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use bevy::reflect::Reflect;
/// Script representable type with pass-by-value semantics
pub trait ScriptValue: Reflect + Clone {}
impl<T: Reflect + Clone> ScriptValue for T {}
/// Script representable type with pass-by-reference semantics
pub trait ScriptReference: Reflect {}
impl<T: Reflect> ScriptReference for T {}
#[macro_export]
macro_rules! ref_only_wrapper_methods {
($type_:ident, $wrapper_name: ident) => {
/// Creates a script reference pointing to the wrapped value.
///
/// Depending on this value it may be a lua owned or reflect relative reference
pub fn script_ref(
&self,
world_ptr: bevy_mod_scripting_core::world::WorldPointer,
) -> $crate::script_ref::ScriptRef {
match self {
Self::Owned(val, valid) => unsafe {
// safety:
// - valid is dropped when the value goes out of scope, so won't be dangling
// - using the valid lock means no incorrect aliasing may occur
// - the pointer points to base of the reference
// invariants are upheld
$crate::script_ref::ScriptRef::new_script_ref(
(val.get() as *mut dyn ::bevy::reflect::Reflect).into(),
::std::sync::Arc::downgrade(valid),
world_ptr,
)
},
Self::Ref(ref_) => ref_.clone(),
}
}
pub fn new(b: $type_) -> Self {
Self::Owned(
::std::cell::UnsafeCell::new(b),
::std::sync::Arc::new($crate::parking_lot::RwLock::new(())),
)
}
pub fn new_ref(b: $crate::script_ref::ScriptRef) -> Self {
Self::Ref(b)
}
/// Perform an operation on the base type and optionally retrieve something by value
/// may require a read lock on the world in case this is a reference
pub fn val<G, F>(&self, accessor: F) -> Result<G, $crate::error::ReflectionError>
where
F: FnOnce(&$type_) -> G,
{
match self {
Self::Owned(ref v, valid) => {
// we lock here in case the accessor has a luaref holding reference to us
let lock = valid.read();
let o = accessor(unsafe { &*(v.get() as *const $type_) });
drop(lock);
Ok(o)
}
Self::Ref(v) => v.get(|s| accessor(s.downcast_ref::<$type_>().unwrap())),
}
}
pub fn val_mut<G, F>(&mut self, accessor: F) -> Result<G, $crate::error::ReflectionError>
where
F: FnOnce(&mut $type_) -> G,
{
match self {
Self::Owned(ref mut v, valid) => {
let lock = valid.read();
let o = accessor(v.get_mut());
drop(lock);
Ok(o)
}
Self::Ref(v) => v.get_mut(|s| accessor(s.downcast_mut::<$type_>().unwrap())),
}
}
/// Applies Self to another ScriptRef.
/// may require a write lock on the world
pub fn apply_self_to_base(
&self,
other: &mut $crate::script_ref::ScriptRef,
) -> Result<(), $crate::error::ReflectionError> {
match self {
Self::Owned(v, valid) => {
let lock = valid.read();
other.get_mut(|other| other.apply(unsafe { &*(v.get() as *const $type_) }))?;
drop(lock);
Ok(())
}
Self::Ref(v) => {
// if we are a ScriptRef, we have to be careful with borrows
// to avoid deadlock
// we take advantage of the fact we know the expected type
other.apply(v)
}
}
}
};
}
#[macro_export]
macro_rules! define_wrapper{
($type_:ident, $wrapper_name:ident) => {
#[allow(clippy::large_enum_variant)]
#[doc=concat!("A script wrapper for the type `",stringify!($type_),"`")]
pub enum $wrapper_name{
Owned(::std::cell::UnsafeCell<$type_>, ::std::sync::Arc<$crate::parking_lot::RwLock<()>>),
Ref($crate::script_ref::ScriptRef),
}
/// Safety: we make this sync via RwLock<()> assuming invariants are upheld
unsafe impl Sync for $wrapper_name {}
impl Drop for $wrapper_name {
fn drop(&mut self) {
match self {
Self::Owned(_, valid) => {
if valid.is_locked() {
panic!(
"Something is referencing a lua value and it's about to go out of scope!"
);
}
}
Self::Ref(_) => {}
}
}
}
}
}
#[macro_export]
macro_rules! make_script_wrapper {
($type_:ident as $wrapper_name:ident with Clone) => {
$crate::define_wrapper!($type_, $wrapper_name);
impl $wrapper_name {
$crate::ref_only_wrapper_methods!($type_, $wrapper_name);
/// retrieves the underlying value by cloning it
pub fn inner(&self) -> Result<$type_, $crate::error::ReflectionError>
where
$type_: Clone,
{
self.val(|s| s.clone())
}
}
impl Clone for $wrapper_name {
fn clone(&self) -> Self {
match self {
Self::Owned(_, _) => Self::Owned(
::std::cell::UnsafeCell::new(
self.val(|s| s.clone())
.expect("Rust aliasing rules broken in cloning wrapper"),
),
::std::sync::Arc::new($crate::parking_lot::RwLock::new(())),
),
Self::Ref(v) => Self::Ref(v.clone()),
}
}
}
};
($type_:ident as $wrapper_name:ident) => {
$crate::define_wrapper!($type_, $wrapper_name);
impl $wrapper_name {
$crate::ref_only_wrapper_methods!($type_, $wrapper_name);
}
};
}
// // TODO: look at this when rust gets better
// // Oh boy, there is no way in current rust to implement this
// // We need trait specialization.
// // This isn't even possible if implemented without generics since then
// // we get a compile error from mlua about how `Clone` may be implemented on the wrapped type in the feature
// // :C
// // impl <'lua, T : ScriptReference + !Clone> FromLua<'lua> for LuaWrapper<T> {
// // fn from_lua(lua_value: tealr::mlu::mlua::Value<'lua>, lua: &'lua tealr::mlu::mlua::Lua) -> tealr::mlu::mlua::Result<Self> {
// // match lua_value {
// // tealr::mlu::mlua::Value::UserData(ud) => {
// // match ud.borrow::<LuaWrapper<T>>()?{
// // // here we need to move out of the value in the lua world
// // LuaWrapper::Owned(_, _) => ud.take(),
// // // we can copy fine here
// // LuaWrapper::Ref(ref_) => Ok(LuaWrapper::new_ref(&ref_)),
// // }
// // }
// // _ => Err(tealr::mlu::mlua::Error::FromLuaConversionError {
// // from: lua_value.type_name(),
// // to: "userdata",
// // message: None,
// // })
// // }
// // }
// // }