alloc/vec/
in_place_drop.rs

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1use core::marker::PhantomData;
2use core::ptr::{self, NonNull, drop_in_place};
3use core::slice::{self};
4
5use crate::alloc::Global;
6use crate::raw_vec::RawVec;
7
8// A helper struct for in-place iteration that drops the destination slice of iteration,
9// i.e. the head. The source slice (the tail) is dropped by IntoIter.
10pub(super) struct InPlaceDrop<T> {
11    pub(super) inner: *mut T,
12    pub(super) dst: *mut T,
13}
14
15impl<T> InPlaceDrop<T> {
16    fn len(&self) -> usize {
17        unsafe { self.dst.offset_from_unsigned(self.inner) }
18    }
19}
20
21impl<T> Drop for InPlaceDrop<T> {
22    #[inline]
23    fn drop(&mut self) {
24        unsafe {
25            ptr::drop_in_place(slice::from_raw_parts_mut(self.inner, self.len()));
26        }
27    }
28}
29
30// A helper struct for in-place collection that drops the destination items together with
31// the source allocation - i.e. before the reallocation happened - to avoid leaking them
32// if some other destructor panics.
33pub(super) struct InPlaceDstDataSrcBufDrop<Src, Dest> {
34    pub(super) ptr: NonNull<Dest>,
35    pub(super) len: usize,
36    pub(super) src_cap: usize,
37    pub(super) src: PhantomData<Src>,
38}
39
40impl<Src, Dest> Drop for InPlaceDstDataSrcBufDrop<Src, Dest> {
41    #[inline]
42    fn drop(&mut self) {
43        unsafe {
44            let _drop_allocation =
45                RawVec::<Src>::from_nonnull_in(self.ptr.cast::<Src>(), self.src_cap, Global);
46            drop_in_place(core::ptr::slice_from_raw_parts_mut::<Dest>(self.ptr.as_ptr(), self.len));
47        };
48    }
49}
alloc/vec/in_place_drop.rs

alloc/vec/
in_place_drop.rs
