pure_stage/
drop_guard.rs

1// Copyright 2025 PRAGMA
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15use std::{
16    fmt,
17    mem::ManuallyDrop,
18    ops::{Deref, DerefMut},
19};
20
21pub struct DropGuard<T, F>
22where
23    F: FnOnce(T),
24{
25    inner: ManuallyDrop<T>,
26    f: ManuallyDrop<F>,
27}
28
29impl<T, F: FnOnce(T)> DropGuard<T, F> {
30    pub const fn new(inner: T, f: F) -> Self {
31        Self { inner: ManuallyDrop::new(inner), f: ManuallyDrop::new(f) }
32    }
33
34    pub fn into_inner(guard: Self) -> T {
35        let mut guard = ManuallyDrop::new(guard);
36        let value = unsafe { ManuallyDrop::take(&mut guard.inner) };
37        unsafe { ManuallyDrop::drop(&mut guard.f) };
38        value
39    }
40}
41
42impl<T, F: FnOnce(T)> Deref for DropGuard<T, F> {
43    type Target = T;
44
45    fn deref(&self) -> &T {
46        &self.inner
47    }
48}
49
50impl<T, F: FnOnce(T)> DerefMut for DropGuard<T, F> {
51    fn deref_mut(&mut self) -> &mut T {
52        &mut self.inner
53    }
54}
55
56impl<T, F: FnOnce(T)> Drop for DropGuard<T, F> {
57    fn drop(&mut self) {
58        let inner = unsafe { ManuallyDrop::take(&mut self.inner) };
59        let f = unsafe { ManuallyDrop::take(&mut self.f) };
60        f(inner);
61    }
62}
63
64impl<T: fmt::Debug, F: FnOnce(T)> fmt::Debug for DropGuard<T, F> {
65    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
66        fmt::Debug::fmt(&**self, f)
67    }
68}
pure_stage/drop_guard.rs

pure_stage/
drop_guard.rs
