Remove ECSEmscripten as Emscripten version is now supported in LDC (+fix compile scripts)

Fix crash in commit() when all components were removed from entity

Closes #2

See merge request Mergul/bubel-ecs!27

.gitlab-ci.yml

@@ -56,7 +56,7 @@ coverage_test_dmd:
         - mkdir reports
         - binaries/dmd_unittest_cov
     after_script:
-        - bash <(curl -s https://codecov.io/bash) -s reports -t 1a0c0169-a721-4085-8252-fed4755dcd8c
+        - bash <(curl -s https://codecov.io/bash) -s reports -t df87b1d8-85f4-4584-96e3-1315d27ec2c5
 
 wasm:
     stage: build_wasm

README.md

@@ -10,6 +10,13 @@ Bubel ECS was tested on Linux, Windows, Android and WASM.
 
 **Currently library is in beta stage so some significant API changes can appear.**
 
+Package is available on [DUB package repository](https://code.dlang.org/packages/bubel-ecs). Usage:
+```
+    "dependencies": {
+        "bubel-ecs": "~>0.1.1"
+    }
+```
+
 ## Design
 
 For core information about Entity-Component-System architectural pattern please read definition described at [Wikipedia](https://en.wikipedia.org/wiki/Entity_component_system).

compile_wasm.py

@@ -13,7 +13,7 @@ def compile(sources, output):
                     if file_extension == '.d' and filename != 'package':
                         files.append(os.path.join(r, file))
 
-    ldc_cmd = 'ldc2 ' + shared_flags + ldc_flags + '-oq -mtriple=wasm32-unknown-unknown-wasm -betterC --output-bc --od=.bc --singleobj --checkaction=C --of=' + output + ' '
+    ldc_cmd = 'ldc2 ' + shared_flags + ldc_flags + '-oq -mtriple=wasm32-unknown-emscripten -betterC --output-bc --od=.bc --singleobj --checkaction=C --of=' + output + ' '
 
     for path in sources:
         ldc_cmd += '-I' + path + ' '
@@ -33,7 +33,7 @@ def compile(sources, output):
 shared_flags = ''
 clean = 0
 emc_flags = ''
-ldc_flags = '--d-version=ECSEmscripten '
+ldc_flags = ''
 import_paths = ['source','tests']
 build_tests = 0
 

demos/compile_wasm.py

@@ -1,7 +1,6 @@
 import os
 import ntpath
 import sys
-import imp
 
 def compile(sources, output):
     files = []
@@ -14,7 +13,7 @@ def compile(sources, output):
                     if file_extension == '.d' and filename != 'package':
                         files.append(os.path.join(r, file))
 
-    ldc_cmd = compiler + shared_flags + ldc_flags + '-oq -mtriple=wasm32-unknown-unknown-wasm -betterC --output-bc --od=.bc --singleobj --checkaction=C --of=' + output + ' '
+    ldc_cmd = compiler + shared_flags + ldc_flags + '-oq -mtriple=wasm32-unknown-emscripten -betterC --output-bc --od=.bc --singleobj --checkaction=C --of=' + output + ' '
 
     for path in sources:
         ldc_cmd += '-I' + path + ' '
@@ -41,7 +40,7 @@ only_bc = 0
 multi = 0
 sources = ['tests', 'source']
 emc_flags = '-s USE_SDL=2 -s USE_SDL_IMAGE=2 -s SDL2_IMAGE_FORMATS="[\'png\']" '
-ldc_flags = '--d-version=ECSEmscripten --d-version=SDL_209 --d-version=BindSDL_Static --d-version=BindSDL_Image --d-version=MM_USE_POSIX_THREADS '
+ldc_flags = '--d-version=SDL_209 --d-version=BindSDL_Static --d-version=BindSDL_Image --d-version=MM_USE_POSIX_THREADS '
 import_paths = ['external/sources', 'external/imports', 'external/wasm_imports', '../source', 'utils/source', 'simple/source']
 
 for arg in sys.argv[1:]:
@@ -121,8 +120,9 @@ emcc_cmd += 'demo.bc '
 
 os.system("mkdir build")
 
-emscripten = imp.load_source('', os.path.expanduser("~") + '/.emscripten')
-pack_cmd = emscripten.EMSCRIPTEN_ROOT + '/tools/file_packager.py build/assets.data --preload assets --js-output=build/assets.js'
+# emscripten = imp.load_source('', os.path.expanduser("~") + '/.emscripten')
+# pack_cmd = emscripten.EMSCRIPTEN_ROOT + '/tools/file_packager.py build/assets.data --preload assets --js-output=build/assets.js'
+pack_cmd = os.path.expandvars('$EMSDK/upstream/emscripten') + '/tools/file_packager.py build/assets.data --preload assets --js-output=build/assets.js'
 print('Packafing files: ' + pack_cmd)
 
 os.system(pack_cmd)

demos/meson.build

@@ -27,7 +27,7 @@ executable('BubelECSDemos', [demos_src, external_src],
 		bindbc_loader_dep,
 		bindbc_sdl_dep,
 		cimgui_dep,
-		decs_dep,
+		bubel_ecs_dep,
 		ecs_utils_dep,
 		sdl2_dep,
 		sdl2_image_dep,

demos/utils/meson.build

@@ -5,12 +5,12 @@ subdir('source/ecs_utils')
 utils_inc = include_directories('source/')
 
 # Dependencies
-ecs_utils_lib = library('ecs_utils', utils_src,
+ecs_utils_lib = library('ECSUtils', utils_src,
 	include_directories : [demos_inc, external_inc, utils_inc],
 	link_args : link_args, 
 	d_module_versions : versions,
 	dependencies : [
-		decs_dep,
+		bubel_ecs_dep,
 		bindbc_loader_dep,
 		bindbc_sdl_dep,
 	]

dub.json

@@ -5,7 +5,7 @@
 		"Michał Masiukiewicz", "Dawid Masiukiewicz"
 	],
 	"description": "Dynamic Entity Component System",
-	"copyright": "Copyright © 2018-2019, Michał Masiukiewicz, Dawid Masiukiewicz",
+	"copyright": "Copyright © 2018-2023, Michał Masiukiewicz, Dawid Masiukiewicz",
 	"license": "BSD 3-clause",
 	"sourcePaths" : ["source\/"],
 	"excludedSourceFiles":[
@@ -63,7 +63,7 @@
 			],
 			"dflags": [
 				"-unittest",
-				"-cov"
+				"-cov=ctfe"
 			]
 		},
 		{

meson.build

@@ -58,7 +58,7 @@ threads_dep = dependency('threads')
 d_versions = []
 deps = []
 if host_machine.cpu_family() == 'wasm32'
-	d_versions += 'ECSEmscripten'
+
 else
 	# meson incorectly adds "-s USE_PTHREADS=1" to ldc2 invocation whe pthreads is added as dependency
 	# add it for non wasm builds

source/bubel/ecs/atomic.d

@@ -4,129 +4,10 @@ It's internal code. Can be used for atomics if emscripten backend will be used.
 This module contain atomic operations which include support for emscripten atomics functions.
 Emscripten functions are contained in API similar to druntime.
 
-Copyright: Copyright © 2018-2019, Dawid Masiukiewicz, Michał Masiukiewicz
+Copyright: Copyright © 2018-2023, Dawid Masiukiewicz, Michał Masiukiewicz
 License: BSD 3-clause, see LICENSE file in project root folder.
 */
 module bubel.ecs.atomic;
 
-version (Emscripten) version = ECSEmscripten;
+public import core.atomic;
 
-version (ECSEmscripten)
-{
-    import std.traits;
-
-    enum MemoryOrder
-    {
-        acq,
-        acq_rel,
-        raw,
-        rel,
-        seq
-    }
-
-    extern (C) ubyte emscripten_atomic_cas_u8(void* addr, ubyte oldVal, ubyte newVal) @nogc nothrow pure;
-    extern (C) ushort emscripten_atomic_cas_u16(void* addr, ushort oldVal, ushort newVal) @nogc nothrow pure;
-    extern (C) uint emscripten_atomic_cas_u32(void* addr, uint oldVal, uint newVal) @nogc nothrow pure;
-
-    extern (C) ubyte emscripten_atomic_load_u8(const void* addr) @nogc nothrow pure;
-    extern (C) ushort emscripten_atomic_load_u16(const void* addr) @nogc nothrow pure;
-    extern (C) uint emscripten_atomic_load_u32(const void* addr) @nogc nothrow pure;
-
-    extern (C) ubyte emscripten_atomic_store_u8(void* addr, ubyte val) @nogc nothrow pure;
-    extern (C) ushort emscripten_atomic_store_u16(void* addr, ushort val) @nogc nothrow pure;
-    extern (C) uint emscripten_atomic_store_u32(void* addr, uint val) @nogc nothrow pure;
-
-    extern (C) ubyte emscripten_atomic_add_u8(void* addr, ubyte val) @nogc nothrow pure;
-    extern (C) ushort emscripten_atomic_add_u16(void* addr, ushort val) @nogc nothrow pure;
-    extern (C) uint emscripten_atomic_add_u32(void* addr, uint val) @nogc nothrow pure;
-
-    extern (C) ubyte emscripten_atomic_sub_u8(void* addr, ubyte val) @nogc nothrow pure;
-    extern (C) ushort emscripten_atomic_sub_u16(void* addr, ushort val) @nogc nothrow pure;
-    extern (C) uint emscripten_atomic_sub_u32(void* addr, uint val) @nogc nothrow pure;
-
-    public pure nothrow @nogc Unqual!T atomicOp(string op, T, V1)(ref shared T val, V1 mod)
-    {
-        static if (op == "+=")
-        {
-            static if (is(T == byte) || is(T == ubyte))
-                return cast(Unqual!T)(emscripten_atomic_add_u8(cast(void*)&val,
-                        cast(Unqual!T) mod) + 1);
-            else static if (is(T == short) || is(T == ushort))
-                return cast(Unqual!T)(emscripten_atomic_add_u16(cast(void*)&val,
-                        cast(Unqual!T) mod) + 1);
-            else static if (is(T == int) || is(T == uint))
-                return cast(Unqual!T)(emscripten_atomic_add_u32(cast(void*)&val,
-                        cast(Unqual!T) mod) + 1);
-            else
-                static assert(0);
-        }
-        else static if (op == "-=")
-        {
-            static if (is(T == byte) || is(T == ubyte))
-                return cast(Unqual!T)(emscripten_atomic_sub_u8(cast(void*)&val,
-                        cast(Unqual!T) mod) - 1);
-            else static if (is(T == short) || is(T == ushort))
-                return cast(Unqual!T)(emscripten_atomic_sub_u16(cast(void*)&val,
-                        cast(Unqual!T) mod) - 1);
-            else static if (is(T == int) || is(T == uint))
-                return cast(Unqual!T)(emscripten_atomic_sub_u32(cast(void*)&val,
-                        cast(Unqual!T) mod) - 1);
-            else
-                static assert(0);
-        }
-    }
-
-    public pure nothrow @nogc @trusted void atomicStore(MemoryOrder ms = MemoryOrder.seq, T, V)(ref T val,
-            V newval)
-    {
-        alias UT = Unqual!T;
-        static if (is(UT == bool) || is(UT == byte) || is(UT == ubyte))
-            emscripten_atomic_store_u8(cast(void*)&val, cast(UT) newval);
-        else static if (is(UT == short) || is(UT == ushort))
-            emscripten_atomic_store_u16(cast(void*)&val, cast(UT) newval);
-        else static if (is(UT == int) || is(UT == uint))
-            emscripten_atomic_store_u32(cast(void*)&val, cast(UT) newval);
-        else
-            static assert(0);
-    }
-
-    public pure nothrow @nogc @trusted T atomicLoad(MemoryOrder ms = MemoryOrder.seq, T)(
-            ref const T val)
-    {
-        alias UT = Unqual!T;
-        static if (is(UT == bool))
-            return emscripten_atomic_load_u8(cast(const void*)&val) != 0;
-        else static if (is(UT == byte) || is(UT == ubyte))
-            return emscripten_atomic_load_u8(cast(const void*)&val);
-        else static if (is(UT == short) || is(UT == ushort))
-            return emscripten_atomic_load_u16(cast(const void*)&val);
-        else static if (is(UT == int) || is(UT == uint))
-            return emscripten_atomic_load_u32(cast(const void*)&val);
-        else
-            static assert(0);
-    }
-
-    public pure nothrow @nogc @trusted bool cas(MemoryOrder succ = MemoryOrder.seq,
-            MemoryOrder fail = MemoryOrder.seq, T, V1, V2)(T* here, V1 ifThis, V2 writeThis)
-    {
-        alias UT = Unqual!T;
-        static if (is(UT == bool))
-            return emscripten_atomic_cas_u8(cast(void*) here,
-                    cast(Unqual!T) ifThis, cast(Unqual!T) writeThis) == ifThis;
-        else static if (is(UT == byte) || is(UT == ubyte))
-            return emscripten_atomic_cas_u8(cast(void*) here,
-                    cast(Unqual!T) ifThis, cast(Unqual!T) writeThis) == ifThis;
-        else static if (is(UT == short) || is(UT == ushort))
-            return emscripten_atomic_cas_u16(cast(void*) here,
-                    cast(Unqual!T) ifThis, cast(Unqual!T) writeThis) == ifThis;
-        else static if (is(UT == int) || is(UT == uint))
-            return emscripten_atomic_cas_u32(cast(void*) here,
-                    cast(Unqual!T) ifThis, cast(Unqual!T) writeThis) == ifThis;
-        else
-            static assert(0);
-    }
-}
-else
-{
-    public import core.atomic;
-}

source/bubel/ecs/attributes.d

@@ -17,7 +17,7 @@ Struct EntitiesData
 }
 ---
 
-Copyright: Copyright © 2018-2019, Dawid Masiukiewicz, Michał Masiukiewicz
+Copyright: Copyright © 2018-2023, Dawid Masiukiewicz, Michał Masiukiewicz
 License: BSD 3-clause, see LICENSE file in project root folder.
 */
 module bubel.ecs.attributes;

source/bubel/ecs/block_allocator.d

@@ -3,7 +3,7 @@ It's internal code.
 
 Module contain memory allocator.
 
-Copyright: Copyright © 2018-2019, Dawid Masiukiewicz, Michał Masiukiewicz
+Copyright: Copyright © 2018-2023, Dawid Masiukiewicz, Michał Masiukiewicz
 License: BSD 3-clause, see LICENSE file in project root folder.
 */
 module bubel.ecs.block_allocator;

source/bubel/ecs/core.d

@@ -67,7 +67,7 @@ Struct System1
 }
 ---
 
-Copyright: Copyright © 2018-2019, Dawid Masiukiewicz, Michał Masiukiewicz
+Copyright: Copyright © 2018-2023, Dawid Masiukiewicz, Michał Masiukiewicz
 License: BSD 3-clause, see LICENSE file in project root folder.
 */
 module bubel.ecs.core;

source/bubel/ecs/entity.d

@@ -1,7 +1,7 @@
 /************************************************************************************************************************
 Entity module.
 
-Copyright: Copyright © 2018-2019, Dawid Masiukiewicz, Michał Masiukiewicz
+Copyright: Copyright © 2018-2023, Dawid Masiukiewicz, Michał Masiukiewicz
 License: BSD 3-clause, see LICENSE file in project root folder.
 */
 module bubel.ecs.entity;
@@ -44,7 +44,7 @@ struct Entity
         return cast(T*)getComponent(becsID!T);
     }
 
-    void* getComponent(ushort component_id) const
+    export void* getComponent(ushort component_id) const
     {
         EntityManager.EntitiesBlock* block = gEntityManager.getMetaData(&this);
         EntityManager.EntityInfo* info = block.type_info;
@@ -54,7 +54,7 @@ struct Entity
         return (cast(void*)block + info.deltas[component_id] + block.entityIndex(&this) * gEntityManager.components[component_id].size);
     }
 
-    bool hasComponent(ushort component_id) const
+    export bool hasComponent(ushort component_id) const
     {
         EntityManager.EntitiesBlock* block = gEntityManager.getMetaData(&this);
         EntityManager.EntityInfo* info = block.type_info;
@@ -62,7 +62,7 @@ struct Entity
         return true;
     }
 
-    EntityMeta getMeta() const
+    export EntityMeta getMeta() const
     {
         EntityMeta meta;
         meta.block = gEntityManager.getMetaData(&this);
@@ -85,7 +85,7 @@ struct EntityMeta
         return cast(T*)getComponent(becsID!T);
     }
     
-    void* getComponent(ushort component_id) const
+    export void* getComponent(ushort component_id) const
     {
         const (EntityManager.EntityInfo)* info = block.type_info;
 
@@ -95,7 +95,7 @@ struct EntityMeta
         return (cast(void*)block + info.deltas[component_id] + index * gEntityManager.components[component_id].size);
     }
 
-    bool hasComponent(ushort component_id) const
+    export bool hasComponent(ushort component_id) const
     {
         const EntityManager.EntityInfo* info = block.type_info;
         if (component_id >= info.deltas.length || info.deltas[component_id] == 0)return false;
@@ -133,7 +133,7 @@ export struct EntityTemplate
     /************************************************************************************************************************
     Get specified component. If component doesn't exist function return null. Returned pointer is valid during EntityTemplate lifetime.
     */
-    void* getComponent(ushort component_id) const nothrow @nogc
+    export void* getComponent(ushort component_id) const nothrow @nogc
     {
         if(component_id >= info.tmpl_deltas.length || info.tmpl_deltas[component_id] == ushort.max)return null;
         return cast(void*)(entity_data.ptr + info.tmpl_deltas[component_id]);

source/bubel/ecs/events.d

@@ -1,5 +1,5 @@
 /************************************************************************************************************************
-Copyright: Copyright © 2018-2019, Dawid Masiukiewicz, Michał Masiukiewicz
+Copyright: Copyright © 2018-2023, Dawid Masiukiewicz, Michał Masiukiewicz
 License: BSD 3-clause, see LICENSE file in project root folder.
 */
 module bubel.ecs.events;

source/bubel/ecs/hash_map.d

@@ -1,5 +1,5 @@
 /************************************************************************************************************************
-Copyright: Copyright © 2018-2019, Dawid Masiukiewicz, Michał Masiukiewicz
+Copyright: Copyright © 2018-2023, Dawid Masiukiewicz, Michał Masiukiewicz
 License: BSD 3-clause, see LICENSE file in project root folder.
 */
 module bubel.ecs.hash_map;
@@ -28,7 +28,7 @@ export ulong defaultHashFunc(T)(auto ref T t) nothrow @nogc
 	}
 }
 
-ulong hash(byte[] array) nothrow @nogc
+export ulong hash(byte[] array) nothrow @nogc
 {
 	ulong hash = 0;
 
@@ -341,7 +341,7 @@ nothrow:
 		int result;
 		foreach (ref Key k; this)
 		{
-			result = (cast(int delegate(ref Key k) nothrow)dg)(k);
+			result = (cast(int delegate(ref Key k) nothrow @nogc)dg)(k);
 			if (result)
 				break;
 		}
@@ -353,7 +353,7 @@ nothrow:
 		int result;
 		foreach (ref Value v; this)
 		{
-			result = (cast(int delegate(ref Value v) nothrow)dg)(v);
+			result = (cast(int delegate(ref Value v) nothrow @nogc)dg)(v);
 			if (result)
 				break;
 		}
@@ -365,7 +365,7 @@ nothrow:
 		int result;
 		foreach (ref Key k, ref Value v; this)
 		{
-			result = (cast(int delegate(ref Key k, ref Value v) nothrow)dg)(k, v);
+			result = (cast(int delegate(ref Key k, ref Value v) nothrow @nogc)dg)(k, v);
 			if (result)
 				break;
 		}

source/bubel/ecs/id_manager.d

@@ -1,5 +1,5 @@
 /************************************************************************************************************************
-Copyright: Copyright © 2018-2019, Dawid Masiukiewicz, Michał Masiukiewicz
+Copyright: Copyright © 2018-2023, Dawid Masiukiewicz, Michał Masiukiewicz
 License: BSD 3-clause, see LICENSE file in project root folder.
 */
 module bubel.ecs.id_manager;

source/bubel/ecs/manager.d

@@ -1,7 +1,7 @@
 /************************************************************************************************************************
 Most important module. Almost every function is called from EntityManager.
 
-Copyright: Copyright © 2018-2019, Dawid Masiukiewicz, Michał Masiukiewicz
+Copyright: Copyright © 2018-2023, Dawid Masiukiewicz, Michał Masiukiewicz
 License: BSD 3-clause, see LICENSE file in project root folder.
 */
 module bubel.ecs.manager;
@@ -10,10 +10,6 @@ import std.algorithm : max;
 import std.conv : to;
 import std.traits;
 
-//import core.atomic;
-//import core.stdc.stdlib : qsort;
-//import core.stdc.string;
-
 import bubel.ecs.system; //not ordered as forward reference bug workaround
 import bubel.ecs.block_allocator;
 import bubel.ecs.entity;
@@ -31,6 +27,8 @@ alias SerializeVector = bubel.ecs.vector.Vector!ubyte;
 ///Global EntityManager used for everything.
 export __gshared EntityManager* gEntityManager = null;
 
+version(D_BetterC) version = NoDRuntime;
+
 /************************************************************************************************************************
 Entity manager is responsible for everything.
 
@@ -69,11 +67,10 @@ export struct EntityManager
     Initialize ECS.
     */
     export static void initialize(uint threads_count = 1, uint page_size = 32768,
-            uint block_pages_count = 128)
+        uint block_pages_count = 128)
     {
         if (gEntityManager is null)
         {
-            //gEntityManager = Mallocator.make!EntityManager(threads_count);
             gEntityManager = Mallocator.make!EntityManager(threads_count, page_size, block_pages_count);
 
             with (gEntityManager)
@@ -81,7 +78,7 @@ export struct EntityManager
                 UpdatePass* pass = Mallocator.make!UpdatePass;
                 pass.name = Mallocator.makeArray(cast(char[]) "update");
                 passes.add(pass);
-                passes_map.add(cast(string) pass.name, cast(ushort)(passes.length - 1));
+                passes_map.add(cast(const(char)[]) pass.name, cast(ushort)(passes.length - 1));
             }
         }
     }
@@ -89,7 +86,7 @@ export struct EntityManager
     /************************************************************************************************************************
     Deinitialize and destroy ECS. This function release whole memory.
     */
-    export static void destroy()
+    export static void destroy() nothrow @nogc
     {
         if (gEntityManager is null)
             return;
@@ -172,6 +169,8 @@ export struct EntityManager
 
         foreach (ref system; systems)
         {
+            if (system.isAlive() == false)
+                continue;
             if (system.m_empty)
             {
                 if (system.m_update)
@@ -181,7 +180,7 @@ export struct EntityManager
             if (system.m_update is null)
             {
                 if (system.m_add_entity || system.m_remove_entity
-                        || system.m_change_entity || system.m_event_callers.length)
+                    || system.m_change_entity || system.m_event_callers.length)
                 {
                     foreach (info; &entities_infos.byValue)
                     {
@@ -236,6 +235,8 @@ export struct EntityManager
 
         foreach (ref system; systems)
         {
+            if (system.isAlive() == false)
+                continue;
             foreach (caller; system.m_event_callers)
             {
                 event_callers[caller.id]++;
@@ -252,6 +253,8 @@ export struct EntityManager
 
         foreach (ref system; systems)
         {
+            if (system.isAlive() == false)
+                continue;
             foreach (caller; system.m_event_callers)
             {
                 events[caller.id].callers[event_callers[caller.id]].callback = caller.callback;
@@ -275,7 +278,7 @@ export struct EntityManager
         foreach (ref event; events)
         {
             qsort(event.callers.ptr, event.callers.length,
-                    EventCaller.sizeof, &comapreEventCaller);
+                EventCaller.sizeof, &comapreEventCaller);
         }
         //qsort(event_callers.ptr, event_callers.length, EventInfo.sizeof, &compareUShorts);
 
@@ -328,13 +331,37 @@ export struct EntityManager
         allocator.freeMemory();
     }
 
+    /************************************************************************************************************************
+    Unregister given system form EntityManager.
+    */
+    void unregisterSystem(Sys)()
+    {
+        ushort system_id = becsID!Sys;
+        System* system = getSystem(system_id);
+
+        unregisterSystem(system);
+    }
+
+    /************************************************************************************************************************
+    Unregister given system form EntityManager.
+    */
+    export void unregisterSystem(System* system) nothrow @nogc
+    {
+        assert(register_state, "unregisterSystem must be called between beginRegister() and endRegister().");
+        assert(system !is null, "System was not registered");
+        assert(system.isAlive, "System already unregistered");
+        
+        //disable, destroy and dispose user created system but keep name and other data
+        system.destroySystemData();
+    }
+
     /************************************************************************************************************************
     Same as "void registerSystem(Sys)(int priority, int pass = 0)" but use pass name instead of id.
     */
     void registerSystem(Sys)(int priority, const(char)[] pass_name)
     {
         ushort pass = passes_map.get(pass_name, ushort.max);
-        version (D_BetterC)
+        version (NoDRuntime)
             assert(pass != ushort.max, "Update pass doesn't exist.");
         else
             assert(pass != ushort.max, "Update pass (Name " ~ pass_name ~ ") doesn't exist.");
@@ -355,8 +382,8 @@ export struct EntityManager
         //alias STC = ParameterStorageClass;
 
         assert(register_state,
-                "registerSystem must be called between beginRegister() and endRegister().");
-        version (D_BetterC)
+            "registerSystem must be called between beginRegister() and endRegister().");
+        version (NoDRuntime)
             assert(pass < passes.length, "Update pass doesn't exist.");
         else
             assert(pass < passes.length, "Update pass (ID " ~ pass.to!string ~ ") doesn't exist.");
@@ -365,7 +392,7 @@ export struct EntityManager
         enum SystemName = fullName!Sys;
         //enum SystemName = Sys.stringof;
 
-        System system;
+        System system = System();
         system.m_pass = pass;
 
         // static if (!(hasMember!(Sys, "system_id")) || !is(typeof(Sys.system_id) == ushort))
@@ -405,7 +432,7 @@ export struct EntityManager
                         // enum EventName = fullyQualifiedName!(Unqual!(EventParamType));//.stringof;
                         ushort evt = events_map.get(cast(char[]) EventName, ushort.max);
                         assert(evt != ushort.max,
-                                "Can't register system \"" ~ SystemName
+                            "Can't register system \"" ~ SystemName
                                 ~ "\" due to non existing event \"" ~ EventName ~ "\".");
 
                         callers[i].callback = cast(void*)&callEventHandler!(EventParamType);
@@ -448,14 +475,14 @@ export struct EntityManager
             bool checkExcludedComponentsSomething(Sys)()
             {
                 return __traits(compiles, allSameType!(string, typeof(Sys.ExcludedComponents))) && allSameType!(string,
-                        typeof(Sys.ExcludedComponents)) && isExpressions!(Sys.ExcludedComponents);
+                    typeof(Sys.ExcludedComponents)) && isExpressions!(Sys.ExcludedComponents);
             }
 
             foreach (member; __traits(allMembers, Sys.EntitiesData))
             {
                 alias MemberType = typeof(__traits(getMember, Sys.EntitiesData, member));
                 if (member == "length" || member == "thread_id" || member == "job_id"
-                        || is(MemberType == Entity[]) || is(MemberType == const(Entity)[]))
+                    || is(MemberType == Entity[]) || is(MemberType == const(Entity)[]))
                 {
                     //continue;
                 }
@@ -638,7 +665,7 @@ export struct EntityManager
         }
 
         static void allocateSystemComponents(ComponentsIndices!component_counts components_info)(
-                ref System system)
+            ref System system)
         {
             size_t req = components_info.req.length;
             size_t opt = components_info.optional.length;
@@ -672,14 +699,14 @@ export struct EntityManager
             bool checkExcludedComponentsSomething(Sys)()
             {
                 return __traits(compiles, allSameType!(string, typeof(Sys.ExcludedComponents))) && allSameType!(string,
-                        typeof(Sys.ExcludedComponents)) && isExpressions!(Sys.ExcludedComponents);
+                    typeof(Sys.ExcludedComponents)) && isExpressions!(Sys.ExcludedComponents);
             }
 
             foreach (member; __traits(allMembers, Sys.EntitiesData))
             {
                 alias MemberType = typeof(__traits(getMember, Sys.EntitiesData, member));
                 if (member == "length" || member == "thread_id" || member == "job_id"
-                        || is(MemberType == Entity[]) || is(MemberType == const(Entity)[]))
+                    || is(MemberType == Entity[]) || is(MemberType == const(Entity)[]))
                 {
                     if (is(MemberType == Entity[]) || is(MemberType == const(Entity)[]))
                         components_info.entites_array = member;
@@ -787,23 +814,23 @@ export struct EntityManager
                 else static if (member == "length")
                 {
                     static assert(isIntegral!(MemberType),
-                            "EntitiesData 'length' member must be integral type.");
+                        "EntitiesData 'length' member must be integral type.");
                     static assert(MemberType.sizeof > 1,
-                            "EntitiesData 'length' member can't be byte or ubyte.");
+                        "EntitiesData 'length' member can't be byte or ubyte.");
                 }
                 else static if (member == "thread_id")
                 {
                     static assert(isIntegral!(MemberType),
-                            "EntitiesData 'thread_id' member must be integral type.");
+                        "EntitiesData 'thread_id' member must be integral type.");
                     static assert(MemberType.sizeof > 1,
-                            "EntitiesData 'thread_id' member can't be byte or ubyte.");
+                        "EntitiesData 'thread_id' member can't be byte or ubyte.");
                 }
                 else static if (member == "job_id")
                 {
                     static assert(isIntegral!(MemberType),
-                            "EntitiesData 'job_id' member must be integral type.");
+                        "EntitiesData 'job_id' member must be integral type.");
                     static assert(MemberType.sizeof > 1,
-                            "EntitiesData 'job_id' member can't be byte or ubyte.");
+                        "EntitiesData 'job_id' member can't be byte or ubyte.");
                 }
                 else static if (!(isArray!(MemberType)))
                     static assert(0, "EntitiesData members should be arrays of elements!");
@@ -815,9 +842,9 @@ export struct EntityManager
             foreach (iii, comp_info; components_info.req)
             {
                 ushort comp = components_map.get(cast(char[]) comp_info.type, ushort.max);
-                version (D_BetterC)
+                version (NoDRuntime)
                     assert(comp != ushort.max,
-                            "Can't register system \"" ~ SystemName
+                        "Can't register system \"" ~ SystemName
                             ~ "\" due to non existing component.");
                 else
                     assert(comp != ushort.max, "Can't register system \"" ~ SystemName
@@ -827,9 +854,9 @@ export struct EntityManager
             foreach (iii, comp_info; components_info.excluded)
             {
                 ushort comp = components_map.get(cast(char[]) comp_info.type, ushort.max);
-                version (D_BetterC)
+                version (NoDRuntime)
                     assert(comp != ushort.max,
-                            "Can't register system \"" ~ SystemName
+                        "Can't register system \"" ~ SystemName
                             ~ "\" due to non existing component.");
                 else
                     assert(comp != ushort.max, "Can't register system \"" ~ SystemName
@@ -839,9 +866,9 @@ export struct EntityManager
             foreach (iii, comp_info; components_info.optional)
             {
                 ushort comp = components_map.get(cast(char[]) comp_info.type, ushort.max);
-                version (D_BetterC)
+                version (NoDRuntime)
                     assert(comp != ushort.max,
-                            "Can't register system \"" ~ SystemName
+                        "Can't register system \"" ~ SystemName
                             ~ "\" due to non existing component.");
                 else
                     assert(comp != ushort.max, "Can't register system \"" ~ SystemName
@@ -851,9 +878,9 @@ export struct EntityManager
             foreach (iii, comp_info; components_info.readonly)
             {
                 ushort comp = components_map.get(cast(char[]) comp_info.type, ushort.max);
-                version (D_BetterC)
+                version (NoDRuntime)
                     assert(comp != ushort.max,
-                            "Can't register system \"" ~ SystemName
+                        "Can't register system \"" ~ SystemName
                             ~ "\" due to non existing component.");
                 else
                     assert(comp != ushort.max, "Can't register system \"" ~ SystemName
@@ -863,9 +890,9 @@ export struct EntityManager
             foreach (iii, comp_info; components_info.mutable)
             {
                 ushort comp = components_map.get(cast(char[]) comp_info.type, ushort.max);
-                version (D_BetterC)
+                version (NoDRuntime)
                     assert(comp != ushort.max,
-                            "Can't register system \"" ~ SystemName
+                        "Can't register system \"" ~ SystemName
                             ~ "\" due to non existing component.");
                 else
                     assert(comp != ushort.max, "Can't register system \"" ~ SystemName
@@ -875,14 +902,14 @@ export struct EntityManager
         }
 
         static void fillInputData(ref Sys.EntitiesData input_data, EntityInfo* info,
-                EntitiesBlock* block, uint offset, uint entities_count, System* system)
+            EntitiesBlock* block, uint offset, uint entities_count, System* system)
         {
             //enum ComponentsIndices components_info = getComponentsInfo();
 
             static if (components_info.entites_array)
             {
                 __traits(getMember, input_data, components_info.entites_array) = (
-                        cast(Entity*) block.dataBegin())[offset .. entities_count];
+                    cast(Entity*) block.dataBegin())[offset .. entities_count];
             }
 
             static if (hasMember!(Sys.EntitiesData, "length"))
@@ -902,8 +929,7 @@ export struct EntityManager
                 __traits(getMember, input_data, comp_info.name) = (
                     cast(typeof(
                         (typeof(__traits(getMember, Sys.EntitiesData, comp_info.name))).init[0]
-                    )*)
-                    (cast(void*) block + info.deltas[system.m_components[iii]])
+                    )*)(cast(void*) block + info.deltas[system.m_components[iii]])
                 )[offset .. entities_count];
             }
 
@@ -911,7 +937,7 @@ export struct EntityManager
                     .. components_info.m_optional_counter])
             {
                 if (system.m_optional_components[iii] < info.deltas.length
-                        && info.deltas[system.m_optional_components[iii]] != 0)
+                    && info.deltas[system.m_optional_components[iii]] != 0)
                 {
                     __traits(getMember, input_data, comp_info.name) = (cast(ForeachType!(typeof(__traits(getMember,
                             Sys.EntitiesData, comp_info.name)))*)(cast(
@@ -1010,7 +1036,7 @@ export struct EntityManager
                             static if (hasMember!(Sys.EntitiesData, "thread_id"))
                             {
                                 input_data.thread_id = cast(
-                                        typeof(input_data.thread_id)) data.thread_id;
+                                    typeof(input_data.thread_id)) data.thread_id;
                             }
 
                             static if (hasMember!(Sys.EntitiesData, "job_id"))
@@ -1021,7 +1047,7 @@ export struct EntityManager
                             //s.onUpdate(input_data);
                             (cast(typeof(&__traits(getOverloads, s,
                                     "onUpdate")[OnUpdateOverloadNum])) data.update_delegate)(
-                                    input_data);
+                                input_data);
                         }
                         block = block.next_block;
                         offset = 0;
@@ -1091,15 +1117,15 @@ export struct EntityManager
                 foreach (func; __traits(getOverloads, Sys, func_name))
                 {
                     static if ((Parameters!(func)).length == 1
-                            && is(Parameters!(func)[0] == Sys.EntitiesData)
-                            && is(ReturnType!(func) == RetType))
+                        && is(Parameters!(func)[0] == Sys.EntitiesData)
+                        && is(ReturnType!(func) == RetType))
                     {
                         static RetType callFunc(ref ListenerCallData data)
                         {
                             Sys* s = cast(Sys*) data.system.m_system_pointer;
                             Sys.EntitiesData input_data;
                             fillInputData(input_data, data.block.type_info,
-                                    data.block, data.begin, data.end, data.system);
+                                data.block, data.begin, data.end, data.system);
                             static if (is(RetTyp == void))
                                 mixin("s." ~ func_name ~ "(input_data)");
                             else
@@ -1120,8 +1146,8 @@ export struct EntityManager
                 foreach (func; __traits(getOverloads, Sys, func_name))
                 {
                     static if ((Parameters!(func)).length == 1
-                            && is(Parameters!(func)[0] == EntityInfo*)
-                            && is(ReturnType!(func) == RetType))
+                        && is(Parameters!(func)[0] == EntityInfo*)
+                        && is(ReturnType!(func) == RetType))
                     {
                         static RetType callFunc(void* system_pointer, EntityInfo* info)
                         {
@@ -1156,14 +1182,16 @@ export struct EntityManager
         system.m_priority = priority;
         //(cast(Sys*) system.m_system_pointer).__ecsInitialize();
         //system.jobs =  (cast(Sys*) system.m_system_pointer)._ecs_jobs;
-        static if(__traits(hasMember, Sys ,"__becs_jobs_count"))system.jobs = Mallocator.makeArray!(Job)(Sys.__becs_jobs_count);
-        else system.jobs = Mallocator.makeArray!(Job)(32);
+        static if (__traits(hasMember, Sys, "__becs_jobs_count"))
+            system.jobs = Mallocator.makeArray!(Job)(Sys.__becs_jobs_count);
+        else
+            system.jobs = Mallocator.makeArray!(Job)(32);
 
         static if (OnUpdateOverloadNum != -1)
         {
             Sys* s = cast(Sys*) system.m_system_pointer;
             system.m_update_delegate = cast(void delegate())&__traits(getOverloads,
-                    s, "onUpdate")[OnUpdateOverloadNum];
+                s, "onUpdate")[OnUpdateOverloadNum];
         }
 
         genCompList(system, components_map);
@@ -1171,10 +1199,10 @@ export struct EntityManager
         foreach (iii, comp_info; components_info.readonlyDeps)
         {
             ushort comp = external_dependencies_map.get(cast(const(char)[]) comp_info.type,
-                    ushort.max);
-            version (D_BetterC)
+                ushort.max);
+            version (NoDRuntime)
                 assert(comp != ushort.max,
-                        "Can't register system \"" ~ SystemName
+                    "Can't register system \"" ~ SystemName
                         ~ "\" due to non existing dependency.");
             else
                 assert(comp != ushort.max, "Can't register system \"" ~ SystemName
@@ -1185,9 +1213,9 @@ export struct EntityManager
         foreach (iii, comp_info; components_info.writableDeps)
         {
             ushort comp = external_dependencies_map.get(cast(char[]) comp_info.type, ushort.max);
-            version (D_BetterC)
+            version (NoDRuntime)
                 assert(comp != ushort.max,
-                        "Can't register system \"" ~ SystemName
+                    "Can't register system \"" ~ SystemName
                         ~ "\" due to non existing dependency.");
             else
                 assert(comp != ushort.max, "Can't register system \"" ~ SystemName
@@ -1229,7 +1257,8 @@ export struct EntityManager
     }
 
     /************************************************************************************************************************
-    Return system ECS api by id
+    Return system ECS api by id.
+    System pointer might become invalid after registration process. It should be get once again after new systems are registered.
     */
     export System* getSystem(ushort id) nothrow @nogc
     {
@@ -1279,8 +1308,8 @@ export struct EntityManager
         // }
 
         static if (hasMember!(Comp, "onDestroy") && isFunction!(Comp.onDestroy)
-                && is(ReturnType!(Comp.onDestroy) == void)
-                && Parameters!(Comp.onDestroy).length == 0)
+            && is(ReturnType!(Comp.onDestroy) == void)
+            && Parameters!(Comp.onDestroy).length == 0)
         {
             static void callDestroy(void* pointer) nothrow @nogc
             {
@@ -1291,7 +1320,7 @@ export struct EntityManager
         }
 
         static if (hasMember!(Comp, "onCreate") && isFunction!(Comp.onCreate)
-                && is(ReturnType!(Comp.onCreate) == void) && Parameters!(Comp.onCreate).length == 0)
+            && is(ReturnType!(Comp.onCreate) == void) && Parameters!(Comp.onCreate).length == 0)
         {
             static void callCreate(void* pointer) nothrow @nogc
             {
@@ -1337,7 +1366,7 @@ export struct EntityManager
         // }
 
         static if (hasMember!(Ev, "onDestroy") && isFunction!(Ev.onDestroy)
-                && is(ReturnType!(Ev.onDestroy) == void) && Parameters!(Ev.onDestroy).length == 0)
+            && is(ReturnType!(Ev.onDestroy) == void) && Parameters!(Ev.onDestroy).length == 0)
         {
             static void callDestroy(void* pointer)
             {
@@ -1371,10 +1400,10 @@ export struct EntityManager
         Sys* s;
         static assert(isDelegate!func, "Function must be delegate.");
         static assert(__traits(hasMember, Sys, "EntitiesData"),
-                "Can't call function with system which hasn't EntitesData structure.");
+            "Can't call function with system which hasn't EntitesData structure.");
         ///TODO: make possibly to call function to group without system with onUpdate function
         static assert(__traits(hasMember, Sys, "onUpdate"),
-                "Can't call function with system which hasn't onUpdate function callback.");
+            "Can't call function with system which hasn't onUpdate function callback.");
         // static assert(is(SetFunctionAttributes!(T, functionLinkage!(s.onUpdate),
         //         functionAttributes!(s.onUpdate)) == typeof(&s.onUpdate)),
         //         "Function must match system update function."); FIXME: It's lead to crash on android build
@@ -1382,7 +1411,9 @@ export struct EntityManager
 
         System* system = getSystem(becsID!Sys);
         assert(system != null,
-                "System must be registered in EntityManager before any funcion can be called.");
+            "System must be registered in EntityManager before any funcion can be called.");
+        assert(system.isAlive(), "System must be alive (registered) in order to call entities function on its entities");
+
         if (!system.m_any_system_caller)
             return;
 
@@ -1424,7 +1455,7 @@ export struct EntityManager
                     foreach (info; caller.infos)
                     {
                         CallData data = CallData(caller.system_id, sys, info,
-                                sys.m_update_delegate);
+                            sys.m_update_delegate);
                         data.update();
                     }
             }
@@ -1446,7 +1477,7 @@ export struct EntityManager
         assert(!register_state);
         assert(pass < passes.length);
         assert(m_dispatch_jobs,
-                "Can't update with multithreading without JobDispatch function. Please use setJobDispatchFunc().");
+            "Can't update with multithreading without JobDispatch function. Please use setJobDispatchFunc().");
         Vector!CallData tmp_datas;
         tmp_datas.reserve(8);
 
@@ -1459,7 +1490,7 @@ export struct EntityManager
                 void nextJob()
                 {
                     CallData[] callers = m_call_data_allocator.getCallData(
-                            cast(uint) tmp_datas.length);
+                        cast(uint) tmp_datas.length);
                     //callers[0 .. $] = tmp_datas[0 .. $];
                     memcpy(callers.ptr, &tmp_datas[0], CallData.sizeof * tmp_datas.length);
                     tmp_datas.clear();
@@ -1514,7 +1545,7 @@ export struct EntityManager
 
                     //if this info will fill job
                     if ((blocks_count - 1) * info.max_entities + entities_count
-                            + info.last_block.entities_count - first_elem >= entities_per_job)
+                        + info.last_block.entities_count - first_elem >= entities_per_job)
                     {
                         int reamaining_entities = (entities_per_job - entities_count - (
                                 first_block.entities_count - first_elem));
@@ -1535,9 +1566,9 @@ export struct EntityManager
                                 assert(entities_per_job == full_blocks_count * info.max_entities + entities_count + (
                                         first_block.entities_count - first_elem));
                                 CallData data = CallData(caller.system_id, sys,
-                                        info, sys.m_update_delegate, first_block,
-                                        cast(ushort)(full_blocks_count + 1),
-                                        cast(ushort) first_elem, 0);
+                                    info, sys.m_update_delegate, first_block,
+                                    cast(ushort)(full_blocks_count + 1),
+                                    cast(ushort) first_elem, 0);
                                 tmp_datas.add(data);
                                 first_elem = 0;
                                 blocks_count -= full_blocks_count + 1;
@@ -1546,14 +1577,14 @@ export struct EntityManager
                             else
                             {
                                 entities_count += full_blocks_count * info.max_entities + (
-                                        first_block.entities_count - first_elem); // - first_elem;
+                                    first_block.entities_count - first_elem); // - first_elem;
                                 uint last_elem = entities_per_job - entities_count; // + first_elem - 1;
                                 assert(last_elem > 0);
                                 assert(last_elem <= block.entities_count);
                                 CallData data = CallData(caller.system_id, sys,
-                                        info, sys.m_update_delegate, first_block,
-                                        cast(ushort)(full_blocks_count + 2),
-                                        cast(ushort) first_elem, cast(ushort) last_elem);
+                                    info, sys.m_update_delegate, first_block,
+                                    cast(ushort)(full_blocks_count + 2),
+                                    cast(ushort) first_elem, cast(ushort) last_elem);
                                 tmp_datas.add(data);
                                 first_elem = last_elem;
                                 blocks_count -= full_blocks_count + 1;
@@ -1570,8 +1601,8 @@ export struct EntityManager
                             uint last_elem = entities_per_job - entities_count;
                             assert(last_elem > 0);
                             CallData data = CallData(caller.system_id, sys,
-                                    info, sys.m_update_delegate, first_block, 1,
-                                    cast(ushort) first_elem, cast(ushort)(first_elem + last_elem));
+                                info, sys.m_update_delegate, first_block, 1,
+                                cast(ushort) first_elem, cast(ushort)(first_elem + last_elem));
                             tmp_datas.add(data);
                             first_elem += last_elem;
                             assert(first_elem <= first_block.entities_count);
@@ -1591,7 +1622,7 @@ export struct EntityManager
                     {
                         //take whole info blocks
                         CallData data = CallData(caller.system_id, sys, info, sys.m_update_delegate,
-                                first_block, cast(ushort) blocks_count, cast(ushort) first_elem);
+                            first_block, cast(ushort) blocks_count, cast(ushort) first_elem);
                         tmp_datas.add(data);
                         entities_count += (blocks_count - 1) * info.max_entities
                             + info.last_block.entities_count - first_elem;
@@ -1606,7 +1637,7 @@ export struct EntityManager
     }
 
     export void setMultithreadingCallbacks(void delegate(JobGroup) dispatch_callback,
-            uint delegate() get_id_callback)
+        uint delegate() get_id_callback)
     {
         m_dispatch_jobs = cast(void delegate(JobGroup jobs) nothrow @nogc) dispatch_callback;
         m_thread_id_func = cast(uint delegate() nothrow @nogc) get_id_callback;
@@ -1671,7 +1702,7 @@ export struct EntityManager
                 if (components[comp].size == 0)
                     continue;
                 memcpy(temp.entity_data.ptr + info.tmpl_deltas[comp],
-                        components[comp].init_data.ptr, components[comp].size);
+                    components[comp].init_data.ptr, components[comp].size);
             }
         }
         else
@@ -1682,8 +1713,8 @@ export struct EntityManager
                 if (components[comp].size == 0)
                     continue;
                 memcpy(cast(void*) temp.entity_data.ptr + info.tmpl_deltas[comp],
-                        cast(void*) block + info.deltas[comp] + components[comp].size * index,
-                        components[comp].size);
+                    cast(void*) block + info.deltas[comp] + components[comp].size * index,
+                    components[comp].size);
             }
         }
 
@@ -1732,7 +1763,7 @@ export struct EntityManager
             if (components[comp].size == 0)
                 continue;
             memcpy(temp.entity_data.ptr + info.tmpl_deltas[comp],
-                    components[comp].init_data.ptr, components[comp].size);
+                components[comp].init_data.ptr, components[comp].size);
         }
 
         return temp;
@@ -1748,18 +1779,18 @@ export struct EntityManager
     remove_components_ids = array of components to remove from base template
     */
     export EntityTemplate* allocateTemplate(EntityTemplate* base_tmpl,
-            ushort[] components_ids, ushort[] remove_components_ids = null)
+        ushort[] components_ids, ushort[] remove_components_ids = null)
     {
         size_t len = base_tmpl.info.components.length + components_ids.length;
         ushort[] ids = (cast(ushort*) alloca(ushort.sizeof * len))[0 .. len];
         memcpy(ids.ptr, base_tmpl.info.components.ptr,
-                ushort.sizeof * base_tmpl.info.components.length);
+            ushort.sizeof * base_tmpl.info.components.length);
         memcpy(ids.ptr + base_tmpl.info.components.length, components_ids.ptr,
-                ushort.sizeof * components_ids.length);
+            ushort.sizeof * components_ids.length);
 
         qsort(ids.ptr, ids.length, ushort.sizeof, &compareUShorts);
         qsort(remove_components_ids.ptr, remove_components_ids.length,
-                ushort.sizeof, &compareUShorts);
+            ushort.sizeof, &compareUShorts);
         {
             uint k = 0;
             uint j = 1;
@@ -1799,20 +1830,20 @@ export struct EntityManager
         foreach (comp; info.components)
         {
             if (comp < base_tmpl.info.tmpl_deltas.length
-                    && base_tmpl.info.tmpl_deltas[comp] != ushort.max) //copy data from base component
-                    {
+                && base_tmpl.info.tmpl_deltas[comp] != ushort.max) //copy data from base component
+                {
                 if (components[comp].size == 0)
                     continue;
                 memcpy(temp.entity_data.ptr + info.tmpl_deltas[comp],
-                        base_tmpl.entity_data.ptr + base_tmpl.info.tmpl_deltas[comp],
-                        components[comp].size);
+                    base_tmpl.entity_data.ptr + base_tmpl.info.tmpl_deltas[comp],
+                    components[comp].size);
             }
             else //fill with default data
             {
                 if (components[comp].size == 0)
                     continue;
                 memcpy(temp.entity_data.ptr + info.tmpl_deltas[comp],
-                        components[comp].init_data.ptr, components[comp].size);
+                    components[comp].init_data.ptr, components[comp].size);
             }
         }
 
@@ -1827,6 +1858,7 @@ export struct EntityManager
     */
     export EntityTemplate* allocateTemplate(EntityTemplate* copy_tmpl)
     {
+        assert(copy_tmpl, "copy_tmpl can't be null");
         EntityTemplate* tmpl = Mallocator.make!EntityTemplate;
         tmpl.info = copy_tmpl.info;
         tmpl.entity_data = Mallocator.makeArray(copy_tmpl.entity_data);
@@ -1841,74 +1873,86 @@ export struct EntityManager
     */
     export EntityInfo* getEntityInfo(ushort[] ids)
     {
+        if(ids.length == 0)ids = null;
         EntityInfo* info = entities_infos.get(ids, null);
         if (info is null)
         {
             info = Mallocator.make!EntityInfo;
 
-            info.components = Mallocator.makeArray(ids);
-            info.deltas = Mallocator.makeArray!ushort(ids[$ - 1] + 1);
-
             info.size = EntityID.sizeof;
             info.alignment = EntityID.alignof;
 
-            info.tmpl_deltas = Mallocator.makeArray!ushort(ids[$ - 1] + 1, ushort.max);
-            uint components_size = EntityID.sizeof;
-
-            foreach (i, id; ids)
+            if(ids is null)
             {
-                info.alignment = max(info.alignment, components[id].alignment);
-                alignNum(info.size, components[id].alignment);
-                info.tmpl_deltas[id] = info.size;
-                info.size += components[id].size;
-                components_size += components[id].size;
+                uint block_memory = cast(uint)(
+                    m_page_size - EntitiesBlock.sizeof - info.size);
+                uint entites_in_block = block_memory / info.size;
+                info.max_entities = cast(ushort) entites_in_block;
             }
-            alignNum(info.size, info.alignment);
-
-            uint block_memory = cast(uint)(
-                    m_page_size - EntitiesBlock.sizeof - (info.size - components_size));
-            //uint entity_comps_size = EntityID.sizeof;
-            uint mem_begin = EntitiesBlock.sizeof;
-
-            uint entites_in_block = block_memory / info.size; //entity_comps_size;
-            info.max_entities = cast(ushort) entites_in_block;
-            ushort current_delta = cast(ushort)(mem_begin + entites_in_block * EntityID.sizeof);
-
-            foreach (i, id; ids)
+            else 
             {
-                if (current_delta == 0)
-                    current_delta = ushort.max;
-                alignNum(current_delta, components[id].alignment);
-                info.deltas[id] = cast(ushort) current_delta;
-                current_delta += entites_in_block * components[id].size;
+                uint components_size = EntityID.sizeof;
+
+                info.components = Mallocator.makeArray(ids);
+                info.deltas = Mallocator.makeArray!ushort(ids[$ - 1] + 1);
+                info.tmpl_deltas = Mallocator.makeArray!ushort(ids[$ - 1] + 1, ushort.max);
+
+                foreach (i, id; ids)
+                {
+                    info.alignment = max(info.alignment, components[id].alignment);
+                    alignNum(info.size, components[id].alignment);
+                    info.tmpl_deltas[id] = info.size;
+                    info.size += components[id].size;
+                    components_size += components[id].size;
+                }
+                alignNum(info.size, info.alignment);
+
+                uint block_memory = cast(uint)(
+                    m_page_size - EntitiesBlock.sizeof - (info.size - components_size));
+                //uint entity_comps_size = EntityID.sizeof;
+                uint mem_begin = EntitiesBlock.sizeof;
+
+                uint entites_in_block = block_memory / info.size; //entity_comps_size;
+                info.max_entities = cast(ushort) entites_in_block;
+                ushort current_delta = cast(ushort)(mem_begin + entites_in_block * EntityID.sizeof);
+
+                foreach (i, id; ids)
+                {
+                    if (current_delta == 0)
+                        current_delta = ushort.max;
+                    alignNum(current_delta, components[id].alignment);
+                    info.deltas[id] = cast(ushort) current_delta;
+                    current_delta += entites_in_block * components[id].size;
+                }
+
+                info.comp_add_info = Mallocator.makeArray!(EntityInfo*)(info.deltas.length);
+                info.comp_rem_info = Mallocator.makeArray!(EntityInfo*)(info.deltas.length);
+
+                foreach (comp; info.components)
+                {
+                    info.comp_add_info[comp] = info;
+                    info.comp_rem_info[comp] = null;
+                }
             }
 
             info.systems = Mallocator.makeArray!bool(systems.length);
 
             foreach (i, ref system; systems)
             {
+                if (system.isAlive() == false)
+                    continue;
                 if (system.m_empty)
                     continue;
                 if (system.m_update is null)
                 {
                     if (system.m_add_entity || system.m_remove_entity
-                            || system.m_change_entity || system.m_event_callers.length)
+                        || system.m_change_entity || system.m_event_callers.length)
                         connectListenerToEntityInfo(*info, cast(uint) i);
                     continue;
                 }
                 addSystemCaller(*info, cast(uint) i);
             }
 
-            info.comp_add_info = Mallocator.makeArray!(EntityInfo*)(gEntityManager.components.length);
-            //info.comp_rem_info = Mallocator.makeArray!(EntityInfo*)(gEntityManager.components.length);
-            info.comp_rem_info = Mallocator.makeArray!(EntityInfo*)(info.deltas.length);
-
-            foreach (comp; info.components)
-            {
-                info.comp_add_info[comp] = info;
-                info.comp_rem_info[comp] = null;
-            }
-
             entities_infos.add(info.components, info);
 
             generateListeners(info);
@@ -2059,7 +2103,9 @@ export struct EntityManager
         }
 
         ///call Custom Entity Filter test if function exists
-        if(system.m_filter_entity && !(cast(bool function(void* system_pointer, EntityInfo* info) @nogc nothrow)system.m_filter_entity)(system, &entity))return;
+        if (system.m_filter_entity && !(cast(bool function(void* system_pointer, EntityInfo* info) @nogc nothrow) system
+                .m_filter_entity)(system, &entity))
+            return;
 
         entity.systems[system_id] = true;
     }
@@ -2104,7 +2150,8 @@ export struct EntityManager
         System* system = &systems[system_id];
 
         connectListenerToEntityInfo(info, system_id);
-        if(!info.systems[system_id])return;
+        if (!info.systems[system_id])
+            return;
 
         uint index = 0;
         for (; index < passes[system.m_pass].system_callers.length; index++)
@@ -2213,7 +2260,7 @@ export struct EntityManager
             if (comp_size == 0)
                 continue;
             memcpy(cast(void*) new_block + new_info.deltas[comp] + new_block.entities_count * comp_size,
-                    cast(void*) block + info.deltas[comp] + ind * comp_size, comp_size);
+                cast(void*) block + info.deltas[comp] + ind * comp_size, comp_size);
         }
 
         new_block.entities_count++;
@@ -2227,7 +2274,7 @@ export struct EntityManager
                 if (!info.systems[listener])
                 {
                     callAddEntityListener(&systems[listener], new_info, new_block,
-                            new_block.entities_count - 1, new_block.entities_count);
+                        new_block.entities_count - 1, new_block.entities_count);
                 }
             }
         }
@@ -2239,7 +2286,7 @@ export struct EntityManager
                 if (info.systems[listener])
                 {
                     callChangeEntityListener(&systems[listener], new_info, new_block,
-                            new_block.entities_count - 1, new_block.entities_count, del_ids);
+                        new_block.entities_count - 1, new_block.entities_count, del_ids);
                 }
             }
         }
@@ -2390,7 +2437,7 @@ export struct EntityManager
                 if (!info.systems[listener])
                 {
                     callAddEntityListener(&systems[listener], new_info, new_block,
-                            new_block.entities_count - 1, new_block.entities_count);
+                        new_block.entities_count - 1, new_block.entities_count);
                 }
             }
         }
@@ -2402,7 +2449,7 @@ export struct EntityManager
                 if (info.systems[listener])
                 {
                     callChangeEntityListener(&systems[listener], new_info, new_block,
-                            new_block.entities_count - 1, new_block.entities_count, new_ids);
+                        new_block.entities_count - 1, new_block.entities_count, new_ids);
                 }
             }
         }
@@ -2445,7 +2492,7 @@ export struct EntityManager
         {
             if (components[ref_.component_id].size != 0)
                 data.changeEntitiesList.add(
-                        (cast(ubyte*) ref_.ptr)[0 .. components[ref_.component_id].size]);
+                    (cast(ubyte*) ref_.ptr)[0 .. components[ref_.component_id].size]);
         }
     }
 
@@ -2495,12 +2542,12 @@ export struct EntityManager
             ushort size = components[comp].size;
             if (size != 0)
                 memcpy(cast(void*) new_block + info.deltas[comp] + new_id * size,
-                        cast(void*) block + info.deltas[comp] + size * index, size);
+                    cast(void*) block + info.deltas[comp] + size * index, size);
 
             if (components[comp].create_callback)
             {
                 components[comp].create_callback(
-                        cast(void*) new_block + info.deltas[comp] + new_id * size);
+                    cast(void*) new_block + info.deltas[comp] + new_id * size);
             }
         }
 
@@ -2519,7 +2566,7 @@ export struct EntityManager
     use you should save ID instead of pointer.
     
     Params:
-    tmpl = pointer entity template allocated by EntityManager.
+    tmpl = pointer entity template allocated by EntityManager. Can be null in which case empty entity would be added (entity without components)
     */
     export Entity* addEntity(EntityTemplate* tmpl)
     {
@@ -2531,12 +2578,14 @@ export struct EntityManager
     use you should save ID instead of pointer.
     
     Params:
-    tmpl = pointer entity template allocated by EntityManager.
+    tmpl = pointer entity template allocated by EntityManager. Can be null in which case empty entity would be added (entity without components)
     replacement = list of components references to used. Memory form list replace data from template inside new entity. Should be used only for data which vary between most entities (like 3D position etc.)
     */
     export Entity* addEntity(EntityTemplate* tmpl, ComponentRef[] replacement)
     {
-        EntityInfo* info = tmpl.info;
+        EntityInfo* info = void;
+        if(tmpl)info = tmpl.info;
+        else info = getEntityInfo(null);
 
         ushort index = 0;
         EntitiesBlock* block;
@@ -2557,7 +2606,7 @@ export struct EntityManager
             uint size = components[comp].size;
             if (size != 0)
                 memcpy(cast(void*) block + info.deltas[comp] + size * id,
-                        tmpl.entity_data.ptr + info.tmpl_deltas[comp], size);
+                    tmpl.entity_data.ptr + info.tmpl_deltas[comp], size);
         }
 
         foreach (comp; replacement)
@@ -2579,7 +2628,7 @@ export struct EntityManager
             if (components[comp].create_callback)
             {
                 components[comp].create_callback(
-                        cast(void*) block + info.deltas[comp] + id * components[comp].size);
+                    cast(void*) block + info.deltas[comp] + id * components[comp].size);
             }
         }
 
@@ -2714,7 +2763,7 @@ export struct EntityManager
     }
 
     private void removeEntityNoID(Entity* entity, EntitiesBlock* block,
-            bool call_destructors = false) nothrow @nogc
+        bool call_destructors = false) nothrow @nogc
     {
         EntityInfo* info = block.type_info;
 
@@ -2846,7 +2895,7 @@ export struct EntityManager
     }
 
     private static void callAddEntityListener(System* system, EntityInfo* info,
-            EntitiesBlock* block, int begin, int end) @nogc nothrow
+        EntitiesBlock* block, int begin, int end) @nogc nothrow
     {
         ListenerCallData data;
         data.system = system;
@@ -2857,7 +2906,7 @@ export struct EntityManager
     }
 
     private void callRemoveEntityListeners(EntityInfo* info, EntitiesBlock* block, int begin,
-            int end) @nogc nothrow
+        int end) @nogc nothrow
     {
         foreach (listener; info.remove_listeners)
         {
@@ -2867,7 +2916,7 @@ export struct EntityManager
     }
 
     private static void callRemoveEntityListener(System* system,
-            EntityInfo* info, EntitiesBlock* block, int begin, int end) @nogc nothrow
+        EntityInfo* info, EntitiesBlock* block, int begin, int end) @nogc nothrow
     {
         ListenerCallData data;
         data.system = system;
@@ -2878,7 +2927,7 @@ export struct EntityManager
     }
 
     private void callChangeEntityListener(System* system, EntityInfo* info,
-            EntitiesBlock* block, int begin, int end, ushort[] ch_ids) @nogc nothrow
+        EntitiesBlock* block, int begin, int end, ushort[] ch_ids) @nogc nothrow
     {
         int i = 0;
         int j = 0;
@@ -3032,7 +3081,7 @@ export struct EntityManager
                             foreach (caller; events[i].callers)
                             {
                                 if (call_data.block.type_info.systems[caller.system.m_id] == false
-                                        || !caller.system.enabled || !caller.system.willExecute)
+                                    || !caller.system.enabled || !caller.system.willExecute)
                                     continue;
                                 call_data.system_pointer = caller.system.m_system_pointer;
                                 (cast(void function(ref EventCallData) nothrow @nogc) caller
@@ -3095,9 +3144,11 @@ export struct EntityManager
 
         foreach (ref system; systems)
         {
+            if (system.isAlive() == false)
+                continue;
             if (system.enabled && system.m_begin)
                 system.m_execute = (cast(bool function(void*)) system.m_begin)(
-                        system.m_system_pointer);
+                    system.m_system_pointer);
         }
     }
 
@@ -3109,6 +3160,9 @@ export struct EntityManager
 
         foreach (ref system; systems)
         {
+            if (system.isAlive() == false)
+                continue;
+
             if (system.enabled && system.m_end)
                 (cast(void function(void*)) system.m_end)(system.m_system_pointer);
         }
@@ -3247,7 +3301,7 @@ export struct EntityManager
             }
 
             qsort(pass.system_callers.array.ptr, pass.system_callers.length,
-                    (SystemCaller*).sizeof, &compareSystems);
+                (SystemCaller*).sizeof, &compareSystems);
 
             foreach (i, caller; pass.system_callers)
                 caller.job_group.id = cast(uint) i;
@@ -3303,6 +3357,16 @@ export struct EntityManager
         export ~this() nothrow @nogc
         {
         }
+
+        export void opAssign(ComponentInfo c)
+        {
+            size = c.size;
+            alignment = c.alignment;
+            init_data = c.init_data;
+            destroy_callback = c.destroy_callback;
+            create_callback = c.create_callback;
+        }
+
         ///Component size
         ushort size;
         ///Component data alignment
@@ -3374,7 +3438,7 @@ export struct EntityManager
             if (comp_add_info.length <= id)
             {
                 EntityInfo*[] new_infos = Mallocator.makeArray!(EntityInfo*)(
-                        gEntityManager.components.length);
+                    gEntityManager.components.length);
                 if (comp_add_info !is null)
                 {
                     //new_infos[0 .. comp_add_info.length] = comp_add_info[0 .. $];
@@ -3408,7 +3472,7 @@ export struct EntityManager
                     break;
                 }
             }
-            if (id > components[$ - 1])
+            if (components.length == 0 || id > components[$ - 1])
                 ids[len++] = id;
 
             assert(len == components.length + 1);
@@ -3462,7 +3526,8 @@ export struct EntityManager
 
         export bool hasComponent(ushort component_id)
         {
-            if(component_id >= deltas.length || !deltas[component_id])return false;
+            if (component_id >= deltas.length || !deltas[component_id])
+                return false;
             return true;
         }
 
@@ -3614,7 +3679,6 @@ export struct EntityManager
 
         export void execute() nothrow @nogc
         {
-            //gEntityManager.getThreadID();
             foreach (ref caller; callers)
             {
                 caller.thread_id = gEntityManager.threadID();

source/bubel/ecs/package.d

@@ -1,5 +1,5 @@
 /************************************************************************************************************************
-Copyright: Copyright © 2018-2019, Dawid Masiukiewicz, Michał Masiukiewicz
+Copyright: Copyright © 2018-2023, Dawid Masiukiewicz, Michał Masiukiewicz
 License: BSD 3-clause, see LICENSE file in project root folder.
 */
 module ecs;

source/bubel/ecs/simple_vector.d

@@ -1,5 +1,5 @@
 /************************************************************************************************************************
-Copyright: Copyright © 2018-2019, Dawid Masiukiewicz, Michał Masiukiewicz
+Copyright: Copyright © 2018-2023, Dawid Masiukiewicz, Michał Masiukiewicz
 License: BSD 3-clause, see LICENSE file in project root folder.
 */
 module bubel.ecs.simple_vector;

source/bubel/ecs/std.d

@@ -2,16 +2,14 @@
 It's internal code!
 This module contain implementation of standard functionality.
 
-Copyright: Copyright © 2018-2019, Dawid Masiukiewicz, Michał Masiukiewicz
+Copyright: Copyright © 2018-2023, Dawid Masiukiewicz, Michał Masiukiewicz
 License: BSD 3-clause, see LICENSE file in project root folder.
 */
 module bubel.ecs.std;
 
-version (Emscripten) version = ECSEmscripten;
-
 import std.traits;
 
-version (ECSEmscripten)
+version (Emscripten)
 {
     extern (C) struct pthread_mutex_t
     {
@@ -29,10 +27,6 @@ version (ECSEmscripten)
 
     extern (C) int memcmp(const void* s1, const void* s2, size_t size);
     extern (C) void exit(int status) nothrow @nogc;
-    extern (C) void __assert(const(char)* msg, const(char)* file, uint line)
-    {
-        exit(-20);
-    }
 
     extern (C) void free(void*) @nogc nothrow @system;
     extern (C) void* malloc(size_t size) @nogc nothrow @system;
@@ -60,7 +54,7 @@ else
     public import core.stdc.stdlib : qsort;
 }
 
-version (ECSEmscripten)
+version (Emscripten)
 {
 }
 else version (Windows)
@@ -89,7 +83,7 @@ else version (Posix)
     import core.sys.posix.stdlib : posix_memalign;
 }
 
-version (ECSEmscripten)
+version (Emscripten)
 {
     private const uint max_alloca = 10000;
     private __gshared byte[max_alloca] alloca_array;
@@ -294,7 +288,7 @@ static struct Mallocator
             posix_memalign(&ret, alignment, length); //ret = aligned_alloc(alignment, length);
         else version (Windows)
             ret = _aligned_malloc(length, alignment);
-        else version (ECSEmscripten)
+        else version (Emscripten)
             posix_memalign(&ret, alignment, length); //malloc(length);
         else
             static assert(0, "Unimplemented platform!");
@@ -341,7 +335,7 @@ static struct Mallocator
             free(cast(void*) object);
         else version (Windows)
             _aligned_free(cast(void*) object);
-        else version (ECSEmscripten)
+        else version (Emscripten)
             free(cast(void*) object);
         else
             static assert(0, "Unimplemented platform!");
@@ -351,7 +345,7 @@ static struct Mallocator
 struct Mutex
 {
 
-    version (ECSEmscripten)
+    version (Emscripten)
     {
         void initialize() nothrow @nogc
         {

source/bubel/ecs/system.d

@@ -1,7 +1,7 @@
 /************************************************************************************************************************
 System module.
 
-Copyright: Copyright © 2018-2019, Dawid Masiukiewicz, Michał Masiukiewicz
+Copyright: Copyright © 2018-2023, Dawid Masiukiewicz, Michał Masiukiewicz
 License: BSD 3-clause, see LICENSE file in project root folder.
 */
 module bubel.ecs.system;
@@ -13,14 +13,14 @@ import bubel.ecs.manager;
 System contain data required to proper glue EntityManager with Systems.
 System callbacks:
 $(LIST
-    * void onUpdate(EntitesData);
+    * void onUpdate(EntitiesData);
     * void onEnable() - called inside system.enable() function
     * void onDisable() - called inside system.disable() function
     * bool onBegin() - called inside manager.begin()
     * void onEnd() - called inside manager.end()
     * void onCreate() - called after registration inside registerSystem function
     * void onDestroy() - called during re-registration and inside manager destructor
-    * void onAddEntity(EntitesData) - called for every entity which are assigned to system (by adding new entity or changing its components)
+    * void onAddEntity(EntitiesData) - called for every entity which are assigned to system (by adding new entity or changing its components)
     * void onRemoveEntity(EntitiesData) - called for every entity removed from system update process
     * void onChangeEntity(EntitiesData) - called for every entity which components are changed but it was previously assigned to system
     * void handleEvent(Entity*, Event) - called for every event supported by system
@@ -89,38 +89,100 @@ struct System
         return cast(const(char)[]) m_name;
     }
 
+    /************************************************************************************************************************
+    Return false if system was unregistered, true otherwise.
+    */
+    export bool isAlive() nothrow @nogc
+    {
+        return m_system_pointer != null;
+    }
+
+    /************************************************************************************************************************
+    Return pointer to user side system object
+    */
+    export void* ptr() nothrow @nogc
+    {
+        return m_system_pointer;
+    }
+
 package:
 
-    void destroy()
+    ///destory system. Dispose all data
+    export void destroy() nothrow @nogc
+    {
+        import bubel.ecs.std : Mallocator;
+
+        destroySystemData();
+
+        if (m_name)
+        {
+            Mallocator.dispose(m_name);
+            m_name = null;
+        }
+    }
+
+    ///destroy all system data but keeps name which is used for case of system re-registration
+    void destroySystemData() nothrow @nogc
     {
         import bubel.ecs.std : Mallocator;
         disable();
         if (m_destroy)
-            (cast(void function(void*)) m_destroy)(m_system_pointer);
+        {
+            (cast(void function(void*) nothrow @nogc) m_destroy)(m_system_pointer);
+            m_destroy = null;
+        }
 
-        if (m_name)
-            Mallocator.dispose(m_name);
         if (m_components)
+        {
             Mallocator.dispose(m_components);
+            m_components = null;
+        }
         if (m_excluded_components)
+        {
             Mallocator.dispose(m_excluded_components);
+            m_excluded_components = null;
+        }
         if (m_optional_components)
+        {
             Mallocator.dispose(m_optional_components);
+            m_optional_components = null;
+        }
         if (jobs)
+        {
             Mallocator.dispose(jobs);
+            jobs = null;
+        }
         if (m_read_only_components)
+        {
             Mallocator.dispose(m_read_only_components);
+            m_read_only_components = null;
+        }
         if (m_writable_components)
+        {
             Mallocator.dispose(m_writable_components);
+            m_writable_components = null;
+        }
         if (m_readonly_dependencies)
+        {
             Mallocator.dispose(m_readonly_dependencies);
+            m_readonly_dependencies = null;
+        }
         if (m_writable_dependencies)
+        {
             Mallocator.dispose(m_writable_dependencies);
+            m_writable_dependencies = null;
+        }
         if (m_event_callers)
+        {
             Mallocator.dispose(m_event_callers);
+            m_event_callers = null;
+        }
 
         if (m_system_pointer)
+        {
             Mallocator.dispose(m_system_pointer);
+            m_system_pointer = null;
+        }
     }
 
     struct EventCaller

source/bubel/ecs/traits.d

@@ -1,5 +1,5 @@
 /************************************************************************************************************************
-Copyright: Copyright © 2018-2019, Dawid Masiukiewicz, Michał Masiukiewicz
+Copyright: Copyright © 2018-2023, Dawid Masiukiewicz, Michał Masiukiewicz
 License: BSD 3-clause, see LICENSE file in project root folder.
 */
 module bubel.ecs.traits;
@@ -11,8 +11,11 @@ import std.traits;
 */
 ref ushort becsID(T)()
 {
-	__gshared ushort id = ushort.max;
-	return id;
+	/// Embed id in struct so export can be added to variable definition
+	static struct LocalStruct {
+		export __gshared ushort id = ushort.max;
+	}
+	return LocalStruct.id;
 }
 
 /************************************************************************************************************************

source/bubel/ecs/vector.d

@@ -1,5 +1,5 @@
 /************************************************************************************************************************
-Copyright: Copyright © 2018-2019, Dawid Masiukiewicz, Michał Masiukiewicz
+Copyright: Copyright © 2018-2023, Dawid Masiukiewicz, Michał Masiukiewicz
 License: BSD 3-clause, see LICENSE file in project root folder.
 */
 module bubel.ecs.vector;

tests/basic.d

@@ -113,6 +113,31 @@ struct EmptySystem
     int count = 0;
 }
 
+struct EntityCounterSystem
+{
+    mixin ECS.System!1;
+
+    struct EntitiesData
+    {
+        int thread_id;
+        uint length;
+        Entity[] entity;
+    }
+
+    bool onBegin()
+    {
+        count = 0;
+        return true;
+    }
+
+    void onUpdate(EntitiesData data)
+    {
+        count += data.length;
+    }
+
+    int count = 0;
+}
+
 void beforeEveryTest()
 {
     becsID!CUnregistered = ushort.max;
@@ -243,7 +268,82 @@ unittest
     gEntityManager.commit();
     entity3 = gEntityManager.getEntity(id);
     assert(!entity3.getComponent!CUnregistered);
+}
 
+@("AddEmptyEntity")
+unittest
+{
+    struct OnAddRemoveChangeCounter
+    {
+        mixin ECS.System!1;
+
+        struct EntitiesData
+        {
+            int thread_id;
+            uint length;
+            Entity[] entity;
+        }
+
+        void onAddEntity(EntitiesData data)
+        {
+            add += data.length;
+        }
+        
+        void onRemoveEntity(EntitiesData data)
+        {
+            assert(0, "It's impossible to remove entity from being updated by system which accept empty entity");
+        }
+
+        int add = 0;
+    }
+
+    gEntityManager.beginRegister();
+
+    gEntityManager.registerSystem!EntityCounterSystem(0);
+    gEntityManager.registerSystem!OnAddRemoveChangeCounter(1);
+
+    gEntityManager.endRegister();
+
+    CLong long_component = CLong(3);
+
+    Entity* entity = null;
+    EntityID entity_id = gEntityManager.addEntity(null).id;
+
+    EntityCounterSystem* system = gEntityManager.getSystem!EntityCounterSystem;
+    assert(system !is null);
+    assert(system.count == 0);
+
+    OnAddRemoveChangeCounter* add_remove_change_system = gEntityManager.getSystem!OnAddRemoveChangeCounter;
+    assert(add_remove_change_system !is null);
+    assert(add_remove_change_system.add == 0);
+
+    gEntityManager.commit();
+    assert(add_remove_change_system.add == 1);
+
+    entity = gEntityManager.getEntity(entity_id);
+    assert(!entity.hasComponent(becsID!CLong));
+    assert(entity.getComponent(becsID!CLong) is null);
+    
+
+    gEntityManager.begin();
+    gEntityManager.update();
+    assert(system.count == 1);
+    gEntityManager.end();
+
+    gEntityManager.addEntityCopy(entity_id);
+    gEntityManager.addEntityCopy(entity_id);
+    gEntityManager.addComponents(entity_id, [ComponentRef(&long_component, becsID(long_component))].staticArray);
+    gEntityManager.commit();
+    assert(add_remove_change_system.add == 3, "onAddEntity missed");
+
+    entity = gEntityManager.getEntity(entity_id);
+    assert(entity.hasComponent(becsID!CLong));
+    assert(*entity.getComponent!CLong == 3);
+
+    gEntityManager.begin();
+    gEntityManager.update();
+    assert(system.count == 3);
+    gEntityManager.end();
 }
 
 //allocate templates

tests/bugs.d

@@ -144,3 +144,32 @@ unittest
 
     gEntityManager.destroy();
 }
+
+@("2-empty-entity-crash")
+unittest
+{
+    
+    gEntityManager.initialize(0);
+
+    gEntityManager.beginRegister();
+
+    gEntityManager.registerComponent!CInt;
+    gEntityManager.registerComponent!CFloat;
+
+    gEntityManager.endRegister();
+
+
+    EntityTemplate* tmpl = gEntityManager.allocateTemplate([becsID!CInt, becsID!CFloat].staticArray);
+    scope(exit) gEntityManager.freeTemplate(tmpl);
+
+    EntityID id = gEntityManager.addEntity(tmpl).id;
+    // EntityID id2 = gEntityManager.addEntity().id;
+
+    gEntityManager.commit();
+
+    gEntityManager.removeComponents(id, [becsID!CInt, becsID!CFloat].staticArray);
+
+    gEntityManager.commit();
+
+    gEntityManager.destroy();
+}