meta: standalone meta_data/meta_func

TODO

@@ -31,16 +31,15 @@ TODO:
 * cleanup common view from tricks to handle single swap-only and in-place, if constexpr branches
 * entity based component_traits
 * review cmake warning about FetchContent_Populate (need .28 and EXCLUDE_FROM_ALL for FetchContent)
-* after removing meta prop vectors, copy meta objects in their handles directly
 * suppress -Wself-move on CI with g++13
 * view specializations for multi, single and filtered elements
 * organizer support to groups
 * meta range: move id to meta objects and return plain types (?), then remove id from meta base and meta ctor too
 * don't pass reactive storage by default to callback
 * runtime types support for meta for types that aren't backed by C++ types
-* dtor, traits and custom should be part of meta descriptor (update meta_factory tests then)
 * allow attaching const values of non-Type type to meta types
 * built-in no-pagination storage - no_pagination page size as limits::max
 * sparse_set shrink_to_fit argument for sparse array shrink policy (none, empty, deep, whatever)
 * any cdynamic to support const ownership construction
 * track meta context on meta elements
+* safer meta_data/meta_func (no blind indirections)

src/entt/meta/meta.hpp

@@ -833,8 +833,8 @@ struct meta_data {
      * @param area The context from which to search for meta types.
      * @param curr The underlying node with which to construct the instance.
      */
-    meta_data(const meta_ctx &area, const internal::meta_data_node &curr) noexcept
-        : node{&curr},
+    meta_data(const meta_ctx &area, internal::meta_data_node curr) noexcept
+        : node{std::move(curr)},
           ctx{&area} {}
 
     /**
@@ -842,7 +842,7 @@ struct meta_data {
      * @return The number of setters available.
      */
     [[nodiscard]] size_type arity() const noexcept {
-        return node->arity;
+        return node.arity;
     }
 
     /**
@@ -850,7 +850,7 @@ struct meta_data {
      * @return True if the data member is constant, false otherwise.
      */
     [[nodiscard]] bool is_const() const noexcept {
-        return static_cast<bool>(node->traits & internal::meta_traits::is_const);
+        return static_cast<bool>(node.traits & internal::meta_traits::is_const);
     }
 
     /**
@@ -858,7 +858,7 @@ struct meta_data {
      * @return True if the data member is static, false otherwise.
      */
     [[nodiscard]] bool is_static() const noexcept {
-        return static_cast<bool>(node->traits & internal::meta_traits::is_static);
+        return static_cast<bool>(node.traits & internal::meta_traits::is_static);
     }
 
     /*! @copydoc meta_any::type */
@@ -874,7 +874,7 @@ struct meta_data {
     template<typename Type>
     // NOLINTNEXTLINE(modernize-use-nodiscard)
     bool set(meta_handle instance, Type &&value) const {
-        return node->set && node->set(meta_handle{*ctx, std::move(instance)}, meta_any{*ctx, std::forward<Type>(value)});
+        return node.set && node.set(meta_handle{*ctx, std::move(instance)}, meta_any{*ctx, std::forward<Type>(value)});
     }
 
     /**
@@ -883,7 +883,7 @@ struct meta_data {
      * @return A wrapper containing the value of the underlying variable.
      */
     [[nodiscard]] meta_any get(meta_handle instance) const {
-        return node->get(*ctx, meta_handle{*ctx, std::move(instance)});
+        return node.get(*ctx, meta_handle{*ctx, std::move(instance)});
     }
 
     /**
@@ -900,7 +900,7 @@ struct meta_data {
      */
     template<typename Type>
     [[nodiscard]] Type traits() const noexcept {
-        return internal::meta_to_user_traits<Type>(node->traits);
+        return internal::meta_to_user_traits<Type>(node.traits);
     }
 
     /**
@@ -908,7 +908,7 @@ struct meta_data {
      * @return User defined arbitrary data.
      */
     [[nodiscard]] meta_custom custom() const noexcept {
-        return {node->custom};
+        return {node.custom};
     }
 
     /**
@@ -925,11 +925,11 @@ struct meta_data {
      * @return True if the objects refer to the same type, false otherwise.
      */
     [[nodiscard]] bool operator==(const meta_data &other) const noexcept {
-        return (ctx == other.ctx && node == other.node);
+        return (ctx == other.ctx) && (node.set == other.node.set) && (node.get == other.node.get);
     }
 
 private:
-    const internal::meta_data_node *node{};
+    internal::meta_data_node node{};
     const meta_ctx *ctx{};
 };
 
@@ -956,8 +956,8 @@ struct meta_func {
      * @param area The context from which to search for meta types.
      * @param curr The underlying node with which to construct the instance.
      */
-    meta_func(const meta_ctx &area, const internal::meta_func_node &curr) noexcept
-        : node{&curr},
+    meta_func(const meta_ctx &area, internal::meta_func_node curr) noexcept
+        : node{std::move(curr)},
           ctx{&area} {}
 
     /**
@@ -965,7 +965,7 @@ struct meta_func {
      * @return The number of arguments accepted by the member function.
      */
     [[nodiscard]] size_type arity() const noexcept {
-        return node->arity;
+        return node.arity;
     }
 
     /**
@@ -973,7 +973,7 @@ struct meta_func {
      * @return True if the member function is constant, false otherwise.
      */
     [[nodiscard]] bool is_const() const noexcept {
-        return static_cast<bool>(node->traits & internal::meta_traits::is_const);
+        return static_cast<bool>(node.traits & internal::meta_traits::is_const);
     }
 
     /**
@@ -981,7 +981,7 @@ struct meta_func {
      * @return True if the member function is static, false otherwise.
      */
     [[nodiscard]] bool is_static() const noexcept {
-        return static_cast<bool>(node->traits & internal::meta_traits::is_static);
+        return static_cast<bool>(node.traits & internal::meta_traits::is_static);
     }
 
     /**
@@ -1005,7 +1005,7 @@ struct meta_func {
      * @return A wrapper containing the returned value, if any.
      */
     meta_any invoke(meta_handle instance, meta_any *const args, const size_type sz) const {
-        return sz == arity() ? node->invoke(*ctx, meta_handle{*ctx, std::move(instance)}, args) : meta_any{meta_ctx_arg, *ctx};
+        return sz == arity() ? node.invoke(*ctx, meta_handle{*ctx, std::move(instance)}, args) : meta_any{meta_ctx_arg, *ctx};
     }
 
     /**
@@ -1025,12 +1025,12 @@ struct meta_func {
     /*! @copydoc meta_data::traits */
     template<typename Type>
     [[nodiscard]] Type traits() const noexcept {
-        return internal::meta_to_user_traits<Type>(node->traits);
+        return internal::meta_to_user_traits<Type>(node.traits);
     }
 
     /*! @copydoc meta_data::custom */
     [[nodiscard]] meta_custom custom() const noexcept {
-        return {node->custom};
+        return {node.custom};
     }
 
     /**
@@ -1038,7 +1038,7 @@ struct meta_func {
      * @return The next overload of the given function, if any.
      */
     [[nodiscard]] meta_func next() const {
-        return node->next ? meta_func{*ctx, *node->next} : meta_func{};
+        return node.next ? meta_func{*ctx, *node.next} : meta_func{};
     }
 
     /**
@@ -1051,11 +1051,11 @@ struct meta_func {
 
     /*! @copydoc meta_data::operator== */
     [[nodiscard]] bool operator==(const meta_func &other) const noexcept {
-        return (ctx == other.ctx && node == other.node);
+        return (ctx == other.ctx) && (node.invoke == other.node.invoke);
     }
 
 private:
-    const internal::meta_func_node *node{};
+    internal::meta_func_node node{};
     const meta_ctx *ctx{};
 };
 
@@ -1582,19 +1582,19 @@ inline bool meta_any::assign(meta_any &&other) {
 }
 
 [[nodiscard]] inline meta_type meta_data::type() const noexcept {
-    return meta_type{*ctx, node->type(internal::meta_context::from(*ctx))};
+    return meta_type{*ctx, node.type(internal::meta_context::from(*ctx))};
 }
 
 [[nodiscard]] inline meta_type meta_data::arg(const size_type index) const noexcept {
-    return index < arity() ? node->arg(*ctx, index) : meta_type{};
+    return index < arity() ? node.arg(*ctx, index) : meta_type{};
 }
 
 [[nodiscard]] inline meta_type meta_func::ret() const noexcept {
-    return meta_type{*ctx, node->ret(internal::meta_context::from(*ctx))};
+    return meta_type{*ctx, node.ret(internal::meta_context::from(*ctx))};
 }
 
 [[nodiscard]] inline meta_type meta_func::arg(const size_type index) const noexcept {
-    return index < arity() ? node->arg(*ctx, index) : meta_type{};
+    return index < arity() ? node.arg(*ctx, index) : meta_type{};
 }
 
 /*! @cond TURN_OFF_DOXYGEN */