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use crate::{Resource, World};
macro_rules! fetch_panic {
() => {{
panic!(
"\
Tried to fetch resource of type `{resource_name_simple}`[^1] from the `World`, but \
the resource does not exist.\n\
\n\
You may ensure the resource exists through one of the following methods:\n\
\n\
* Inserting it when the world is created: `world.insert(..)`.\n\
* If the resource implements `Default`, include it in a system's `SystemData`, \
and ensure the system is registered in the dispatcher.\n\
* If the resource does not implement `Default`, insert it in the world during \
`System::setup`.\n\
\n\
[^1]: Full type name: `{resource_name_full}`\
",
resource_name_simple = tynm::type_name::<T>(),
resource_name_full = std::any::type_name::<T>(),
)
}};
}
pub struct DefaultProvider;
impl<T> SetupHandler<T> for DefaultProvider
where
T: Default + Resource,
{
fn setup(world: &mut World) {
world.entry().or_insert_with(T::default);
}
}
pub trait SetupHandler<T>: Sized {
fn setup(world: &mut World);
}
pub struct PanicHandler;
impl<T> SetupHandler<T> for PanicHandler
where
T: Resource,
{
fn setup(_: &mut World) {}
}