meta: get the context from the instance in the meta invoke (and deprecate old API)

TODO

@@ -37,3 +37,4 @@ TODO:
 * allow passing arguments to meta setter/getter (we can fallback on meta invoke probably)
 * meta: remove ctx arg from utilities (handle/any), container ctors/funcs (it), func invoke (any, with check)
 * meta: remove ctx member from meta_data, meta_func, ... (use handles and the like)
+* meta: do not rebind args or instances internally

src/entt/meta/meta.hpp

@@ -1017,7 +1017,7 @@ 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 ((node.invoke != nullptr) && (sz == arity())) ? node.invoke(*ctx, meta_handle{*ctx, std::move(instance)}, args) : meta_any{meta_ctx_arg, *ctx};
+        return ((node.invoke != nullptr) && (sz == arity())) ? node.invoke(meta_handle{*ctx, std::move(instance)}, args) : meta_any{meta_ctx_arg, *ctx};
     }
 
     /**
@@ -1438,7 +1438,7 @@ public:
         if(node.details) {
             if(auto *elem = internal::find_member<&internal::meta_func_node::id>(node.details->func, id); elem != nullptr) {
                 if(const auto *candidate = lookup(args, sz, (instance->base().policy() == any_policy::cref), [curr = elem]() mutable { return (curr != nullptr) ? std::exchange(curr, curr->next.get()) : nullptr; }); candidate) {
-                    return candidate->invoke(*ctx, meta_handle{*ctx, std::move(instance)}, args);
+                    return candidate->invoke(meta_handle{*ctx, std::move(instance)}, args);
                 }
             }
         }

src/entt/meta/node.hpp

@@ -112,7 +112,7 @@ struct meta_func_node {
     size_type arity{0u};
     meta_type_node (*ret)(const meta_context &) noexcept {};
     meta_type (*arg)(const meta_ctx &, const size_type) noexcept {};
-    meta_any (*invoke)(const meta_ctx &, meta_handle, meta_any *const){};
+    meta_any (*invoke)(meta_handle, meta_any *const){};
     std::shared_ptr<meta_func_node> next;
     meta_custom_node custom{};
 };

src/entt/meta/utility.hpp

@@ -204,26 +204,26 @@ template<typename Policy, typename Candidate, typename... Args>
 }
 
 template<typename Type, typename Policy, typename Candidate, std::size_t... Index>
-[[nodiscard]] meta_any meta_invoke(const meta_ctx &ctx, [[maybe_unused]] meta_handle instance, Candidate &&candidate, [[maybe_unused]] meta_any *const args, std::index_sequence<Index...>) {
+[[nodiscard]] meta_any meta_invoke(meta_handle instance, Candidate &&candidate, [[maybe_unused]] meta_any *const args, std::index_sequence<Index...>) {
     using descriptor = meta_function_helper_t<Type, std::remove_reference_t<Candidate>>;
 
     // NOLINTBEGIN(cppcoreguidelines-pro-bounds-pointer-arithmetic) - waiting for C++20 (and std::span)
     if constexpr(std::is_invocable_v<std::remove_reference_t<Candidate>, const Type &, type_list_element_t<Index, typename descriptor::args_type>...>) {
         if(const auto *const clazz = instance->try_cast<const Type>(); clazz && ((args + Index)->allow_cast<type_list_element_t<Index, typename descriptor::args_type>>() && ...)) {
-            return meta_invoke_with_args<Policy>(ctx, std::forward<Candidate>(candidate), *clazz, (args + Index)->cast<type_list_element_t<Index, typename descriptor::args_type>>()...);
+            return meta_invoke_with_args<Policy>(instance->context(), std::forward<Candidate>(candidate), *clazz, (args + Index)->cast<type_list_element_t<Index, typename descriptor::args_type>>()...);
         }
     } else if constexpr(std::is_invocable_v<std::remove_reference_t<Candidate>, Type &, type_list_element_t<Index, typename descriptor::args_type>...>) {
         if(auto *const clazz = instance->try_cast<Type>(); clazz && ((args + Index)->allow_cast<type_list_element_t<Index, typename descriptor::args_type>>() && ...)) {
-            return meta_invoke_with_args<Policy>(ctx, std::forward<Candidate>(candidate), *clazz, (args + Index)->cast<type_list_element_t<Index, typename descriptor::args_type>>()...);
+            return meta_invoke_with_args<Policy>(instance->context(), std::forward<Candidate>(candidate), *clazz, (args + Index)->cast<type_list_element_t<Index, typename descriptor::args_type>>()...);
         }
     } else {
         if(((args + Index)->allow_cast<type_list_element_t<Index, typename descriptor::args_type>>() && ...)) {
-            return meta_invoke_with_args<Policy>(ctx, std::forward<Candidate>(candidate), (args + Index)->cast<type_list_element_t<Index, typename descriptor::args_type>>()...);
+            return meta_invoke_with_args<Policy>(instance->context(), std::forward<Candidate>(candidate), (args + Index)->cast<type_list_element_t<Index, typename descriptor::args_type>>()...);
         }
     }
     // NOLINTEND(cppcoreguidelines-pro-bounds-pointer-arithmetic)
 
-    return meta_any{meta_ctx_arg, ctx};
+    return meta_any{meta_ctx_arg, instance->context()};
 }
 
 template<typename Type, typename... Args, std::size_t... Index>
@@ -358,14 +358,8 @@ template<typename Type, auto Data, typename Policy = as_is_t>
 
 /**
  * @brief Tries to _invoke_ an object given a list of erased parameters.
- *
- * @warning
- * The context provided is used only for the return type.<br/>
- * It's up to the caller to bind the arguments to the right context(s).
- *
  * @tparam Type Reflected type to which the object to _invoke_ is associated.
  * @tparam Policy Optional policy (no policy set by default).
- * @param ctx The context from which to search for meta types.
  * @tparam Candidate The type of the actual object to _invoke_.
  * @param instance An opaque instance of the underlying type, if required.
  * @param candidate The actual object to _invoke_.
@@ -373,14 +367,15 @@ template<typename Type, auto Data, typename Policy = as_is_t>
  * @return A meta any containing the returned value, if any.
  */
 template<typename Type, typename Policy = as_is_t, typename Candidate>
-[[nodiscard]] std::enable_if_t<is_meta_policy_v<Policy>, meta_any> meta_invoke(const meta_ctx &ctx, meta_handle instance, Candidate &&candidate, meta_any *const args) {
-    return internal::meta_invoke<Type, Policy>(ctx, std::move(instance), std::forward<Candidate>(candidate), args, std::make_index_sequence<meta_function_helper_t<Type, std::remove_reference_t<Candidate>>::args_type::size>{});
+[[nodiscard]] std::enable_if_t<is_meta_policy_v<Policy>, meta_any> meta_invoke(meta_handle instance, Candidate &&candidate, meta_any *const args) {
+    return internal::meta_invoke<Type, Policy>(std::move(instance), std::forward<Candidate>(candidate), args, std::make_index_sequence<meta_function_helper_t<Type, std::remove_reference_t<Candidate>>::args_type::size>{});
 }
 
 /**
  * @brief Tries to _invoke_ an object given a list of erased parameters.
  * @tparam Type Reflected type to which the object to _invoke_ is associated.
  * @tparam Policy Optional policy (no policy set by default).
+ * @param ctx The context from which to search for meta types.
  * @tparam Candidate The type of the actual object to _invoke_.
  * @param instance An opaque instance of the underlying type, if required.
  * @param candidate The actual object to _invoke_.
@@ -388,28 +383,22 @@ template<typename Type, typename Policy = as_is_t, typename Candidate>
  * @return A meta any containing the returned value, if any.
  */
 template<typename Type, typename Policy = as_is_t, typename Candidate>
-[[nodiscard]] std::enable_if_t<is_meta_policy_v<Policy>, meta_any> meta_invoke(meta_handle instance, Candidate &&candidate, meta_any *const args) {
-    return meta_invoke<Type, Policy>(locator<meta_ctx>::value_or(), std::move(instance), std::forward<Candidate>(candidate), args);
+[[deprecated("a context is no longer required, it is inferred from the meta_handle")]] [[nodiscard]] std::enable_if_t<is_meta_policy_v<Policy>, meta_any> meta_invoke(const meta_ctx &ctx, meta_handle instance, Candidate &&candidate, meta_any *const args) {
+    return meta_invoke<Type, Policy>(meta_handle{ctx, std::move(instance)}, std::forward<Candidate>(candidate), args);
 }
 
 /**
  * @brief Tries to invoke a function given a list of erased parameters.
- *
- * @warning
- * The context provided is used only for the return type.<br/>
- * It's up to the caller to bind the arguments to the right context(s).
- *
  * @tparam Type Reflected type to which the function is associated.
  * @tparam Candidate The actual function to invoke.
  * @tparam Policy Optional policy (no policy set by default).
- * @param ctx The context from which to search for meta types.
  * @param instance An opaque instance of the underlying type, if required.
  * @param args Parameters to use to invoke the function.
  * @return A meta any containing the returned value, if any.
  */
 template<typename Type, auto Candidate, typename Policy = as_is_t>
-[[nodiscard]] std::enable_if_t<is_meta_policy_v<Policy>, meta_any> meta_invoke(const meta_ctx &ctx, meta_handle instance, meta_any *const args) {
-    return internal::meta_invoke<Type, Policy>(ctx, std::move(instance), Candidate, args, std::make_index_sequence<meta_function_helper_t<Type, std::remove_reference_t<decltype(Candidate)>>::args_type::size>{});
+[[nodiscard]] std::enable_if_t<is_meta_policy_v<Policy>, meta_any> meta_invoke(meta_handle instance, meta_any *const args) {
+    return internal::meta_invoke<Type, Policy>(std::move(instance), Candidate, args, std::make_index_sequence<meta_function_helper_t<Type, std::remove_reference_t<decltype(Candidate)>>::args_type::size>{});
 }
 
 /**
@@ -417,13 +406,14 @@ template<typename Type, auto Candidate, typename Policy = as_is_t>
  * @tparam Type Reflected type to which the function is associated.
  * @tparam Candidate The actual function to invoke.
  * @tparam Policy Optional policy (no policy set by default).
+ * @param ctx The context from which to search for meta types.
  * @param instance An opaque instance of the underlying type, if required.
  * @param args Parameters to use to invoke the function.
  * @return A meta any containing the returned value, if any.
  */
 template<typename Type, auto Candidate, typename Policy = as_is_t>
-[[nodiscard]] std::enable_if_t<is_meta_policy_v<Policy>, meta_any> meta_invoke(meta_handle instance, meta_any *const args) {
-    return meta_invoke<Type, Candidate, Policy>(locator<meta_ctx>::value_or(), std::move(instance), args);
+[[deprecated("a context is no longer required, it is inferred from the meta_handle")]] [[nodiscard]] std::enable_if_t<is_meta_policy_v<Policy>, meta_any> meta_invoke(const meta_ctx &ctx, meta_handle instance, meta_any *const args) {
+    return meta_invoke<Type, Candidate, Policy>(meta_handle{ctx, std::move(instance)}, args);
 }
 
 /**
@@ -474,10 +464,11 @@ template<typename Type, typename... Args>
 template<typename Type, typename Policy = as_is_t, typename Candidate>
 [[nodiscard]] meta_any meta_construct(const meta_ctx &ctx, Candidate &&candidate, meta_any *const args) {
     if constexpr(meta_function_helper_t<Type, Candidate>::is_static || std::is_class_v<std::remove_cv_t<std::remove_reference_t<Candidate>>>) {
-        return internal::meta_invoke<Type, Policy>(ctx, {}, std::forward<Candidate>(candidate), args, std::make_index_sequence<meta_function_helper_t<Type, std::remove_reference_t<Candidate>>::args_type::size>{});
+        return internal::meta_invoke<Type, Policy>(meta_handle{meta_ctx_arg, ctx}, std::forward<Candidate>(candidate), args, std::make_index_sequence<meta_function_helper_t<Type, std::remove_reference_t<Candidate>>::args_type::size>{});
     } else {
+        meta_any handle{ctx, args->as_ref()};
         // NOLINTNEXTLINE(cppcoreguidelines-pro-bounds-pointer-arithmetic) - waiting for C++20 (and std::span)
-        return internal::meta_invoke<Type, Policy>(ctx, *args, std::forward<Candidate>(candidate), args + 1u, std::make_index_sequence<meta_function_helper_t<Type, std::remove_reference_t<Candidate>>::args_type::size>{});
+        return internal::meta_invoke<Type, Policy>(handle, std::forward<Candidate>(candidate), args + 1u, std::make_index_sequence<meta_function_helper_t<Type, std::remove_reference_t<Candidate>>::args_type::size>{});
     }
 }