1 | // Extracted from the scopeguard crate |
2 | use core::{ |
3 | mem::ManuallyDrop, |
4 | ops::{Deref, DerefMut}, |
5 | ptr, |
6 | }; |
7 | |
8 | pub struct ScopeGuard<T, F> |
9 | where |
10 | F: FnMut(&mut T), |
11 | { |
12 | dropfn: F, |
13 | value: T, |
14 | } |
15 | |
16 | #[inline ] |
17 | pub fn guard<T, F>(value: T, dropfn: F) -> ScopeGuard<T, F> |
18 | where |
19 | F: FnMut(&mut T), |
20 | { |
21 | ScopeGuard { dropfn, value } |
22 | } |
23 | |
24 | impl<T, F> ScopeGuard<T, F> |
25 | where |
26 | F: FnMut(&mut T), |
27 | { |
28 | #[inline ] |
29 | pub fn into_inner(guard: Self) -> T { |
30 | // Cannot move out of Drop-implementing types, so |
31 | // ptr::read the value out of a ManuallyDrop<Self> |
32 | // Don't use mem::forget as that might invalidate value |
33 | let guard = ManuallyDrop::new(guard); |
34 | unsafe { |
35 | let value: T = ptr::read(&guard.value); |
36 | // read the closure so that it is dropped |
37 | let _ = ptr::read(&guard.dropfn); |
38 | value |
39 | } |
40 | } |
41 | } |
42 | |
43 | impl<T, F> Deref for ScopeGuard<T, F> |
44 | where |
45 | F: FnMut(&mut T), |
46 | { |
47 | type Target = T; |
48 | #[inline ] |
49 | fn deref(&self) -> &T { |
50 | &self.value |
51 | } |
52 | } |
53 | |
54 | impl<T, F> DerefMut for ScopeGuard<T, F> |
55 | where |
56 | F: FnMut(&mut T), |
57 | { |
58 | #[inline ] |
59 | fn deref_mut(&mut self) -> &mut T { |
60 | &mut self.value |
61 | } |
62 | } |
63 | |
64 | impl<T, F> Drop for ScopeGuard<T, F> |
65 | where |
66 | F: FnMut(&mut T), |
67 | { |
68 | #[inline ] |
69 | fn drop(&mut self) { |
70 | (self.dropfn)(&mut self.value); |
71 | } |
72 | } |
73 | |