-added pure annotation for some functions

-addEntity now returns pointer instead of reference (it's has more sense)
-added function addEntityCopy(EntityID) which adds copy of entity with it's whole data

source/ecs/manager.d

@@ -1056,7 +1056,7 @@ export class EntityManager
         m_dispatch_jobs = func;
     }
 
-    static void alignNum(ref ushort num, ushort alignment) nothrow @nogc
+    static void alignNum(ref ushort num, ushort alignment) nothrow @nogc pure
     {
         num = cast(ushort)((num + alignment - 1) & (-cast(int) alignment)); //num += alignment - (num & (alignment - 1));
     }
@@ -1459,10 +1459,7 @@ export class EntityManager
         new_entity.id = entity.id;
         new_entity.updateID();
 
-        static if (EntityID.sizeof == 8)
+        uint ind = block.entityIndex(entity);
-            uint ind = cast(uint)((cast(void*) entity - block.dataBegin()) >> 3);
-        else
-            uint ind = cast(uint)((cast(void*) entity - block.dataBegin()) / EntityID.sizeof());
 
         if (info.remove_listeners)
         {
@@ -1636,10 +1633,7 @@ export class EntityManager
 
         uint j = 0;
         uint k = 0;
-        static if (EntityID.sizeof == 8)
+        uint ind = block.entityIndex(entity);
-            uint ind = cast(uint)((cast(void*) entity - block.dataBegin()) >> 3);
-        else
-            uint ind = cast(uint)((cast(void*) entity - block.dataBegin()) / EntityID.sizeof());
 
         if (info.remove_listeners)
         {
@@ -1761,12 +1755,66 @@ export class EntityManager
     }
 
     /************************************************************************************************************************
-    *Add entity to system.
+    *Add copy of entity to system and returns pointer to it. Added copy has same data as copied entity. Returen pointer is 
+    *valid only before one from commit(), begin() or end() will be called. To save entity to further use you should save ID 
+    *instead of pointer.
     *
     *Params:
     *tmpl = pointer entity template allocated by EntityManager.
     */
-    export ref Entity addEntity(EntityTemplate* tmpl)
+    export Entity* addEntityCopy(EntityID id)
+    {
+        Entity* entity = getEntity(id);
+        EntitiesBlock* block = getMetaData(entity);
+        EntityInfo* info = block.type_info;
+
+        ushort index = block.entityIndex(entity);
+
+        ushort new_index = 0;
+        EntitiesBlock* new_block;
+        do
+        {
+            new_block = findBlockWithFreeSpaceMT(info);
+            new_index = new_block.added_count.atomicOp!"+="(1);
+        }
+        while (new_block.entities_count + new_index > info.max_entities);
+
+        ushort new_id = cast(ushort)(new_block.entities_count + new_index - 1);
+        const void* data_begin = new_block.dataBegin();
+        const void* start = data_begin + EntityID.sizeof * new_id;
+
+        foreach (i, comp; info.components)
+        {
+            memcpy(cast(void*) new_block + info.deltas[comp] + components[comp].size * new_id,
+                    cast(void*) block + info.deltas[comp] + components[comp].size * index, components[comp].size);
+
+            if (components[comp].create_callback)
+            {
+                components[comp].create_callback(
+                        cast(void*) block + info.deltas[comp] + new_id * components[comp].size);
+            }
+        }
+
+        if (new_index == 1)
+            threads[thread_id].blocks_to_update.add(new_block);
+
+        Entity* new_entity = cast(Entity*) start;
+        //add_mutex.lock_nothrow();
+        new_entity.id = id_manager.getNewID();
+        //add_mutex.unlock_nothrow();
+        new_entity.updateID();
+
+        return new_entity;
+    }
+
+    /************************************************************************************************************************
+    *Add entity to system. Returen pointer is valid only before one from commit(), begin() or end() will be called. To save entity to further
+    *use you should save ID instead of pointer.
+    *
+    *Params:
+    *tmpl = pointer entity template allocated by EntityManager.
+    */
+    export Entity* addEntity(EntityTemplate* tmpl)
     {
         EntityInfo* info = tmpl.info;
 
@@ -1806,7 +1854,7 @@ export class EntityManager
         //add_mutex.unlock_nothrow();
         entity.updateID();
 
-        return *entity;
+        return entity;
     }
 
     /************************************************************************************************************************
@@ -1903,11 +1951,7 @@ export class EntityManager
         EntityInfo* info = block.type_info;
         if (info.remove_listeners)
         {
-            void* data_begin = block.dataBegin();
+            uint pos = block.entityIndex(entity);
-            static if (EntityID.sizeof == 8)
-                uint pos = cast(uint)((cast(void*) entity - data_begin) >> 3);
-            else
-                uint pos = cast(uint)((cast(void*) entity - data_begin) / EntityID.sizeof());
 
             callRemoveEntityListeners(info, block, pos, pos + 1);
         }
@@ -1920,16 +1964,11 @@ export class EntityManager
     private void removeEntityNoID(Entity* entity, EntitiesBlock* block,
             bool call_destructors = false) nothrow @nogc
     {
-        //pos is Entity number in block
-        void* data_begin = block.dataBegin();
         EntityInfo* info = block.type_info;
 
         info.last_block.entities_count--;
 
-        static if (EntityID.sizeof == 8)
+        uint pos = block.entityIndex(entity);
-            uint pos = cast(uint)((cast(void*) entity - data_begin) >> 3);
-        else
-            uint pos = cast(uint)((cast(void*) entity - data_begin) / EntityID.sizeof());
 
         if (call_destructors)
         {
@@ -2173,14 +2212,7 @@ export class EntityManager
                             EntityID entity_id = *cast(EntityID*) event_pointer;
                             Entity* entity = id_manager.getEntityPointer(entity_id);
                             call_data.block = getMetaData(entity);
-
+                            call_data.id = call_data.block.entityIndex(entity);
-                            static if (EntityID.sizeof == 8)
-                                call_data.id = cast(ushort)(
-                                        (cast(void*) entity - call_data.block.dataBegin()) >> 3);
-                            else
-                                call_data.id = cast(ushort)(
-                                        (cast(void*) entity - call_data.block.dataBegin()) / EntityID
-                                        .sizeof);
 
                             foreach (caller; events[i].callers)
                             {
@@ -2580,7 +2612,7 @@ export class EntityManager
     struct EntitiesBlock
     {
         ///return distance (in bytes) from begin of block to data
-        export uint dataDelta() nothrow @nogc
+        export uint dataDelta() nothrow @nogc pure
         {
             ushort dif = EntitiesBlock.sizeof;
             alignNum(dif, type_info.alignment);
@@ -2588,12 +2620,20 @@ export class EntityManager
         }
 
         ///return pointer to first element in block
-        export void* dataBegin() nothrow @nogc
+        export void* dataBegin() nothrow @nogc pure
         {
             ushort dif = EntitiesBlock.sizeof;
             return cast(void*)&this + dif;
         }
 
+        export ushort entityIndex(Entity* entity) nothrow @nogc pure
+        {
+            static if (EntityID.sizeof == 8)
+                return cast(ushort)((cast(void*) entity - dataBegin()) >> 3);
+            else
+                return cast(ushort)((cast(void*) entity - dataBegin()) / EntityID.sizeof());
+        }
+
         ///pointer to Entity type info
         EntityInfo* type_info = null;
         ///number of entities in block

tests/tests.d

@@ -526,13 +526,13 @@ int main()
 	dur = (MonoTime.currTime - time).total!"usecs";
 	writeln("Template allocating: ", dur, " usecs");
 
-	Entity entity;
+	EntityID entity;
 
 	{
-		entity = gEM.addEntity(tmpl);
+		entity = gEM.addEntity(tmpl).id;
-		writeEntityComponents(gEM.getEntity(entity.id));
+		writeEntityComponents(gEM.getEntity(entity));
 		EntityManager.EntitiesBlock* block = EntityManager.instance.getMetaData(
-				gEM.getEntity(entity.id));
+				gEM.getEntity(entity));
 		EntityManager.EntityInfo* info = block.type_info;
 		writeln(info.add_listeners);
 		//if(info)assert(0);
@@ -586,15 +586,15 @@ int main()
 	//assert(*(cast(EntityID*)(cast(void*)tmpl.info.first_block+24)) == EntityID(1,1));
 	//assert(*(cast(EntityID*)(cast(void*)tmpl.info.first_block+48)) == EntityID(1,1));
 
-	Entity entity2;
+	EntityID entity2;
 
 	time = MonoTime.currTime;
 
 	EntityID[] entities = Mallocator.instance.makeArray!EntityID(1_000_000);
 	foreach (i; 0 .. 500_000)
 	{
-		entity2 = gEM.addEntity(tmpl);
+		entity2 = gEM.addEntity(tmpl).id;
-		entities[i*2] = entity2.id;
+		entities[i*2] = entity2;
 		entities[i*2+1] = gEM.addEntity(tmpl2).id;
 	}
 
@@ -638,7 +638,7 @@ int main()
 	dur = (MonoTime.currTime - time).total!"usecs";
 	writeln("Update: ", dur, " usecs");
 
-	writeEntityComponents(gEM.getEntity(entity2.id));
+	writeEntityComponents(gEM.getEntity(entity2));
 
 	time = MonoTime.currTime;
 
@@ -650,7 +650,7 @@ int main()
 	dur = (MonoTime.currTime - time).total!"usecs";
 	writeln("Update: ", dur, " usecs");
 
-	writeEntityComponents(gEM.getEntity(entity2.id));
+	writeEntityComponents(gEM.getEntity(entity2));
 
 	time = MonoTime.currTime;
 
@@ -662,9 +662,9 @@ int main()
 	dur = (MonoTime.currTime - time).total!"usecs";
 	writeln("Update: ", dur, " usecs");
 
-	writeEntityComponents(gEM.getEntity(entity2.id));
+	writeEntityComponents(gEM.getEntity(entity2));
 
-	entity = gEM.addEntity(tmpl);
+	entity = gEM.addEntity(tmpl).id;
 
 	gEM.begin();
 	gEM.update();
@@ -672,40 +672,39 @@ int main()
 
 	//Entity* pp;// = gEM.getEntity(entity.id);
 	//writeln((cast(uint*) pp)[0 .. 14], " ", pp);
-	writeEntityComponents(gEM.getEntity(entity.id));
+	writeEntityComponents(gEM.getEntity(entity));
 
 	gEM.addEntity(tmpl);
+	gEM.addEntityCopy(entity);
 
-	gEM.addComponents(entity.id, TestComp4());
+	gEM.addComponents(entity, TestComp4());
-	gEM.addComponents(entity.id, TestComp3());
+	gEM.addComponents(entity, TestComp3());
 
 	gEM.begin();
 	gEM.update();
 	gEM.end();
 
-	writeEntityComponents(gEM.getEntity(entity.id));
+	writeEntityComponents(gEM.getEntity(entity));
 
-	gEM.removeComponents!(TestComp)(entity.id);
+	gEM.removeComponents!(TestComp)(entity);
-	gEM.addComponents(entity.id, TestComp());
+	gEM.addComponents(entity, TestComp());
-	gEM.addComponents(entity.id, TestComp5());
+	gEM.addComponents(entity, TestComp5());
 
 	gEM.begin();
 	gEM.update();
 	gEM.update("fixed");
 	gEM.end();
 
-	gEM.removeComponents!(TestComp4)(entity.id);
+	gEM.removeComponents!(TestComp4)(entity);
 
 	gEM.commit();//*/
 
-	writeEntityComponents(gEM.getEntity(entity.id));
+	writeEntityComponents(gEM.getEntity(entity));
 	//import std.stdio;
 	//writeln((cast(uint*)tmpl.info.first_block)[0..48]);
 	gEM.freeTemplate(tmpl);
 	gEM.freeTemplate(tmpl2);
 	EntityManager.destroy();
 
-	
-
 	return 0;
 }