Replace glibc tsearch() with a custom red-black tree implementation.
The library supplied tree estructure is not enought for our needs, due to its limited API. Thus, we have implemented a suitable red-black tree.release-1.5.4.branch
Vreixo Formoso
15 years ago
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5eb3a7e038
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/*
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* Copyright (c) 2007 Vreixo Formoso
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*
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* This file is part of the libisofs project; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation. See COPYING file for details.
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*/
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#include "util.h"
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#include "error.h"
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#include <stdlib.h>
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/*
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* This implementation of Red-Black tree is based on the public domain
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* implementation of Julienne Walker.
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*/
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struct iso_rbnode {
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void *data;
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struct iso_rbnode *ch[2];
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unsigned int red:1;
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};
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struct iso_rbtree {
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struct iso_rbnode *root;
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size_t size;
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int (*compare)(const void *a, const void *b);
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};
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/**
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* Create a new binary tree. libisofs binary trees allow you to add any data
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* passing it as a pointer. You must provide a function suitable for compare
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* two elements.
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*
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* @param compare
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* A function to compare two elements. It takes a pointer to both elements
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* and return 0, -1 or 1 if the first element is equal, less or greater
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* than the second one.
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* @param tree
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* Location where the tree structure will be stored.
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*/
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int
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iso_rbtree_new(int (*compare)(const void*, const void*), IsoRBTree **tree)
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{
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if (compare == NULL || tree == NULL) {
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return ISO_NULL_POINTER;
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}
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*tree = calloc(1, sizeof(IsoRBTree));
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if (*tree == NULL) {
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return ISO_MEM_ERROR;
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}
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(*tree)->compare = compare;
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return ISO_SUCCESS;
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}
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static
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void rbtree_destroy_aux(struct iso_rbnode *root, void (*free_data)(void *))
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{
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if (root == NULL) {
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return;
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}
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if (free_data != NULL) {
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free_data(root->data);
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}
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rbtree_destroy_aux(root->ch[0], free_data);
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rbtree_destroy_aux(root->ch[1], free_data);
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free(root);
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}
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/**
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* Destroy a given tree.
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*
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* Note that only the structure itself is deleted. To delete the elements, you
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* should provide a valid free_data function. It will be called for each
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* element of the tree, so you can use it to free any related data.
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*/
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void
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iso_rbtree_destroy(IsoRBTree *tree, void (*free_data)(void *))
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{
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if (tree == NULL) {
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return;
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}
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rbtree_destroy_aux(tree->root, free_data);
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free(tree);
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}
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static inline
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int is_red(struct iso_rbnode *root)
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{
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return root != NULL && root->red;
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}
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static
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struct iso_rbnode *iso_rbtree_single(struct iso_rbnode *root, int dir)
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{
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struct iso_rbnode *save = root->ch[!dir];
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root->ch[!dir] = save->ch[dir];
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save->ch[dir] = root;
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root->red = 1;
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save->red = 0;
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return save;
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}
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static
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struct iso_rbnode *iso_rbtree_double(struct iso_rbnode *root, int dir)
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{
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root->ch[!dir] = iso_rbtree_single(root->ch[!dir], !dir);
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return iso_rbtree_single(root, dir);
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}
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static
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struct iso_rbnode *iso_rbnode_new(void *data)
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{
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struct iso_rbnode *rn = malloc(sizeof(struct iso_rbnode));
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if ( rn != NULL ) {
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rn->data = data;
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rn->red = 1;
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rn->ch[0] = NULL;
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rn->ch[1] = NULL;
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}
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return rn;
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}
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/**
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* Inserts a given element in a Red-Black tree.
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*
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* @param tree
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* the tree where to insert
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* @param data
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* element to be inserted on the tree. It can't be NULL
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* @param item
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* if not NULL, it will point to a location where the tree element ptr
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* will be stored. If data was inserted, *item == data. If data was
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* already on the tree, *item points to the previously inserted object
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* that is equal to data.
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* @return
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* 1 success, 0 element already inserted, < 0 error
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*/
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int iso_rbtree_insert(IsoRBTree *tree, void *data, void **item)
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{
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struct iso_rbnode *new;
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int added = 0; /* has a new node been added? */
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if (tree == NULL || data == NULL) {
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return ISO_NULL_POINTER;
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}
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if (tree->root == NULL) {
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/* Empty tree case */
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tree->root = iso_rbnode_new(data);
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if (tree->root == NULL) {
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return ISO_MEM_ERROR;
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}
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new = data;
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added = 1;
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} else {
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struct iso_rbnode head = {0}; /* False tree root */
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struct iso_rbnode *g, *t; /* Grandparent & parent */
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struct iso_rbnode *p, *q; /* Iterator & parent */
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int dir = 0, last = 0;
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int comp;
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/* Set up helpers */
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t = &head;
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g = p = NULL;
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q = t->ch[1] = tree->root;
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/* Search down the tree */
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while (1) {
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if (q == NULL) {
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/* Insert new node at the bottom */
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p->ch[dir] = q = iso_rbnode_new(data);
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if (q == NULL) {
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return ISO_MEM_ERROR;
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}
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added = 1;
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} else if (is_red(q->ch[0]) && is_red(q->ch[1])) {
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/* Color flip */
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q->red = 1;
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q->ch[0]->red = 0;
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q->ch[1]->red = 0;
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}
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/* Fix red violation */
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if (is_red(q) && is_red(p)) {
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int dir2 = (t->ch[1] == g);
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if (q == p->ch[last]) {
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t->ch[dir2] = iso_rbtree_single(g, !last);
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} else {
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t->ch[dir2] = iso_rbtree_double(g, !last);
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}
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}
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comp = tree->compare(q->data, data);
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/* Stop if found */
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if (comp == 0) {
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new = q->data;
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break;
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}
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last = dir;
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dir = (comp < 0);
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/* Update helpers */
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if (g != NULL)
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t = g;
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g = p, p = q;
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q = q->ch[dir];
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}
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/* Update root */
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tree->root = head.ch[1];
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}
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/* Make root black */
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tree->root->red = 0;
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if (item != NULL) {
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*item = new;
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}
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if (added) {
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/* a new element has been added */
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tree->size++;
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return 1;
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} else {
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return 0;
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}
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}
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/**
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* Get the number of elements in a given tree.
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*/
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size_t iso_rbtree_get_size(IsoRBTree *tree)
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{
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return tree->size;
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}
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static
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int rbtree_to_array_aux(struct iso_rbnode *root, void **array, size_t pos)
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{
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if (root == NULL) {
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return pos;
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}
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pos = rbtree_to_array_aux(root->ch[0], array, pos);
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array[pos++] = root->data;
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pos = rbtree_to_array_aux(root->ch[1], array, pos);
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return pos;
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}
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/**
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* Get an array view of the elements of the tree.
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*
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* @return
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* A sorted array with the contents of the tree, or NULL if there is not
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* enought memory to allocate the array. You should free(3) the array when
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* no more needed. Note that the array is NULL-terminated, and thus it
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* has size + 1 length.
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*/
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void **
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iso_rbtree_to_array(IsoRBTree *tree)
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{
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void **array;
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array = malloc((tree->size + 1) * sizeof(void*));
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if (array == NULL) {
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return NULL;
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}
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/* fill array */
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rbtree_to_array_aux(tree->root, array, 0);
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array[tree->size] = NULL;
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return array;
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}
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