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559a218c9b
These sys/cdefs.h are not needed. Purge them. They are mostly left-over from the $FreeBSD$ removal. A few in libc are still required for macros that cdefs.h defines. Keep those. Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D42385
195 lines
5 KiB
C
195 lines
5 KiB
C
/*-
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* Copyright (c) 2015 Nuxi, https://nuxi.nl/
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#define _SEARCH_PRIVATE
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#include <search.h>
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#include <stdlib.h>
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#include "tsearch_path.h"
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posix_tnode *
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tsearch(const void *key, posix_tnode **rootp,
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int (*compar)(const void *, const void *))
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{
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struct path path;
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posix_tnode **leaf, *result, *n, *x, *y, *z;
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int cmp;
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/* POSIX requires that tsearch() returns NULL if rootp is NULL. */
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if (rootp == NULL)
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return (NULL);
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/*
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* Find the leaf where the new key needs to be inserted. Return
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* if we've found an existing entry. Keep track of the path that
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* is taken to get to the node, as we will need it to adjust the
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* balances.
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*/
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path_init(&path);
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leaf = rootp;
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while (*leaf != NULL) {
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if ((*leaf)->balance != 0) {
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/*
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* If we reach a node that has a non-zero
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* balance on the way, we know that we won't
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* need to perform any rotations above this
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* point. In this case rotations are always
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* capable of keeping the subtree in balance.
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* Make this the root node and reset the path.
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*/
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rootp = leaf;
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path_init(&path);
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}
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cmp = compar(key, (*leaf)->key);
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if (cmp < 0) {
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path_taking_left(&path);
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leaf = &(*leaf)->llink;
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} else if (cmp > 0) {
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path_taking_right(&path);
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leaf = &(*leaf)->rlink;
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} else {
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return (*leaf);
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}
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}
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/* Did not find a matching key in the tree. Insert a new node. */
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result = *leaf = malloc(sizeof(**leaf));
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if (result == NULL)
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return (NULL);
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result->key = (void *)key;
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result->llink = NULL;
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result->rlink = NULL;
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result->balance = 0;
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/*
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* Walk along the same path a second time and adjust the
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* balances. Except for the first node, all of these nodes must
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* have a balance of zero, meaning that these nodes will not get
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* out of balance.
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*/
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for (n = *rootp; n != *leaf;) {
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if (path_took_left(&path)) {
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n->balance += 1;
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n = n->llink;
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} else {
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n->balance -= 1;
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n = n->rlink;
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}
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}
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/*
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* Adjusting the balances may have pushed the balance of the
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* root node out of range. Perform a rotation to bring the
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* balance back in range.
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*/
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x = *rootp;
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if (x->balance > 1) {
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y = x->llink;
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if (y->balance < 0) {
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/*
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* Left-right case.
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*
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* x
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* / \ z
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* y D / \
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* / \ --> y x
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* A z /| |\
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* / \ A B C D
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* B C
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*/
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z = y->rlink;
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y->rlink = z->llink;
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z->llink = y;
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x->llink = z->rlink;
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z->rlink = x;
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*rootp = z;
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x->balance = z->balance > 0 ? -1 : 0;
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y->balance = z->balance < 0 ? 1 : 0;
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z->balance = 0;
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} else {
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/*
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* Left-left case.
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*
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* x y
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* / \ / \
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* y C --> A x
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* / \ / \
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* A B B C
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*/
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x->llink = y->rlink;
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y->rlink = x;
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*rootp = y;
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x->balance = 0;
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y->balance = 0;
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}
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} else if (x->balance < -1) {
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y = x->rlink;
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if (y->balance > 0) {
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/*
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* Right-left case.
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*
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* x
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* / \ z
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* A y / \
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* / \ --> x y
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* z D /| |\
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* / \ A B C D
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* B C
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*/
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posix_tnode *z = y->llink;
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x->rlink = z->llink;
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z->llink = x;
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y->llink = z->rlink;
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z->rlink = y;
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*rootp = z;
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x->balance = z->balance < 0 ? 1 : 0;
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y->balance = z->balance > 0 ? -1 : 0;
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z->balance = 0;
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} else {
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/*
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* Right-right case.
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*
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* x y
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* / \ / \
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* A y --> x C
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* / \ / \
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* B C A B
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*/
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x->rlink = y->llink;
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y->llink = x;
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*rootp = y;
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x->balance = 0;
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y->balance = 0;
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}
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}
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/* Return the new entry. */
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return (result);
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}
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