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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $URL$
* $Id$
*
*/
#include "sci/include/aatree.h"
#include "sci/include/sci_memory.h"
namespace Sci {
struct aatree {
struct aatree *left, *right;
int level;
void *key;
};
// Sentinel node
static aatree_t bottom = {&bottom, &bottom, 0, NULL};
static void skew(aatree_t **t) {
if ((*t)->left->level == (*t)->level) {
// Rotate right
aatree_t *temp = *t;
*t = (*t)->left;
temp->left = (*t)->right;
(*t)->right = temp;
}
}
static void split(aatree_t **t) {
if ((*t)->right->right->level == (*t)->level) {
// Rotate left
aatree_t *temp = *t;
*t = (*t)->right;
temp->right = (*t)->left;
(*t)->left = temp;
(*t)->level++;
}
}
static int delete_node(void *x, aatree_t **t, aatree_t *deleted, int (*compar)(const void *, const void *)) {
int retval = -1;
if (*t != &bottom) {
// Search down the tree
aatree_t **n;
if (compar(x, (*t)->key) < 0)
n = &(*t)->left;
else {
n = &(*t)->right;
deleted = *t;
}
retval = delete_node(x, n, deleted, compar);
// At the bottom of the tree we remove the element (if it is present)
if ((*n == &bottom) && (deleted != &bottom) && (compar(x, deleted->key) == 0)) {
aatree_t *temp;
deleted->key = (*t)->key;
temp = *t;
*t = (*t)->right;
free(temp);
retval = 0;
} else if (((*t)->left->level < (*t)->level - 1) || ((*t)->right->level < (*t)->level - 1)) {
(*t)->level--;
if ((*t)->right->level > (*t)->level)
(*t)->right->level = (*t)->level;
skew(t);
skew(&(*t)->right);
skew(&(*t)->right->right);
split(t);
split(&(*t)->right);
}
}
return retval;
}
aatree_t *aatree_new() {
return ⊥
}
int aatree_insert(void *x, aatree_t **t, int (*compar)(const void *, const void *)) {
int retval = -1;
int c;
if (*t == &bottom) {
*t = (aatree_t *)sci_malloc(sizeof(aatree_t));
if (*t == NULL)
return 1;
(*t)->key = x;
(*t)->left = ⊥
(*t)->right = ⊥
(*t)->level = 1;
return 0;
}
c = compar(x, (*t)->key);
if (c < 0)
retval = aatree_insert(x, &(*t)->left, compar);
else if (c > 0)
retval = aatree_insert(x, &(*t)->right, compar);
skew(t);
split(t);
return retval;
}
int aatree_delete(void *x, aatree_t **t, int (*compar)(const void *, const void *)) {
return delete_node(x, t, &bottom, compar);
}
aatree_t *aatree_walk(aatree_t *t, int direction) {
if ((direction == AATREE_WALK_LEFT) && (t->left != &bottom))
return t->left;
if ((direction == AATREE_WALK_RIGHT) && (t->right != &bottom))
return t->right;
return NULL;
}
void *aatree_get_data(aatree_t *t) {
return t->key;
}
void aatree_free(aatree_t *t) {
if (t == &bottom)
return;
aatree_free(t->left);
aatree_free(t->right);
free(t);
}
} // End of namespace Sci
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