insert *untested*

diff --git a/source/rb/rb.c b/source/rb/rb.c
index cc2b0c41079b457bc2f0e4ea4bb6c44079a181d2..69d24a7061cc7b53ae4a63a5e884cc9f04def1aa 100644 (file)
--- a/source/rb/rb.c
+++ b/source/rb/rb.c
@@ -38,6 +38,45 @@ static rb_color_t node_color(rb_node_t* node){
        return (node ? node->color : BLACK);
 }
 
+static void rb_tree_rotate_outside_left(rb_node_t* node){
+       rb_node_t* parent = node->parent;
+       rb_node_t* grandparent = (parent ? parent->parent : NULL);
+       //rb_node_t* uncle = (grandparent ? (parent == grandparent->left ? grandparent->right : grandparent->left) : NULL);
+       rb_node_t* greatgrand = (grandparent ? grandparent->parent : NULL);
+       //move parent to grandparent's position:
+       //first point greatgrand at parent on the appropriate side:
+       if(greatgrand && grandparent == greatgrand->left) greatgrand->left = parent;
+       else if(greatgrand && grandparent == greatgrand->right) greatgrand->right = parent;
+       //update parent's parent pointer.
+       parent->parent = greatgrand;
+       //parent->right shouldn't actually be anything.. but save it anyway
+       grandparent->left = parent->right; //safe to overwrite gp->left. it is parent.
+       parent->right = grandparent;
+       grandparent->parent = parent;
+       //repaint nodes as needed:
+       parent->color = BLACK;
+       grandparent->color = RED;
+}
+
+//mirror of above:
+static void rb_tree_rotate_outside_right(rb_node_t* node){
+       rb_node_t* parent = node->parent;
+       rb_node_t* grandparent = (parent ? parent->parent : NULL);
+       //rb_node_t* uncle = (grandparent ? (parent == grandparent->left ? grandparent->right : grandparent->left) : NULL);
+       rb_node_t* greatgrand = (grandparent ? grandparent->parent : NULL);
+       //move parent to grandparent's position
+       if(greatgrand && grandparent == greatgrand->left) greatgrand->left = parent;
+       else if(greatgrand && grandparent == greatgrand->right) greatgrand->right = parent;
+       parent->parent = greatgrand;
+       //perform swap
+       grandparent->right = parent->left; //safe to overwrite gp->right. it is parent.
+       parent->left = grandparent;
+       grandparent->parent = parent;
+       //repaint nodes
+       parent->color = BLACK;
+       grandparent->color = RED;
+}
+
 //NODE:the node to be inserted
 static void rb_tree_recolor(rb_node_t* node){
        rb_node_t* parent = node->parent;
@@ -47,15 +86,41 @@ static void rb_tree_recolor(rb_node_t* node){
                node->color = BLACK;
        }else if(BLACK == node_color(parent)){
                /* dont need to do anything */
-       }else if(node_color(parent) == RED && node_color(uncle) == RED){
+       }else if(node_color(uncle) == RED){
+               //parent and uncle are both red. both can be painted black
                grandparent->color = RED;
                parent->color = BLACK;
                uncle->color = BLACK;
                rb_tree_recolor(grandparent);
-       }else{
-               //TODO
+       }else if(node == parent->right && parent == grandparent->left){
+               //parent is red, uncle is black, "inside left" case
+               //first rotate node and parent
+               grandparent->left = node;
+               node->parent = grandparent;
+               node->left = parent;
+               parent->parent = node;
+               parent->right = NULL;
+               //tree now transformed to an "outside left" case
+               rb_tree_rotate_outside_left(parent);
+       }else if(node == parent->left && parent == grandparent->right){
+               //parent is red, uncle is black, "inside right" case
+               //first rotate node and parent
+               grandparent->right = node;
+               node->parent = grandparent;
+               node->right = parent;
+               parent->parent = node;
+               parent->left = NULL;
+               //tree now transformed to an "outside right" case
+               rb_tree_rotate_outside_right(parent);
+       }else if(node == parent->left && parent == grandparent->left){
+               //parent is red, uncle is black, "outside left" case
+               rb_tree_rotate_outside_left(node);
+       }else if(node == parent->right && parent == grandparent->right){
+               //parent is red, uncle is black, "outside right" case
+               rb_tree_rotate_outside_right(node);
        }
 }
+
 static void rb_tree_insert_node(rb_tree_t* tree, rb_node_t* node, rb_node_t* parent){
        if(NULL == parent){ /* inserting root of the tree */
                tree->root = node;