insert.c
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/**
* \file
*
* \author Georg Hopp
*
* \copyright
* Copyright © 2012 Georg Hopp
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "trbase.h"
#include "tr/tree.h"
void *
TR_treeInsert(TR_Tree * this, const void * search, TR_TreeComp comp)
{
TR_Tree node = *this;
TR_Tree new_node = NULL;
int found;
TR_TREE_FIND(node, search, found, comp);
/*
* insert the node or return the one in tree if comparison
* succeeds.
*/
if (NULL == node) {
/*
* if the root is NULL we simple add the element and set
* node to it.
*/
*this = node = new_node = TR_new(TR_Tree, search);
} else {
if (found == 0) {
// we found an element
// as this is insert and not find this will overwrite an existing
// value, but return the previous one so that it can be freed if
// neccessary.
void * data = node->data;
node->data = (void *)search;
return data;
} else {
// not found
if (0 < found) {
node->left = TR_new(TR_Tree, search);
node->left->parent = node;
node = new_node = node->left;
} else {
node->right = TR_new(TR_Tree, search);
node->right->parent = node;
node = new_node = node->right;
}
}
}
/*
* we expect node not to be NULL and pointing to our
* new node at this point...now rabalance the tree
*/
while (1) {
// case 1
if (NULL == TR_TREE_PARENT(node)) {
node->color = rbBlack;
break;
}
// case 2
if (rbBlack == node->parent->color) {
break;
}
// case 3
TR_Tree uncle = TR_TREE_UNCLE(node);
if (NULL != uncle && rbRed == uncle->color) {
node->parent->color = rbBlack;
uncle->color = rbBlack;
node->parent->parent->color = rbRed;
node = node->parent->parent;
continue;
}
// case 4
if (node == node->parent->right
&& node->parent == node->parent->parent->left) {
TR_TREE_ROTATE(left, this, node->parent);
node = node->left;
} else if (node == node->parent->left
&& node->parent == node->parent->parent->right) {
TR_TREE_ROTATE(right, this, node->parent);
node = node->right;
}
// case 5
node->parent->color = rbBlack;
node->parent->parent->color = rbRed;
if (node == node->parent->left) {
TR_TREE_ROTATE(right, this, node->parent->parent);
} else {
TR_TREE_ROTATE(left, this, node->parent->parent);
}
break;
}
return new_node->data;
}
// vim: set ts=4 sw=4: