73 lines
1.3 KiB
Rust
73 lines
1.3 KiB
Rust
// Extracted from the scopeguard crate
|
|
use core::{
|
|
mem::ManuallyDrop,
|
|
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 out of a ManuallyDrop<Self>
|
|
// Don't use mem::forget as that might invalidate value
|
|
let guard = ManuallyDrop::new(guard);
|
|
unsafe {
|
|
let value = ptr::read(&guard.value);
|
|
// read the closure so that it is dropped
|
|
let _ = ptr::read(&guard.dropfn);
|
|
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);
|
|
}
|
|
}
|