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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, see <http://www.gnu.org/licenses/>. */
/*
* 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);
}
libc_hidden_def(tsearch)
#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;
}
libc_hidden_def(tfind)
#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
#ifdef __USE_GNU
#ifdef L_tdestroy
/* The standardized functions miss an important functionality: the
tree cannot be removed easily. We provide a function to do this. */
static void
internal_function
tdestroy_recurse (node *root, __free_fn_t freefct)
{
if (root->left != NULL)
tdestroy_recurse (root->left, freefct);
if (root->right != NULL)
tdestroy_recurse (root->right, freefct);
(*freefct) ((void *) root->key);
/* Free the node itself. */
free (root);
}
void tdestroy (void *vroot, __free_fn_t freefct)
{
node *root = (node *) vroot;
if (root != NULL) {
tdestroy_recurse (root, freefct);
}
}
libc_hidden_def(tdestroy)
#endif
#endif
/* tsearch.c ends here */
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