[] ); /* ------------------------------------------------------------------------ ** * Returns a set of strings that identify the module. * * Input: size - The number of elements in the array <list>. * list - An array of pointers of type (char *). This array * should, initially, be empty. This function will fill * in the array with pointers to strings. * Output: The number of elements of <list> that were used. If this value * is less than <size>, the values of the remaining elements are * not guaranteed. * * Notes: Please keep in mind that the pointers returned indicate strings * stored in static memory. Don't free() them, don't write over * them, etc. Just read them. * ------------------------------------------------------------------------ ** */ /* -------------------------------------------------------------------------- ** * Masquarade... * * This set of defines allows you to write programs that will use any of the * implemented binary tree modules (currently BinTree, AVLtree, and SplayTree). * Instead of using ubi_avl... or ubi_bt, use ubi_tr... and select the tree * type by including the appropriate module header. */ #undef ubi_trNode #undef ubi_trNodePtr #define ubi_trNode ubi_avlNode #define ubi_trNodePtr ubi_avlNodePtr #undef ubi_trInitNode #define ubi_trInitNode( Np ) ubi_avlInitNode( (ubi_avlNodePtr)(Np) ) #undef ubi_trInsert #define ubi_trInsert( Rp, Nn, Ip, On ) \ ubi_avlInsert( (ubi_btRootPtr)(Rp), (ubi_avlNodePtr)(Nn), \ (ubi_btItemPtr)(Ip), (ubi_avlNodePtr *)(On) ) #undef ubi_trRemove #define ubi_trRemove( Rp, Dn ) \ ubi_avlRemove( (ubi_btRootPtr)(Rp), (ubi_avlNodePtr)(Dn) ) #undef ubi_trLocate #define ubi_trLocate( Rp, Ip, Op ) \ (ubi_avlNodePtr)ubi_btLocate( (ubi_btRootPtr)(Rp), \ (ubi_btItemPtr)(Ip), \ (ubi_trCompOps)(Op) ) #undef ubi_trFind #define ubi_trFind( Rp, Ip ) \ (ubi_avlNodePtr)ubi_btFind( (ubi_btRootPtr)(Rp), (ubi_btItemPtr)(Ip) ) #undef ubi_trNext #define ubi_trNext( P ) (ubi_avlNodePtr)ubi_btNext( (ubi_btNodePtr)(P) ) #undef ubi_trPrev #define ubi_trPrev( P ) (ubi_avlNodePtr)ubi_btPrev( (ubi_btNodePtr)(P) ) #undef ubi_trFirst #define ubi_trFirst( P ) (ubi_avlNodePtr)ubi_btFirst( (ubi_btNodePtr)(P) ) #undef ubi_trLast #define ubi_trLast( P ) (ubi_avlNodePtr)ubi_btLast( (ubi_btNodePtr)(P) ) #undef ubi_trFirstOf #define ubi_trFirstOf( Rp, Ip, P ) \ (ubi_avlNodePtr)ubi_btFirstOf( (ubi_btRootPtr)(Rp), \ (ubi_btItemPtr)(Ip), \ (ubi_btNodePtr)(P) ) #undef ubi_trLastOf #define ubi_trLastOf( Rp, Ip, P ) \ (ubi_avlNodePtr)ubi_btLastOf( (ubi_btRootPtr)(Rp), \ (ubi_btItemPtr)(Ip), \ (ubi_btNodePtr)(P) ) #undef ubi_trLeafNode #define ubi_trLeafNode( Nd ) \ (ubi_avlNodePtr)ubi_btLeafNode( (ubi_btNodePtr)(Nd) ) #undef ubi_trModuleID #define ubi_trModuleID( s, l ) ubi_avlModuleID( s, l ) /* =========================== End ubi_AVLtree.h =========================== */ #endif /* ubi_AVLtree_H */