Class meta_factory< Type, Spec... >

Synopsis

#include <src/entt/meta/factory.hpp>

template<typename Type, typename... Spec>
class meta_factory<Type, Spec...>: public meta_factory<Type>

Description

Extended meta factory to be used for reflection purposes.

Template Parameters

Type - Reflected type for which the factory was created.

Spec - Property specialization pack used to disambiguate overloads.

Inheritance

Ancestors: meta_factory< Type >

Methods

	meta_factory	Constructs an extended factory from a given node.
	prop	Assigns a property to the last meta object created.
	props	Assigns properties to the last meta object created.

Source

Lines 220-329 in src/entt/meta/factory.hpp.

template<typename Type, typename... Spec>
class meta_factory<Type, Spec...>: public meta_factory<Type> {
    [[nodiscard]] bool exists(const meta_any &key, const internal::meta_prop_node *node) ENTT_NOEXCEPT {
        return node && (node->key() == key || exists(key, node->next));
    }

    template<std::size_t Step = 0, std::size_t... Index, typename... Property, typename... Other>
    void unpack(std::index_sequence<Index...>, std::tuple<Property...> property, Other &&... other) {
        unroll<Step>(choice<3>, std::move(std::get<Index>(property))..., std::forward<Other>(other)...);
    }

    template<std::size_t Step = 0, typename... Property, typename... Other>
    void unroll(choice_t<3>, std::tuple<Property...> property, Other &&... other) {
        unpack<Step>(std::index_sequence_for<Property...>{}, std::move(property), std::forward<Other>(other)...);
    }

    template<std::size_t Step = 0, typename... Property, typename... Other>
    void unroll(choice_t<2>, std::pair<Property...> property, Other &&... other) {
        assign<Step>(std::move(property.first), std::move(property.second));
        unroll<Step+1>(choice<3>, std::forward<Other>(other)...);
    }

    template<std::size_t Step = 0, typename Property, typename... Other>
    std::enable_if_t<!std::is_invocable_v<Property>>
    unroll(choice_t<1>, Property &&property, Other &&... other) {
        assign<Step>(std::forward<Property>(property));
        unroll<Step+1>(choice<3>, std::forward<Other>(other)...);
    }

    template<std::size_t Step = 0, typename Func, typename... Other>
    void unroll(choice_t<0>, Func &&invocable, Other &&... other) {
        unroll<Step>(choice<3>, std::forward<Func>(invocable)(), std::forward<Other>(other)...);
    }

    template<std::size_t>
    void unroll(choice_t<0>) {}

    template<std::size_t = 0, typename Key, typename... Value>
    void assign(Key &&key, Value &&... value) {
        static const auto property{std::make_tuple(std::forward<Key>(key), std::forward<Value>(value)...)};

        static internal::meta_prop_node node{
            nullptr,
            []() -> meta_any {
                return std::get<0>(property);
            },
            []() -> meta_any {
                if constexpr(sizeof...(Value) == 0) {
                    return {};
                } else {
                    return std::get<1>(property);
                }
            }
        };

        ENTT_ASSERT(!exists(node.key(), *curr));
        node.next = *curr;
        *curr = &node;
    }

public:
    /**
     * @brief Constructs an extended factory from a given node.
     * @param target The underlying node to which to assign the properties.
     */
    meta_factory(internal::meta_prop_node **target) ENTT_NOEXCEPT
        : curr{target}
    {}

    /**
     * @brief Assigns a property to the last meta object created.
     *
     * Both the key and the value (if any) must be at least copy constructible.
     *
     * @tparam PropertyOrKey Type of the property or property key.
     * @tparam Value Optional type of the property value.
     * @param property_or_key Property or property key.
     * @param value Optional property value.
     * @return A meta factory for the parent type.
     */
    template<typename PropertyOrKey, typename... Value>
    auto prop(PropertyOrKey &&property_or_key, Value &&... value) && {
        if constexpr(sizeof...(Value) == 0) {
            unroll(choice<3>, std::forward<PropertyOrKey>(property_or_key));
        } else {
            assign(std::forward<PropertyOrKey>(property_or_key), std::forward<Value>(value)...);
        }

        return meta_factory<Type, Spec..., PropertyOrKey, Value...>{curr};
    }

    /**
     * @brief Assigns properties to the last meta object created.
     *
     * Both the keys and the values (if any) must be at least copy
     * constructible.
     *
     * @tparam Property Types of the properties.
     * @param property Properties to assign to the last meta object created.
     * @return A meta factory for the parent type.
     */
    template <typename... Property>
    auto props(Property... property) && {
        unroll(choice<3>, std::forward<Property>(property)...);
        return meta_factory<Type, Spec..., Property...>{curr};
    }

private:
    internal::meta_prop_node **curr;
};