alloc/vec/
in_place_drop.rs

1use core::marker::PhantomData;
2use core::ptr::{self, NonNull, drop_in_place};
3
4use crate::alloc::Global;
5use crate::raw_vec::RawVec;
6
7// A helper struct for in-place iteration that drops the destination slice of iteration,
8// i.e. the head. The source slice (the tail) is dropped by IntoIter.
9pub(super) struct InPlaceDrop<T> {
10    pub(super) inner: *mut T,
11    pub(super) dst: *mut T,
12}
13
14impl<T> InPlaceDrop<T> {
15    fn len(&self) -> usize {
16        unsafe { self.dst.offset_from_unsigned(self.inner) }
17    }
18}
19
20impl<T> Drop for InPlaceDrop<T> {
21    #[inline]
22    fn drop(&mut self) {
23        unsafe {
24            ptr::drop_in_place(ptr::slice_from_raw_parts_mut(self.inner, self.len()));
25        }
26    }
27}
28
29// A helper struct for in-place collection that drops the destination items together with
30// the source allocation - i.e. before the reallocation happened - to avoid leaking them
31// if some other destructor panics.
32pub(super) struct InPlaceDstDataSrcBufDrop<Src, Dest> {
33    pub(super) ptr: NonNull<Dest>,
34    pub(super) len: usize,
35    pub(super) src_cap: usize,
36    pub(super) src: PhantomData<Src>,
37}
38
39impl<Src, Dest> Drop for InPlaceDstDataSrcBufDrop<Src, Dest> {
40    #[inline]
41    fn drop(&mut self) {
42        unsafe {
43            let _drop_allocation =
44                RawVec::<Src>::from_nonnull_in(self.ptr.cast::<Src>(), self.src_cap, Global);
45            drop_in_place(core::ptr::slice_from_raw_parts_mut::<Dest>(self.ptr.as_ptr(), self.len));
46        };
47    }
48}
alloc/vec/in_place_drop.rs

alloc/vec/
in_place_drop.rs
