1use crate::util::AnyValue;
2use crate::util::AnyValueId;
3use crate::util::FlatMap;
4
5#[derive(Default, Clone, Debug)]
6pub(crate) struct Extensions {
7 extensions: FlatMap<AnyValueId, AnyValue>,
8}
9
10impl Extensions {
11 #[allow(dead_code)]
12 pub(crate) fn get<T: Extension>(&self) -> Option<&T> {
13 let id = AnyValueId::of::<T>();
14 self.extensions.get(&id).map(|e| {
15 e.downcast_ref::<T>()
16 .expect("`Extensions` tracks values by type")
17 })
18 }
19
20 #[allow(dead_code)]
21 pub(crate) fn set<T: Extension>(&mut self, tagged: T) -> bool {
22 let value = AnyValue::new(tagged);
23 let id = value.type_id();
24 self.extensions.insert(id, value).is_some()
25 }
26
27 #[allow(dead_code)]
28 pub(crate) fn remove<T: Extension>(&mut self) -> Option<T> {
29 let id = AnyValueId::of::<T>();
30 self.extensions.remove(&id).map(|e| {
31 e.downcast_into::<T>()
32 .expect("`Extensions` tracks values by type")
33 })
34 }
35
36 pub(crate) fn update(&mut self, other: &Self) {
37 for (key, value) in other.extensions.iter() {
38 self.extensions.insert(*key, value.clone());
39 }
40 }
41}
42
43#[allow(unreachable_pub)]
44pub trait Extension: std::fmt::Debug + Clone + std::any::Any + Send + Sync + 'static {}
45
46impl<T> Extension for T where T: std::fmt::Debug + Clone + std::any::Any + Send + Sync + 'static {}
47