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stop treating Rc cycles as unsafe

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This commit is contained in:
Daniel Micay
2013-12-11 18:03:25 -05:00
parent 63ba93f91d
commit b36a948831
5 changed files with 13 additions and 70 deletions
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54
src/libstd/rc.rs
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@@ -19,9 +19,8 @@ overhead of atomic reference counting.
use ptr::RawPtr;
use unstable::intrinsics::transmute;
use ops::Drop;
use kinds::{Freeze, Send};
use kinds::NonManaged;
use clone::{Clone, DeepClone};
use cell::RefCell;
use cmp::{Eq, TotalEq, Ord, TotalOrd, Ordering};
struct RcBox<T> {
@@ -36,46 +35,17 @@ pub struct Rc<T> {
priv ptr: *mut RcBox<T>
}
impl<T: Freeze> Rc<T> {
/// Construct a new reference-counted box from a `Freeze` value
impl<T: NonManaged> Rc<T> {
/// Construct a new reference-counted box
#[inline]
pub fn new(value: T) -> Rc<T> {
unsafe {
Rc::new_unchecked(value)
}
}
}
impl<T: Send> Rc<T> {
/// Construct a new reference-counted box from a `Send` value
#[inline]
pub fn from_send(value: T) -> Rc<T> {
unsafe {
Rc::new_unchecked(value)
}
}
}
impl<T: Freeze> Rc<RefCell<T>> {
/// Construct a new reference-counted box from a `RefCell`-wrapped `Freeze` value
#[inline]
pub fn from_mut(value: RefCell<T>) -> Rc<RefCell<T>> {
unsafe {
Rc::new_unchecked(value)
Rc { ptr: transmute(~RcBox { value: value, count: 1 }) }
}
}
}
impl<T> Rc<T> {
/// Unsafety construct a new reference-counted box from any value.
///
/// It is possible to create cycles, which will leak, and may interact
/// poorly with managed pointers.
#[inline]
pub unsafe fn new_unchecked(value: T) -> Rc<T> {
Rc{ptr: transmute(~RcBox{value: value, count: 1})}
}
/// Borrow the value contained in the reference-counted box
#[inline]
pub fn borrow<'r>(&'r self) -> &'r T {
@@ -147,10 +117,10 @@ impl<T> Clone for Rc<T> {
}
}
impl<T: DeepClone> DeepClone for Rc<T> {
impl<T: NonManaged + DeepClone> DeepClone for Rc<T> {
#[inline]
fn deep_clone(&self) -> Rc<T> {
unsafe { Rc::new_unchecked(self.borrow().deep_clone()) }
Rc::new(self.borrow().deep_clone())
}
}
@@ -176,7 +146,7 @@ mod test_rc {
#[test]
fn test_clone() {
let x = Rc::from_send(RefCell::new(5));
let x = Rc::new(RefCell::new(5));
let y = x.clone();
x.borrow().with_mut(|inner| {
*inner = 20;
@@ -186,7 +156,7 @@ mod test_rc {
#[test]
fn test_deep_clone() {
let x = Rc::from_send(RefCell::new(5));
let x = Rc::new(RefCell::new(5));
let y = x.deep_clone();
x.borrow().with_mut(|inner| {
*inner = 20;
@@ -210,13 +180,7 @@ mod test_rc {
#[test]
fn test_destructor() {
let x = Rc::from_send(~5);
let x = Rc::new(~5);
assert_eq!(**x.borrow(), 5);
}
#[test]
fn test_from_mut() {
let a = 10;
let _x = Rc::from_mut(RefCell::new(&a));
}
}