From da1f56d046d4de0949017da3db3a8c8f0f41a1b4 Mon Sep 17 00:00:00 2001
From: Michele Caini <michele.caini@gmail.com>
Date: Thu, 27 Feb 2025 09:52:05 +0100
Subject: [PATCH] mixin: support custom private/protected registries - close
 #1222

---
 src/entt/entity/mixin.hpp           | 32 ++++++++++++++---------------
 test/common/registry.h              | 21 ++++++++++++++++++-
 test/entt/entity/reactive_mixin.cpp |  6 +++---
 test/entt/entity/sigh_mixin.cpp     | 11 +++-------
 4 files changed, 42 insertions(+), 28 deletions(-)

diff --git a/src/entt/entity/mixin.hpp b/src/entt/entity/mixin.hpp
index 5793a6f67..00267684f 100644
--- a/src/entt/entity/mixin.hpp
+++ b/src/entt/entity/mixin.hpp
@@ -36,20 +36,6 @@ template<typename Type, typename Registry>
 struct has_on_destroy<Type, Registry, std::void_t<decltype(Type::on_destroy(std::declval<Registry &>(), std::declval<Registry>().create()))>>
     : std::true_type {};
 
-template<typename Type>
-auto *any_to_owner(any &value) noexcept {
-    using base_type = basic_registry<typename Type::entity_type, typename Type::allocator_type>;
-    auto *reg = any_cast<base_type>(&value);
-
-    if constexpr(!std::is_same_v<Type, base_type>) {
-        if(!reg) {
-            reg = any_cast<Type>(&value);
-        }
-    }
-
-    return reg;
-}
-
 } // namespace internal
 /*! @endcond */
 
@@ -130,7 +116,14 @@ private:
     }
 
     void bind_any(any value) noexcept final {
-        owner = internal::any_to_owner<registry_type>(value);
+        owner = any_cast<basic_registry_type>(&value);
+
+        if constexpr(!std::is_same_v<registry_type, basic_registry_type>) {
+            if(owner == nullptr) {
+                owner = any_cast<registry_type>(&value);
+            }
+        }
+
         underlying_type::bind_any(std::move(value));
     }
 
@@ -421,7 +414,14 @@ class basic_reactive_mixin final: public Type {
 
 private:
     void bind_any(any value) noexcept final {
-        owner = internal::any_to_owner<registry_type>(value);
+        owner = any_cast<basic_registry_type>(&value);
+
+        if constexpr(!std::is_same_v<registry_type, basic_registry_type>) {
+            if(owner == nullptr) {
+                owner = any_cast<registry_type>(&value);
+            }
+        }
+
         underlying_type::bind_any(std::move(value));
     }
 
diff --git a/test/common/registry.h b/test/common/registry.h
index 55db7f1fd..93bff384b 100644
--- a/test/common/registry.h
+++ b/test/common/registry.h
@@ -6,7 +6,26 @@
 namespace test {
 
 template<typename Entity>
-struct basic_custom_registry: entt::basic_registry<Entity> {};
+struct custom_registry: private entt::basic_registry<Entity> {
+    using base_type = entt::basic_registry<Entity>;
+
+    template<typename, typename>
+    friend class entt::basic_sigh_mixin;
+
+    template<typename, typename>
+    friend class entt::basic_reactive_mixin;
+
+public:
+    using allocator_type = typename base_type::allocator_type;
+    using entity_type = typename base_type::entity_type;
+
+    using base_type::base_type;
+
+    using base_type::storage;
+    using base_type::create;
+    using base_type::emplace;
+    using base_type::insert;
+};
 
 } // namespace test
 
diff --git a/test/entt/entity/reactive_mixin.cpp b/test/entt/entity/reactive_mixin.cpp
index e26907051..579242eca 100644
--- a/test/entt/entity/reactive_mixin.cpp
+++ b/test/entt/entity/reactive_mixin.cpp
@@ -31,7 +31,7 @@ void remove(Type &storage, const typename Type::registry_type &, const typename
 
 template<typename Type>
 struct entt::storage_type<Type, test::entity, std::allocator<Type>, std::enable_if_t<!std::is_same_v<Type, test::entity>>> {
-    using type = entt::basic_sigh_mixin<entt::basic_storage<Type, test::entity>, test::basic_custom_registry<test::entity>>;
+    using type = entt::basic_sigh_mixin<entt::basic_storage<Type, test::entity>, test::custom_registry<test::entity>>;
 };
 
 template<typename Type>
@@ -454,7 +454,7 @@ ENTT_DEBUG_TYPED_TEST(ReactiveMixinDeathTest, Registry) {
 
 TYPED_TEST(ReactiveMixin, CustomRegistry) {
     using value_type = typename TestFixture::type;
-    using registry_type = test::basic_custom_registry<test::entity>;
+    using registry_type = test::custom_registry<test::entity>;
 
     registry_type registry;
     entt::basic_reactive_mixin<entt::basic_storage<value_type, test::entity>, registry_type> pool;
@@ -476,7 +476,7 @@ TYPED_TEST(ReactiveMixin, CustomRegistry) {
 
 ENTT_DEBUG_TYPED_TEST(ReactiveMixinDeathTest, CustomRegistry) {
     using value_type = typename TestFixture::type;
-    using registry_type = test::basic_custom_registry<test::entity>;
+    using registry_type = test::custom_registry<test::entity>;
     entt::basic_reactive_mixin<entt::basic_storage<value_type, test::entity>, registry_type> pool;
     ASSERT_DEATH([[maybe_unused]] auto &registry = pool.registry(), "");
     ASSERT_DEATH([[maybe_unused]] const auto &registry = std::as_const(pool).registry(), "");
diff --git a/test/entt/entity/sigh_mixin.cpp b/test/entt/entity/sigh_mixin.cpp
index 4406618df..0ecbf8eb9 100644
--- a/test/entt/entity/sigh_mixin.cpp
+++ b/test/entt/entity/sigh_mixin.cpp
@@ -48,11 +48,6 @@ void listener(std::size_t &counter, Registry &, typename Registry::entity_type)
     ++counter;
 }
 
-template<typename Type>
-struct entt::storage_type<Type, test::entity, std::allocator<Type>, std::enable_if_t<!std::is_same_v<Type, test::entity>>> {
-    using type = entt::basic_sigh_mixin<entt::basic_storage<Type, test::entity>, test::basic_custom_registry<test::entity>>;
-};
-
 template<typename Type>
 struct SighMixin: testing::Test {
     using type = Type;
@@ -433,7 +428,7 @@ TYPED_TEST(SighMixin, Swap) {
 
 TEST(SighMixin, AutoSignal) {
     entt::registry registry;
-    auto const entity = registry.create();
+    const auto entity = registry.create();
 
     bool created{};
     bool updated{};
@@ -488,7 +483,7 @@ ENTT_DEBUG_TYPED_TEST(SighMixinDeathTest, Registry) {
 
 TYPED_TEST(SighMixin, CustomRegistry) {
     using value_type = typename TestFixture::type;
-    using registry_type = test::basic_custom_registry<test::entity>;
+    using registry_type = test::custom_registry<test::entity>;
 
     registry_type registry;
     entt::basic_sigh_mixin<entt::basic_storage<value_type, test::entity>, registry_type> pool;
@@ -520,7 +515,7 @@ TYPED_TEST(SighMixin, CustomRegistry) {
 
 ENTT_DEBUG_TYPED_TEST(SighMixinDeathTest, CustomRegistry) {
     using value_type = typename TestFixture::type;
-    using registry_type = test::basic_custom_registry<test::entity>;
+    using registry_type = test::custom_registry<test::entity>;
     entt::basic_sigh_mixin<entt::basic_storage<value_type, test::entity>, registry_type> pool;
     ASSERT_DEATH([[maybe_unused]] auto &registry = pool.registry(), "");
     ASSERT_DEATH([[maybe_unused]] const auto &registry = std::as_const(pool).registry(), "");