1 /* Copyright (C) 1994 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Library General Public License as
6 published by the Free Software Foundation; either version 2 of the
7 License, or (at your option) any later version.
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Library General Public License for more details.
14 You should have received a copy of the GNU Library General Public
15 License along with the GNU C Library; see the file COPYING.LIB. If
16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
17 Cambridge, MA 02139, USA. */
20 * Tree search generalized from Knuth (6.2.2) Algorithm T just like
21 * the AT&T man page says.
23 * The node_t structure is for internal use only, lint doesn't grok it.
25 * Written by reading the System V Interface Definition, not the code.
27 * Totally public domain.
34 /* This routine is not very bad. It makes many assumptions about
35 * the compiler. It assumpts that the first field in node must be
36 * the "key" field, which points to the datum. It is a very trick
43 struct node_t *left, *right;
47 /* find or insert datum into search tree.
48 char *key; key to be located
49 register node **rootp; address of tree root
50 int (*compar)(); ordering function
53 void *tsearch(__const void *key, void **vrootp, __compar_fn_t compar)
56 register node **rootp = (node **) vrootp;
58 if (rootp == (struct node_t **)0)
59 return ((struct node_t *)0);
60 while (*rootp != (struct node_t *)0) /* Knuth's T1: */
64 if ((r = (*compar)(key, (*rootp)->key)) == 0) /* T2: */
65 return (*rootp); /* we found it! */
67 &(*rootp)->left : /* T3: follow left branch */
68 &(*rootp)->right; /* T4: follow right branch */
70 q = (node *) malloc(sizeof(node)); /* T5: key not found */
71 if (q != (struct node_t *)0) /* make new node */
73 *rootp = q; /* link new node to old */
74 q->key = (void *)key; /* initialize new node */
75 q->left = q->right = (struct node_t *)0;
79 libc_hidden_def(tsearch)
83 void *tfind(__const void *key, void * __const *vrootp, __compar_fn_t compar)
85 register node **rootp = (node **) vrootp;
87 if (rootp == (struct node_t **)0)
88 return ((struct node_t *)0);
89 while (*rootp != (struct node_t *)0) /* Knuth's T1: */
93 if ((r = (*compar)(key, (*rootp)->key)) == 0) /* T2: */
94 return (*rootp); /* we found it! */
96 &(*rootp)->left : /* T3: follow left branch */
97 &(*rootp)->right; /* T4: follow right branch */
101 libc_hidden_def(tfind)
105 /* delete node with given key
106 char *key; key to be deleted
107 register node **rootp; address of the root of tree
108 int (*compar)(); comparison function
110 void *tdelete(__const void *key, void ** vrootp, __compar_fn_t compar)
116 register node **rootp = (node **) vrootp;
118 if (rootp == (struct node_t **)0 || (p = *rootp) == (struct node_t *)0)
119 return ((struct node_t *)0);
120 while ((cmp = (*compar)(key, (*rootp)->key)) != 0)
124 &(*rootp)->left : /* follow left branch */
125 &(*rootp)->right; /* follow right branch */
126 if (*rootp == (struct node_t *)0)
127 return ((struct node_t *)0); /* key not found */
129 r = (*rootp)->right; /* D1: */
130 if ((q = (*rootp)->left) == (struct node_t *)0) /* Left (struct node_t *)0? */
132 else if (r != (struct node_t *)0) /* Right link is null? */
134 if (r->left == (struct node_t *)0) /* D2: Find successor */
140 { /* D3: Find (struct node_t *)0 link */
141 for (q = r->left; q->left != (struct node_t *)0; q = r->left)
144 q->left = (*rootp)->left;
145 q->right = (*rootp)->right;
148 free((struct node_t *) *rootp); /* D4: Free node */
149 *rootp = q; /* link parent to new node */
155 /* Walk the nodes of a tree
156 register node *root; Root of the tree to be walked
157 register void (*action)(); Function to be called at each node
160 static void trecurse(__const void *vroot, __action_fn_t action, int level)
162 register node *root = (node *) vroot;
164 if (root->left == (struct node_t *)0 && root->right == (struct node_t *)0)
165 (*action)(root, leaf, level);
168 (*action)(root, preorder, level);
169 if (root->left != (struct node_t *)0)
170 trecurse(root->left, action, level + 1);
171 (*action)(root, postorder, level);
172 if (root->right != (struct node_t *)0)
173 trecurse(root->right, action, level + 1);
174 (*action)(root, endorder, level);
178 /* void twalk(root, action) Walk the nodes of a tree
179 node *root; Root of the tree to be walked
180 void (*action)(); Function to be called at each node
183 void twalk(__const void *vroot, __action_fn_t action)
185 register __const node *root = (node *) vroot;
187 if (root != (node *)0 && action != (__action_fn_t) 0)
188 trecurse(root, action, 0);
194 /* The standardized functions miss an important functionality: the
195 tree cannot be removed easily. We provide a function to do this. */
198 tdestroy_recurse (node *root, __free_fn_t freefct)
200 if (root->left != NULL)
201 tdestroy_recurse (root->left, freefct);
202 if (root->right != NULL)
203 tdestroy_recurse (root->right, freefct);
204 (*freefct) ((void *) root->key);
205 /* Free the node itself. */
209 void tdestroy (void *vroot, __free_fn_t freefct)
211 node *root = (node *) vroot;
213 tdestroy_recurse (root, freefct);
216 libc_hidden_def(tdestroy)
220 /* tsearch.c ends here */