bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

simplify pointer arithmetic

Browse source
This commit is contained in:
The8472 2019-11-15 21:02:54 +01:00
parent f904d0339a
commit bead910b21
1 changed files with 15 additions and 11 deletions
Download patch file Download diff file Expand all files Collapse all files

26
library/alloc/src/vec.rs
View file

@ -2128,16 +2128,22 @@ where
struct InPlaceIterFront<T> {
inner: *mut T,
count: usize,
dst: *mut T,
did_panic: bool,
}
impl<T> InPlaceIterFront<T> {
unsafe fn len(&self) -> usize {
self.dst.offset_from(self.inner) as usize
}
}
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 _);
ptr::drop_in_place(slice::from_raw_parts_mut(self.inner, self.len()) as *mut _);
}
}
}
@ -2148,28 +2154,26 @@ where
I: Iterator<Item = T> + InPlaceIterable + SourceIter<Source = IntoIter<T>>,
{
let original_ptr = iterator.as_inner().buf.as_ptr();
let mut front_buffer = InPlaceIterFront { inner: original_ptr, count: 0, did_panic: true };
let mut front_buffer =
InPlaceIterFront { inner: original_ptr, dst: original_ptr, did_panic: true };
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;
debug_assert_eq!(original_ptr, source_iter.buf.as_ptr());
unsafe {
let dst = src_buf.add(front_buffer.count);
debug_assert!(
dst as *const _ < src_idx,
front_buffer.dst as *const _ < source_iter.ptr,
"InPlaceIterable implementation produced more\
items than it consumed from the source"
);
ptr::write(dst, item)
ptr::write(front_buffer.dst, item);
front_buffer.dst = front_buffer.dst.add(1);
}
front_buffer.count += 1;
}
let src = iterator.as_inner();
front_buffer.did_panic = false;
let vec = unsafe { Vec::from_raw_parts(src.buf.as_ptr(), front_buffer.count, src.cap) };
let vec = unsafe { Vec::from_raw_parts(src.buf.as_ptr(), front_buffer.len(), src.cap) };
src.cap = 0;
src.buf = unsafe { NonNull::new_unchecked(RawVec::NEW.ptr()) };
src.ptr = src.buf.as_ptr();