74 lines
1.5 KiB
Rust
74 lines
1.5 KiB
Rust
// Extracted from the scopeguard crate
|
|
use core::{
|
|
mem,
|
|
ops::{Deref, DerefMut},
|
|
ptr,
|
|
};
|
|
|
|
pub struct ScopeGuard<T, F>
|
|
where
|
|
F: FnMut(&mut T),
|
|
{
|
|
dropfn: F,
|
|
value: T,
|
|
}
|
|
|
|
#[inline]
|
|
pub fn guard<T, F>(value: T, dropfn: F) -> ScopeGuard<T, F>
|
|
where
|
|
F: FnMut(&mut T),
|
|
{
|
|
ScopeGuard { dropfn, value }
|
|
}
|
|
|
|
impl<T, F> ScopeGuard<T, F>
|
|
where
|
|
F: FnMut(&mut T),
|
|
{
|
|
#[inline]
|
|
pub fn into_inner(guard: Self) -> T {
|
|
// Cannot move out of Drop-implementing types, so
|
|
// ptr::read the value and forget the guard.
|
|
unsafe {
|
|
let value = ptr::read(&guard.value);
|
|
// read the closure so that it is dropped, and assign it to a local
|
|
// variable to ensure that it is only dropped after the guard has
|
|
// been forgotten. (In case the Drop impl of the closure, or that
|
|
// of any consumed captured variable, panics).
|
|
let _dropfn = ptr::read(&guard.dropfn);
|
|
mem::forget(guard);
|
|
value
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<T, F> Deref for ScopeGuard<T, F>
|
|
where
|
|
F: FnMut(&mut T),
|
|
{
|
|
type Target = T;
|
|
#[inline]
|
|
fn deref(&self) -> &T {
|
|
&self.value
|
|
}
|
|
}
|
|
|
|
impl<T, F> DerefMut for ScopeGuard<T, F>
|
|
where
|
|
F: FnMut(&mut T),
|
|
{
|
|
#[inline]
|
|
fn deref_mut(&mut self) -> &mut T {
|
|
&mut self.value
|
|
}
|
|
}
|
|
|
|
impl<T, F> Drop for ScopeGuard<T, F>
|
|
where
|
|
F: FnMut(&mut T),
|
|
{
|
|
#[inline]
|
|
fn drop(&mut self) {
|
|
(self.dropfn)(&mut self.value);
|
|
}
|
|
}
|