feat: add onchange for systems

ecsact/entt/detail/apply_pending.hh

@@ -13,10 +13,11 @@ auto apply_pending_add(::entt::registry& registry) -> void {
 			registry.emplace<C>(entity);
 		});
 	} else {
-		registry.view<pending_add<C>>().each(
+		registry.view<pending_add<C>>().each( //
 			[&](auto entity, const pending_add<C>& comp) {
 				registry.emplace<C>(entity, comp.value);
-				registry.emplace<beforechange_storage<C>>(entity, comp.value, false);
+				registry
+					.emplace<exec_beforechange_storage<C>>(entity, comp.value, false);
 			}
 		);
 	}
@@ -27,7 +28,7 @@ template<typename C>
 auto apply_pending_remove(::entt::registry& registry) -> void {
 	registry.view<pending_remove<C>>().each([&](auto entity) {
 		if constexpr(!std::is_empty_v<C>) {
-			registry.erase<beforechange_storage<C>>(entity);
+			registry.erase<exec_beforechange_storage<C>>(entity);
 		}
 		registry.erase<C>(entity);
 	});

ecsact/entt/detail/internal_markers.hh

@@ -37,11 +37,17 @@ struct beforeremove_storage<C> {
 
 template<typename C>
 	requires(!std::is_empty_v<C>)
-struct beforechange_storage {
+struct exec_beforechange_storage {
 	C    value;
 	bool has_update_occurred = false;
 };
 
+template<typename C>
+	requires(!std::is_empty_v<C>)
+struct exec_itr_beforechange_storage {
+	C value;
+};
+
 template<typename C>
 struct pending_add;
 
@@ -107,4 +113,18 @@ auto remove_system_markers_if_needed( //
 )");
 }
 
+template<typename C>
+auto add_exec_itr_beforechange_if_needed( //
+	::entt::registry&,
+	ecsact::entt::entity_id
+) -> void {
+	static_assert(system_markers_unimplemented_by_codegen<C>, R"(
+ -----------------------------------------------------------------------------
+| (!) CODEGEN ERROR                                                           |
+| `add_exec_itr_beforechange_if_needed<>` template specialization cannot be found |
+| This is typically generated by ecsact_rt_entt_codegen.                      |
+ -----------------------------------------------------------------------------
+)");
+}
+
 } // namespace ecsact::entt::detail

ecsact/entt/wrapper/core.hh

@@ -59,7 +59,7 @@ inline auto add_component( //
 		if constexpr(std::is_empty_v<C>) {
 			reg.emplace<C>(entity);
 		} else {
-			reg.emplace<detail::beforechange_storage<C>>(
+			reg.emplace<detail::exec_beforechange_storage<C>>(
 				entity,
 				*static_cast<const C*>(component_data),
 				false
@@ -68,6 +68,7 @@ inline auto add_component( //
 		}
 
 		ecsact::entt::detail::add_system_markers_if_needed<C>(reg, entity);
+		ecsact::entt::detail::add_exec_itr_beforechange_if_needed<C>(reg, entity);
 	}
 
 	return err;
@@ -96,14 +97,15 @@ inline auto add_component_exec_options( //
 		if constexpr(std::is_empty_v<C>) {
 			reg.emplace<C>(entity);
 		} else {
-			reg.emplace<detail::beforechange_storage<C>>(
+			reg.emplace<detail::exec_beforechange_storage<C>>(
 				entity,
 				*static_cast<const C*>(component_data)
 			);
 			reg.emplace<C>(entity, *static_cast<const C*>(component_data));
 		}
 		reg.template emplace_or_replace<component_added<C>>(entity);
 		ecsact::entt::detail::add_system_markers_if_needed<C>(reg, entity);
+		ecsact::entt::detail::add_exec_itr_beforechange_if_needed<C>(reg, entity);
 	}
 
 	return err;
@@ -172,7 +174,7 @@ auto remove_component(
 
 	reg.remove<C>(entity);
 	if constexpr(!std::is_empty_v<C>) {
-		reg.remove<detail::beforechange_storage<C>>(entity);
+		reg.remove<detail::exec_beforechange_storage<C>>(entity);
 	}
 	reg.template remove<component_added<C>>(entity);
 	reg.template remove<component_updated<C>>(entity);
@@ -205,7 +207,7 @@ auto remove_component_exec_options(
 	reg.template emplace_or_replace<component_removed<C>>(entity);
 
 	if constexpr(!std::is_empty_v<C>) {
-		reg.template remove<detail::beforechange_storage<C>>(entity);
+		reg.template remove<detail::exec_beforechange_storage<C>>(entity);
 	}
 
 	ecsact::entt::detail::remove_system_markers_if_needed<C>(reg, entity);
@@ -294,7 +296,7 @@ auto _trigger_update_component_event(
 	ecsact::entt::detail::execution_events_collector& events_collector
 ) -> void {
 	using ecsact::entt::component_updated;
-	using ecsact::entt::detail::beforechange_storage;
+	using ecsact::entt::detail::exec_beforechange_storage;
 
 	if(!events_collector.has_update_callback()) {
 		return;
@@ -304,12 +306,13 @@ auto _trigger_update_component_event(
 	if constexpr(!C::transient && !std::is_empty_v<C>) {
 		::entt::basic_view changed_view{
 			reg.template storage<C>(),
-			reg.template storage<beforechange_storage<C>>(),
+			reg.template storage<exec_beforechange_storage<C>>(),
 			reg.template storage<component_updated<C>>(),
 		};
 
 		for(ecsact::entt::entity_id entity : changed_view) {
-			auto& before = changed_view.template get<beforechange_storage<C>>(entity);
+			auto& before =
+				changed_view.template get<exec_beforechange_storage<C>>(entity);
 			auto& current = changed_view.template get<C>(entity);
 			before.has_update_occurred = false;
 
@@ -403,9 +406,33 @@ inline auto prepare_component(ecsact_registry_id registry_id) -> void {
 	reg.template storage<component_removed<C>>();
 
 	if constexpr(!std::is_empty_v<C>) {
-		reg.storage<detail::beforechange_storage<C>>();
+		reg.storage<detail::exec_beforechange_storage<C>>();
 		reg.template storage<component_updated<C>>();
 	}
 }
 
+template<typename C, typename V>
+auto has_component_changed(entt::entity_id entity, V& view) -> bool {
+	using detail::exec_itr_beforechange_storage;
+
+	const auto& current_comp = view.template get<C>(entity);
+	const auto& before_comp =
+		view.template get<exec_itr_beforechange_storage<C>>(entity);
+
+	if(before_comp.value != current_comp) {
+		return true;
+	}
+	return false;
+}
+
+template<typename C>
+auto update_exec_itr_beforechange(entt::entity_id entity, ::entt::registry& reg)
+	-> void {
+	auto  comp = reg.get<C>(entity);
+	auto& beforechange_comp =
+		reg.get<detail::exec_itr_beforechange_storage<C>>(entity);
+
+	beforechange_comp.value = comp;
+}
+
 } // namespace ecsact::entt::wrapper::core

ecsact/entt/wrapper/dynamic.hh

@@ -20,8 +20,8 @@ auto context_add(
 ) -> void {
 	using ecsact::entt::component_added;
 	using ecsact::entt::component_removed;
-	using ecsact::entt::detail::beforechange_storage;
 	using ecsact::entt::detail::beforeremove_storage;
+	using ecsact::entt::detail::exec_beforechange_storage;
 	using ecsact::entt::detail::pending_add;
 
 	assert(ecsact_id_cast<ecsact_component_like_id>(C::id) == component_id);
@@ -34,7 +34,6 @@ auto context_add(
 	} else {
 		const C* component = static_cast<const C*>(component_data);
 		registry.template emplace_or_replace<pending_add<C>>(entity, *component);
-
 		registry.template remove<beforeremove_storage<C>>(entity);
 	}
 
@@ -54,8 +53,6 @@ auto component_add_trivial(
 ) -> void {
 	using ecsact::entt::component_added;
 	using ecsact::entt::component_removed;
-	using ecsact::entt::detail::beforechange_storage;
-	using ecsact::entt::detail::beforeremove_storage;
 	using ecsact::entt::detail::pending_add;
 
 	registry.template emplace_or_replace<pending_add<C>>(entity_id);
@@ -146,7 +143,7 @@ auto context_update(
 	const void*                               in_component_data
 ) -> void {
 	using ecsact::entt::component_updated;
-	using ecsact::entt::detail::beforechange_storage;
+	using ecsact::entt::detail::exec_beforechange_storage;
 	// TODO(Kelwan): for remove, beforeremove_storage
 
 	auto  entity = context->entity;
@@ -155,7 +152,8 @@ auto context_update(
 	const auto& in_component = *static_cast<const C*>(in_component_data);
 
 	auto& current_component = registry.template get<C>(entity);
-	auto& beforechange = registry.template get<beforechange_storage<C>>(entity);
+	auto& beforechange =
+		registry.template get<exec_beforechange_storage<C>>(entity);
 	if(!beforechange.has_update_occurred) {
 		beforechange.value = current_component;
 		beforechange.has_update_occurred = true;

rt_entt_codegen/core/BUILD.bazel

@@ -32,8 +32,10 @@ _CORE_CODEGEN_METHODS = {
     ],
     "system_markers": [
         "//rt_entt_codegen/shared:sorting",
+        "//rt_entt_codegen/shared:system_util",
     ],
     "system_notify": ["//rt_entt_codegen/shared:system_util"],
+    "update_beforechange": [],
 }
 
 [cc_library(

rt_entt_codegen/core/core.hh

@@ -66,6 +66,11 @@ auto print_system_marker_remove_fn(
 	const ecsact_entt_details& details
 ) -> void;
 
+auto print_add_sys_beforestorage_fn(
+	codegen_plugin_context&    ctx,
+	const ecsact_entt_details& details
+) -> void;
+
 auto print_cleanup_system_notifies(
 	codegen_plugin_context&    ctx,
 	const ecsact_entt_details& details
@@ -76,4 +81,9 @@ auto print_entity_match_fn(
 	const ecsact_entt_details& details
 ) -> void;
 
+auto print_update_all_beforechange_storage(
+	codegen_plugin_context&    ctx,
+	const ecsact_entt_details& details
+) -> void;
+
 } // namespace ecsact::rt_entt_codegen::core

rt_entt_codegen/core/execute_systems.cc

@@ -67,6 +67,9 @@ auto ecsact::rt_entt_codegen::core::print_execute_systems( //
 		}
 	}
 
+	ctx.write("\nupdate_all_beforechange_storage(registry_id);\n");
+	ctx.write("cleanup_system_notifies(registry_id);\n");
+
 	ctx.indentation -= 1;
 	ctx.write("\n}\n\n");
 
@@ -88,9 +91,9 @@ auto ecsact::rt_entt_codegen::core::print_execute_systems( //
 				"trigger_component_events_all(registry_id, events_collector);\n\n"
 			);
 		});
-		ctx.write("cleanup_component_events(registry_id);\n");
-		ctx.write("cleanup_system_notifies(registry_id);\n");
 	});
 
+	ctx.write("cleanup_component_events(registry_id);\n");
+
 	ctx.write("return ECSACT_EXEC_SYS_OK;");
 }

rt_entt_codegen/core/system_markers.cc

@@ -6,6 +6,7 @@
 #include "ecsact/lang-support/lang-cc.hh"
 #include "ecsact/cpp_codegen_plugin_util.hh"
 #include "rt_entt_codegen/shared/sorting.hh"
+#include "rt_entt_codegen/shared/system_util.hh"
 
 using ecsact::cpp_codegen_plugin_util::block;
 using ecsact::cpp_codegen_plugin_util::method_printer;
@@ -93,3 +94,50 @@ auto ecsact::rt_entt_codegen::core::print_system_marker_remove_fn(
 		ctx.write("//TODO\n");
 	}
 }
+
+auto ecsact::rt_entt_codegen::core::print_add_sys_beforestorage_fn(
+	codegen_plugin_context&    ctx,
+	const ecsact_entt_details& details
+) -> void {
+	using cc_lang_support::cpp_identifier;
+	using ecsact::meta::decl_full_name;
+
+	auto already_printed_ = std::set<ecsact_component_id>{};
+
+	for(auto comp_id : details.all_components) {
+		auto comp_name = cpp_identifier(decl_full_name(comp_id));
+
+		ctx.write("template<>\n");
+		auto printer =
+			method_printer{
+				ctx,
+				std::format(
+					"ecsact::entt::detail::add_exec_itr_beforechange_if_needed< {}>",
+					comp_name
+				)
+			}
+				.parameter("::entt::registry&", "reg")
+				.parameter("ecsact::entt::entity_id", "entity")
+				.return_type("void");
+
+		for(auto system_id : details.all_systems) {
+			auto notify_settings = ecsact::meta::system_notify_settings(system_id);
+
+			for(auto const [comp_id_to_compare, notify_setting] : notify_settings) {
+				if(comp_id == static_cast<ecsact_component_id>(comp_id_to_compare)) {
+					if(notify_setting == ECSACT_SYS_NOTIFY_ONCHANGE) {
+						if(already_printed_.contains(comp_id)) {
+							break;
+						}
+						already_printed_.insert(comp_id);
+						ctx.write(std::format( //
+							"reg.emplace<exec_itr_beforechange_storage<{}>>(entity);\n",
+							comp_name
+						));
+						break;
+					}
+				}
+			}
+		}
+	}
+}

rt_entt_codegen/core/update_beforechange.cc

@@ -0,0 +1,54 @@
+#include "core.hh"
+
+#include <format>
+
+#include "ecsact/lang-support/lang-cc.hh"
+#include "rt_entt_codegen/shared/util.hh"
+#include "ecsact/runtime/common.h"
+#include "ecsact/cpp_codegen_plugin_util.hh"
+
+auto ecsact::rt_entt_codegen::core::print_update_all_beforechange_storage(
+	codegen_plugin_context&    ctx,
+	const ecsact_entt_details& details
+) -> void {
+	using ecsact::cc_lang_support::c_identifier;
+	using ecsact::cc_lang_support::cpp_identifier;
+	using ecsact::cpp_codegen_plugin_util::block;
+	using ecsact::cpp_codegen_plugin_util::method_printer;
+	using ecsact::meta::decl_full_name;
+
+	auto printer = //
+		method_printer{ctx, "update_all_beforechange_storage"}
+			.parameter("ecsact_registry_id", "registry_id")
+			.return_type("void");
+
+	ctx.write("auto& reg = ecsact::entt::get_registry(registry_id);\n\n");
+
+	for(auto comp_id : details.all_components) {
+		if(ecsact::meta::get_field_ids(comp_id).empty()) {
+			continue;
+		}
+
+		auto comp_name = c_identifier(decl_full_name((comp_id)));
+		auto cpp_comp_name = cpp_identifier(decl_full_name(comp_id));
+		auto comp_change_name = std::format( //
+			"ecsact::entt::detail::exec_itr_beforechange_storage<{}>",
+			cpp_comp_name
+		);
+
+		auto view_name = std::format("{}_view", comp_name);
+		auto comp_list = std::format("{}, {}", cpp_comp_name, comp_change_name);
+
+		ctx.write( //
+			std::format("auto {} = reg.view<{}>();\n", view_name, comp_list)
+		);
+
+		block(ctx, std::format("for(auto entity: {})", view_name), [&]() {
+			ctx.write(std::format(
+				"ecsact::entt::wrapper::core::update_exec_itr_beforechange<{}>(entity, "
+				"reg);\n",
+				cpp_comp_name
+			));
+		});
+	}
+}