1// Take a look at the license at the top of the repository in the LICENSE file.
2
3use std::{
4 marker::PhantomData,
5 rc::{self, Rc},
6 sync::{self, Arc},
7};
8
9// rustdoc-stripper-ignore-next
10/// Trait for generalizing downgrading a strong reference to a weak reference.
11pub trait Downgrade
12where
13 Self: Sized,
14{
15 // rustdoc-stripper-ignore-next
16 /// Weak reference type.
17 type Weak;
18
19 // rustdoc-stripper-ignore-next
20 /// Downgrade to a weak reference.
21 fn downgrade(&self) -> Self::Weak;
22}
23
24// rustdoc-stripper-ignore-next
25/// Trait for generalizing upgrading a weak reference to a strong reference.
26pub trait Upgrade
27where
28 Self: Sized,
29{
30 // rustdoc-stripper-ignore-next
31 /// Strong reference type.
32 type Strong;
33
34 // rustdoc-stripper-ignore-next
35 /// Try upgrading a weak reference to a strong reference.
36 fn upgrade(&self) -> Option<Self::Strong>;
37}
38
39impl<T: Downgrade + crate::ObjectType> Upgrade for crate::WeakRef<T> {
40 type Strong = T;
41
42 fn upgrade(&self) -> Option<Self::Strong> {
43 self.upgrade()
44 }
45}
46
47impl<T> Downgrade for PhantomData<T> {
48 type Weak = PhantomData<T>;
49
50 fn downgrade(&self) -> Self::Weak {
51 PhantomData
52 }
53}
54
55impl<T: Downgrade> Downgrade for &T {
56 type Weak = T::Weak;
57
58 fn downgrade(&self) -> Self::Weak {
59 T::downgrade(*self)
60 }
61}
62
63impl<T> Downgrade for Arc<T> {
64 type Weak = sync::Weak<T>;
65
66 fn downgrade(&self) -> Self::Weak {
67 Arc::downgrade(self)
68 }
69}
70
71impl<T> Upgrade for PhantomData<T> {
72 type Strong = PhantomData<T>;
73
74 fn upgrade(&self) -> Option<Self::Strong> {
75 Some(PhantomData)
76 }
77}
78
79impl<T> Upgrade for sync::Weak<T> {
80 type Strong = Arc<T>;
81
82 fn upgrade(&self) -> Option<Self::Strong> {
83 self.upgrade()
84 }
85}
86
87impl<T> Downgrade for Rc<T> {
88 type Weak = rc::Weak<T>;
89
90 fn downgrade(&self) -> Self::Weak {
91 Rc::downgrade(self)
92 }
93}
94
95impl<T> Upgrade for rc::Weak<T> {
96 type Strong = Rc<T>;
97
98 fn upgrade(&self) -> Option<Self::Strong> {
99 self.upgrade()
100 }
101}
102