1 /* $NetBSD: tdelete.c,v 1.6 2012/06/25 22:32:45 abs Exp $ */ 2 3 /* 4 * Tree search generalized from Knuth (6.2.2) Algorithm T just like 5 * the AT&T man page says. 6 * 7 * The node_t structure is for internal use only, lint doesn't grok it. 8 * 9 * Written by reading the System V Interface Definition, not the code. 10 * 11 * Totally public domain. 12 */ 13 14 #include <sys/cdefs.h> 15 #if defined(LIBC_SCCS) && !defined(lint) 16 __RCSID("$NetBSD: tdelete.c,v 1.6 2012/06/25 22:32:45 abs Exp $"); 17 #endif /* LIBC_SCCS and not lint */ 18 19 #include <assert.h> 20 #define _SEARCH_PRIVATE 21 #include <search.h> 22 #include <stdlib.h> 23 24 25 /* find a node with key "vkey" in tree "vrootp" */ 26 void * 27 tdelete(const void *vkey, void **vrootp, 28 int (*compar)(const void *, const void *)) 29 { 30 node_t **rootp = (node_t **)vrootp; 31 node_t *p, *q, *r; 32 int cmp; 33 34 _DIAGASSERT(vkey != NULL); 35 _DIAGASSERT(compar != NULL); 36 37 if (rootp == NULL || (p = *rootp) == NULL) 38 return NULL; 39 40 while ((cmp = (*compar)(vkey, (*rootp)->key)) != 0) { 41 p = *rootp; 42 rootp = (cmp < 0) ? 43 &(*rootp)->llink : /* follow llink branch */ 44 &(*rootp)->rlink; /* follow rlink branch */ 45 if (*rootp == NULL) 46 return NULL; /* key not found */ 47 } 48 r = (*rootp)->rlink; /* D1: */ 49 if ((q = (*rootp)->llink) == NULL) /* Left NULL? */ 50 q = r; 51 else if (r != NULL) { /* Right link is NULL? */ 52 if (r->llink == NULL) { /* D2: Find successor */ 53 r->llink = q; 54 q = r; 55 } else { /* D3: Find NULL link */ 56 for (q = r->llink; q->llink != NULL; q = r->llink) 57 r = q; 58 r->llink = q->rlink; 59 q->llink = (*rootp)->llink; 60 q->rlink = (*rootp)->rlink; 61 } 62 } 63 if (p != *rootp) 64 free(*rootp); /* D4: Free node */ 65 *rootp = q; /* link parent to new node */ 66 return p; 67 } 68
