combine rotate functions into one w/ param for direction

diff --git a/source/rbt/rbt.c b/source/rbt/rbt.c
index 14400a3028e9f750e4c4f0dab8396ae044b19861..8ddda43162d3a3e845a3562c95e40bc22415f91c 100644 (file)
--- a/source/rbt/rbt.c
+++ b/source/rbt/rbt.c
@@ -44,46 +44,34 @@ static rbt_color_t node_color(rbt_node_t* node){
        return (node ? node->color : BLACK);
 }
 
-static void rotate_right(rbt_t* tree, rbt_node_t* node){
-       rbt_node_t* edon = node->left;
-       if(edon) {
-               //attach edon in node's place:
-               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;
-               //reattach edon's right to node's left
-               //safe to overwrite node->left : is edon
-               node->left = edon->right;
-               if(edon->right) edon->right->parent = node;
-               //attach node to edon
-               edon->right = node;
-               node->parent = edon;
-       } /* else something went wrong... */
-}
+typedef enum {
+       LEFT = 0, RIGHT
+} direction_t;
 
-static void rotate_left(rbt_t* tree, rbt_node_t* node){
-       rbt_node_t* edon = node->right;
-       if(edon) {
-               //attach edon in node's place:
+static void rotate(rbt_t* tree, rbt_node_t* node, direction_t direction){
+       rbt_node_t* edon = (direction == LEFT) ? node->right : node->left;
+       if(edon){
                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;
-               //reattach edon's left to node's right
-               //safe to overwrite node->right : is edon
-               node->right = edon->left;
-               if(edon->left) edon->left->parent = node;
-               //attach node to edon
-               edon->left = node;
+               if(direction == LEFT){
+                       node->right = edon->left; //safe to overwrite node->right : is edon
+                       if(edon->left) edon->left->parent = node;
+                       edon->left = node;
+               } else { //mirror of above
+                       node->left = edon->right; //safe to overwrite node->left : is edon
+                       if(edon->right) edon->right->parent = node;
+                       edon->right = node;
+               }
                node->parent = edon;
-       } /* else something went wrong... */
+       } /* else rotation isn't allowed */
 }
 
 static void rbt_rotate_outside_left(rbt_t* tree, rbt_node_t* node){
        rbt_node_t* parent = node->parent;
        rbt_node_t* grandparent = (parent ? parent->parent : NULL);
-       rotate_right(tree, grandparent);
+       rotate(tree, grandparent, RIGHT);
        parent->color = BLACK;
        grandparent->color = RED;
 }
@@ -92,7 +80,7 @@ static void rbt_rotate_outside_left(rbt_t* tree, rbt_node_t* node){
 static void rbt_rotate_outside_right(rbt_t* tree, rbt_node_t* node){
        rbt_node_t* parent = node->parent;
        rbt_node_t* grandparent = (parent ? parent->parent : NULL);
-       rotate_left(tree, grandparent);
+       rotate(tree, grandparent, LEFT);
        parent->color = BLACK;
        grandparent->color = RED;
 }
@@ -115,13 +103,13 @@ static void rbt_ins_recolor(rbt_t* tree, rbt_node_t* node){
        }else if(node == parent->right && parent == grandparent->left){
                //parent is red, uncle is black, "inside left" case
                //first rotate node and parent
-               rotate_left(tree, parent);
+               rotate(tree, parent, LEFT);
                //tree now transformed to an "outside left" case
                rbt_rotate_outside_left(tree, parent);
        }else if(node == parent->left && parent == grandparent->right){
                //parent is red, uncle is black, "inside right" case
                //first rotate node and parent
-               rotate_right(tree, parent);
+               rotate(tree, parent, RIGHT);
                //tree now transformed to an "outside right" case
                rbt_rotate_outside_right(tree, parent);
        }else if(node == parent->left && parent == grandparent->left){
@@ -186,8 +174,8 @@ static void rbt_del_rebalance(rbt_t* tree, rbt_node_t* node){
                rbt_node_t* sib = (node == parent->left ? parent->right : parent->left);
                if(RED == node_color(sib)){
                        //if sibbling is red, rotate to make sibbling black
-                       if(node == parent->left) rotate_left(tree, parent);
-                       else rotate_right(tree, parent);
+                       if(node == parent->left) rotate(tree, parent, LEFT);
+                       else rotate(tree, parent, RIGHT);
                        parent->color = RED;
                        sib->color = BLACK;
                        //recurse with new sibbling / parent
@@ -201,10 +189,10 @@ static void rbt_del_rebalance(rbt_t* tree, rbt_node_t* node){
                        //convert "inside" case to "outside" case
                        sib->left->color = BLACK;
                        sib->color = RED;
-                       rotate_right(tree, sib);
+                       rotate(tree, sib, RIGHT);
                        rbt_del_rebalance(tree, node);
                }else if(node == parent->left && RED == node_color(sib->right)){
-                       rotate_left(tree, parent);
+                       rotate(tree, parent, LEFT);
                        sib->color = parent->color;
                        parent->color = BLACK;
                        sib->right->color = BLACK;
@@ -212,10 +200,10 @@ static void rbt_del_rebalance(rbt_t* tree, rbt_node_t* node){
                        //convert "inside" case to "outside" case
                        sib->right->color = BLACK;
                        sib->color = RED;
-                       rotate_left(tree, sib);
+                       rotate(tree, sib, LEFT);
                        rbt_del_rebalance(tree, node);
                }else{
-                       rotate_right(tree, parent);
+                       rotate(tree, parent, RIGHT);
                        sib->color = parent->color;
                        parent->color = BLACK;
                        sib->left->color = BLACK;