-Components onDestroy() support (called when component is destoryed)

-EntityCallers pointers to systems now are updated after adding new system (or in future system reloading)
-fixed compilation issue referenced to filling components with default values

source/ecs/manager.d

@@ -124,22 +124,38 @@ class EntityManager
 
         foreach (info; &entities_infos.byValue)
         {
-            addEntityCaller(*info, systems[$ - 1]);
+            addEntityCaller(*info, cast(uint)systems.length - 1);
         }
+
+        updateEntityCallers();
     }
 
     void registerComponent(Comp)()
     {
+
+        ComponentInfo info;
+
         static if (!(hasMember!(Comp, "component_id")) || !is(typeof(Comp.component_id) == ushort))
         {
             static assert(0, "Component should have \"__gshared ushort component_id");
         }
 
-        ComponentInfo info;
+        static if (hasMember!(Comp, "onDestroy") && isFunction!(Comp.onDestroy)
+                && is(ReturnType!(Comp.onDestroy) == void)
+                && Parameters!(Comp.onDestroy).length == 0)
+        {
+            static void callDestroy(void* pointer)
+            {
+                (cast(Comp*) pointer).onDestroy();
+            }
+
+            info.destroy_callback = &callDestroy;
+        }
+
         info.size = Comp.sizeof;
         info.aligment = Comp.alignof; //8;
         info.init_data = Mallocator.instance.makeArray!ubyte(Comp.sizeof);
-        *cast(Comp*)info.init_data.ptr = Comp();
+        *cast(Comp*) info.init_data.ptr = Comp.init; // = Comp();
 
         components.add(info);
         Comp.component_id = cast(ushort)(components.length - 1);
@@ -203,9 +219,10 @@ class EntityManager
         temp.info = info;
 
         //fill components with default data
-        foreach(comp;info.components)
+        foreach (comp; info.components)
         {
-            temp.entity_data[info.deltas[comp]..info.deltas[comp]+components[comp].size] = components[comp].init_data;
+            temp.entity_data[info.deltas[comp] .. info.deltas[comp] + components[comp].size]
+                = components[comp].init_data;
         }
 
         return temp;
@@ -233,21 +250,35 @@ class EntityManager
             }
             alignNum(info.size, info.alignment);
 
-            foreach (ref system; systems)
+            foreach (uint i, ref system; systems)
             {
                 if (system.m_update is null)
                     continue;
-                addEntityCaller(*info, system);
+                addEntityCaller(*info, i);
             }
 
+            updateEntityCallers();
+
             entities_infos.add(info.components, info);
         }
         return info;
     }
 
-    void addEntityCaller(ref EntityInfo entity, ref System system)
+    void updateEntityCallers()
     {
-        CallData call_data = CallData(&system, &entity, null);
+        foreach(entity;&entities_infos.byValue)
+        {
+            foreach(caller;entity.callers)
+            {
+                caller.system = &systems[caller.system_id];
+            }
+        }
+    }
+
+    void addEntityCaller(ref EntityInfo entity, uint system_id)
+    {
+        System* system = &systems[system_id];
+        CallData call_data = CallData(system_id, system, &entity, null);
         ushort[] deltas = (cast(ushort*) alloca(system.m_components.length * ushort.sizeof))[0
             .. system.m_components.length];
         foreach (i, id; system.m_components)
@@ -443,10 +474,12 @@ class EntityManager
         EntitiesBlock* block = getMetaData(entity);
         id_manager.releaseID(id); //release id from manager
 
-        removeEntityNoID(entity, block);
+        removeEntityNoID(entity, block, true);
+
     }
 
-    private void removeEntityNoID(Entity* entity, EntitiesBlock* block)
+    private void removeEntityNoID(Entity* entity, EntitiesBlock* block,
+            bool call_destructors = false)
     {
         //pos is Entity number in block
         void* data_begin = block.dataBegin();
@@ -458,6 +491,18 @@ class EntityManager
         if (block.type_data.first_with_free_space.id > block.id)
             block.type_data.first_with_free_space = block;
 
+        if(call_destructors)
+        {
+            void* data = data_begin + pos * block.type_data.size;
+            foreach(comp;block.type_data.components)
+            {
+                if(components[comp].destroy_callback)
+                {
+                    components[comp].destroy_callback(data + block.type_data.deltas[comp]);
+                }
+            }
+        }
+
         if (pos == block.entities_count)
             return;
 
@@ -488,6 +533,7 @@ class EntityManager
         ushort size;
         ushort aligment;
         ubyte[] init_data;
+        void function(void* pointer) destroy_callback;
     }
 
     /************************************************************************************************************************
@@ -548,6 +594,8 @@ class EntityManager
     */
     struct CallData
     {
+        ///system ID. Used to update system pointer after system reload.
+        uint system_id;
         ///pointer to used system
         System* system;
         ///poiner to Entity type info