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implement drop handling

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This commit is contained in:
The8472 2019-11-15 02:37:55 +01:00
parent 73a982e9ec
commit 88b7ae642c
1 changed files with 26 additions and 7 deletions
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33
library/alloc/src/vec.rs
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@ -2126,22 +2126,37 @@ where
}
}
struct InPlaceIterFront<T> {
inner: *mut T,
count: usize,
did_panic: bool,
}
impl<T> Drop for InPlaceIterFront<T> {
#[inline]
fn drop(&mut self) {
unsafe {
if mem::needs_drop::<T>() && self.did_panic {
ptr::drop_in_place(slice::from_raw_parts_mut(self.inner, self.count) as *mut _);
}
}
}
}
fn from_into_iter_source<T, I>(mut iterator: I) -> Vec<T>
where
I: Iterator<Item = T> + InPlaceIterable + SourceIter<Source = IntoIter<T>>,
{
let mut insert_pos = 0;
let original_ptr = iterator.as_inner().buf.as_ptr();
let mut front_buffer = InPlaceIterFront { inner: original_ptr, count: 0, did_panic: true };
// FIXME: how to drop values written into source when iteration panics?
// tail already gets cleaned by IntoIter::drop
while let Some(item) = iterator.next() {
let source_iter = iterator.as_inner();
let src_buf = source_iter.buf.as_ptr();
debug_assert_eq!(original_ptr, src_buf);
let src_idx = source_iter.ptr;
unsafe {
let dst = src_buf.offset(insert_pos as isize);
let dst = src_buf.offset(front_buffer.count as isize);
debug_assert!(
dst as *const _ < src_idx,
"InPlaceIterable implementation produced more\
@ -2149,12 +2164,16 @@ where
);
ptr::write(dst, item)
}
insert_pos += 1;
front_buffer.count += 1;
}
let src = iterator.as_inner();
let vec = unsafe { Vec::from_raw_parts(src.buf.as_ptr(), insert_pos, src.cap) };
mem::forget(iterator);
front_buffer.did_panic = false;
let vec = unsafe { Vec::from_raw_parts(src.buf.as_ptr(), front_buffer.count, src.cap) };
src.cap = 0;
src.buf = unsafe { NonNull::new_unchecked(RawVec::NEW.ptr()) };
src.ptr = src.buf.as_ptr();
src.end = src.buf.as_ptr();
vec
}