| 1 | /* $Id: kAvlBase.h 2 2007-11-16 16:07:14Z bird $ */
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| 2 | /** @file
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| 3 | * kAvlTmpl - Templated AVL Trees, The Mandatory Base Code.
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (c) 2001-2007 knut st. osmundsen <bird-src-spam@anduin.net>
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| 8 | *
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| 9 | * This file is part of kStuff.
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| 10 | *
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| 11 | * kStuff is free software; you can redistribute it and/or
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| 12 | * modify it under the terms of the GNU Lesser General Public
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| 13 | * License as published by the Free Software Foundation; either
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| 14 | * version 2.1 of the License, or (at your option) any later version.
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| 15 | *
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| 16 | * kStuff is distributed in the hope that it will be useful,
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| 17 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 19 | * Lesser General Public License for more details.
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| 20 | *
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| 21 | * You should have received a copy of the GNU Lesser General Public
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| 22 | * License along with kStuff; if not, write to the Free Software
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| 23 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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| 24 | *
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| 25 | *
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| 26 | * As a special exception, since this is a source file and not a header
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| 27 | * file, you are granted permission to #include this file as you wish
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| 28 | * without this in itself causing the resulting program or whatever to be
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| 29 | * covered by the LGPL license. This exception does not however invalidate
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| 30 | * any other reasons why the resulting program/whatever should not be
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| 31 | * covered the LGPL or GPL.
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| 32 | */
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| 33 |
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| 34 | /** @page pg_kAvlTmpl Template Configuration.
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| 35 | *
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| 36 | * This is a templated implementation of AVL trees in C. The template
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| 37 | * parameters relates to the kind of key used and how duplicates are
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| 38 | * treated.
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| 39 | *
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| 40 | * \#define KAVL_EQUAL_ALLOWED
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| 41 | * Define this to tell us that equal keys are allowed.
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| 42 | * Then Equal keys will be put in a list pointed to by KAVLNODE::pList.
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| 43 | * This is by default not defined.
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| 44 | *
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| 45 | * \#define KAVL_CHECK_FOR_EQUAL_INSERT
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| 46 | * Define this to enable insert check for equal nodes.
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| 47 | * This is by default not defined.
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| 48 | *
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| 49 | * \#define KAVL_MAX_STACK
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| 50 | * Use this to specify the max number of stack entries the stack will use when inserting
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| 51 | * and removing nodes from the tree. The size should be something like
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| 52 | * log2(<max nodes>) + 3
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| 53 | * Must be defined.
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| 54 | *
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| 55 | * \#define KAVL_RANGE
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| 56 | * Define this to enable key ranges.
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| 57 | *
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| 58 | * \#define KAVL_OFFSET
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| 59 | * Define this to link the tree together using self relative offset
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| 60 | * instead of memory pointers, thus making the entire tree relocatable
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| 61 | * provided all the nodes - including the root node variable - are moved
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| 62 | * the exact same distance.
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| 63 | *
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| 64 | * \#define KAVLKEY
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| 65 | * Define this to the name of the AVL key type.
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| 66 | *
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| 67 | * \#define KAVL_STD_KEY_COMP
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| 68 | * Define this to use the standard key compare macros. If not set all the
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| 69 | * compare operations for KAVLKEY have to be defined: KAVL_G, KAVL_E, KAVL_NE,
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| 70 | * KAVL_R_IS_IDENTICAL, KAVL_R_IS_INTERSECTING and KAVL_R_IS_IN_RANGE. The latter
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| 71 | * three are only required when KAVL_RANGE is defined.
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| 72 | *
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| 73 | * \#define KAVLNODE
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| 74 | * Define this to the name (typedef) of the AVL node structure. This
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| 75 | * structure must have a mpLeft, mpRight, mKey and mHeight member.
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| 76 | * If KAVL_RANGE is defined a mKeyLast is also required.
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| 77 | * If KAVL_EQUAL_ALLOWED is defined a mpList member is required.
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| 78 | * It's possible to use other member names by redefining the names.
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| 79 | *
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| 80 | * \#define KAVLTREEPTR
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| 81 | * Define this to the name (typedef) of the tree pointer type. This is
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| 82 | * required when KAVL_OFFSET is defined. When not defined it defaults
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| 83 | * to KAVLNODE *.
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| 84 | *
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| 85 | * \#define KAVL_FN
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| 86 | * Use this to alter the names of the AVL functions.
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| 87 | * Must be defined.
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| 88 | *
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| 89 | * \#define KAVL_TYPE(prefix, name)
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| 90 | * Use this to make external type names and unique. The prefix may be empty.
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| 91 | * Must be defined.
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| 92 | *
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| 93 | * \#define KAVL_INT(name)
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| 94 | * Use this to make internal type names and unique. The prefix may be empty.
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| 95 | * Must be defined.
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| 96 | *
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| 97 | * \#define KAVL_DECL(rettype)
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| 98 | * Function declaration macro that should be set according to the scope
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| 99 | * the instantiated template should have. For instance an inlined scope
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| 100 | * (private or public) should K_DECL_INLINE(rettype) here.
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| 101 | *
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| 102 | * This version of the kAVL tree offers the option of inlining the entire
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| 103 | * implementation. This depends on the compiler doing a decent job in both
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| 104 | * making use of the inlined code and to eliminate const variables.
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| 105 | */
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| 106 |
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| 107 |
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| 108 | /*******************************************************************************
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| 109 | * Internal Functions *
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| 110 | *******************************************************************************/
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| 111 | #include <k/kDefs.h>
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| 112 | #include <k/kTypes.h>
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| 113 | #include <k/kHlpAssert.h>
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| 114 |
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| 115 |
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| 116 | /*******************************************************************************
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| 117 | * Defined Constants And Macros *
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| 118 | *******************************************************************************/
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| 119 | #define KAVL_HEIGHTOF(pNode) ((KU8)((pNode) != NULL ? (pNode)->mHeight : 0))
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| 120 |
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| 121 | /** @def KAVL_GET_POINTER
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| 122 | * Reads a 'pointer' value.
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| 123 | *
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| 124 | * @returns The native pointer.
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| 125 | * @param pp Pointer to the pointer to read.
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| 126 | * @internal
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| 127 | */
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| 128 |
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| 129 | /** @def KAVL_GET_POINTER_NULL
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| 130 | * Reads a 'pointer' value which can be KAVL_NULL.
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| 131 | *
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| 132 | * @returns The native pointer.
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| 133 | * @returns NULL pointer if KAVL_NULL.
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| 134 | * @param pp Pointer to the pointer to read.
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| 135 | * @internal
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| 136 | */
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| 137 |
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| 138 | /** @def KAVL_SET_POINTER
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| 139 | * Writes a 'pointer' value.
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| 140 | * For offset-based schemes offset relative to pp is calculated and assigned to *pp.
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| 141 | *
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| 142 | * @returns stored pointer.
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| 143 | * @param pp Pointer to where to store the pointer.
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| 144 | * @param p Native pointer to assign to *pp.
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| 145 | * @internal
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| 146 | */
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| 147 |
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| 148 | /** @def KAVL_SET_POINTER_NULL
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| 149 | * Writes a 'pointer' value which can be KAVL_NULL.
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| 150 | *
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| 151 | * For offset-based schemes offset relative to pp is calculated and assigned to *pp,
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| 152 | * if p is not KAVL_NULL of course.
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| 153 | *
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| 154 | * @returns stored pointer.
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| 155 | * @param pp Pointer to where to store the pointer.
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| 156 | * @param pp2 Pointer to where to pointer to assign to pp. This can be KAVL_NULL
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| 157 | * @internal
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| 158 | */
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| 159 |
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| 160 | #ifndef KAVLTREEPTR
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| 161 | # define KAVLTREEPTR KAVLNODE *
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| 162 | #endif
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| 163 |
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| 164 | #ifdef KAVL_OFFSET
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| 165 | # define KAVL_GET_POINTER(pp) ( (KAVLNODE *)((KIPTR)(pp) + *(pp)) )
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| 166 | # define KAVL_GET_POINTER_NULL(pp) ( *(pp) != KAVL_NULL ? KAVL_GET_POINTER(pp) : NULL )
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| 167 | # define KAVL_SET_POINTER(pp, p) ( (*(pp)) = ((KIPTR)(p) - (KIPTR)(pp)) )
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| 168 | # define KAVL_SET_POINTER_NULL(pp, pp2) ( (*(pp)) = *(pp2) != KAVL_NULL ? (KIPTR)KAVL_GET_POINTER(pp2) - (KIPTR)(pp) : KAVL_NULL )
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| 169 | #else
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| 170 | # define KAVL_GET_POINTER(pp) ( *(pp) )
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| 171 | # define KAVL_GET_POINTER_NULL(pp) ( *(pp) )
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| 172 | # define KAVL_SET_POINTER(pp, p) ( (*(pp)) = (p) )
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| 173 | # define KAVL_SET_POINTER_NULL(pp, pp2) ( (*(pp)) = *(pp2) )
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| 174 | #endif
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| 175 |
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| 176 |
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| 177 | /** @def KAVL_NULL
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| 178 | * The NULL 'pointer' equivalent.
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| 179 | */
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| 180 | #ifdef KAVL_OFFSET
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| 181 | # define KAVL_NULL 0
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| 182 | #else
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| 183 | # define KAVL_NULL NULL
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| 184 | #endif
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| 185 |
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| 186 | #ifdef KAVL_STD_KEY_COMP
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| 187 | # define KAVL_G(key1, key2) ( (key1) > (key2) )
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| 188 | # define KAVL_E(key1, key2) ( (key1) == (key2) )
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| 189 | # define KAVL_NE(key1, key2) ( (key1) != (key2) )
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| 190 | # ifdef KAVL_RANGE
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| 191 | # define KAVL_R_IS_IDENTICAL(key1B, key2B, key1E, key2E) ( (key1B) == (key2B) && (key1E) == (key2E) )
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| 192 | # define KAVL_R_IS_INTERSECTING(key1B, key2B, key1E, key2E) ( (key1B) <= (key2E) && (key1E) >= (key2B) )
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| 193 | # define KAVL_R_IS_IN_RANGE(key1B, key1E, key2) KAVL_R_IS_INTERSECTING(key1B, key2, key1E, key2)
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| 194 | # endif
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| 195 | #endif
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| 196 |
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| 197 | #ifndef KAVL_RANGE
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| 198 | # define KAVL_R_IS_INTERSECTING(key1B, key2B, key1E, key2E) KAVL_E(key1B, key2B)
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| 199 | # define KAVL_R_IS_IDENTICAL(key1B, key2B, key1E, key2E) KAVL_E(key1B, key2B)
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| 200 | #endif
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| 201 |
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| 202 |
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| 203 |
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| 204 | /*******************************************************************************
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| 205 | * Structures and Typedefs *
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| 206 | *******************************************************************************/
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| 207 | /**
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| 208 | * Stack used to avoid recursive calls during insert and removal.
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| 209 | */
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| 210 | typedef struct
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| 211 | {
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| 212 | unsigned cEntries;
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| 213 | KAVLTREEPTR *aEntries[KAVL_MAX_STACK];
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| 214 | } KAVL_INT(STACK);
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| 215 |
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| 216 | /**
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| 217 | * The callback used by the Destroy and DoWithAll functions.
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| 218 | */
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| 219 | typedef int (* KAVL_TYPE(PFN,CALLBACK))(KAVLNODE *, void *);
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| 220 |
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| 221 |
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| 222 |
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| 223 | /**
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| 224 | * Rewinds a stack of node pointer pointers, rebalancing the tree.
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| 225 | *
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| 226 | * @param pStack Pointer to stack to rewind.
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| 227 | * @sketch LOOP thru all stack entries
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| 228 | * BEGIN
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| 229 | * Get pointer to pointer to node (and pointer to node) from the stack.
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| 230 | * IF 2 higher left subtree than in right subtree THEN
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| 231 | * BEGIN
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| 232 | * IF higher (or equal) left-sub-subtree than right-sub-subtree THEN
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| 233 | * * n+2|n+3
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| 234 | * / \ / \
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| 235 | * n+2 n ==> n+1 n+1|n+2
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| 236 | * / \ / \
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| 237 | * n+1 n|n+1 n|n+1 n
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| 238 | *
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| 239 | * Or with keys:
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| 240 | *
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| 241 | * 4 2
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| 242 | * / \ / \
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| 243 | * 2 5 ==> 1 4
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| 244 | * / \ / \
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| 245 | * 1 3 3 5
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| 246 | *
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| 247 | * ELSE
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| 248 | * * n+2
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| 249 | * / \ / \
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| 250 | * n+2 n n+1 n+1
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| 251 | * / \ ==> / \ / \
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| 252 | * n n+1 n L R n
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| 253 | * / \
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| 254 | * L R
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| 255 | *
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| 256 | * Or with keys:
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| 257 | * 6 4
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| 258 | * / \ / \
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| 259 | * 2 7 ==> 2 6
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| 260 | * / \ / \ / \
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| 261 | * 1 4 1 3 5 7
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| 262 | * / \
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| 263 | * 3 5
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| 264 | * END
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| 265 | * ELSE IF 2 higher in right subtree than in left subtree THEN
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| 266 | * BEGIN
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| 267 | * Same as above but left <==> right. (invert the picture)
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| 268 | * ELSE
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| 269 | * IF correct height THEN break
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| 270 | * ELSE correct height.
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| 271 | * END
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| 272 | */
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| 273 | K_DECL_INLINE(void) KAVL_FN(Rebalance)(KAVL_INT(STACK) *pStack)
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| 274 | {
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| 275 | while (pStack->cEntries > 0)
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| 276 | {
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| 277 | KAVLTREEPTR *ppNode = pStack->aEntries[--pStack->cEntries];
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| 278 | KAVLNODE *pNode = KAVL_GET_POINTER(ppNode);
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| 279 | KAVLNODE *pLeftNode = KAVL_GET_POINTER_NULL(&pNode->mpLeft);
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| 280 | KU8 uLeftHeight = KAVL_HEIGHTOF(pLeftNode);
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| 281 | KAVLNODE *pRightNode = KAVL_GET_POINTER_NULL(&pNode->mpRight);
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| 282 | KU8 uRightHeight = KAVL_HEIGHTOF(pRightNode);
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| 283 |
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| 284 | if (uRightHeight + 1 < uLeftHeight)
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| 285 | {
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| 286 | KAVLNODE *pLeftLeftNode = KAVL_GET_POINTER_NULL(&pLeftNode->mpLeft);
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| 287 | KAVLNODE *pLeftRightNode = KAVL_GET_POINTER_NULL(&pLeftNode->mpRight);
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| 288 | KU8 uLeftRightHeight = KAVL_HEIGHTOF(pLeftRightNode);
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| 289 |
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| 290 | if (KAVL_HEIGHTOF(pLeftLeftNode) >= uLeftRightHeight)
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| 291 | {
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| 292 | KAVL_SET_POINTER_NULL(&pNode->mpLeft, &pLeftNode->mpRight);
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| 293 | KAVL_SET_POINTER(&pLeftNode->mpRight, pNode);
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| 294 | pLeftNode->mHeight = (KU8)(1 + (pNode->mHeight = (KU8)(1 + uLeftRightHeight)));
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| 295 | KAVL_SET_POINTER(ppNode, pLeftNode);
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| 296 | }
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| 297 | else
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| 298 | {
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| 299 | KAVL_SET_POINTER_NULL(&pLeftNode->mpRight, &pLeftRightNode->mpLeft);
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| 300 | KAVL_SET_POINTER_NULL(&pNode->mpLeft, &pLeftRightNode->mpRight);
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| 301 | KAVL_SET_POINTER(&pLeftRightNode->mpLeft, pLeftNode);
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| 302 | KAVL_SET_POINTER(&pLeftRightNode->mpRight, pNode);
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| 303 | pLeftNode->mHeight = pNode->mHeight = uLeftRightHeight;
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| 304 | pLeftRightNode->mHeight = uLeftHeight;
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| 305 | KAVL_SET_POINTER(ppNode, pLeftRightNode);
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| 306 | }
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| 307 | }
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| 308 | else if (uLeftHeight + 1 < uRightHeight)
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| 309 | {
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| 310 | KAVLNODE *pRightLeftNode = KAVL_GET_POINTER_NULL(&pRightNode->mpLeft);
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| 311 | KU8 uRightLeftHeight = KAVL_HEIGHTOF(pRightLeftNode);
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| 312 | KAVLNODE *pRightRightNode = KAVL_GET_POINTER_NULL(&pRightNode->mpRight);
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| 313 |
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| 314 | if (KAVL_HEIGHTOF(pRightRightNode) >= uRightLeftHeight)
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| 315 | {
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| 316 | KAVL_SET_POINTER_NULL(&pNode->mpRight, &pRightNode->mpLeft);
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| 317 | KAVL_SET_POINTER(&pRightNode->mpLeft, pNode);
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| 318 | pRightNode->mHeight = (KU8)(1 + (pNode->mHeight = (KU8)(1 + uRightLeftHeight)));
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| 319 | KAVL_SET_POINTER(ppNode, pRightNode);
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| 320 | }
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| 321 | else
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| 322 | {
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| 323 | KAVL_SET_POINTER_NULL(&pRightNode->mpLeft, &pRightLeftNode->mpRight);
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| 324 | KAVL_SET_POINTER_NULL(&pNode->mpRight, &pRightLeftNode->mpLeft);
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| 325 | KAVL_SET_POINTER(&pRightLeftNode->mpRight, pRightNode);
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| 326 | KAVL_SET_POINTER(&pRightLeftNode->mpLeft, pNode);
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| 327 | pRightNode->mHeight = pNode->mHeight = uRightLeftHeight;
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| 328 | pRightLeftNode->mHeight = uRightHeight;
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| 329 | KAVL_SET_POINTER(ppNode, pRightLeftNode);
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| 330 | }
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| 331 | }
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| 332 | else
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| 333 | {
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| 334 | KU8 uHeight = (KU8)(K_MAX(uLeftHeight, uRightHeight) + 1);
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| 335 | if (uHeight == pNode->mHeight)
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| 336 | break;
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| 337 | pNode->mHeight = uHeight;
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| 338 | }
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| 339 | }
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| 340 |
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| 341 | }
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| 342 |
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| 343 |
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| 344 | /**
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| 345 | * Inserts a node into the AVL-tree.
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| 346 | * @returns TRUE if inserted.
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| 347 | * FALSE if node exists in tree.
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| 348 | * @param ppTree Pointer to the AVL-tree root node pointer.
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| 349 | * @param pNode Pointer to the node which is to be added.
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| 350 | * @sketch Find the location of the node (using binary tree algorithm.):
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| 351 | * LOOP until NULL leaf pointer
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| 352 | * BEGIN
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| 353 | * Add node pointer pointer to the AVL-stack.
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| 354 | * IF new-node-key < node key THEN
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| 355 | * left
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| 356 | * ELSE
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| 357 | * right
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| 358 | * END
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| 359 | * Fill in leaf node and insert it.
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| 360 | * Rebalance the tree.
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| 361 | */
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| 362 | KAVL_DECL(KBOOL) KAVL_FN(Insert)(KAVLTREEPTR *ppTree, KAVLNODE *pNode)
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| 363 | {
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| 364 | KAVL_INT(STACK) AVLStack;
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| 365 | KAVLTREEPTR *ppCurNode = ppTree;
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| 366 | register KAVLKEY Key = pNode->mKey;
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| 367 | #ifdef KAVL_RANGE
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| 368 | register KAVLKEY KeyLast = pNode->mKeyLast;
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| 369 | #endif
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| 370 |
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| 371 | #ifdef KAVL_RANGE
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| 372 | if (Key > KeyLast)
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| 373 | return false;
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| 374 | #endif
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| 375 |
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| 376 | AVLStack.cEntries = 0;
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| 377 | while (*ppCurNode != KAVL_NULL)
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| 378 | {
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| 379 | register KAVLNODE *pCurNode = KAVL_GET_POINTER(ppCurNode);
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| 380 |
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| 381 | kHlpAssert(AVLStack.cEntries < KAVL_MAX_STACK);
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| 382 | AVLStack.aEntries[AVLStack.cEntries++] = ppCurNode;
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| 383 | #ifdef KAVL_EQUAL_ALLOWED
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| 384 | if (KAVL_R_IS_IDENTICAL(pCurNode->mKey, Key, pCurNode->mKeyLast, KeyLast))
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| 385 | {
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| 386 | /*
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| 387 | * If equal then we'll use a list of equal nodes.
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| 388 | */
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| 389 | pNode->mpLeft = pNode->mpRight = KAVL_NULL;
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| 390 | pNode->mHeight = 0;
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| 391 | KAVL_SET_POINTER_NULL(&pNode->mpList, &pCurNode->mpList);
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| 392 | KAVL_SET_POINTER(&pCurNode->mpList, pNode);
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| 393 | return K_TRUE;
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| 394 | }
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| 395 | #endif
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| 396 | #ifdef KAVL_CHECK_FOR_EQUAL_INSERT
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| 397 | if (KAVL_R_IS_INTERSECTING(pCurNode->mKey, Key, pCurNode->mKeyLast, KeyLast))
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| 398 | return K_FALSE;
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| 399 | #endif
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| 400 | if (KAVL_G(pCurNode->mKey, Key))
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| 401 | ppCurNode = &pCurNode->mpLeft;
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| 402 | else
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| 403 | ppCurNode = &pCurNode->mpRight;
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| 404 | }
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| 405 |
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| 406 | pNode->mpLeft = pNode->mpRight = KAVL_NULL;
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| 407 | #ifdef KAVL_EQUAL_ALLOWED
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| 408 | pNode->mpList = KAVL_NULL;
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| 409 | #endif
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| 410 | pNode->mHeight = 1;
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| 411 | KAVL_SET_POINTER(ppCurNode, pNode);
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| 412 |
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| 413 | KAVL_FN(Rebalance)(&AVLStack);
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| 414 | return K_TRUE;
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| 415 | }
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| 416 |
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| 417 |
|
|---|
| 418 | /**
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| 419 | * Removes a node from the AVL-tree.
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| 420 | * @returns Pointer to the node.
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| 421 | * @param ppTree Pointer to the AVL-tree root node pointer.
|
|---|
| 422 | * @param Key Key value of the node which is to be removed.
|
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| 423 | * @sketch Find the node which is to be removed:
|
|---|
| 424 | * LOOP until not found
|
|---|
| 425 | * BEGIN
|
|---|
| 426 | * Add node pointer pointer to the AVL-stack.
|
|---|
| 427 | * IF the keys matches THEN break!
|
|---|
| 428 | * IF remove key < node key THEN
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| 429 | * left
|
|---|
| 430 | * ELSE
|
|---|
| 431 | * right
|
|---|
| 432 | * END
|
|---|
| 433 | * IF found THEN
|
|---|
| 434 | * BEGIN
|
|---|
| 435 | * IF left node not empty THEN
|
|---|
| 436 | * BEGIN
|
|---|
| 437 | * Find the right most node in the left tree while adding the pointer to the pointer to it's parent to the stack:
|
|---|
| 438 | * Start at left node.
|
|---|
| 439 | * LOOP until right node is empty
|
|---|
| 440 | * BEGIN
|
|---|
| 441 | * Add to stack.
|
|---|
| 442 | * go right.
|
|---|
| 443 | * END
|
|---|
| 444 | * Link out the found node.
|
|---|
| 445 | * Replace the node which is to be removed with the found node.
|
|---|
| 446 | * Correct the stack entry for the pointer to the left tree.
|
|---|
| 447 | * END
|
|---|
| 448 | * ELSE
|
|---|
| 449 | * BEGIN
|
|---|
| 450 | * Move up right node.
|
|---|
| 451 | * Remove last stack entry.
|
|---|
| 452 | * END
|
|---|
| 453 | * Balance tree using stack.
|
|---|
| 454 | * END
|
|---|
| 455 | * return pointer to the removed node (if found).
|
|---|
| 456 | */
|
|---|
| 457 | KAVL_DECL(KAVLNODE *) KAVL_FN(Remove)(KAVLTREEPTR *ppTree, KAVLKEY Key)
|
|---|
| 458 | {
|
|---|
| 459 | KAVL_INT(STACK) AVLStack;
|
|---|
| 460 | KAVLTREEPTR *ppDeleteNode = ppTree;
|
|---|
| 461 | register KAVLNODE *pDeleteNode;
|
|---|
| 462 |
|
|---|
| 463 | AVLStack.cEntries = 0;
|
|---|
| 464 | for (;;)
|
|---|
| 465 | {
|
|---|
| 466 | if (*ppDeleteNode == KAVL_NULL)
|
|---|
| 467 | return NULL;
|
|---|
| 468 | pDeleteNode = KAVL_GET_POINTER(ppDeleteNode);
|
|---|
| 469 |
|
|---|
| 470 | kHlpAssert(AVLStack.cEntries < KAVL_MAX_STACK);
|
|---|
| 471 | AVLStack.aEntries[AVLStack.cEntries++] = ppDeleteNode;
|
|---|
| 472 | if (KAVL_E(pDeleteNode->mKey, Key))
|
|---|
| 473 | break;
|
|---|
| 474 |
|
|---|
| 475 | if (KAVL_G(pDeleteNode->mKey, Key))
|
|---|
| 476 | ppDeleteNode = &pDeleteNode->mpLeft;
|
|---|
| 477 | else
|
|---|
| 478 | ppDeleteNode = &pDeleteNode->mpRight;
|
|---|
| 479 | }
|
|---|
| 480 |
|
|---|
| 481 | if (pDeleteNode->mpLeft != KAVL_NULL)
|
|---|
| 482 | {
|
|---|
| 483 | /* find the rightmost node in the left tree. */
|
|---|
| 484 | const unsigned iStackEntry = AVLStack.cEntries;
|
|---|
| 485 | KAVLTREEPTR *ppLeftLeast = &pDeleteNode->mpLeft;
|
|---|
| 486 | register KAVLNODE *pLeftLeast = KAVL_GET_POINTER(ppLeftLeast);
|
|---|
| 487 |
|
|---|
| 488 | while (pLeftLeast->mpRight != KAVL_NULL)
|
|---|
| 489 | {
|
|---|
| 490 | kHlpAssert(AVLStack.cEntries < KAVL_MAX_STACK);
|
|---|
| 491 | AVLStack.aEntries[AVLStack.cEntries++] = ppLeftLeast;
|
|---|
| 492 | ppLeftLeast = &pLeftLeast->mpRight;
|
|---|
| 493 | pLeftLeast = KAVL_GET_POINTER(ppLeftLeast);
|
|---|
| 494 | }
|
|---|
| 495 |
|
|---|
| 496 | /* link out pLeftLeast */
|
|---|
| 497 | KAVL_SET_POINTER_NULL(ppLeftLeast, &pLeftLeast->mpLeft);
|
|---|
| 498 |
|
|---|
| 499 | /* link it in place of the delete node. */
|
|---|
| 500 | KAVL_SET_POINTER_NULL(&pLeftLeast->mpLeft, &pDeleteNode->mpLeft);
|
|---|
| 501 | KAVL_SET_POINTER_NULL(&pLeftLeast->mpRight, &pDeleteNode->mpRight);
|
|---|
| 502 | pLeftLeast->mHeight = pDeleteNode->mHeight;
|
|---|
| 503 | KAVL_SET_POINTER(ppDeleteNode, pLeftLeast);
|
|---|
| 504 | AVLStack.aEntries[iStackEntry] = &pLeftLeast->mpLeft;
|
|---|
| 505 | }
|
|---|
| 506 | else
|
|---|
| 507 | {
|
|---|
| 508 | KAVL_SET_POINTER_NULL(ppDeleteNode, &pDeleteNode->mpRight);
|
|---|
| 509 | AVLStack.cEntries--;
|
|---|
| 510 | }
|
|---|
| 511 |
|
|---|
| 512 | KAVL_FN(Rebalance)(&AVLStack);
|
|---|
| 513 | return pDeleteNode;
|
|---|
| 514 | }
|
|---|
| 515 |
|
|---|
