less shitty code in node deletion

diff --git a/source/rbt/rbt.c b/source/rbt/rbt.c
index 630e6e1187a15a93e06873922618862ed64905bd..216679fc4ff48125255323f75a638f4b337629dc 100644 (file)
--- a/source/rbt/rbt.c
+++ b/source/rbt/rbt.c
@@ -258,118 +258,32 @@ static void rbt_delete_node(rbt_t* tree, rbt_node_t* node){
                        else parent->right = NULL;
                        node->parent = NULL;
                        mem_release(node);
-               } else if(RED == node_color(node->left) && BLACK == node_color(node->right)){
-                       //single red child, to the left
-                       rbt_node_t* child = node->left;
+               } else if(RED == node_color(node->left) || RED == node_color(node->right)){
+                       rbt_node_t* child = node->left ? node->left : node->right;
                        child->parent = parent;
                        if(NULL == parent) tree->root = child;
                        else if(parent->left == node) parent->left = child;
                        else parent->right = child;
-                       //safe to destroy node->right ; it is a NULL leaf
                        child->color = BLACK;
                        node->left = NULL;
-                       node->parent = NULL;
-                       mem_release(node);
-               } else if(RED == node_color(node->right) && BLACK == node_color(node->left)){
-                       //single red child, to the right
-                       rbt_node_t* child = node->right;
-                       child->parent = parent;
-                       if(NULL == parent) tree->root = child;
-                       else if(parent->left == node) parent->left = child;
-                       else parent->right = child;
-                       child->color = BLACK;
                        node->right = NULL;
                        node->parent = NULL;
                        mem_release(node);
-               } else if(node == tree->root){
-                       //at most one child & no red children :: no children.
-                       tree->root = NULL;
-                       //pointers should already be null.
-                       mem_release(node);
-               } else if(RED == node_color(node->parent)){
-                       node->parent = NULL;
-                       if(parent->right == node){
-                               rbt_node_t* sib = parent->left;
-                               parent->right = NULL;
-                               if(sib->right && !sib->left){
-                                       rotate_left(tree, sib);
-                                       parent->color = BLACK;
-                               }
-                               rotate_right(tree, parent);
-                       } else {
-                               rbt_node_t* sib = parent->right;
-                               parent->left = NULL;
-                               if(sib->left && !sib->right){
-                                       rotate_right(tree, sib);
-                                       parent->color = BLACK;
-                               }
-                               rotate_left(tree, parent);
-                       }
-                       mem_release(node);
-               } else if(node == parent->right && (parent->left->left || parent->left->right)){
-                       //node is black. parent is black. node is parent's right child.
-                       //sibbling has at least one non-leaf child
-                       rbt_node_t* sib = parent->left;
-                       //remove/release the node
-                       parent->right = NULL;
-                       node->parent = NULL;
-                       mem_release(node);
-                       //rebalance the tree
-                       //fix sibbling if red first
-                       if(RED == node_color(sib)){
-                               sib->color = BLACK;
-                               sib->right->color = RED;
-                               //sib->left->color = RED; //unnecessary; gets overwritten anyway.
-                       }
-                       //rotate "inside" case to "outside"
-                       if(sib->right && !sib->left){
-                               sib->right->color = BLACK;
-                               rotate_left(tree, sib);
-                       }
-                       if(sib->left) sib->left->color = BLACK;
-                       rotate_right(tree, parent);
-               } else if(node == parent->left && (parent->right->left || parent->right->right)){
-                       //node is black. parent is black. node is parent's left child.
-                       //sibbling has at least one non-leaf child
-                       rbt_node_t* sib = parent->right;
-                       //remove/release the node
-                       parent->left = NULL;
-                       node->parent = NULL;
-                       mem_release(node);
-                       //rebalance the tree
-                       //fix sibbling if red first
-                       if(RED == node_color(sib)){
-                               sib->color = BLACK;
-                               sib->left->color = RED;
-                               //sib->right->color = RED; //unnecessary; gets overwritten anyway.
-                       }
-                       //rotate "inside" case to "outside"
-                       if(sib->left && !sib->right){
-                               sib->left->color = BLACK;
-                               rotate_right(tree, sib);
+               } else if(BLACK == node_color(node)){
+                       rbt_del_rebalance(tree, node);
+                       parent = node->parent;
+                       rbt_node_t* child = node->left ? node->left : node->right;
+                       if(!parent){
+                               tree->root = child;
+                               if(child) child->color = BLACK;
                        }
-                       if(sib->right) sib->right->color = BLACK;
-                       rotate_left(tree, parent);
-               } else if(node == parent->right){
-                       //node is black, parent is black, sibbling has no children
-                       rbt_node_t* sib = parent->left;
-                       //remove/release the node;
-                       parent->right = NULL;
-                       node->parent = NULL;
-                       mem_release(node);
-                       //rebalance the tree
-                       sib->color = RED;
-                       rbt_del_rebalance(tree, parent);
-               } else {
-                       //node is black, parent is black, sibbling has no children
-                       rbt_node_t* sib = parent->right;
-                       //remove/release the node;
-                       parent->left = NULL;
+                       else if(node == parent->right) parent->right = child;
+                       else parent->left = child;
+                       if(child) child->parent = parent;
+                       node->left = NULL;
+                       node->right = NULL;
                        node->parent = NULL;
                        mem_release(node);
-                       //rebalance the tree
-                       sib->color = RED;
-                       rbt_del_rebalance(tree, parent);
                }
        }
 }