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use {
crate::{
extern_::{Extern, UnguardedExtern},
store::{Store, StoreId},
},
std::any::Any,
};
/// A nullable reference to an external object.
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub struct ExternRef(Option<Extern>);
impl ExternRef {
/// Creates a new [`ExternRef`] wrapping the given underlying object.
pub fn new<T>(store: &mut Store, object: impl Into<Option<T>>) -> Self
where
T: Any + Send + Sync + 'static,
{
Self(object.into().map(|object| Extern::new(store, object)))
}
/// Creates a null [`ExternRef`].
pub fn null() -> Self {
Self(None)
}
/// Returns `true` if this [`ExternRef`] is null.
pub fn is_null(self) -> bool {
self.0.is_none()
}
/// Returns a reference to the underlying object if this `ExternRef` is not null.
pub fn get(self, store: &Store) -> Option<&dyn Any> {
self.0.as_ref().map(|extern_| extern_.get(store))
}
/// Converts the given [`UnguardedExternRef`] to a [`ExternRef`].
///
/// # Safety
///
/// The given [`UnguardedExternRef`] must be owned by the [`Store`] with the given [`StoreId`].
pub(crate) unsafe fn from_unguarded(extern_: UnguardedExternRef, store_id: StoreId) -> Self {
Self(extern_.map(|extern_| unsafe { Extern::from_unguarded(extern_, store_id) }))
}
/// Converts this [`ExternRef`] to an [`UnguardedExternRef`].
///
/// # Panics
///
/// This [`FuncRef`] is not owned by the [`Store`] with the given [`StoreId`].
pub(crate) fn to_unguarded(self, store_id: StoreId) -> UnguardedExternRef {
self.0.map(|extern_| extern_.to_unguarded(store_id))
}
}
/// An unguarded [`ExternRef`].
pub(crate) type UnguardedExternRef = Option<UnguardedExtern>;