From cb896fae1a0dd7e718d0b631e8fb658dbddb3324 Mon Sep 17 00:00:00 2001
From: Guillaume Bittoun <guillaume.bittoun@gmail.com>
Date: Wed, 8 Oct 2014 13:58:44 +0000
Subject: [PATCH] avl_tree: first incomplete draft
---
src/lol/base/avl_tree.h | 177 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 177 insertions(+)
create mode 100644 src/lol/base/avl_tree.h
diff --git a/src/lol/base/avl_tree.h b/src/lol/base/avl_tree.h
new file mode 100644
index 00000000..8157e66d
--- /dev/null
+++ b/src/lol/base/avl_tree.h
@@ -0,0 +1,177 @@
+//
+// Lol Engine
+//
+// Copyright: (c) 2010-2014 Sam Hocevar <sam@hocevar.net>
+// (c) 2013-2014 Benjamin "Touky" Huet <huet.benjamin@gmail.com>
+// (c) 2013-2014 Guillaume Bittoun <guillaume.bittoun@gmail.com>
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the Do What The Fuck You Want To
+// Public License, Version 2, as published by Sam Hocevar. See
+// http://www.wtfpl.net/ for more details.
+//
+
+#pragma once
+
+
+namespace lol
+{
+
+
+template<typename K, typename V>
+class avl_tree
+{
+ avl_tree() :
+ m_root(0)
+ {
+ }
+
+ bool insert(K const & key, V const & value)
+ {
+ if (!m_root)
+ this->m_root = new tree_node(key, value);
+ else
+ {
+ tree_node * created = this->m_root->insert(key, value);
+
+ if (created)
+ {
+ this->m_root->path_update_balance(created);
+
+ tree_node * new_root = this->m_root->path_rebalance(created);
+ if (new_root)
+ this->m_root = new_root;
+ }
+ else
+ return false;
+ }
+
+ return true;
+ }
+
+private:
+
+ class tree_node
+ {
+ tree_node(K key, V value) :
+ m_key(key),
+ m_value(value),
+ m_lo(0),
+ m_hi(0)
+ m_stairs_lo(0),
+ m_stairs_hi(0),
+ {
+ }
+
+ tree_node * insert(K const & key, V const & value)
+ {
+ tree_node * ret = 0;
+
+ if (key < this->m_key)
+ {
+ if (this->m_lo)
+ ret = this->m_lo->insert(key, value);
+ else
+ ret = this->m_lo = new tree_node(key, value);
+ }
+ else if (this->m_key < key)
+ {
+ if (this->m_hi)
+ ret = this->m_hi->insert(key, value);
+ else
+ ret = this->m_hi = new tree_node(key, value);
+ }
+ else
+ this->m_value = value;
+
+ return ret;
+ }
+
+ int path_update_balance(K const & key)
+ {
+ if (key < this->m_key)
+ this->m_stairs_lo = lol::max(this->m_lo->path_update_balance(node), this->m_stairs_lo);
+ else if (this->m_key < key)
+ this->m_stairs_hi = lol::max(this->m_hi->path_update_balance(node), this->m_stairs_hi);
+
+ return lol::max(this->m_stairs_lo, this->m_stairs_hi) + 1;
+ }
+
+ tree_node * path_rebalance(K const & key)
+ {
+ if (key < this->m_key)
+ {
+ tree_node * node = this->m_lo->path_rebalance();
+ if (node)
+ {
+ this->m_lo = node;
+ --this->m_lo;
+ }
+ }
+ else if (this->m_key < key)
+ {
+ tree_node * node = this->m_hi->path_rebalance();
+ if (node)
+ {
+ this->m_hi = node;
+ --this->m_hi;
+ }
+ }
+
+ if (this->m_stairs_lo - this->m_stairs_hi == 2)
+ {
+ return this->rotate();
+ }
+ else if (this->m_stairs_lo - this->m_stairs_hi == -2)
+ {
+ return this->rotate();
+ }
+ else
+ assert(lol::abs(this->m_stairs_lo - this->m_stairs_hi) < 3);
+ }
+
+ enum Rotation { CW = 0, CCW = 1 };
+
+ tree_node * rotate(Rotation rotation)
+ {
+ if (rotation == CW)
+ {
+ tree_node * lo = this->m_lo;
+ tree_node * lo_hi = this->m_lo->m_hi;
+
+ this->m_lo->m_hi = this;
+ this->m_lo = lo_hi;
+
+ // TODO : Rebalance
+
+ return lo;
+ }
+ else // rotation == CCW
+ {
+ tree_node * lo = this->m_lo;
+ tree_node * lo_hi = this->m_lo->m_hi;
+
+ this->m_lo->m_hi = this;
+ this->m_lo = lo_hi;
+
+ // TODO : Rebalance
+
+ return lo;
+ }
+ }
+
+ private:
+
+ K m_key;
+ V m_value;
+
+ tree_node * m_lo;
+ tree_node * m_hi;
+
+ int m_stairs_lo;
+ int m_stairs_hi;
+ };
+
+ tree_node * m_root;
+};
+
+}