Struct meta_func

Synopsis

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

struct meta_func

Description

Opaque wrapper for meta functions.

Mentioned in

• Runtime Reflection System / Enjoy the runtime

Methods

	meta_func	Constructs an instance from a given node.
	arg	Returns the meta type of the i-th argument of a meta function.
	id	Returns the identifier assigned to a meta object.
	invoke	Invokes the underlying function, if possible.
	is_const	Indicates whether a meta function is constant or not.
	is_static	Indicates whether a meta function is static or not.
	operator bool	Returns true if a meta object is valid, false otherwise.
	parent	Returns the meta type to which a meta object belongs.
	prop	Returns a range to use to visit all meta properties.
	ret	Returns the meta type of the return type of a meta function.
	size	Returns the number of arguments accepted by a meta function.

Source

Lines 886-1002 in src/entt/meta/meta.hpp.

struct meta_func {
    /*! @brief Node type. */
    using node_type = internal::meta_func_node;
    /*! @brief Unsigned integer type. */
    using size_type = typename node_type::size_type;

    /*! @copydoc meta_prop::meta_prop */
    meta_func(const node_type *curr = nullptr) ENTT_NOEXCEPT
        : node{curr}
    {}

    /*! @copydoc meta_type::id */
    [[nodiscard]] id_type id() const ENTT_NOEXCEPT {
        return node->id;
    }

    /*! @copydoc meta_base::parent */
    [[nodiscard]] inline meta_type parent() const ENTT_NOEXCEPT;

    /**
     * @brief Returns the number of arguments accepted by a meta function.
     * @return The number of arguments accepted by the meta function.
     */
    [[nodiscard]] size_type size() const ENTT_NOEXCEPT {
        return node->size;
    }

    /**
     * @brief Indicates whether a meta function is constant or not.
     * @return True if the meta function is constant, false otherwise.
     */
    [[nodiscard]] bool is_const() const ENTT_NOEXCEPT {
        return node->is_const;
    }

    /**
     * @brief Indicates whether a meta function is static or not.
     * @return True if the meta function is static, false otherwise.
     */
    [[nodiscard]] bool is_static() const ENTT_NOEXCEPT {
        return node->is_static;
    }

    /**
     * @brief Returns the meta type of the return type of a meta function.
     * @return The meta type of the return type of the meta function.
     */
    [[nodiscard]] inline meta_type ret() const ENTT_NOEXCEPT;

    /**
     * @brief Returns the meta type of the i-th argument of a meta function.
     * @param index The index of the argument of which to return the meta type.
     * @return The meta type of the i-th argument of a meta function, if any.
     */
    [[nodiscard]] inline meta_type arg(size_type index) const ENTT_NOEXCEPT;

    /**
     * @brief Invokes the underlying function, if possible.
     *
     * To invoke a meta function, the parameters must be such that a cast or
     * conversion to the required types is possible. Otherwise, an empty and
     * thus invalid wrapper is returned.<br/>
     * It must be possible to cast the instance to the parent type of the meta
     * function. Otherwise, invoking the underlying function results in an
     * undefined behavior.
     *
     * @param instance An opaque instance of the underlying type.
     * @param args Parameters to use to invoke the function.
     * @param sz Number of parameters to use to invoke the function.
     * @return A meta any containing the returned value, if any.
     */
    meta_any invoke(meta_handle instance, meta_any * const args, const std::size_t sz) const {
        return sz == size() ? node->invoke(instance, args) : meta_any{};
    }

    /**
     * @copybrief invoke
     *
     * @sa invoke
     *
     * @tparam Args Types of arguments to use to invoke the function.
     * @param instance An opaque instance of the underlying type.
     * @param args Parameters to use to invoke the function.
     * @return A meta any containing the new instance, if any.
     */
    template<typename... Args>
    meta_any invoke(meta_handle instance, Args &&... args) const {
        std::array<meta_any, sizeof...(Args)> arguments{std::forward<Args>(args)...};
        return invoke(instance, arguments.data(), sizeof...(Args));
    }

    /*! @copydoc meta_ctor::prop */
    [[nodiscard]] meta_range<meta_prop> prop() const ENTT_NOEXCEPT {
        return node->prop;
    }

    /**
     * @brief Returns the property associated with a given key.
     * @param key The key to use to search for a property.
     * @return The property associated with the given key, if any.
     */
    [[nodiscard]] meta_prop prop(meta_any key) const {
        internal::meta_range range{node->prop};
        return std::find_if(range.begin(), range.end(), [&key](const auto &curr) { return curr.key() == key; }).operator->();
    }

    /**
     * @brief Returns true if a meta object is valid, false otherwise.
     * @return True if the meta object is valid, false otherwise.
     */
    [[nodiscard]] explicit operator bool() const ENTT_NOEXCEPT {
        return !(node == nullptr);
    }

private:
    const node_type *node;
};

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