1// Take a look at the license at the top of the repository in the LICENSE file.
2
3use crate::prelude::*;
4use std::{
5 marker::PhantomData,
6 rc::{self, Rc},
7 sync::{self, Arc},
8};
9
10// rustdoc-stripper-ignore-next
11/// Trait for generalizing downgrading a strong reference to a weak reference.
12pub trait Downgrade
13where
14 Self: Sized,
15{
16 // rustdoc-stripper-ignore-next
17 /// Weak reference type.
18 type Weak: Upgrade;
19
20 // rustdoc-stripper-ignore-next
21 /// Downgrade to a weak reference.
22 fn downgrade(&self) -> Self::Weak;
23}
24
25// rustdoc-stripper-ignore-next
26/// Trait for generalizing upgrading a weak reference to a strong reference.
27pub trait Upgrade
28where
29 Self: Sized,
30{
31 // rustdoc-stripper-ignore-next
32 /// Strong reference type.
33 type Strong;
34
35 // rustdoc-stripper-ignore-next
36 /// Try upgrading a weak reference to a strong reference.
37 fn upgrade(&self) -> Option<Self::Strong>;
38}
39
40impl<T: Downgrade + ObjectType> Upgrade for crate::WeakRef<T> {
41 type Strong = T;
42
43 fn upgrade(&self) -> Option<Self::Strong> {
44 self.upgrade()
45 }
46}
47
48impl<T> Downgrade for PhantomData<T> {
49 type Weak = PhantomData<T>;
50
51 fn downgrade(&self) -> Self::Weak {
52 PhantomData
53 }
54}
55
56impl<T: Downgrade> Downgrade for &T {
57 type Weak = T::Weak;
58
59 fn downgrade(&self) -> Self::Weak {
60 T::downgrade(*self)
61 }
62}
63
64impl<T> Downgrade for Arc<T> {
65 type Weak = sync::Weak<T>;
66
67 fn downgrade(&self) -> Self::Weak {
68 Arc::downgrade(self)
69 }
70}
71
72impl<T> Upgrade for PhantomData<T> {
73 type Strong = PhantomData<T>;
74
75 fn upgrade(&self) -> Option<Self::Strong> {
76 Some(PhantomData)
77 }
78}
79
80impl<T> Upgrade for sync::Weak<T> {
81 type Strong = Arc<T>;
82
83 fn upgrade(&self) -> Option<Self::Strong> {
84 self.upgrade()
85 }
86}
87
88impl<T> Downgrade for Rc<T> {
89 type Weak = rc::Weak<T>;
90
91 fn downgrade(&self) -> Self::Weak {
92 Rc::downgrade(self)
93 }
94}
95
96impl<T> Upgrade for rc::Weak<T> {
97 type Strong = Rc<T>;
98
99 fn upgrade(&self) -> Option<Self::Strong> {
100 self.upgrade()
101 }
102}
103