revert Deref

This commit is contained in:
F001 2018-07-17 11:30:17 +08:00
parent 7e1b983579
commit 8812c6bae9
2 changed files with 10 additions and 18 deletions

View File

@ -200,8 +200,9 @@ use cmp::Ordering;
use fmt::{self, Debug, Display};
use marker::Unsize;
use mem;
use ops::{Deref, DerefMut, CoerceUnsized};
use ops::{Deref, DerefMut, CoerceUnsized, Index};
use ptr;
use slice::SliceIndex;
/// A mutable memory location.
///
@ -510,7 +511,7 @@ impl<T: ?Sized> Cell<T> {
///
/// let slice: &mut [i32] = &mut [1, 2, 3];
/// let cell_slice: &Cell<[i32]> = Cell::from_mut(slice);
/// assert_eq!(cell_slice.len(), 3);
/// assert_eq!(cell_slice[..].len(), 3);
///
/// let slice_cell: &[Cell<i32>] = &cell_slice[..];
/// assert_eq!(slice_cell.len(), 3);
@ -548,23 +549,14 @@ impl<T: Default> Cell<T> {
impl<T: CoerceUnsized<U>, U> CoerceUnsized<Cell<U>> for Cell<T> {}
#[unstable(feature = "as_cell", issue="43038")]
impl<T> Deref for Cell<[T]> {
type Target = [Cell<T>];
impl<T, I> Index<I> for Cell<[T]>
where I: SliceIndex<[Cell<T>]>
{
type Output = I::Output;
#[inline]
fn deref(&self) -> &[Cell<T>] {
fn index(&self, index: I) -> &Self::Output {
unsafe {
&*(self as *const Cell<[T]> as *const [Cell<T>])
}
}
}
#[unstable(feature = "as_cell", issue="43038")]
impl<T> DerefMut for Cell<[T]> {
#[inline]
fn deref_mut(&mut self) -> &mut [Cell<T>] {
unsafe {
&mut *(self as *mut Cell<[T]> as *mut [Cell<T>])
Index::index(&*(self as *const Cell<[T]> as *const [Cell<T>]), index)
}
}
}

View File

@ -15,7 +15,7 @@ use std::cell::Cell;
fn main() {
let slice: &mut [i32] = &mut [1, 2, 3];
let cell_slice: &Cell<[i32]> = Cell::from_mut(slice);
assert_eq!(cell_slice.len(), 3);
assert_eq!(cell_slice[..].len(), 3);
let sub_slice: &[Cell<i32>] = &cell_slice[1..];
assert_eq!(sub_slice.len(), 2);