1/* $NetBSD: tsearch.c,v 1.2 2017/01/28 21:31:50 christos Exp $ */ 2 3/* 4 * Tree search generalized from Knuth (6.2.2) Algorithm T just like 5 * the AT&T man page says. 6 * 7 * The node_t structure is for internal use only, lint doesn't grok it. 8 * 9 * Written by reading the System V Interface Definition, not the code. 10 * 11 * Totally public domain. 12 * 13 * NetBSD: tsearch.c,v 1.3 1999/09/16 11:45:37 lukem Exp 14 * NetBSD: twalk.c,v 1.1 1999/02/22 10:33:16 christos Exp 15 * NetBSD: tdelete.c,v 1.2 1999/09/16 11:45:37 lukem Exp 16 * NetBSD: tfind.c,v 1.2 1999/09/16 11:45:37 lukem Exp 17 */ 18 19#include <config.h> 20#include <krb5/roken.h> 21#include "search.h" 22#include <stdlib.h> 23 24typedef struct node { 25 char *key; 26 struct node *llink, *rlink; 27} node_t; 28 29#ifndef __DECONST 30#define __DECONST(type, var) ((type)(uintptr_t)(const void *)(var)) 31#endif 32 33/* 34 * find or insert datum into search tree 35 * 36 * Parameters: 37 * vkey: key to be located 38 * vrootp: address of tree root 39 */ 40 41ROKEN_LIB_FUNCTION void * 42rk_tsearch(const void *vkey, void **vrootp, 43 int (*compar)(const void *, const void *)) 44{ 45 node_t *q; 46 node_t **rootp = (node_t **)vrootp; 47 48 if (rootp == NULL) 49 return NULL; 50 51 while (*rootp != NULL) { /* Knuth's T1: */ 52 int r; 53 54 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */ 55 return *rootp; /* we found it! */ 56 57 rootp = (r < 0) ? 58 &(*rootp)->llink : /* T3: follow left branch */ 59 &(*rootp)->rlink; /* T4: follow right branch */ 60 } 61 62 q = malloc(sizeof(node_t)); /* T5: key not found */ 63 if (q != 0) { /* make new node */ 64 *rootp = q; /* link new node to old */ 65 /* LINTED const castaway ok */ 66 q->key = __DECONST(void *, vkey); /* initialize new node */ 67 q->llink = q->rlink = NULL; 68 } 69 return q; 70} 71 72/* 73 * Walk the nodes of a tree 74 * 75 * Parameters: 76 * root: Root of the tree to be walked 77 */ 78static void 79trecurse(const node_t *root, void (*action)(const void *, VISIT, int), 80 int level) 81{ 82 83 if (root->llink == NULL && root->rlink == NULL) 84 (*action)(root, leaf, level); 85 else { 86 (*action)(root, preorder, level); 87 if (root->llink != NULL) 88 trecurse(root->llink, action, level + 1); 89 (*action)(root, postorder, level); 90 if (root->rlink != NULL) 91 trecurse(root->rlink, action, level + 1); 92 (*action)(root, endorder, level); 93 } 94} 95 96/* 97 * Walk the nodes of a tree 98 * 99 * Parameters: 100 * vroot: Root of the tree to be walked 101 */ 102ROKEN_LIB_FUNCTION void 103rk_twalk(const void *vroot, 104 void (*action)(const void *, VISIT, int)) 105{ 106 if (vroot != NULL && action != NULL) 107 trecurse(vroot, action, 0); 108} 109 110/* 111 * delete node with given key 112 * 113 * vkey: key to be deleted 114 * vrootp: address of the root of the tree 115 * compar: function to carry out node comparisons 116 */ 117ROKEN_LIB_FUNCTION void * 118rk_tdelete(const void * vkey, void ** vrootp, 119 int (*compar)(const void *, const void *)) 120{ 121 node_t **rootp = (node_t **)vrootp; 122 node_t *q, *r; 123 int cmp; 124 125 if (rootp == NULL || *rootp == NULL) 126 return NULL; 127 128 while ((cmp = (*compar)(vkey, (*rootp)->key)) != 0) { 129 rootp = (cmp < 0) ? 130 &(*rootp)->llink : /* follow llink branch */ 131 &(*rootp)->rlink; /* follow rlink branch */ 132 if (*rootp == NULL) 133 return NULL; /* key not found */ 134 } 135 r = (*rootp)->rlink; /* D1: */ 136 if ((q = (*rootp)->llink) == NULL) /* Left NULL? */ 137 q = r; 138 else if (r != NULL) { /* Right link is NULL? */ 139 if (r->llink == NULL) { /* D2: Find successor */ 140 r->llink = q; 141 q = r; 142 } else { /* D3: Find NULL link */ 143 for (q = r->llink; q->llink != NULL; q = r->llink) 144 r = q; 145 r->llink = q->rlink; 146 q->llink = (*rootp)->llink; 147 q->rlink = (*rootp)->rlink; 148 } 149 } 150 free(*rootp); /* D4: Free node */ 151 *rootp = q; /* link parent to new node */ 152 return *rootp; 153} 154 155/* 156 * find a node, or return 0 157 * 158 * Parameters: 159 * vkey: key to be found 160 * vrootp: address of the tree root 161 */ 162ROKEN_LIB_FUNCTION void * 163rk_tfind(const void *vkey, void * const *vrootp, 164 int (*compar)(const void *, const void *)) 165{ 166 node_t **rootp = (node_t **)vrootp; 167 168 if (rootp == NULL) 169 return NULL; 170 171 while (*rootp != NULL) { /* T1: */ 172 int r; 173 174 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */ 175 return *rootp; /* key found */ 176 rootp = (r < 0) ? 177 &(*rootp)->llink : /* T3: follow left branch */ 178 &(*rootp)->rlink; /* T4: follow right branch */ 179 } 180 return NULL; 181} 182