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use crate::util::AnyValue;
use crate::util::AnyValueId;
use crate::util::FlatMap;
#[derive(Default, Clone, Debug)]
pub(crate) struct Extensions {
extensions: FlatMap<AnyValueId, AnyValue>,
}
impl Extensions {
#[allow(dead_code)]
pub(crate) fn get<T: Extension>(&self) -> Option<&T> {
let id = AnyValueId::of::<T>();
self.extensions.get(&id).map(|e| {
e.downcast_ref::<T>()
.expect("`Extensions` tracks values by type")
})
}
#[allow(dead_code)]
pub(crate) fn set<T: Extension>(&mut self, tagged: T) -> bool {
let value = AnyValue::new(tagged);
let id = value.type_id();
self.extensions.insert(id, value).is_some()
}
#[allow(dead_code)]
pub(crate) fn remove<T: Extension>(&mut self) -> Option<T> {
let id = AnyValueId::of::<T>();
self.extensions.remove(&id).map(|e| {
e.downcast_into::<T>()
.expect("`Extensions` tracks values by type")
})
}
pub(crate) fn update(&mut self, other: &Self) {
for (key, value) in other.extensions.iter() {
self.extensions.insert(*key, value.clone());
}
}
}
#[allow(unreachable_pub)]
pub trait Extension: std::fmt::Debug + Clone + std::any::Any + Send + Sync + 'static {}
impl<T> Extension for T where T: std::fmt::Debug + Clone + std::any::Any + Send + Sync + 'static {}