function for replacing node in tree

diff --git a/source/rbt/rbt.c b/source/rbt/rbt.c
index 533c3b556fc70455d3aeb50902f5ae73c83fbe58..764a83c3b1089c813fb24b0e1818c62eb9e56dcd 100644 (file)
--- a/source/rbt/rbt.c
+++ b/source/rbt/rbt.c
@@ -71,6 +71,13 @@ rbt_node_t* rbt_lookup(rbt_t* tree, void* value){
 /*    generally helpful tree manipulation    */
 /* ----------------------------------------- */
 
+static void rbt_node_replace(rbt_t* tree, rbt_node_t* target, rbt_node_t* replacement){
+       if(NULL == target->parent) tree->root = replacement;
+       else if(target == target->parent->left) target->parent->left = replacement;
+       else target->parent->right = replacement;
+       if(replacement) replacement->parent = target->parent;
+}
+
 typedef enum {
        LEFT = 0, RIGHT
 } direction_t;
@@ -80,10 +87,7 @@ static void rotate(rbt_t* tree, rbt_node_t* node, direction_t direction){
        if(edon){
                rbt_node_t** edon_side = (direction == LEFT ? &(edon->left) : &(edon->right));
                rbt_node_t** node_side = (direction == LEFT ? &(node->right) : &(node->left));
-               if(NULL == node->parent) tree->root = edon;
-               else if(node->parent->left == node) node->parent->left = edon;
-               else node->parent->right = edon;
-               edon->parent = node->parent;
+               rbt_node_replace(tree, node, edon);
                *node_side = *edon_side; //safe to overwrite; points to edon
                if(*edon_side) (*edon_side)->parent = node;
                *edon_side = node;
@@ -208,11 +212,8 @@ static void rbt_delete_node(rbt_t* tree, rbt_node_t* node){
                if(node->right) node->right->parent = replacement;
                replacement->left = node->left;
                replacement->right = node->right;
-               replacement->parent = node->parent;
                replacement->color = node->color;
-               if(NULL == parent) tree->root = replacement;
-               else if(node == parent->left) parent->left = replacement;
-               else parent->right = replacement;
+               rbt_node_replace(tree, node, replacement);
        }else{
                //node has at most one non-leaf child
                rbt_node_t* child = NULL;
@@ -229,10 +230,7 @@ static void rbt_delete_node(rbt_t* tree, rbt_node_t* node){
                        parent = node->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;
+               rbt_node_replace(tree, node, child);
        }
        node->left = NULL;
        node->right = NULL;