From 6fd247b9eb47fbb3d5060aa928d8ca7c882237a6 Mon Sep 17 00:00:00 2001
From: Guillaume Bittoun <guillaume.bittoun@gmail.com>
Date: Sat, 28 Feb 2015 09:12:34 +0000
Subject: [PATCH] map: starting bug fix

---
 src/lol/base/avl_tree.h | 105 ++++++++++++++++++++++++++++------------
 src/t/base/map.cpp      |   6 +--
 2 files changed, 76 insertions(+), 35 deletions(-)

diff --git a/src/lol/base/avl_tree.h b/src/lol/base/avl_tree.h
index 3a7b1b28..ccb6c76f 100644
--- a/src/lol/base/avl_tree.h
+++ b/src/lol/base/avl_tree.h
@@ -223,19 +223,15 @@ protected:
         {
             int i = -1 + (key < m_key) + 2 * (m_key < key);
 
+            bool created = false;
+
             if (i < 0)
-            {
                 m_value = value;
-                return false;
-            }
-
-            bool b_created = false;
-
-            if (m_child[i])
-                b_created = m_child[i]->insert(key, value);
+            else if (m_child[i])
+                created = m_child[i]->insert(key, value);
             else
             {
-                b_created = true;
+                created = true;
 
                 m_child[i] = new tree_node(key, value, &m_child[i]);
 
@@ -247,10 +243,13 @@ protected:
                 m_chain[i] = m_child[i];
             }
 
-            if (b_created)
+            if (created)
+            {
                 rebalance_if_needed();
+            }
+
 
-            return b_created;
+            return created;
         }
 
         /* Erase a value in tree and return true or return false */
@@ -258,19 +257,21 @@ protected:
         {
             int i = -1 + (key < m_key) + 2 * (m_key < key);
 
+            bool erased = false;
+
             if (i < 0)
             {
                 erase_self();
                 delete this;
-                return true;
+                erased = true;
             }
             else if (m_child[i] && m_child[i]->erase(key))
             {
                 rebalance_if_needed();
-                return true;
+                erased = true;
             }
 
-            return false;
+            return erased;
         }
 
         bool try_get(K const & key, V * & value_ptr)
@@ -345,30 +346,57 @@ protected:
         {
             update_balance();
 
-            int i = (get_balance() ==  2);
-            int j = (get_balance() == -2);
+            int i = -1 + (get_balance() == -2) + 2 * (get_balance() == 2);
 
-            if (i || j)
+            if (i != -1)
             {
-                tree_node * save = m_child[i];
-                tree_node ** save_parent = m_parent_slot;
+                tree_node * replacement = nullptr;
 
-                set_child(i, save->m_child[j]);
-                save->set_child(j, this);
 
-                save->m_parent_slot = save_parent;
-                *save_parent = save;
+                if (get_balance() / 2 + m_child[i]->get_balance() == 0)
+                {
+                    replacement = m_child[i]->m_child[1 - i];
+                    tree_node * save0 = replacement->m_child[i];
+                    tree_node * save1 = replacement->m_child[1 - i];
 
-                update_balance();
-                save->update_balance();
-            }
-        }
+                    replacement->m_parent_slot = this->m_parent_slot;
+                    *replacement->m_parent_slot = replacement;
 
-        void set_child(int i, tree_node * node)
-        {
-            m_child[i] = node;
-            if (node)
-                node->m_parent_slot = &m_child[i];
+                    replacement->m_child[i] = m_child[i];
+                    m_child[i]->m_parent_slot = &replacement->m_child[i];
+
+                    replacement->m_child[1 - i] = this;
+                    this->m_parent_slot = &replacement->m_child[1 - i];
+
+                    replacement->m_child[i]->m_child[1 - i] = save0;
+                    if (save0)
+                        save0->m_parent_slot = &replacement->m_child[i]->m_child[1 - i];
+
+                    replacement->m_child[1 - i]->m_child[i] = save1;
+                    if (save1)
+                        save1->m_parent_slot = &replacement->m_child[i]->m_child[1 - i];
+                }
+                else
+                {
+
+                    replacement = m_child[i];
+                    tree_node * save = replacement->m_child[1 - i];
+
+                    replacement->m_parent_slot = this->m_parent_slot;
+                    *replacement->m_parent_slot = replacement;
+
+                    replacement->m_child[1 - i] = this;
+                    this->m_parent_slot = &replacement->m_child[1 - i];
+
+                    this->m_child[i] = save;
+                    if (save)
+                        save->m_parent_slot = &this->m_child[i];
+                }
+
+                replacement->m_child[0]->update_balance();
+                replacement->m_child[1]->update_balance();
+                replacement->update_balance();
+            }
         }
 
         void erase_self()
@@ -398,6 +426,9 @@ protected:
                 if (replacement->m_child[1])
                     replacement->m_child[1]->m_parent_slot = &replacement->m_child[1];
 
+                if (replacement->m_child[1-i])
+                    replacement->m_child[1-i]->deep_balance(replacement->m_key);
+
                 replacement->update_balance();
             }
             else
@@ -406,6 +437,16 @@ protected:
             replace_chain(replacement);
         }
 
+        void deep_balance(K const & key)
+        {
+            int i = -1 + (key < m_key) + 2 * (m_key < key);
+
+            if (i != -1 && m_child[i])
+                m_child[i]->deep_balance(key);
+
+            update_balance();
+        }
+
         void replace_chain(tree_node * replacement)
         {
             if (replacement)
diff --git a/src/t/base/map.cpp b/src/t/base/map.cpp
index 996214b1..ab1eed46 100644
--- a/src/t/base/map.cpp
+++ b/src/t/base/map.cpp
@@ -125,6 +125,9 @@ lolunit_declare_fixture(MapTest)
 
         for (int i = 0 ; i < 10000 ; ++i)
         {
+            // debug output
+            // std::cout << "i " << i << ", a " << (int)a << ", b " << (int)b  << std::endl;
+
             m[a] = b;
             m.remove(b);
 
@@ -132,9 +135,6 @@ lolunit_declare_fixture(MapTest)
             value[a] = b;
             presence[b] = 0;
 
-            // debug output
-            // std::cout << "a " << (int)a << ", b " << (int)b  << std::endl;
-
             a = a * b + c;
             b = b * c + a;
             c = c * a + b;