b902641d73
I've also added insque(3) and remque(3) (from NetBSD because the OpenBSD ones are currently broken for non-circular lists). I've not added the three hash table functions that should be in this header because they operate on a single global hash table and thus aren't likely to be useful. Bug: https://code.google.com/p/android/issues/detail?id=73719 (cherry picked from commit 3e424d0a241f8ae5194514dabc4ad899f5a5416d) Change-Id: I5882a6b48c80fea8ac6b9c27e7b9de10b202b4ff
120 lines
3.3 KiB
C
120 lines
3.3 KiB
C
/* $OpenBSD: tsearch.c,v 1.8 2014/03/16 18:38:30 guenther Exp $ */
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/*
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* Tree search generalized from Knuth (6.2.2) Algorithm T just like
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* the AT&T man page says.
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*
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* The node_t structure is for internal use only
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*
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* Written by reading the System V Interface Definition, not the code.
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*
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* Totally public domain.
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*/
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/*LINTLIBRARY*/
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#include <search.h>
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#include <stdlib.h>
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typedef struct node_t {
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char *key;
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struct node_t *left, *right;
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} node;
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/* find or insert datum into search tree */
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void *
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tsearch(const void *vkey, void **vrootp,
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int (*compar)(const void *, const void *))
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{
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node *q;
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char *key = (char *)vkey;
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node **rootp = (node **)vrootp;
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if (rootp == (struct node_t **)0)
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return ((void *)0);
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while (*rootp != (struct node_t *)0) { /* Knuth's T1: */
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int r;
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if ((r = (*compar)(key, (*rootp)->key)) == 0) /* T2: */
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return ((void *)*rootp); /* we found it! */
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rootp = (r < 0) ?
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&(*rootp)->left : /* T3: follow left branch */
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&(*rootp)->right; /* T4: follow right branch */
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}
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q = (node *) malloc(sizeof(node)); /* T5: key not found */
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if (q != (struct node_t *)0) { /* make new node */
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*rootp = q; /* link new node to old */
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q->key = key; /* initialize new node */
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q->left = q->right = (struct node_t *)0;
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}
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return ((void *)q);
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}
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/* delete node with given key */
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void *
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tdelete(const void *vkey, void **vrootp,
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int (*compar)(const void *, const void *))
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{
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node **rootp = (node **)vrootp;
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char *key = (char *)vkey;
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node *p = (node *)1;
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node *q;
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node *r;
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int cmp;
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if (rootp == (struct node_t **)0 || *rootp == (struct node_t *)0)
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return ((struct node_t *)0);
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while ((cmp = (*compar)(key, (*rootp)->key)) != 0) {
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p = *rootp;
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rootp = (cmp < 0) ?
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&(*rootp)->left : /* follow left branch */
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&(*rootp)->right; /* follow right branch */
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if (*rootp == (struct node_t *)0)
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return ((void *)0); /* key not found */
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}
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r = (*rootp)->right; /* D1: */
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if ((q = (*rootp)->left) == (struct node_t *)0) /* Left (struct node_t *)0? */
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q = r;
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else if (r != (struct node_t *)0) { /* Right link is null? */
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if (r->left == (struct node_t *)0) { /* D2: Find successor */
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r->left = q;
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q = r;
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} else { /* D3: Find (struct node_t *)0 link */
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for (q = r->left; q->left != (struct node_t *)0; q = r->left)
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r = q;
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r->left = q->right;
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q->left = (*rootp)->left;
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q->right = (*rootp)->right;
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}
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}
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free((struct node_t *) *rootp); /* D4: Free node */
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*rootp = q; /* link parent to new node */
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return(p);
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}
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/* Walk the nodes of a tree */
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static void
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trecurse(node *root, void (*action)(const void *, VISIT, int), int level)
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{
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if (root->left == (struct node_t *)0 && root->right == (struct node_t *)0)
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(*action)(root, leaf, level);
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else {
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(*action)(root, preorder, level);
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if (root->left != (struct node_t *)0)
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trecurse(root->left, action, level + 1);
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(*action)(root, postorder, level);
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if (root->right != (struct node_t *)0)
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trecurse(root->right, action, level + 1);
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(*action)(root, endorder, level);
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}
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}
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/* Walk the nodes of a tree */
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void
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twalk(const void *vroot, void (*action)(const void *, VISIT, int))
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{
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node *root = (node *)vroot;
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if (root != (node *)0 && action != (void (*)(const void *, VISIT, int))0)
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trecurse(root, action, 0);
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}
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