红黑树插入代码学习

算法导论的伪代码的注释看的很晕啊，网上找到代码，研究下：

void rb_tree_insert(rb_tree * &T, int value)
{
   rb_tree *z = new rb_tree();
   z->data = value;//即将插入的节点
   rb_tree *y = nil;
   rb_tree *x = T;
   while (x != nil)
   {
       y = x;
       if(x->data > z->data)
           x = x->left;
       else
           x = x->right;
   }
   z->parent = y;
   if(y == nil)
       T = z;
   else
   {
       if (z->data < y->data)
       {
           y->left = z;
       } 
       else
       {
           y->right = z;
       }
   }
   z->left = z->right = nil;
   z->color = red;
}

rb_tree * rb_insert_fixup(rb_tree *T, rb_tree *z)
{
   rb_tree *y = NULL;
   while(z != T && z->parent->color == red)//z不是根节点而且父节点为红
   {
       if (z->parent == z->parent->parent->left)//父节点是祖父节点的左子树
       {
           y = z->parent->parent->left;//y为z的叔节点
           if(y && y->color == red)//叔节点存在而且为红
           {
              z->parent->color = black;//更改父节点为黑
              y->color = black;//叔节点也改为黑
              z->parent->parent->color = red;//祖父节点改为红
              z = z->parent->parent;//z上升至祖父节点继续迭代确保红黑树的性质
           }
           else //无叔节点或者叔节点为黑
           {   
               if (z == z->parent->right)//如果新节点是父节点的右子树
               {
                   z = z->parent;
                   left_rotate(z);
               } 
               z->parent->color = black;//父节点改为黑色
               z->parent->parent->color = red;//祖父节点改为红色
               right_rotate(z->parent->parent);
           }
       }
       else
       {
           y = z->parent->parent->right;//y为z的叔节点
           if(y && y->color == red)//叔节点存在而且为红
           {
               z->parent->color = black;//更改父节点为黑
               y->color = black;//叔节点也改为黑
               z->parent->parent->color = red;//祖父节点改为红
               z = z->parent->parent;//z上升至祖父节点继续迭代确保红黑树的性质
           }
           else //无叔节点或者叔节点为黑
           {   
               if (z == z->parent->left)//如果新节点是父节点的右子树
               {
                   z = z->parent;
                   right_rotate(z);
               } 
               z->parent->color = black;//父节点改为黑色
               z->parent->parent->color = red;//祖父节点改为红色
               left_rotate(z->parent->parent);
           }
       }
   }
   T->color = black;
   return T;
}