3 /* ========================================================================== **
6 * Copyright (C) 1991-1997 by Christopher R. Hertel
8 * Email: crh@ubiqx.mn.org
9 * -------------------------------------------------------------------------- **
11 * This module provides an implementation of AVL height balanced binary
12 * trees. (Adelson-Velskii, Landis 1962)
14 * This header file contains the basic AVL structure and pointer typedefs
15 * as well as the prototypes needed to access the functions in the AVL
16 * module ubi_AVLtree. The .c file implements the low-level height balancing
17 * routines that manage the AVL tree, plus all of the basic primops for
18 * adding, searching for, and deleting nodes.
20 * -------------------------------------------------------------------------- **
22 * This library is free software; you can redistribute it and/or
23 * modify it under the terms of the GNU Library General Public
24 * License as published by the Free Software Foundation; either
25 * version 2 of the License, or (at your option) any later version.
27 * This library is distributed in the hope that it will be useful,
28 * but WITHOUT ANY WARRANTY; without even the implied warranty of
29 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
30 * Library General Public License for more details.
32 * You should have received a copy of the GNU Library General Public
33 * License along with this library; if not, write to the Free
34 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
36 * -------------------------------------------------------------------------- **
37 * Log: ubi_AVLtree.h,v
38 * Revision 3.1 1997/12/18 06:27:01 crh
39 * Fixed some comment bugs.
41 * Revision 3.0 1997/12/08 05:39:01 crh
42 * This is a new major revision level. The handling of the pointers in the
43 * ubi_trNode structure was redesigned. The result is that there are fewer
44 * macros floating about, and fewer cases in which values have to be
45 * incremented or decremented. See ubi_BinTree for more information.
47 * Revision 2; 1995/03/05 - 1997/12/07:
48 * An overhaul to the node delete process. I had gotten it wrong in a
49 * couple of places, thought I'd fixed it, and then found that I'd missed
50 * something more. Thanks to Andrew Leppard for the bug report!
52 * Revision 1; 93/10/15 - 95/03/05:
53 * Added the ubi_tr defines. See ubi_BinTree.h for more info.
55 * V0.0 - May, 1990 - Written by Christopher R. Hertel (CRH).
57 * ========================================================================= **
60 #include "ubi_BinTree.h" /* Base erg binary tree support. */
62 /* ------------------------------------------------------------------------- **
63 * AVL Tree Node Structure: This structure defines the basic elements of
64 * the AVL tree nodes. In general you *SHOULD NOT PLAY WITH THESE
65 * FIELDS*! But, of course, I have to put the structure into this
66 * header so that you can use the structure as a building block.
68 * The fields are as follows:
69 * leftlink - A space filler. This field will be accessed as Link[-1].
70 * Link - An array of pointers. These pointers are manipulated by the
71 * BT and AVL routines, and indicate the left and right child
72 * nodes, plus the parent node. By keeping track of the parent
73 * pointer, we avoid the need for recursive routines or hand-
74 * tooled stacks to keep track of our path back to the root.
75 * The use of these pointers is subject to change without
77 * gender - For tree rebalancing purposes, it is necessary that each node
78 * know whether it is the left or right child of its parent, or
79 * if it is the root. This information is stored in this field.
80 * balance - This field is also needed for AVL balancing purposes. It
81 * indicates which subtree of the current node is longer, or if
82 * the subtrees are, in fact, balanced with respect to each
87 typedef struct ubi_avlNodeStruct
89 struct ubi_avlNodeStruct *leftlink;
90 struct ubi_avlNodeStruct *Link[2];
95 typedef ubi_avlNode *ubi_avlNodePtr; /* a Pointer to an AVL node. */
97 /* -------------------------------------------------------------------------- **
98 * Function prototypes...
101 ubi_avlNodePtr ubi_avlInitNode( ubi_avlNodePtr NodePtr );
102 /* ------------------------------------------------------------------------ **
103 * Initialize a tree node.
105 * Input: NodePtr - a pointer to a ubi_btNode structure to be
107 * Output: a pointer to the initialized ubi_avlNode structure (ie. the
108 * same as the input pointer).
109 * ------------------------------------------------------------------------ **
112 ubi_trBool ubi_avlInsert( ubi_btRootPtr RootPtr,
113 ubi_avlNodePtr NewNode,
114 ubi_btItemPtr ItemPtr,
115 ubi_avlNodePtr *OldNode );
116 /* ------------------------------------------------------------------------ **
117 * This function uses a non-recursive algorithm to add a new element to
120 * Input: RootPtr - a pointer to the ubi_btRoot structure that indicates
121 * the root of the tree to which NewNode is to be added.
122 * NewNode - a pointer to an ubi_avlNode structure that is NOT
124 * ItemPtr - A pointer to the sort key that is stored within
125 * *NewNode. ItemPtr MUST point to information stored
126 * in *NewNode or an EXACT DUPLICATE. The key data
127 * indicated by ItemPtr is used to place the new node
129 * OldNode - a pointer to an ubi_btNodePtr. When searching
130 * the tree, a duplicate node may be found. If
131 * duplicates are allowed, then the new node will
132 * be simply placed into the tree. If duplicates
133 * are not allowed, however, then one of two things
135 * 1) if overwritting *is not* allowed, this
136 * function will return FALSE (indicating that
137 * the new node could not be inserted), and
138 * *OldNode will point to the duplicate that is
140 * 2) if overwritting *is* allowed, then this
141 * function will swap **OldNode for *NewNode.
142 * In this case, *OldNode will point to the node
143 * that was removed (thus allowing you to free
145 * ** If you are using overwrite mode, ALWAYS **
146 * ** check the return value of this parameter! **
147 * Note: You may pass NULL in this parameter, the
148 * function knows how to cope. If you do this,
149 * however, there will be no way to return a
150 * pointer to an old (ie. replaced) node (which is
151 * a problem if you are using overwrite mode).
153 * Output: a boolean value indicating success or failure. The function
154 * will return FALSE if the node could not be added to the tree.
155 * Such failure will only occur if duplicates are not allowed,
156 * nodes cannot be overwritten, AND a duplicate key was found
158 * ------------------------------------------------------------------------ **
161 ubi_avlNodePtr ubi_avlRemove( ubi_btRootPtr RootPtr,
162 ubi_avlNodePtr DeadNode );
163 /* ------------------------------------------------------------------------ **
164 * This function removes the indicated node from the tree, after which the
165 * tree is rebalanced.
167 * Input: RootPtr - A pointer to the header of the tree that contains
168 * the node to be removed.
169 * DeadNode - A pointer to the node that will be removed.
171 * Output: This function returns a pointer to the node that was removed
172 * from the tree (ie. the same as DeadNode).
174 * Note: The node MUST be in the tree indicated by RootPtr. If not,
175 * strange and evil things will happen to your trees.
176 * ------------------------------------------------------------------------ **
179 int ubi_avlModuleID( int size, char *list[] );
180 /* ------------------------------------------------------------------------ **
181 * Returns a set of strings that identify the module.
183 * Input: size - The number of elements in the array <list>.
184 * list - An array of pointers of type (char *). This array
185 * should, initially, be empty. This function will fill
186 * in the array with pointers to strings.
187 * Output: The number of elements of <list> that were used. If this value
188 * is less than <size>, the values of the remaining elements are
191 * Notes: Please keep in mind that the pointers returned indicate strings
192 * stored in static memory. Don't free() them, don't write over
193 * them, etc. Just read them.
194 * ------------------------------------------------------------------------ **
197 /* -------------------------------------------------------------------------- **
200 * This set of defines allows you to write programs that will use any of the
201 * implemented binary tree modules (currently BinTree, AVLtree, and SplayTree).
202 * Instead of using ubi_avl... or ubi_bt, use ubi_tr... and select the tree
203 * type by including the appropriate module header.
208 #define ubi_trNode ubi_avlNode
209 #define ubi_trNodePtr ubi_avlNodePtr
211 #undef ubi_trInitNode
212 #define ubi_trInitNode( Np ) ubi_avlInitNode( (ubi_avlNodePtr)(Np) )
215 #define ubi_trInsert( Rp, Nn, Ip, On ) \
216 ubi_avlInsert( (ubi_btRootPtr)(Rp), (ubi_avlNodePtr)(Nn), \
217 (ubi_btItemPtr)(Ip), (ubi_avlNodePtr *)(On) )
220 #define ubi_trRemove( Rp, Dn ) \
221 ubi_avlRemove( (ubi_btRootPtr)(Rp), (ubi_avlNodePtr)(Dn) )
224 #define ubi_trLocate( Rp, Ip, Op ) \
225 (ubi_avlNodePtr)ubi_btLocate( (ubi_btRootPtr)(Rp), \
226 (ubi_btItemPtr)(Ip), \
227 (ubi_trCompOps)(Op) )
230 #define ubi_trFind( Rp, Ip ) \
231 (ubi_avlNodePtr)ubi_btFind( (ubi_btRootPtr)(Rp), (ubi_btItemPtr)(Ip) )
234 #define ubi_trNext( P ) (ubi_avlNodePtr)ubi_btNext( (ubi_btNodePtr)(P) )
237 #define ubi_trPrev( P ) (ubi_avlNodePtr)ubi_btPrev( (ubi_btNodePtr)(P) )
240 #define ubi_trFirst( P ) (ubi_avlNodePtr)ubi_btFirst( (ubi_btNodePtr)(P) )
243 #define ubi_trLast( P ) (ubi_avlNodePtr)ubi_btLast( (ubi_btNodePtr)(P) )
246 #define ubi_trFirstOf( Rp, Ip, P ) \
247 (ubi_avlNodePtr)ubi_btFirstOf( (ubi_btRootPtr)(Rp), \
248 (ubi_btItemPtr)(Ip), \
252 #define ubi_trLastOf( Rp, Ip, P ) \
253 (ubi_avlNodePtr)ubi_btLastOf( (ubi_btRootPtr)(Rp), \
254 (ubi_btItemPtr)(Ip), \
257 #undef ubi_trLeafNode
258 #define ubi_trLeafNode( Nd ) \
259 (ubi_avlNodePtr)ubi_btLeafNode( (ubi_btNodePtr)(Nd) )
261 #undef ubi_trModuleID
262 #define ubi_trModuleID( s, l ) ubi_avlModuleID( s, l )
265 /* =========================== End ubi_AVLtree.h =========================== */
266 #endif /* ubi_AVLtree_H */