entity: use entity_like as needed to constrain types in the ecs module

src/entt/entity/component.hpp

@@ -39,7 +39,7 @@ struct page_size<Type, std::void_t<decltype(Type::page_size)>>
  * @tparam Type Element type.
  * @tparam Entity A valid entity type.
  */
-template<typename Type, typename Entity, typename>
+template<typename Type, entity_like Entity, typename>
 struct component_traits {
     static_assert(std::is_same_v<std::decay_t<Type>, Type>, "Unsupported type");
 

src/entt/entity/fwd.hpp

@@ -43,13 +43,13 @@ enum class deletion_policy : std::uint8_t {
     unspecified = swap_and_pop
 };
 
-template<typename Type, typename Entity = entity, typename = void>
+template<typename Type, entity_like Entity = entity, typename = void>
 struct component_traits;
 
-template<typename Entity = entity, typename = std::allocator<Entity>>
+template<entity_like Entity = entity, typename = std::allocator<Entity>>
 class basic_sparse_set;
 
-template<typename Type, typename = entity, typename = std::allocator<Type>, typename = void>
+template<typename Type, entity_like = entity, typename = std::allocator<Type>, typename = void>
 class basic_storage;
 
 template<typename, typename>
@@ -58,7 +58,7 @@ class basic_sigh_mixin;
 template<typename, typename>
 class basic_reactive_mixin;
 
-template<typename Entity = entity, typename = std::allocator<Entity>>
+template<entity_like Entity = entity, typename = std::allocator<Entity>>
 class basic_registry;
 
 template<typename, typename, typename = void>
@@ -240,7 +240,7 @@ struct type_list_transform<owned_t<Type...>, Op> {
  * @tparam Entity A valid entity type.
  * @tparam Allocator Type of allocator used to manage memory and elements.
  */
-template<typename Type, typename Entity = entity, typename Allocator = std::allocator<Type>, typename = void>
+template<typename Type, entity_like Entity = entity, typename Allocator = std::allocator<Type>, typename = void>
 struct storage_type {
     /*! @brief Type-to-storage conversion result. */
     using type = ENTT_STORAGE(sigh_mixin, basic_storage<Type, Entity, Allocator>);
@@ -254,7 +254,7 @@ struct reactive final {};
  * @tparam Entity A valid entity type.
  * @tparam Allocator Type of allocator used to manage memory and elements.
  */
-template<typename Entity, typename Allocator>
+template<entity_like Entity, typename Allocator>
 struct storage_type<reactive, Entity, Allocator> {
     /*! @brief Type-to-storage conversion result. */
     using type = ENTT_STORAGE(reactive_mixin, basic_storage<reactive, Entity, Allocator>);
@@ -273,7 +273,7 @@ using storage_type_t = storage_type<Args...>::type;
  * @tparam Entity A valid entity type.
  * @tparam Allocator Type of allocator used to manage memory and elements.
  */
-template<typename Type, typename Entity = entity, typename Allocator = std::allocator<std::remove_const_t<Type>>>
+template<typename Type, entity_like Entity = entity, typename Allocator = std::allocator<std::remove_const_t<Type>>>
 struct storage_for {
     /*! @brief Type-to-storage conversion result. */
     using type = constness_as_t<storage_type_t<std::remove_const_t<Type>, Entity, Allocator>, Type>;

src/entt/entity/registry.hpp

@@ -206,7 +206,7 @@ private:
  * @tparam Entity A valid entity type.
  * @tparam Allocator Type of allocator used to manage memory and elements.
  */
-template<typename Entity, typename Allocator>
+template<entity_like Entity, typename Allocator>
 class basic_registry {
     using base_type = basic_sparse_set<Entity, Allocator>;
     using alloc_traits = std::allocator_traits<Allocator>;

src/entt/entity/sparse_set.hpp

@@ -134,7 +134,7 @@ private:
  * @tparam Entity A valid entity type.
  * @tparam Allocator Type of allocator used to manage memory and elements.
  */
-template<typename Entity, typename Allocator>
+template<entity_like Entity, typename Allocator>
 class basic_sparse_set {
     using alloc_traits = std::allocator_traits<Allocator>;
     static_assert(std::is_same_v<typename alloc_traits::value_type, Entity>, "Invalid value type");

src/entt/entity/storage.hpp

@@ -202,7 +202,7 @@ private:
  * @tparam Entity A valid entity type.
  * @tparam Allocator Type of allocator used to manage memory and elements.
  */
-template<typename Type, typename Entity, typename Allocator, typename>
+template<typename Type, entity_like Entity, typename Allocator, typename>
 class basic_storage: public basic_sparse_set<Entity, typename std::allocator_traits<Allocator>::template rebind_alloc<Entity>> {
     using alloc_traits = std::allocator_traits<Allocator>;
     static_assert(std::is_same_v<typename alloc_traits::value_type, Type>, "Invalid value type");
@@ -762,7 +762,7 @@ private:
 };
 
 /*! @copydoc basic_storage */
-template<typename Type, typename Entity, typename Allocator>
+template<typename Type, entity_like Entity, typename Allocator>
 class basic_storage<Type, Entity, Allocator, std::enable_if_t<component_traits<Type, Entity>::page_size == 0u>>
     : public basic_sparse_set<Entity, typename std::allocator_traits<Allocator>::template rebind_alloc<Entity>> {
     using alloc_traits = std::allocator_traits<Allocator>;
@@ -946,7 +946,7 @@ public:
  * @tparam Entity A valid entity type.
  * @tparam Allocator Type of allocator used to manage memory and elements.
  */
-template<typename Entity, typename Allocator>
+template<entity_like Entity, typename Allocator>
 class basic_storage<Entity, Entity, Allocator>
     : public basic_sparse_set<Entity, Allocator> {
     using alloc_traits = std::allocator_traits<Allocator>;

src/entt/entity/view.hpp

@@ -29,13 +29,13 @@ const Type *view_placeholder() {
     return &placeholder;
 }
 
-template<typename It, typename Entity>
+template<typename It, entity_like Entity>
 [[nodiscard]] bool all_of(It first, const It last, const Entity entt) noexcept {
     for(; (first != last) && (*first)->contains(entt); ++first) {}
     return first == last;
 }
 
-template<typename It, typename Entity>
+template<typename It, entity_like Entity>
 [[nodiscard]] bool none_of(It first, const It last, const Entity entt) noexcept {
     for(; (first != last) && !(*first)->contains(entt); ++first) {}
     return first == last;

src/entt/tools/davey.hpp

@@ -22,7 +22,7 @@ namespace entt {
 /*! @cond TURN_OFF_DOXYGEN */
 namespace internal {
 
-template<typename Entity, typename OnEntity>
+template<entity_like Entity, typename OnEntity>
 static void present_element(const meta_any &obj, OnEntity on_entity) {
     for([[maybe_unused]] const auto [id, data]: obj.type().data()) {
         const auto elem = data.get(obj);
@@ -133,7 +133,7 @@ static void present_element(const meta_any &obj, OnEntity on_entity) {
     }
 }
 
-template<typename Entity, typename Allocator>
+template<entity_like Entity, typename Allocator>
 static void present_storage(const meta_ctx &ctx, const basic_sparse_set<Entity, Allocator> &storage) {
     if(auto type = resolve(ctx, storage.info()); type) {
         for(auto entt: storage) {
@@ -158,7 +158,7 @@ static void present_storage(const meta_ctx &ctx, const basic_sparse_set<Entity,
     }
 }
 
-template<typename Entity, typename It>
+template<entity_like Entity, typename It>
 static void present_entity(const meta_ctx &ctx, const Entity entt, const It from, const It to) {
     for(auto it = from; it != to; ++it) {
         if(const auto &storage = it->second; storage.contains(entt)) {
@@ -234,7 +234,7 @@ static void present_view(const meta_ctx &ctx, const basic_view<get_t<Get...>, ex
  * @param ctx The context from which to search for meta types.
  * @param storage An instance of the storage type.
  */
-template<typename Type, typename Entity, typename Allocator>
+template<typename Type, entity_like Entity, typename Allocator>
 void davey(const meta_ctx &ctx, const basic_storage<Type, Entity, Allocator> &storage) {
     internal::present_storage(ctx, storage);
 }
@@ -246,7 +246,7 @@ void davey(const meta_ctx &ctx, const basic_storage<Type, Entity, Allocator> &st
  * @tparam Allocator Storage allocator type.
  * @param storage An instance of the storage type.
  */
-template<typename Type, typename Entity, typename Allocator>
+template<typename Type, entity_like Entity, typename Allocator>
 void davey(const basic_storage<Type, Entity, Allocator> &storage) {
     davey(locator<meta_ctx>::value_or(), storage);
 }
@@ -281,7 +281,7 @@ void davey(const basic_view<get_t<Get...>, exclude_t<Exclude...>> &view) {
  * @param ctx The context from which to search for meta types.
  * @param registry An instance of the registry type.
  */
-template<typename Entity, typename Allocator>
+template<entity_like Entity, typename Allocator>
 void davey(const meta_ctx &ctx, const basic_registry<Entity, Allocator> &registry) {
     ImGui::BeginTabBar("#tabs");
 
@@ -325,7 +325,7 @@ void davey(const meta_ctx &ctx, const basic_registry<Entity, Allocator> &registr
  * @tparam Allocator Registry allocator type.
  * @param registry An instance of the registry type.
  */
-template<typename Entity, typename Allocator>
+template<entity_like Entity, typename Allocator>
 void davey(const basic_registry<Entity, Allocator> &registry) {
     davey(locator<meta_ctx>::value_or(), registry);
 }

test/common/mixin.hpp

@@ -28,7 +28,7 @@ public:
 
 } // namespace test
 
-template<typename Entity>
+template<entt::entity_like Entity>
 struct entt::storage_type<test::assure_loop, Entity> {
     using type = test::assure_loop_mixin<entt::basic_storage<test::assure_loop, Entity>>;
 };

test/common/registry.h

@@ -5,7 +5,7 @@
 
 namespace test {
 
-template<typename Entity>
+template<entt::entity_like Entity>
 struct custom_registry: private entt::basic_registry<Entity> {
     using base_type = entt::basic_registry<Entity>;
 
@@ -21,10 +21,10 @@ public:
 
     using base_type::base_type;
 
-    using base_type::storage;
     using base_type::create;
     using base_type::emplace;
     using base_type::insert;
+    using base_type::storage;
 };
 
 } // namespace test

test/entt/entity/component.cpp

@@ -36,7 +36,7 @@ struct entt::component_traits<ComponentBase::traits_based, ComponentBase::other_
     static constexpr auto page_size = 16u;
 };
 
-template<typename Entity>
+template<entt::entity_like Entity>
 struct entt::component_traits<ComponentBase::traits_based, Entity> {
     using entity_type = Entity;
     using element_type = ComponentBase::traits_based;