a85b5759f3
These files were pulled from the 1.6.3 release tarball. This new version builds against OpenSSL version 1.1 which will be the default in the new Debian Stable which is due to be released RealSoonNow (tm).
627 lines
16 KiB
C
627 lines
16 KiB
C
/*
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* rbtree.c -- generic red black tree
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*
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* Copyright (c) 2001-2007, NLnet Labs. All rights reserved.
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*
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* This software is open source.
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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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*
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* Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* Neither the name of the NLNET LABS nor the names of its contributors may
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* be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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/**
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* \file
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* Implementation of a redblack tree.
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*/
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#include "config.h"
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#include "log.h"
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#include "fptr_wlist.h"
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#include "util/rbtree.h"
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/** Node colour black */
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#define BLACK 0
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/** Node colour red */
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#define RED 1
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/** the NULL node, global alloc */
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rbnode_type rbtree_null_node = {
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RBTREE_NULL, /* Parent. */
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RBTREE_NULL, /* Left. */
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RBTREE_NULL, /* Right. */
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NULL, /* Key. */
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BLACK /* Color. */
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};
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/** rotate subtree left (to preserve redblack property) */
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static void rbtree_rotate_left(rbtree_type *rbtree, rbnode_type *node);
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/** rotate subtree right (to preserve redblack property) */
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static void rbtree_rotate_right(rbtree_type *rbtree, rbnode_type *node);
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/** Fixup node colours when insert happened */
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static void rbtree_insert_fixup(rbtree_type *rbtree, rbnode_type *node);
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/** Fixup node colours when delete happened */
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static void rbtree_delete_fixup(rbtree_type* rbtree, rbnode_type* child,
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rbnode_type* child_parent);
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/*
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* Creates a new red black tree, initializes and returns a pointer to it.
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*
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* Return NULL on failure.
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*
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*/
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rbtree_type *
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rbtree_create (int (*cmpf)(const void *, const void *))
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{
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rbtree_type *rbtree;
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/* Allocate memory for it */
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rbtree = (rbtree_type *) malloc(sizeof(rbtree_type));
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if (!rbtree) {
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return NULL;
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}
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/* Initialize it */
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rbtree_init(rbtree, cmpf);
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return rbtree;
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}
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void
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rbtree_init(rbtree_type *rbtree, int (*cmpf)(const void *, const void *))
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{
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/* Initialize it */
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rbtree->root = RBTREE_NULL;
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rbtree->count = 0;
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rbtree->cmp = cmpf;
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}
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/*
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* Rotates the node to the left.
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*
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*/
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static void
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rbtree_rotate_left(rbtree_type *rbtree, rbnode_type *node)
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{
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rbnode_type *right = node->right;
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node->right = right->left;
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if (right->left != RBTREE_NULL)
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right->left->parent = node;
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right->parent = node->parent;
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if (node->parent != RBTREE_NULL) {
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if (node == node->parent->left) {
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node->parent->left = right;
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} else {
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node->parent->right = right;
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}
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} else {
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rbtree->root = right;
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}
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right->left = node;
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node->parent = right;
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}
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/*
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* Rotates the node to the right.
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*
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*/
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static void
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rbtree_rotate_right(rbtree_type *rbtree, rbnode_type *node)
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{
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rbnode_type *left = node->left;
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node->left = left->right;
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if (left->right != RBTREE_NULL)
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left->right->parent = node;
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left->parent = node->parent;
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if (node->parent != RBTREE_NULL) {
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if (node == node->parent->right) {
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node->parent->right = left;
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} else {
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node->parent->left = left;
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}
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} else {
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rbtree->root = left;
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}
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left->right = node;
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node->parent = left;
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}
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static void
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rbtree_insert_fixup(rbtree_type *rbtree, rbnode_type *node)
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{
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rbnode_type *uncle;
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/* While not at the root and need fixing... */
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while (node != rbtree->root && node->parent->color == RED) {
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/* If our parent is left child of our grandparent... */
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if (node->parent == node->parent->parent->left) {
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uncle = node->parent->parent->right;
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/* If our uncle is red... */
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if (uncle->color == RED) {
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/* Paint the parent and the uncle black... */
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node->parent->color = BLACK;
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uncle->color = BLACK;
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/* And the grandparent red... */
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node->parent->parent->color = RED;
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/* And continue fixing the grandparent */
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node = node->parent->parent;
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} else { /* Our uncle is black... */
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/* Are we the right child? */
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if (node == node->parent->right) {
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node = node->parent;
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rbtree_rotate_left(rbtree, node);
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}
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/* Now we're the left child, repaint and rotate... */
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node->parent->color = BLACK;
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node->parent->parent->color = RED;
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rbtree_rotate_right(rbtree, node->parent->parent);
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}
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} else {
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uncle = node->parent->parent->left;
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/* If our uncle is red... */
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if (uncle->color == RED) {
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/* Paint the parent and the uncle black... */
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node->parent->color = BLACK;
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uncle->color = BLACK;
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/* And the grandparent red... */
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node->parent->parent->color = RED;
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/* And continue fixing the grandparent */
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node = node->parent->parent;
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} else { /* Our uncle is black... */
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/* Are we the right child? */
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if (node == node->parent->left) {
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node = node->parent;
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rbtree_rotate_right(rbtree, node);
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}
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/* Now we're the right child, repaint and rotate... */
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node->parent->color = BLACK;
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node->parent->parent->color = RED;
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rbtree_rotate_left(rbtree, node->parent->parent);
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}
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}
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}
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rbtree->root->color = BLACK;
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}
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/*
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* Inserts a node into a red black tree.
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*
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* Returns NULL on failure or the pointer to the newly added node
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* otherwise.
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*/
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rbnode_type *
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rbtree_insert (rbtree_type *rbtree, rbnode_type *data)
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{
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/* XXX Not necessary, but keeps compiler quiet... */
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int r = 0;
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/* We start at the root of the tree */
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rbnode_type *node = rbtree->root;
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rbnode_type *parent = RBTREE_NULL;
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fptr_ok(fptr_whitelist_rbtree_cmp(rbtree->cmp));
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/* Lets find the new parent... */
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while (node != RBTREE_NULL) {
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/* Compare two keys, do we have a duplicate? */
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if ((r = rbtree->cmp(data->key, node->key)) == 0) {
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return NULL;
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}
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parent = node;
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if (r < 0) {
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node = node->left;
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} else {
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node = node->right;
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}
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}
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/* Initialize the new node */
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data->parent = parent;
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data->left = data->right = RBTREE_NULL;
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data->color = RED;
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rbtree->count++;
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/* Insert it into the tree... */
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if (parent != RBTREE_NULL) {
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if (r < 0) {
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parent->left = data;
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} else {
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parent->right = data;
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}
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} else {
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rbtree->root = data;
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}
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/* Fix up the red-black properties... */
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rbtree_insert_fixup(rbtree, data);
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return data;
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}
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/*
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* Searches the red black tree, returns the data if key is found or NULL otherwise.
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*
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*/
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rbnode_type *
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rbtree_search (rbtree_type *rbtree, const void *key)
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{
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rbnode_type *node;
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if (rbtree_find_less_equal(rbtree, key, &node)) {
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return node;
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} else {
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return NULL;
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}
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}
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/** helpers for delete: swap node colours */
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static void swap_int8(uint8_t* x, uint8_t* y)
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{
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uint8_t t = *x; *x = *y; *y = t;
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}
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/** helpers for delete: swap node pointers */
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static void swap_np(rbnode_type** x, rbnode_type** y)
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{
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rbnode_type* t = *x; *x = *y; *y = t;
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}
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/** Update parent pointers of child trees of 'parent' */
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static void change_parent_ptr(rbtree_type* rbtree, rbnode_type* parent,
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rbnode_type* old, rbnode_type* new)
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{
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if(parent == RBTREE_NULL)
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{
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log_assert(rbtree->root == old);
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if(rbtree->root == old) rbtree->root = new;
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return;
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}
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log_assert(parent->left == old || parent->right == old
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|| parent->left == new || parent->right == new);
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if(parent->left == old) parent->left = new;
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if(parent->right == old) parent->right = new;
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}
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/** Update parent pointer of a node 'child' */
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static void change_child_ptr(rbnode_type* child, rbnode_type* old,
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rbnode_type* new)
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{
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if(child == RBTREE_NULL) return;
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log_assert(child->parent == old || child->parent == new);
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if(child->parent == old) child->parent = new;
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}
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rbnode_type*
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rbtree_delete(rbtree_type *rbtree, const void *key)
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{
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rbnode_type *to_delete;
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rbnode_type *child;
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if((to_delete = rbtree_search(rbtree, key)) == 0) return 0;
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rbtree->count--;
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/* make sure we have at most one non-leaf child */
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if(to_delete->left != RBTREE_NULL && to_delete->right != RBTREE_NULL)
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{
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/* swap with smallest from right subtree (or largest from left) */
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rbnode_type *smright = to_delete->right;
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while(smright->left != RBTREE_NULL)
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smright = smright->left;
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/* swap the smright and to_delete elements in the tree,
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* but the rbnode_type is first part of user data struct
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* so cannot just swap the keys and data pointers. Instead
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* readjust the pointers left,right,parent */
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/* swap colors - colors are tied to the position in the tree */
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swap_int8(&to_delete->color, &smright->color);
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/* swap child pointers in parents of smright/to_delete */
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change_parent_ptr(rbtree, to_delete->parent, to_delete, smright);
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if(to_delete->right != smright)
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change_parent_ptr(rbtree, smright->parent, smright, to_delete);
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/* swap parent pointers in children of smright/to_delete */
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change_child_ptr(smright->left, smright, to_delete);
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change_child_ptr(smright->left, smright, to_delete);
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change_child_ptr(smright->right, smright, to_delete);
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change_child_ptr(smright->right, smright, to_delete);
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change_child_ptr(to_delete->left, to_delete, smright);
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if(to_delete->right != smright)
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change_child_ptr(to_delete->right, to_delete, smright);
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if(to_delete->right == smright)
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{
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/* set up so after swap they work */
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to_delete->right = to_delete;
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smright->parent = smright;
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}
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/* swap pointers in to_delete/smright nodes */
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swap_np(&to_delete->parent, &smright->parent);
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swap_np(&to_delete->left, &smright->left);
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swap_np(&to_delete->right, &smright->right);
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/* now delete to_delete (which is at the location where the smright previously was) */
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}
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log_assert(to_delete->left == RBTREE_NULL || to_delete->right == RBTREE_NULL);
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if(to_delete->left != RBTREE_NULL) child = to_delete->left;
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else child = to_delete->right;
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/* unlink to_delete from the tree, replace to_delete with child */
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change_parent_ptr(rbtree, to_delete->parent, to_delete, child);
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change_child_ptr(child, to_delete, to_delete->parent);
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if(to_delete->color == RED)
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{
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/* if node is red then the child (black) can be swapped in */
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}
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else if(child->color == RED)
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{
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/* change child to BLACK, removing a RED node is no problem */
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if(child!=RBTREE_NULL) child->color = BLACK;
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}
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else rbtree_delete_fixup(rbtree, child, to_delete->parent);
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/* unlink completely */
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to_delete->parent = RBTREE_NULL;
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to_delete->left = RBTREE_NULL;
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to_delete->right = RBTREE_NULL;
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to_delete->color = BLACK;
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return to_delete;
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}
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static void rbtree_delete_fixup(rbtree_type* rbtree, rbnode_type* child,
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rbnode_type* child_parent)
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{
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rbnode_type* sibling;
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int go_up = 1;
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/* determine sibling to the node that is one-black short */
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if(child_parent->right == child) sibling = child_parent->left;
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else sibling = child_parent->right;
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while(go_up)
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{
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if(child_parent == RBTREE_NULL)
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{
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/* removed parent==black from root, every path, so ok */
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return;
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}
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if(sibling->color == RED)
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{ /* rotate to get a black sibling */
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child_parent->color = RED;
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sibling->color = BLACK;
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if(child_parent->right == child)
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rbtree_rotate_right(rbtree, child_parent);
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else rbtree_rotate_left(rbtree, child_parent);
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/* new sibling after rotation */
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if(child_parent->right == child) sibling = child_parent->left;
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else sibling = child_parent->right;
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}
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if(child_parent->color == BLACK
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&& sibling->color == BLACK
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&& sibling->left->color == BLACK
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&& sibling->right->color == BLACK)
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{ /* fixup local with recolor of sibling */
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if(sibling != RBTREE_NULL)
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sibling->color = RED;
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child = child_parent;
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child_parent = child_parent->parent;
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/* prepare to go up, new sibling */
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if(child_parent->right == child) sibling = child_parent->left;
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else sibling = child_parent->right;
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}
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else go_up = 0;
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}
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if(child_parent->color == RED
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&& sibling->color == BLACK
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&& sibling->left->color == BLACK
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&& sibling->right->color == BLACK)
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{
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/* move red to sibling to rebalance */
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if(sibling != RBTREE_NULL)
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sibling->color = RED;
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child_parent->color = BLACK;
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return;
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}
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log_assert(sibling != RBTREE_NULL);
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/* get a new sibling, by rotating at sibling. See which child
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of sibling is red */
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if(child_parent->right == child
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&& sibling->color == BLACK
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&& sibling->right->color == RED
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&& sibling->left->color == BLACK)
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{
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sibling->color = RED;
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sibling->right->color = BLACK;
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rbtree_rotate_left(rbtree, sibling);
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/* new sibling after rotation */
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if(child_parent->right == child) sibling = child_parent->left;
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else sibling = child_parent->right;
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}
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else if(child_parent->left == child
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&& sibling->color == BLACK
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&& sibling->left->color == RED
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&& sibling->right->color == BLACK)
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{
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sibling->color = RED;
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sibling->left->color = BLACK;
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rbtree_rotate_right(rbtree, sibling);
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/* new sibling after rotation */
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if(child_parent->right == child) sibling = child_parent->left;
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else sibling = child_parent->right;
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}
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/* now we have a black sibling with a red child. rotate and exchange colors. */
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sibling->color = child_parent->color;
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child_parent->color = BLACK;
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if(child_parent->right == child)
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{
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log_assert(sibling->left->color == RED);
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sibling->left->color = BLACK;
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rbtree_rotate_right(rbtree, child_parent);
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}
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else
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{
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log_assert(sibling->right->color == RED);
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sibling->right->color = BLACK;
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rbtree_rotate_left(rbtree, child_parent);
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}
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}
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int
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rbtree_find_less_equal(rbtree_type *rbtree, const void *key,
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rbnode_type **result)
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{
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int r;
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rbnode_type *node;
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|
|
log_assert(result);
|
|
|
|
/* We start at root... */
|
|
node = rbtree->root;
|
|
|
|
*result = NULL;
|
|
fptr_ok(fptr_whitelist_rbtree_cmp(rbtree->cmp));
|
|
|
|
/* While there are children... */
|
|
while (node != RBTREE_NULL) {
|
|
r = rbtree->cmp(key, node->key);
|
|
if (r == 0) {
|
|
/* Exact match */
|
|
*result = node;
|
|
return 1;
|
|
}
|
|
if (r < 0) {
|
|
node = node->left;
|
|
} else {
|
|
/* Temporary match */
|
|
*result = node;
|
|
node = node->right;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Finds the first element in the red black tree
|
|
*
|
|
*/
|
|
rbnode_type *
|
|
rbtree_first (rbtree_type *rbtree)
|
|
{
|
|
rbnode_type *node;
|
|
|
|
for (node = rbtree->root; node->left != RBTREE_NULL; node = node->left);
|
|
return node;
|
|
}
|
|
|
|
rbnode_type *
|
|
rbtree_last (rbtree_type *rbtree)
|
|
{
|
|
rbnode_type *node;
|
|
|
|
for (node = rbtree->root; node->right != RBTREE_NULL; node = node->right);
|
|
return node;
|
|
}
|
|
|
|
/*
|
|
* Returns the next node...
|
|
*
|
|
*/
|
|
rbnode_type *
|
|
rbtree_next (rbnode_type *node)
|
|
{
|
|
rbnode_type *parent;
|
|
|
|
if (node->right != RBTREE_NULL) {
|
|
/* One right, then keep on going left... */
|
|
for (node = node->right; node->left != RBTREE_NULL; node = node->left);
|
|
} else {
|
|
parent = node->parent;
|
|
while (parent != RBTREE_NULL && node == parent->right) {
|
|
node = parent;
|
|
parent = parent->parent;
|
|
}
|
|
node = parent;
|
|
}
|
|
return node;
|
|
}
|
|
|
|
rbnode_type *
|
|
rbtree_previous(rbnode_type *node)
|
|
{
|
|
rbnode_type *parent;
|
|
|
|
if (node->left != RBTREE_NULL) {
|
|
/* One left, then keep on going right... */
|
|
for (node = node->left; node->right != RBTREE_NULL; node = node->right);
|
|
} else {
|
|
parent = node->parent;
|
|
while (parent != RBTREE_NULL && node == parent->left) {
|
|
node = parent;
|
|
parent = parent->parent;
|
|
}
|
|
node = parent;
|
|
}
|
|
return node;
|
|
}
|
|
|
|
/** recursive descent traverse */
|
|
static void
|
|
traverse_post(void (*func)(rbnode_type*, void*), void* arg, rbnode_type* node)
|
|
{
|
|
if(!node || node == RBTREE_NULL)
|
|
return;
|
|
/* recurse */
|
|
traverse_post(func, arg, node->left);
|
|
traverse_post(func, arg, node->right);
|
|
/* call user func */
|
|
(*func)(node, arg);
|
|
}
|
|
|
|
void
|
|
traverse_postorder(rbtree_type* tree, void (*func)(rbnode_type*, void*),
|
|
void* arg)
|
|
{
|
|
traverse_post(func, arg, tree->root);
|
|
}
|