refactor rm code

diff --git a/source/rbt/rbt.c b/source/rbt/rbt.c
index 745dfea4107f347db2ad2e7cd9759be57410c086..14400a3028e9f750e4c4f0dab8396ae044b19861 100644 (file)
--- a/source/rbt/rbt.c
+++ b/source/rbt/rbt.c
@@ -230,9 +230,8 @@ static rbt_node_t* rightmost_descendent(rbt_node_t* node){
 }
 
 static void rbt_delete_node(rbt_t* tree, rbt_node_t* node){
-       (void) tree;
+       rbt_node_t* parent = node->parent;
        if(node->left && node->right){
-               rbt_node_t* parent = node->parent;
                rbt_node_t* replacement = rightmost_descendent(node->left);
                mem_retain(replacement);
                rbt_delete_node(tree, replacement);
@@ -247,30 +246,24 @@ static void rbt_delete_node(rbt_t* tree, rbt_node_t* node){
                else parent->right = replacement;
        }else{
                //node has at most one non-leaf child
-               rbt_node_t* parent = node->parent;
+               rbt_node_t* child = NULL;
                if(RED == node_color(node)){
-                       //node is red and has only leaf children or tree is invalid.
+                       //node cannot have children
                        if(node == parent->left) parent->left = NULL;
                        else parent->right = NULL;
                } 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;
+                       child = node->left ? node->left : node->right;
                        child->color = BLACK;
-               } else if(BLACK == node_color(node)){
+               } else {
                        rbt_del_rebalance(tree, node);
+                       //reset child/parent after rebalance; tree may have been rotated
                        parent = node->parent;
-                       rbt_node_t* child = node->left ? node->left : node->right;
-                       if(!parent){
-                               tree->root = child;
-                               if(child) child->color = BLACK;
-                       }
-                       else if(node == parent->right) parent->right = child;
-                       else parent->left = child;
-                       if(child) child->parent = parent;
+                       child = node->left ? node->left : node->right;
                }
+               if(child) child->parent = parent;
+               if(NULL == parent) tree->root = child;
+               else if(node == parent->right) parent->right = child;
+               else parent->left = child;
        }
        node->left = NULL;
        node->right = NULL;