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- /* Copyright (C) 1994 Free Software Foundation, Inc.
- This file is part of the GNU C Library.
- The GNU C 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.
- The GNU C 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 the GNU C Library; see the file COPYING.LIB. If
- not, write to the Free Software Foundation, Inc., 675 Mass Ave,
- Cambridge, MA 02139, USA. */
- /*
- * Tree search generalized from Knuth (6.2.2) Algorithm T just like
- * the AT&T man page says.
- *
- * The node_t structure is for internal use only, lint doesn't grok it.
- *
- * Written by reading the System V Interface Definition, not the code.
- *
- * Totally public domain.
- */
- /*LINTLIBRARY*/
- #include <search.h>
- #include <stdlib.h>
- /* This routine is not very bad. It makes many assumptions about
- * the compiler. It assumpts that the first field in node must be
- * the "key" field, which points to the datum. It is a very trick
- * stuff. H.J.
- */
- typedef struct node_t
- {
- void *key;
- struct node_t *left, *right;
- } node;
- #ifdef L_tsearch
- /* find or insert datum into search tree.
- char *key; key to be located
- register node **rootp; address of tree root
- int (*compar)(); ordering function
- */
- void *tsearch(__const void *key, void **vrootp, __compar_fn_t compar)
- {
- register node *q;
- register node **rootp = (node **) vrootp;
- if (rootp == (struct node_t **)0)
- return ((struct node_t *)0);
- while (*rootp != (struct node_t *)0) /* Knuth's T1: */
- {
- int r;
- if ((r = (*compar)(key, (*rootp)->key)) == 0) /* T2: */
- return (*rootp); /* we found it! */
- rootp = (r < 0) ?
- &(*rootp)->left : /* T3: follow left branch */
- &(*rootp)->right; /* T4: follow right branch */
- }
- q = (node *) malloc(sizeof(node)); /* T5: key not found */
- if (q != (struct node_t *)0) /* make new node */
- {
- *rootp = q; /* link new node to old */
- q->key = (void *)key; /* initialize new node */
- q->left = q->right = (struct node_t *)0;
- }
- return (q);
- }
- #endif
- #ifdef L_tfind
- void *tfind(__const void *key, void * __const *vrootp, __compar_fn_t compar)
- {
- register node **rootp = (node **) vrootp;
- if (rootp == (struct node_t **)0)
- return ((struct node_t *)0);
- while (*rootp != (struct node_t *)0) /* Knuth's T1: */
- {
- int r;
- if ((r = (*compar)(key, (*rootp)->key)) == 0) /* T2: */
- return (*rootp); /* we found it! */
- rootp = (r < 0) ?
- &(*rootp)->left : /* T3: follow left branch */
- &(*rootp)->right; /* T4: follow right branch */
- }
- return NULL;
- }
- #endif
- #ifdef L_tdelete
- /* delete node with given key
- char *key; key to be deleted
- register node **rootp; address of the root of tree
- int (*compar)(); comparison function
- */
- void *tdelete(__const void *key, void ** vrootp, __compar_fn_t compar)
- {
- node *p;
- register node *q;
- register node *r;
- int cmp;
- register node **rootp = (node **) vrootp;
- if (rootp == (struct node_t **)0 || (p = *rootp) == (struct node_t *)0)
- return ((struct node_t *)0);
- while ((cmp = (*compar)(key, (*rootp)->key)) != 0)
- {
- p = *rootp;
- rootp = (cmp < 0) ?
- &(*rootp)->left : /* follow left branch */
- &(*rootp)->right; /* follow right branch */
- if (*rootp == (struct node_t *)0)
- return ((struct node_t *)0); /* key not found */
- }
- r = (*rootp)->right; /* D1: */
- if ((q = (*rootp)->left) == (struct node_t *)0) /* Left (struct node_t *)0? */
- q = r;
- else if (r != (struct node_t *)0) /* Right link is null? */
- {
- if (r->left == (struct node_t *)0) /* D2: Find successor */
- {
- r->left = q;
- q = r;
- }
- else
- { /* D3: Find (struct node_t *)0 link */
- for (q = r->left; q->left != (struct node_t *)0; q = r->left)
- r = q;
- r->left = q->right;
- q->left = (*rootp)->left;
- q->right = (*rootp)->right;
- }
- }
- free((struct node_t *) *rootp); /* D4: Free node */
- *rootp = q; /* link parent to new node */
- return(p);
- }
- #endif
- #ifdef L_twalk
- /* Walk the nodes of a tree
- register node *root; Root of the tree to be walked
- register void (*action)(); Function to be called at each node
- register int level;
- */
- static void trecurse(__const void *vroot, __action_fn_t action, int level)
- {
- register node *root = (node *) vroot;
- if (root->left == (struct node_t *)0 && root->right == (struct node_t *)0)
- (*action)(root, leaf, level);
- else
- {
- (*action)(root, preorder, level);
- if (root->left != (struct node_t *)0)
- trecurse(root->left, action, level + 1);
- (*action)(root, postorder, level);
- if (root->right != (struct node_t *)0)
- trecurse(root->right, action, level + 1);
- (*action)(root, endorder, level);
- }
- }
- /* void twalk(root, action) Walk the nodes of a tree
- node *root; Root of the tree to be walked
- void (*action)(); Function to be called at each node
- PTR
- */
- void twalk(__const void *vroot, __action_fn_t action)
- {
- register __const node *root = (node *) vroot;
- if (root != (node *)0 && action != (__action_fn_t) 0)
- trecurse(root, action, 0);
- }
- #endif
- /* tsearch.c ends here */
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