/* 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 */