mlua-rs-mlua/src/userdata/registry.rs

#![allow(clippy::await_holding_refcell_ref, clippy::await_holding_lock)]

use std::any::TypeId;
use std::cell::RefCell;
use std::marker::PhantomData;
use std::os::raw::c_void;
use std::string::String as StdString;

use crate::error::{Error, Result};
use crate::state::{Lua, LuaGuard};
use crate::traits::{FromLua, FromLuaMulti, IntoLua, IntoLuaMulti};
use crate::types::{Callback, MaybeSend};
use crate::userdata::{AnyUserData, MetaMethod, UserData, UserDataFields, UserDataMethods, UserDataStorage};
use crate::util::{get_userdata, short_type_name};
use crate::value::Value;

#[cfg(feature = "async")]
use {
    crate::types::AsyncCallback,
    crate::userdata::{UserDataRef, UserDataRefMut},
    std::future::{self, Future},
};

#[cfg(all(feature = "userdata-wrappers", not(feature = "send")))]
use std::rc::Rc;
#[cfg(feature = "userdata-wrappers")]
use std::sync::{Arc, Mutex, RwLock};

#[derive(Clone, Copy)]
enum UserDataTypeId {
    Shared(TypeId),
    Unique(*mut c_void),

    #[cfg(all(feature = "userdata-wrappers", not(feature = "send")))]
    Rc(TypeId),
    #[cfg(all(feature = "userdata-wrappers", not(feature = "send")))]
    RcRefCell(TypeId),
    #[cfg(feature = "userdata-wrappers")]
    Arc(TypeId),
    #[cfg(feature = "userdata-wrappers")]
    ArcMutex(TypeId),
    #[cfg(feature = "userdata-wrappers")]
    ArcRwLock(TypeId),
    #[cfg(feature = "userdata-wrappers")]
    ArcParkingLotMutex(TypeId),
    #[cfg(feature = "userdata-wrappers")]
    ArcParkingLotRwLock(TypeId),
}

/// Handle to registry for userdata methods and metamethods.
pub struct UserDataRegistry<T> {
    lua: LuaGuard,
    raw: RawUserDataRegistry,
    ud_type_id: UserDataTypeId,
    _type: PhantomData<T>,
}

pub(crate) struct RawUserDataRegistry {
    // Fields
    pub(crate) fields: Vec<(String, Result<Value>)>,
    pub(crate) field_getters: Vec<(String, Callback)>,
    pub(crate) field_setters: Vec<(String, Callback)>,
    pub(crate) meta_fields: Vec<(String, Result<Value>)>,

    // Methods
    pub(crate) methods: Vec<(String, Callback)>,
    #[cfg(feature = "async")]
    pub(crate) async_methods: Vec<(String, AsyncCallback)>,
    pub(crate) meta_methods: Vec<(String, Callback)>,
    #[cfg(feature = "async")]
    pub(crate) async_meta_methods: Vec<(String, AsyncCallback)>,

    pub(crate) destructor: ffi::lua_CFunction,
    pub(crate) type_id: Option<TypeId>,
    pub(crate) type_name: StdString,
}

impl UserDataTypeId {
    #[inline]
    pub(crate) fn type_id(self) -> Option<TypeId> {
        match self {
            UserDataTypeId::Shared(type_id) => Some(type_id),
            UserDataTypeId::Unique(_) => None,
            #[cfg(all(feature = "userdata-wrappers", not(feature = "send")))]
            UserDataTypeId::Rc(type_id) => Some(type_id),
            #[cfg(all(feature = "userdata-wrappers", not(feature = "send")))]
            UserDataTypeId::RcRefCell(type_id) => Some(type_id),
            #[cfg(feature = "userdata-wrappers")]
            UserDataTypeId::Arc(type_id) => Some(type_id),
            #[cfg(feature = "userdata-wrappers")]
            UserDataTypeId::ArcMutex(type_id) => Some(type_id),
            #[cfg(feature = "userdata-wrappers")]
            UserDataTypeId::ArcRwLock(type_id) => Some(type_id),
            #[cfg(feature = "userdata-wrappers")]
            UserDataTypeId::ArcParkingLotMutex(type_id) => Some(type_id),
            #[cfg(feature = "userdata-wrappers")]
            UserDataTypeId::ArcParkingLotRwLock(type_id) => Some(type_id),
        }
    }
}

#[cfg(feature = "send")]
unsafe impl Send for UserDataTypeId {}

impl<T> UserDataRegistry<T> {
    #[inline(always)]
    pub(crate) fn new(lua: &Lua, type_id: TypeId) -> Self {
        Self::with_type_id(lua, UserDataTypeId::Shared(type_id))
    }

    #[inline(always)]
    pub(crate) fn new_unique(lua: &Lua, ud_ptr: *mut c_void) -> Self {
        Self::with_type_id(lua, UserDataTypeId::Unique(ud_ptr))
    }

    #[inline(always)]
    fn with_type_id(lua: &Lua, ud_type_id: UserDataTypeId) -> Self {
        let raw = RawUserDataRegistry {
            fields: Vec::new(),
            field_getters: Vec::new(),
            field_setters: Vec::new(),
            meta_fields: Vec::new(),
            methods: Vec::new(),
            #[cfg(feature = "async")]
            async_methods: Vec::new(),
            meta_methods: Vec::new(),
            #[cfg(feature = "async")]
            async_meta_methods: Vec::new(),
            destructor: super::util::userdata_destructor::<T>,
            type_id: ud_type_id.type_id(),
            type_name: short_type_name::<T>(),
        };

        UserDataRegistry {
            lua: lua.lock_arc(),
            raw,
            ud_type_id,
            _type: PhantomData,
        }
    }

    fn box_method<M, A, R>(&self, name: &str, method: M) -> Callback
    where
        M: Fn(&Lua, &T, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
        R: IntoLuaMulti,
    {
        let name = get_function_name::<T>(name);
        macro_rules! try_self_arg {
            ($res:expr) => {
                $res.map_err(|err| Error::bad_self_argument(&name, err))?
            };
        }

        let target_type_id = self.ud_type_id;
        Box::new(move |rawlua, nargs| unsafe {
            if nargs == 0 {
                let err = Error::from_lua_conversion("missing argument", "userdata", None);
                try_self_arg!(Err(err));
            }
            let state = rawlua.state();
            // Find absolute "self" index before processing args
            let self_index = ffi::lua_absindex(state, -nargs);
            // Self was at position 1, so we pass 2 here
            let args = A::from_stack_args(nargs - 1, 2, Some(&name), rawlua);

            match target_type_id {
                #[rustfmt::skip]
                UserDataTypeId::Shared(target_type_id)
                    if try_self_arg!(rawlua.get_userdata_type_id::<T>(self_index)) == Some(target_type_id) =>
                {
                    let ud = get_userdata::<UserDataStorage<T>>(state, self_index);
                    try_self_arg!((*ud).try_borrow_scoped(|ud| {
                        method(rawlua.lua(), ud, args?)?.push_into_stack_multi(rawlua)
                    }))
                }
                #[rustfmt::skip]
                UserDataTypeId::Unique(target_ptr)
                    if get_userdata::<UserDataStorage<T>>(state, self_index) as *mut c_void == target_ptr =>
                {
                    let ud = target_ptr as *mut UserDataStorage<T>;
                    try_self_arg!((*ud).try_borrow_scoped(|ud| {
                        method(rawlua.lua(), ud, args?)?.push_into_stack_multi(rawlua)
                    }))
                }
                #[cfg(all(feature = "userdata-wrappers", not(feature = "send")))]
                #[rustfmt::skip]
                UserDataTypeId::Rc(target_type_id)
                    if try_self_arg!(rawlua.get_userdata_type_id::<Rc<T>>(self_index)) == Some(target_type_id) =>
                {
                    let ud = get_userdata::<UserDataStorage<Rc<T>>>(state, self_index);
                    try_self_arg!((*ud).try_borrow_scoped(|ud| {
                        method(rawlua.lua(), ud, args?)?.push_into_stack_multi(rawlua)
                    }))
                }
                #[cfg(all(feature = "userdata-wrappers", not(feature = "send")))]
                #[rustfmt::skip]
                UserDataTypeId::RcRefCell(target_type_id)
                    if try_self_arg!(rawlua.get_userdata_type_id::<Rc<RefCell<T>>>(self_index)) == Some(target_type_id) =>
                {
                    let ud = get_userdata::<UserDataStorage<Rc<RefCell<T>>>>(state, self_index);
                    try_self_arg!((*ud).try_borrow_scoped(|ud| {
                        let ud = ud.try_borrow().map_err(|_| Error::UserDataBorrowError)?;
                        method(rawlua.lua(), &ud, args?)?.push_into_stack_multi(rawlua)
                    }))
                }
                #[cfg(feature = "userdata-wrappers")]
                #[rustfmt::skip]
                UserDataTypeId::Arc(target_type_id)
                    if try_self_arg!(rawlua.get_userdata_type_id::<Arc<T>>(self_index)) == Some(target_type_id) =>
                {
                    let ud = get_userdata::<UserDataStorage<Arc<T>>>(state, self_index);
                    try_self_arg!((*ud).try_borrow_scoped(|ud| {
                        method(rawlua.lua(), ud, args?)?.push_into_stack_multi(rawlua)
                    }))
                }
                #[cfg(feature = "userdata-wrappers")]
                #[rustfmt::skip]
                UserDataTypeId::ArcMutex(target_type_id)
                    if try_self_arg!(rawlua.get_userdata_type_id::<Arc<Mutex<T>>>(self_index)) == Some(target_type_id) =>
                {
                    let ud = get_userdata::<UserDataStorage<Arc<Mutex<T>>>>(state, self_index);
                    try_self_arg!((*ud).try_borrow_scoped(|ud| {
                        let ud = ud.try_lock().map_err(|_| Error::UserDataBorrowError)?;
                        method(rawlua.lua(), &ud, args?)?.push_into_stack_multi(rawlua)
                    }))
                }
                #[cfg(feature = "userdata-wrappers")]
                #[rustfmt::skip]
                UserDataTypeId::ArcRwLock(target_type_id)
                    if try_self_arg!(rawlua.get_userdata_type_id::<Arc<RwLock<T>>>(self_index)) == Some(target_type_id) =>
                {
                    let ud = get_userdata::<UserDataStorage<Arc<RwLock<T>>>>(state, self_index);
                    try_self_arg!((*ud).try_borrow_scoped(|ud| {
                        let ud = ud.try_read().map_err(|_| Error::UserDataBorrowError)?;
                        method(rawlua.lua(), &ud, args?)?.push_into_stack_multi(rawlua)
                    }))
                }
                #[cfg(feature = "userdata-wrappers")]
                #[rustfmt::skip]
                UserDataTypeId::ArcParkingLotMutex(target_type_id)
                    if try_self_arg!(rawlua.get_userdata_type_id::<Arc<parking_lot::Mutex<T>>>(self_index))
                        == Some(target_type_id) =>
                {
                    let ud = get_userdata::<UserDataStorage<Arc<parking_lot::Mutex<T>>>>(state, self_index);
                    try_self_arg!((*ud).try_borrow_scoped(|ud| {
                        let ud = ud.try_lock().ok_or(Error::UserDataBorrowError)?;
                        method(rawlua.lua(), &ud, args?)?.push_into_stack_multi(rawlua)
                    }))
                }
                #[cfg(feature = "userdata-wrappers")]
                #[rustfmt::skip]
                UserDataTypeId::ArcParkingLotRwLock(target_type_id)
                    if try_self_arg!(rawlua.get_userdata_type_id::<Arc<parking_lot::RwLock<T>>>(self_index))
                        == Some(target_type_id) =>
                {
                    let ud = get_userdata::<UserDataStorage<Arc<parking_lot::RwLock<T>>>>(state, self_index);
                    try_self_arg!((*ud).try_borrow_scoped(|ud| {
                        let ud = ud.try_read().ok_or(Error::UserDataBorrowError)?;
                        method(rawlua.lua(), &ud, args?)?.push_into_stack_multi(rawlua)
                    }))
                }
                _ => Err(Error::bad_self_argument(&name, Error::UserDataTypeMismatch)),
            }
        })
    }

    fn box_method_mut<M, A, R>(&self, name: &str, method: M) -> Callback
    where
        M: FnMut(&Lua, &mut T, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
        R: IntoLuaMulti,
    {
        let name = get_function_name::<T>(name);
        macro_rules! try_self_arg {
            ($res:expr) => {
                $res.map_err(|err| Error::bad_self_argument(&name, err))?
            };
        }

        let method = RefCell::new(method);
        let target_type_id = self.ud_type_id;
        Box::new(move |rawlua, nargs| unsafe {
            let mut method = method.try_borrow_mut().map_err(|_| Error::RecursiveMutCallback)?;
            if nargs == 0 {
                let err = Error::from_lua_conversion("missing argument", "userdata", None);
                try_self_arg!(Err(err));
            }
            let state = rawlua.state();
            // Find absolute "self" index before processing args
            let self_index = ffi::lua_absindex(state, -nargs);
            // Self was at position 1, so we pass 2 here
            let args = A::from_stack_args(nargs - 1, 2, Some(&name), rawlua);

            match target_type_id {
                #[rustfmt::skip]
                UserDataTypeId::Shared(target_type_id)
                    if try_self_arg!(rawlua.get_userdata_type_id::<T>(self_index)) == Some(target_type_id) =>
                {
                    let ud = get_userdata::<UserDataStorage<T>>(state, self_index);
                    try_self_arg!((*ud).try_borrow_scoped_mut(|ud| {
                        method(rawlua.lua(), ud, args?)?.push_into_stack_multi(rawlua)
                    }))
                }
                #[rustfmt::skip]
                UserDataTypeId::Unique(target_ptr)
                    if get_userdata::<UserDataStorage<T>>(state, self_index) as *mut c_void == target_ptr =>
                {
                    let ud = target_ptr as *mut UserDataStorage<T>;
                    try_self_arg!((*ud).try_borrow_scoped_mut(|ud| {
                        method(rawlua.lua(), ud, args?)?.push_into_stack_multi(rawlua)
                    }))
                }
                #[cfg(all(feature = "userdata-wrappers", not(feature = "send")))]
                #[rustfmt::skip]
                UserDataTypeId::Rc(target_type_id)
                    if try_self_arg!(rawlua.get_userdata_type_id::<Rc<T>>(self_index)) == Some(target_type_id) =>
                {
                    Err(Error::UserDataBorrowMutError)
                },
                #[cfg(all(feature = "userdata-wrappers", not(feature = "send")))]
                #[rustfmt::skip]
                UserDataTypeId::RcRefCell(target_type_id)
                    if try_self_arg!(rawlua.get_userdata_type_id::<Rc<RefCell<T>>>(self_index)) == Some(target_type_id) =>
                {
                    let ud = get_userdata::<UserDataStorage<Rc<RefCell<T>>>>(state, self_index);
                    try_self_arg!((*ud).try_borrow_scoped(|ud| {
                        let mut ud = ud.try_borrow_mut().map_err(|_| Error::UserDataBorrowMutError)?;
                        method(rawlua.lua(), &mut ud, args?)?.push_into_stack_multi(rawlua)
                    }))
                }
                #[cfg(feature = "userdata-wrappers")]
                #[rustfmt::skip]
                UserDataTypeId::Arc(target_type_id)
                    if try_self_arg!(rawlua.get_userdata_type_id::<Arc<T>>(self_index)) == Some(target_type_id) =>
                {
                    Err(Error::UserDataBorrowMutError)
                },
                #[cfg(feature = "userdata-wrappers")]
                #[rustfmt::skip]
                UserDataTypeId::ArcMutex(target_type_id)
                    if try_self_arg!(rawlua.get_userdata_type_id::<Arc<Mutex<T>>>(self_index)) == Some(target_type_id) =>
                {
                    let ud = get_userdata::<UserDataStorage<Arc<Mutex<T>>>>(state, self_index);
                    try_self_arg!((*ud).try_borrow_scoped(|ud| {
                        let mut ud = ud.try_lock().map_err(|_| Error::UserDataBorrowMutError)?;
                        method(rawlua.lua(), &mut ud, args?)?.push_into_stack_multi(rawlua)
                    }))
                }
                #[cfg(feature = "userdata-wrappers")]
                #[rustfmt::skip]
                UserDataTypeId::ArcRwLock(target_type_id)
                    if try_self_arg!(rawlua.get_userdata_type_id::<Arc<RwLock<T>>>(self_index)) == Some(target_type_id) =>
                {
                    let ud = get_userdata::<UserDataStorage<Arc<RwLock<T>>>>(state, self_index);
                    try_self_arg!((*ud).try_borrow_scoped(|ud| {
                        let mut ud = ud.try_write().map_err(|_| Error::UserDataBorrowMutError)?;
                        method(rawlua.lua(), &mut ud, args?)?.push_into_stack_multi(rawlua)
                    }))
                }
                #[cfg(feature = "userdata-wrappers")]
                #[rustfmt::skip]
                UserDataTypeId::ArcParkingLotMutex(target_type_id)
                    if try_self_arg!(rawlua.get_userdata_type_id::<Arc<parking_lot::Mutex<T>>>(self_index))
                        == Some(target_type_id) =>
                {
                    let ud = get_userdata::<UserDataStorage<Arc<parking_lot::Mutex<T>>>>(state, self_index);
                    try_self_arg!((*ud).try_borrow_scoped(|ud| {
                        let mut ud = ud.try_lock().ok_or(Error::UserDataBorrowMutError)?;
                        method(rawlua.lua(), &mut ud, args?)?.push_into_stack_multi(rawlua)
                    }))
                }
                #[cfg(feature = "userdata-wrappers")]
                #[rustfmt::skip]
                UserDataTypeId::ArcParkingLotRwLock(target_type_id)
                    if try_self_arg!(rawlua.get_userdata_type_id::<Arc<parking_lot::RwLock<T>>>(self_index))
                        == Some(target_type_id) =>
                {
                    let ud = get_userdata::<UserDataStorage<Arc<parking_lot::RwLock<T>>>>(state, self_index);
                    try_self_arg!((*ud).try_borrow_scoped(|ud| {
                        let mut ud = ud.try_write().ok_or(Error::UserDataBorrowMutError)?;
                        method(rawlua.lua(), &mut ud, args?)?.push_into_stack_multi(rawlua)
                    }))
                }
                _ => Err(Error::bad_self_argument(&name, Error::UserDataTypeMismatch)),
            }
        })
    }

    #[cfg(feature = "async")]
    fn box_async_method<M, A, MR, R>(&self, name: &str, method: M) -> AsyncCallback
    where
        T: 'static,
        M: Fn(Lua, UserDataRef<T>, A) -> MR + MaybeSend + 'static,
        A: FromLuaMulti,
        MR: Future<Output = Result<R>> + MaybeSend + 'static,
        R: IntoLuaMulti,
    {
        let name = get_function_name::<T>(name);
        macro_rules! try_self_arg {
            ($res:expr) => {
                match $res {
                    Ok(res) => res,
                    Err(err) => return Box::pin(future::ready(Err(Error::bad_self_argument(&name, err)))),
                }
            };
        }

        Box::new(move |rawlua, nargs| unsafe {
            if nargs == 0 {
                let err = Error::from_lua_conversion("missing argument", "userdata", None);
                try_self_arg!(Err(err));
            }
            // Stack will be empty when polling the future, keep `self` on the ref thread
            let self_ud = try_self_arg!(AnyUserData::from_stack(-nargs, rawlua));
            let args = A::from_stack_args(nargs - 1, 2, Some(&name), rawlua);

            let self_ud = try_self_arg!(self_ud.borrow());
            let args = match args {
                Ok(args) => args,
                Err(e) => return Box::pin(future::ready(Err(e))),
            };
            let lua = rawlua.lua();
            let fut = method(lua.clone(), self_ud, args);
            // Lua is locked when the future is polled
            Box::pin(async move { fut.await?.push_into_stack_multi(lua.raw_lua()) })
        })
    }

    #[cfg(feature = "async")]
    fn box_async_method_mut<M, A, MR, R>(&self, name: &str, method: M) -> AsyncCallback
    where
        T: 'static,
        M: Fn(Lua, UserDataRefMut<T>, A) -> MR + MaybeSend + 'static,
        A: FromLuaMulti,
        MR: Future<Output = Result<R>> + MaybeSend + 'static,
        R: IntoLuaMulti,
    {
        let name = get_function_name::<T>(name);
        macro_rules! try_self_arg {
            ($res:expr) => {
                match $res {
                    Ok(res) => res,
                    Err(err) => return Box::pin(future::ready(Err(Error::bad_self_argument(&name, err)))),
                }
            };
        }

        Box::new(move |rawlua, nargs| unsafe {
            if nargs == 0 {
                let err = Error::from_lua_conversion("missing argument", "userdata", None);
                try_self_arg!(Err(err));
            }
            // Stack will be empty when polling the future, keep `self` on the ref thread
            let self_ud = try_self_arg!(AnyUserData::from_stack(-nargs, rawlua));
            let args = A::from_stack_args(nargs - 1, 2, Some(&name), rawlua);

            let self_ud = try_self_arg!(self_ud.borrow_mut());
            let args = match args {
                Ok(args) => args,
                Err(e) => return Box::pin(future::ready(Err(e))),
            };
            let lua = rawlua.lua();
            let fut = method(lua.clone(), self_ud, args);
            // Lua is locked when the future is polled
            Box::pin(async move { fut.await?.push_into_stack_multi(lua.raw_lua()) })
        })
    }

    fn box_function<F, A, R>(&self, name: &str, function: F) -> Callback
    where
        F: Fn(&Lua, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
        R: IntoLuaMulti,
    {
        let name = get_function_name::<T>(name);
        Box::new(move |lua, nargs| unsafe {
            let args = A::from_stack_args(nargs, 1, Some(&name), lua)?;
            function(lua.lua(), args)?.push_into_stack_multi(lua)
        })
    }

    fn box_function_mut<F, A, R>(&self, name: &str, function: F) -> Callback
    where
        F: FnMut(&Lua, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
        R: IntoLuaMulti,
    {
        let name = get_function_name::<T>(name);
        let function = RefCell::new(function);
        Box::new(move |lua, nargs| unsafe {
            let function = &mut *function
                .try_borrow_mut()
                .map_err(|_| Error::RecursiveMutCallback)?;
            let args = A::from_stack_args(nargs, 1, Some(&name), lua)?;
            function(lua.lua(), args)?.push_into_stack_multi(lua)
        })
    }

    #[cfg(feature = "async")]
    fn box_async_function<F, A, FR, R>(&self, name: &str, function: F) -> AsyncCallback
    where
        F: Fn(Lua, A) -> FR + MaybeSend + 'static,
        A: FromLuaMulti,
        FR: Future<Output = Result<R>> + MaybeSend + 'static,
        R: IntoLuaMulti,
    {
        let name = get_function_name::<T>(name);
        Box::new(move |rawlua, nargs| unsafe {
            let args = match A::from_stack_args(nargs, 1, Some(&name), rawlua) {
                Ok(args) => args,
                Err(e) => return Box::pin(future::ready(Err(e))),
            };
            let lua = rawlua.lua();
            let fut = function(lua.clone(), args);
            Box::pin(async move { fut.await?.push_into_stack_multi(lua.raw_lua()) })
        })
    }

    pub(crate) fn check_meta_field(lua: &Lua, name: &str, value: impl IntoLua) -> Result<Value> {
        let value = value.into_lua(lua)?;
        if name == MetaMethod::Index || name == MetaMethod::NewIndex {
            match value {
                Value::Nil | Value::Table(_) | Value::Function(_) => {}
                _ => {
                    return Err(Error::MetaMethodTypeError {
                        method: name.to_string(),
                        type_name: value.type_name(),
                        message: Some("expected nil, table or function".to_string()),
                    })
                }
            }
        }
        value.into_lua(lua)
    }

    #[inline(always)]
    pub(crate) fn into_raw(self) -> RawUserDataRegistry {
        self.raw
    }
}

// Returns function name for the type `T`, without the module path
fn get_function_name<T>(name: &str) -> StdString {
    format!("{}.{name}", short_type_name::<T>())
}

impl<T> UserDataFields<T> for UserDataRegistry<T> {
    fn add_field<V>(&mut self, name: impl ToString, value: V)
    where
        V: IntoLua + 'static,
    {
        let name = name.to_string();
        self.raw.fields.push((name, value.into_lua(self.lua.lua())));
    }

    fn add_field_method_get<M, R>(&mut self, name: impl ToString, method: M)
    where
        M: Fn(&Lua, &T) -> Result<R> + MaybeSend + 'static,
        R: IntoLua,
    {
        let name = name.to_string();
        let callback = self.box_method(&name, move |lua, data, ()| method(lua, data));
        self.raw.field_getters.push((name, callback));
    }

    fn add_field_method_set<M, A>(&mut self, name: impl ToString, method: M)
    where
        M: FnMut(&Lua, &mut T, A) -> Result<()> + MaybeSend + 'static,
        A: FromLua,
    {
        let name = name.to_string();
        let callback = self.box_method_mut(&name, method);
        self.raw.field_setters.push((name, callback));
    }

    fn add_field_function_get<F, R>(&mut self, name: impl ToString, function: F)
    where
        F: Fn(&Lua, AnyUserData) -> Result<R> + MaybeSend + 'static,
        R: IntoLua,
    {
        let name = name.to_string();
        let callback = self.box_function(&name, function);
        self.raw.field_getters.push((name, callback));
    }

    fn add_field_function_set<F, A>(&mut self, name: impl ToString, mut function: F)
    where
        F: FnMut(&Lua, AnyUserData, A) -> Result<()> + MaybeSend + 'static,
        A: FromLua,
    {
        let name = name.to_string();
        let callback = self.box_function_mut(&name, move |lua, (data, val)| function(lua, data, val));
        self.raw.field_setters.push((name, callback));
    }

    fn add_meta_field<V>(&mut self, name: impl ToString, value: V)
    where
        V: IntoLua + 'static,
    {
        let lua = self.lua.lua();
        let name = name.to_string();
        let field = Self::check_meta_field(lua, &name, value).and_then(|v| v.into_lua(lua));
        self.raw.meta_fields.push((name, field));
    }

    fn add_meta_field_with<F, R>(&mut self, name: impl ToString, f: F)
    where
        F: FnOnce(&Lua) -> Result<R> + 'static,
        R: IntoLua,
    {
        let lua = self.lua.lua();
        let name = name.to_string();
        let field = f(lua).and_then(|v| Self::check_meta_field(lua, &name, v).and_then(|v| v.into_lua(lua)));
        self.raw.meta_fields.push((name, field));
    }
}

impl<T> UserDataMethods<T> for UserDataRegistry<T> {
    fn add_method<M, A, R>(&mut self, name: impl ToString, method: M)
    where
        M: Fn(&Lua, &T, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
        R: IntoLuaMulti,
    {
        let name = name.to_string();
        let callback = self.box_method(&name, method);
        self.raw.methods.push((name, callback));
    }

    fn add_method_mut<M, A, R>(&mut self, name: impl ToString, method: M)
    where
        M: FnMut(&Lua, &mut T, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
        R: IntoLuaMulti,
    {
        let name = name.to_string();
        let callback = self.box_method_mut(&name, method);
        self.raw.methods.push((name, callback));
    }

    #[cfg(feature = "async")]
    fn add_async_method<M, A, MR, R>(&mut self, name: impl ToString, method: M)
    where
        T: 'static,
        M: Fn(Lua, UserDataRef<T>, A) -> MR + MaybeSend + 'static,
        A: FromLuaMulti,
        MR: Future<Output = Result<R>> + MaybeSend + 'static,
        R: IntoLuaMulti,
    {
        let name = name.to_string();
        let callback = self.box_async_method(&name, method);
        self.raw.async_methods.push((name, callback));
    }

    #[cfg(feature = "async")]
    fn add_async_method_mut<M, A, MR, R>(&mut self, name: impl ToString, method: M)
    where
        T: 'static,
        M: Fn(Lua, UserDataRefMut<T>, A) -> MR + MaybeSend + 'static,
        A: FromLuaMulti,
        MR: Future<Output = Result<R>> + MaybeSend + 'static,
        R: IntoLuaMulti,
    {
        let name = name.to_string();
        let callback = self.box_async_method_mut(&name, method);
        self.raw.async_methods.push((name, callback));
    }

    fn add_function<F, A, R>(&mut self, name: impl ToString, function: F)
    where
        F: Fn(&Lua, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
        R: IntoLuaMulti,
    {
        let name = name.to_string();
        let callback = self.box_function(&name, function);
        self.raw.methods.push((name, callback));
    }

    fn add_function_mut<F, A, R>(&mut self, name: impl ToString, function: F)
    where
        F: FnMut(&Lua, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
        R: IntoLuaMulti,
    {
        let name = name.to_string();
        let callback = self.box_function_mut(&name, function);
        self.raw.methods.push((name, callback));
    }

    #[cfg(feature = "async")]
    fn add_async_function<F, A, FR, R>(&mut self, name: impl ToString, function: F)
    where
        F: Fn(Lua, A) -> FR + MaybeSend + 'static,
        A: FromLuaMulti,
        FR: Future<Output = Result<R>> + MaybeSend + 'static,
        R: IntoLuaMulti,
    {
        let name = name.to_string();
        let callback = self.box_async_function(&name, function);
        self.raw.async_methods.push((name, callback));
    }

    fn add_meta_method<M, A, R>(&mut self, name: impl ToString, method: M)
    where
        M: Fn(&Lua, &T, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
        R: IntoLuaMulti,
    {
        let name = name.to_string();
        let callback = self.box_method(&name, method);
        self.raw.meta_methods.push((name, callback));
    }

    fn add_meta_method_mut<M, A, R>(&mut self, name: impl ToString, method: M)
    where
        M: FnMut(&Lua, &mut T, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
        R: IntoLuaMulti,
    {
        let name = name.to_string();
        let callback = self.box_method_mut(&name, method);
        self.raw.meta_methods.push((name, callback));
    }

    #[cfg(all(feature = "async", not(any(feature = "lua51", feature = "luau"))))]
    fn add_async_meta_method<M, A, MR, R>(&mut self, name: impl ToString, method: M)
    where
        T: 'static,
        M: Fn(Lua, UserDataRef<T>, A) -> MR + MaybeSend + 'static,
        A: FromLuaMulti,
        MR: Future<Output = Result<R>> + MaybeSend + 'static,
        R: IntoLuaMulti,
    {
        let name = name.to_string();
        let callback = self.box_async_method(&name, method);
        self.raw.async_meta_methods.push((name, callback));
    }

    #[cfg(all(feature = "async", not(any(feature = "lua51", feature = "luau"))))]
    fn add_async_meta_method_mut<M, A, MR, R>(&mut self, name: impl ToString, method: M)
    where
        T: 'static,
        M: Fn(Lua, UserDataRefMut<T>, A) -> MR + MaybeSend + 'static,
        A: FromLuaMulti,
        MR: Future<Output = Result<R>> + MaybeSend + 'static,
        R: IntoLuaMulti,
    {
        let name = name.to_string();
        let callback = self.box_async_method_mut(&name, method);
        self.raw.async_meta_methods.push((name, callback));
    }

    fn add_meta_function<F, A, R>(&mut self, name: impl ToString, function: F)
    where
        F: Fn(&Lua, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
        R: IntoLuaMulti,
    {
        let name = name.to_string();
        let callback = self.box_function(&name, function);
        self.raw.meta_methods.push((name, callback));
    }

    fn add_meta_function_mut<F, A, R>(&mut self, name: impl ToString, function: F)
    where
        F: FnMut(&Lua, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
        R: IntoLuaMulti,
    {
        let name = name.to_string();
        let callback = self.box_function_mut(&name, function);
        self.raw.meta_methods.push((name, callback));
    }

    #[cfg(all(feature = "async", not(any(feature = "lua51", feature = "luau"))))]
    fn add_async_meta_function<F, A, FR, R>(&mut self, name: impl ToString, function: F)
    where
        F: Fn(Lua, A) -> FR + MaybeSend + 'static,
        A: FromLuaMulti,
        FR: Future<Output = Result<R>> + MaybeSend + 'static,
        R: IntoLuaMulti,
    {
        let name = name.to_string();
        let callback = self.box_async_function(&name, function);
        self.raw.async_meta_methods.push((name, callback));
    }
}

macro_rules! lua_userdata_impl {
    ($type:ty => $type_variant:tt) => {
        lua_userdata_impl!($type, UserDataTypeId::$type_variant(TypeId::of::<$type>()));
    };

    ($type:ty, $type_id:expr) => {
        impl<T: UserData + 'static> UserData for $type {
            fn register(registry: &mut UserDataRegistry<Self>) {
                let mut orig_registry = UserDataRegistry::with_type_id(registry.lua.lua(), $type_id);
                T::register(&mut orig_registry);

                // Copy all fields, methods, etc. from the original registry
                (registry.raw.fields).extend(orig_registry.raw.fields);
                (registry.raw.field_getters).extend(orig_registry.raw.field_getters);
                (registry.raw.field_setters).extend(orig_registry.raw.field_setters);
                (registry.raw.meta_fields).extend(orig_registry.raw.meta_fields);
                (registry.raw.methods).extend(orig_registry.raw.methods);
                #[cfg(feature = "async")]
                (registry.raw.async_methods).extend(orig_registry.raw.async_methods);
                (registry.raw.meta_methods).extend(orig_registry.raw.meta_methods);
                #[cfg(feature = "async")]
                (registry.raw.async_meta_methods).extend(orig_registry.raw.async_meta_methods);
            }
        }
    };
}

// A special proxy object for UserData
pub(crate) struct UserDataProxy<T>(pub(crate) PhantomData<T>);

lua_userdata_impl!(UserDataProxy<T>, UserDataTypeId::Shared(TypeId::of::<T>()));

#[cfg(all(feature = "userdata-wrappers", not(feature = "send")))]
lua_userdata_impl!(Rc<T> => Rc);
#[cfg(all(feature = "userdata-wrappers", not(feature = "send")))]
lua_userdata_impl!(Rc<RefCell<T>> => RcRefCell);
#[cfg(feature = "userdata-wrappers")]
lua_userdata_impl!(Arc<T> => Arc);
#[cfg(feature = "userdata-wrappers")]
lua_userdata_impl!(Arc<Mutex<T>> => ArcMutex);
#[cfg(feature = "userdata-wrappers")]
lua_userdata_impl!(Arc<RwLock<T>> => ArcRwLock);
#[cfg(feature = "userdata-wrappers")]
lua_userdata_impl!(Arc<parking_lot::Mutex<T>> => ArcParkingLotMutex);
#[cfg(feature = "userdata-wrappers")]
lua_userdata_impl!(Arc<parking_lot::RwLock<T>> => ArcParkingLotRwLock);

#[cfg(test)]
mod assertions {
    #[cfg(feature = "send")]
    static_assertions::assert_impl_all!(super::RawUserDataRegistry: Send);
}