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rc: Use ~T for allocation #8022

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90 changes: 43 additions & 47 deletions src/libextra/rc.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -23,11 +23,17 @@ cycle cannot be created with `Rc<T>` because there is no way to modify it after


use std::cast;
use std::libc::{c_void, size_t, malloc, free};
use std::ptr;
use std::sys;
use std::unstable::intrinsics;

// Convert ~T into *mut T without dropping it
#[inline]
unsafe fn owned_to_raw<T>(mut box: ~T) -> *mut T {
let ptr = ptr::to_mut_unsafe_ptr(box);
intrinsics::forget(box);
ptr
}

struct RcBox<T> {
value: T,
count: uint
Expand All @@ -42,21 +48,20 @@ pub struct Rc<T> {

impl<T> Rc<T> {
unsafe fn new(value: T) -> Rc<T> {
let ptr = malloc(sys::size_of::<RcBox<T>>() as size_t) as *mut RcBox<T>;
assert!(!ptr::is_null(ptr));
intrinsics::move_val_init(&mut *ptr, RcBox{value: value, count: 1});
Rc{ptr: ptr}
Rc{ptr: owned_to_raw(~RcBox{value: value, count: 1})}
}
}

// FIXME: #6516: should be a static method
pub fn rc_from_owned<T: Send>(value: T) -> Rc<T> {
unsafe { Rc::new(value) }
impl<T: Send> Rc<T> {
pub fn from_owned(value: T) -> Rc<T> {
unsafe { Rc::new(value) }
}
}

// FIXME: #6516: should be a static method
pub fn rc_from_const<T: Freeze>(value: T) -> Rc<T> {
unsafe { Rc::new(value) }
impl<T: Freeze> Rc<T> {
pub fn from_const(value: T) -> Rc<T> {
unsafe { Rc::new(value) }
}
}

impl<T> Rc<T> {
Expand All @@ -73,8 +78,7 @@ impl<T> Drop for Rc<T> {
if self.ptr.is_not_null() {
(*self.ptr).count -= 1;
if (*self.ptr).count == 0 {
ptr::read_ptr(self.ptr);
free(self.ptr as *c_void)
let _: ~T = cast::transmute(self.ptr);
}
}
}
Expand Down Expand Up @@ -107,7 +111,7 @@ mod test_rc {

#[test]
fn test_clone() {
let x = rc_from_owned(Cell::new(5));
let x = Rc::from_owned(Cell::new(5));
let y = x.clone();
do x.borrow().with_mut_ref |inner| {
*inner = 20;
Expand All @@ -117,7 +121,7 @@ mod test_rc {

#[test]
fn test_deep_clone() {
let x = rc_from_owned(Cell::new(5));
let x = Rc::from_owned(Cell::new(5));
let y = x.deep_clone();
do x.borrow().with_mut_ref |inner| {
*inner = 20;
Expand All @@ -127,31 +131,25 @@ mod test_rc {

#[test]
fn test_simple() {
let x = rc_from_const(5);
let x = Rc::from_const(5);
assert_eq!(*x.borrow(), 5);
}

#[test]
fn test_simple_clone() {
let x = rc_from_const(5);
let x = Rc::from_const(5);
let y = x.clone();
assert_eq!(*x.borrow(), 5);
assert_eq!(*y.borrow(), 5);
}

#[test]
fn test_destructor() {
let x = rc_from_owned(~5);
let x = Rc::from_owned(~5);
assert_eq!(**x.borrow(), 5);
}
}

#[abi = "rust-intrinsic"]
extern "rust-intrinsic" {
fn init<T>() -> T;
fn uninit<T>() -> T;
}

#[deriving(Eq)]
enum Borrow {
Mutable,
Expand All @@ -175,21 +173,20 @@ pub struct RcMut<T> {

impl<T> RcMut<T> {
unsafe fn new(value: T) -> RcMut<T> {
let ptr = malloc(sys::size_of::<RcMutBox<T>>() as size_t) as *mut RcMutBox<T>;
assert!(!ptr::is_null(ptr));
intrinsics::move_val_init(&mut *ptr, RcMutBox{value: value, count: 1, borrow: Nothing});
RcMut{ptr: ptr}
RcMut{ptr: owned_to_raw(~RcMutBox{value: value, count: 1, borrow: Nothing})}
}
}

// FIXME: #6516: should be a static method
pub fn rc_mut_from_owned<T: Send>(value: T) -> RcMut<T> {
unsafe { RcMut::new(value) }
impl<T: Send> RcMut<T> {
pub fn from_owned(value: T) -> RcMut<T> {
unsafe { RcMut::new(value) }
}
}

// FIXME: #6516: should be a static method
pub fn rc_mut_from_const<T: Freeze>(value: T) -> RcMut<T> {
unsafe { RcMut::new(value) }
impl<T: Freeze> RcMut<T> {
pub fn from_const(value: T) -> RcMut<T> {
unsafe { RcMut::new(value) }
}
}

impl<T> RcMut<T> {
Expand Down Expand Up @@ -226,8 +223,7 @@ impl<T> Drop for RcMut<T> {
if self.ptr.is_not_null() {
(*self.ptr).count -= 1;
if (*self.ptr).count == 0 {
ptr::replace_ptr(self.ptr, uninit());
free(self.ptr as *c_void)
let _: ~T = cast::transmute(self.ptr);
}
}
}
Expand Down Expand Up @@ -262,7 +258,7 @@ mod test_rc_mut {

#[test]
fn test_clone() {
let x = rc_mut_from_owned(5);
let x = RcMut::from_owned(5);
let y = x.clone();
do x.with_mut_borrow |value| {
*value = 20;
Expand All @@ -274,7 +270,7 @@ mod test_rc_mut {

#[test]
fn test_deep_clone() {
let x = rc_mut_from_const(5);
let x = RcMut::from_const(5);
let y = x.deep_clone();
do x.with_mut_borrow |value| {
*value = 20;
Expand All @@ -286,7 +282,7 @@ mod test_rc_mut {

#[test]
fn borrow_many() {
let x = rc_mut_from_owned(5);
let x = RcMut::from_owned(5);
let y = x.clone();

do x.with_borrow |a| {
Expand All @@ -302,7 +298,7 @@ mod test_rc_mut {

#[test]
fn modify() {
let x = rc_mut_from_const(5);
let x = RcMut::from_const(5);
let y = x.clone();

do y.with_mut_borrow |a| {
Expand All @@ -317,22 +313,22 @@ mod test_rc_mut {

#[test]
fn release_immutable() {
let x = rc_mut_from_owned(5);
let x = RcMut::from_owned(5);
do x.with_borrow |_| {}
do x.with_mut_borrow |_| {}
}

#[test]
fn release_mutable() {
let x = rc_mut_from_const(5);
let x = RcMut::from_const(5);
do x.with_mut_borrow |_| {}
do x.with_borrow |_| {}
}

#[test]
#[should_fail]
fn frozen() {
let x = rc_mut_from_owned(5);
let x = RcMut::from_owned(5);
let y = x.clone();

do x.with_borrow |_| {
Expand All @@ -344,7 +340,7 @@ mod test_rc_mut {
#[test]
#[should_fail]
fn mutable_dupe() {
let x = rc_mut_from_const(5);
let x = RcMut::from_const(5);
let y = x.clone();

do x.with_mut_borrow |_| {
Expand All @@ -356,7 +352,7 @@ mod test_rc_mut {
#[test]
#[should_fail]
fn mutable_freeze() {
let x = rc_mut_from_owned(5);
let x = RcMut::from_owned(5);
let y = x.clone();

do x.with_mut_borrow |_| {
Expand All @@ -368,7 +364,7 @@ mod test_rc_mut {
#[test]
#[should_fail]
fn restore_freeze() {
let x = rc_mut_from_const(5);
let x = RcMut::from_const(5);
let y = x.clone();

do x.with_borrow |_| {
Expand Down
2 changes: 1 addition & 1 deletion src/test/compile-fail/rcmut-not-const-and-not-owned.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@ fn o<T: Send>(_: &T) {}
fn c<T: Freeze>(_: &T) {}

fn main() {
let x = extra::rc::rc_mut_from_owned(0);
let x = extra::rc::RcMut::from_owned(0);
o(&x); //~ ERROR instantiating a type parameter with an incompatible type `extra::rc::RcMut<int>`, which does not fulfill `Send`
c(&x); //~ ERROR instantiating a type parameter with an incompatible type `extra::rc::RcMut<int>`, which does not fulfill `Freeze`
}