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Diffstat (limited to 'libc/misc/search/tsearch.c')
| -rw-r--r-- | libc/misc/search/tsearch.c | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/libc/misc/search/tsearch.c b/libc/misc/search/tsearch.c new file mode 100644 index 000000000..b584e2f15 --- /dev/null +++ b/libc/misc/search/tsearch.c @@ -0,0 +1,190 @@ +/* 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 */ |