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rc: Use ~T for allocation

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Simplify Rc<T>/RcMut<T> by using ~T when allocating a reference counted
box.
This commit is contained in:
blake2-ppc 2013-07-24 14:11:49 +02:00 committed by Daniel Micay
parent 4a2d22bdb1
commit 8f86fa3b31
2 changed files with 44 additions and 48 deletions
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82
src/libextra/rc.rs
View File

@ -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::cast;
use std::libc::{c_void, size_t, malloc, free};
use std::ptr; use std::ptr;
use std::sys;
use std::unstable::intrinsics; 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> { struct RcBox<T> {
value: T, value: T,
count: uint count: uint
@ -42,22 +48,21 @@ pub struct Rc<T> {
impl<T> Rc<T> { impl<T> Rc<T> {
unsafe fn new(value: 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>; Rc{ptr: owned_to_raw(~RcBox{value: value, count: 1})}
assert!(!ptr::is_null(ptr));
intrinsics::move_val_init(&mut *ptr, RcBox{value: value, count: 1});
Rc{ptr: ptr}
} }
} }
// FIXME: #6516: should be a static method impl<T: Send> Rc<T> {
pub fn rc_from_owned<T: Send>(value: T) -> Rc<T> { pub fn from_owned(value: T) -> Rc<T> {
unsafe { Rc::new(value) } unsafe { Rc::new(value) }
} }
}
// FIXME: #6516: should be a static method impl<T: Freeze> Rc<T> {
pub fn rc_from_const<T: Freeze>(value: T) -> Rc<T> { pub fn from_const(value: T) -> Rc<T> {
unsafe { Rc::new(value) } unsafe { Rc::new(value) }
} }
}
impl<T> Rc<T> { impl<T> Rc<T> {
#[inline] #[inline]
@ -73,8 +78,7 @@ impl<T> Drop for Rc<T> {
if self.ptr.is_not_null() { if self.ptr.is_not_null() {
(*self.ptr).count -= 1; (*self.ptr).count -= 1;
if (*self.ptr).count == 0 { if (*self.ptr).count == 0 {
ptr::read_ptr(self.ptr); let _: ~T = cast::transmute(self.ptr);
free(self.ptr as *c_void)
} }
} }
} }
@ -107,7 +111,7 @@ mod test_rc {
#[test] #[test]
fn test_clone() { fn test_clone() {
let x = rc_from_owned(Cell::new(5)); let x = Rc::from_owned(Cell::new(5));
let y = x.clone(); let y = x.clone();
do x.borrow().with_mut_ref |inner| { do x.borrow().with_mut_ref |inner| {
*inner = 20; *inner = 20;
@ -117,7 +121,7 @@ mod test_rc {
#[test] #[test]
fn test_deep_clone() { 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(); let y = x.deep_clone();
do x.borrow().with_mut_ref |inner| { do x.borrow().with_mut_ref |inner| {
*inner = 20; *inner = 20;
@ -127,13 +131,13 @@ mod test_rc {
#[test] #[test]
fn test_simple() { fn test_simple() {
let x = rc_from_const(5); let x = Rc::from_const(5);
assert_eq!(*x.borrow(), 5); assert_eq!(*x.borrow(), 5);
} }
#[test] #[test]
fn test_simple_clone() { fn test_simple_clone() {
let x = rc_from_const(5); let x = Rc::from_const(5);
let y = x.clone(); let y = x.clone();
assert_eq!(*x.borrow(), 5); assert_eq!(*x.borrow(), 5);
assert_eq!(*y.borrow(), 5); assert_eq!(*y.borrow(), 5);
@ -141,17 +145,11 @@ mod test_rc {
#[test] #[test]
fn test_destructor() { fn test_destructor() {
let x = rc_from_owned(~5); let x = Rc::from_owned(~5);
assert_eq!(**x.borrow(), 5); assert_eq!(**x.borrow(), 5);
} }
} }
#[abi = "rust-intrinsic"]
extern "rust-intrinsic" {
fn init<T>() -> T;
fn uninit<T>() -> T;
}
#[deriving(Eq)] #[deriving(Eq)]
enum Borrow { enum Borrow {
Mutable, Mutable,
@ -175,22 +173,21 @@ pub struct RcMut<T> {
impl<T> RcMut<T> { impl<T> RcMut<T> {
unsafe fn new(value: 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>; RcMut{ptr: owned_to_raw(~RcMutBox{value: value, count: 1, borrow: Nothing})}
assert!(!ptr::is_null(ptr));
intrinsics::move_val_init(&mut *ptr, RcMutBox{value: value, count: 1, borrow: Nothing});
RcMut{ptr: ptr}
} }
} }
// FIXME: #6516: should be a static method impl<T: Send> RcMut<T> {
pub fn rc_mut_from_owned<T: Send>(value: T) -> RcMut<T> { pub fn from_owned(value: T) -> RcMut<T> {
unsafe { RcMut::new(value) } unsafe { RcMut::new(value) }
} }
}
// FIXME: #6516: should be a static method impl<T: Freeze> RcMut<T> {
pub fn rc_mut_from_const<T: Freeze>(value: T) -> RcMut<T> { pub fn from_const(value: T) -> RcMut<T> {
unsafe { RcMut::new(value) } unsafe { RcMut::new(value) }
} }
}
impl<T> RcMut<T> { impl<T> RcMut<T> {
/// Fails if there is already a mutable borrow of the box /// Fails if there is already a mutable borrow of the box
@ -226,8 +223,7 @@ impl<T> Drop for RcMut<T> {
if self.ptr.is_not_null() { if self.ptr.is_not_null() {
(*self.ptr).count -= 1; (*self.ptr).count -= 1;
if (*self.ptr).count == 0 { if (*self.ptr).count == 0 {
ptr::replace_ptr(self.ptr, uninit()); let _: ~T = cast::transmute(self.ptr);
free(self.ptr as *c_void)
} }
} }
} }
@ -262,7 +258,7 @@ mod test_rc_mut {
#[test] #[test]
fn test_clone() { fn test_clone() {
let x = rc_mut_from_owned(5); let x = RcMut::from_owned(5);
let y = x.clone(); let y = x.clone();
do x.with_mut_borrow |value| { do x.with_mut_borrow |value| {
*value = 20; *value = 20;
@ -274,7 +270,7 @@ mod test_rc_mut {
#[test] #[test]
fn test_deep_clone() { fn test_deep_clone() {
let x = rc_mut_from_const(5); let x = RcMut::from_const(5);
let y = x.deep_clone(); let y = x.deep_clone();
do x.with_mut_borrow |value| { do x.with_mut_borrow |value| {
*value = 20; *value = 20;
@ -286,7 +282,7 @@ mod test_rc_mut {
#[test] #[test]
fn borrow_many() { fn borrow_many() {
let x = rc_mut_from_owned(5); let x = RcMut::from_owned(5);
let y = x.clone(); let y = x.clone();
do x.with_borrow |a| { do x.with_borrow |a| {
@ -302,7 +298,7 @@ mod test_rc_mut {
#[test] #[test]
fn modify() { fn modify() {
let x = rc_mut_from_const(5); let x = RcMut::from_const(5);
let y = x.clone(); let y = x.clone();
do y.with_mut_borrow |a| { do y.with_mut_borrow |a| {
@ -317,14 +313,14 @@ mod test_rc_mut {
#[test] #[test]
fn release_immutable() { fn release_immutable() {
let x = rc_mut_from_owned(5); let x = RcMut::from_owned(5);
do x.with_borrow |_| {} do x.with_borrow |_| {}
do x.with_mut_borrow |_| {} do x.with_mut_borrow |_| {}
} }
#[test] #[test]
fn release_mutable() { fn release_mutable() {
let x = rc_mut_from_const(5); let x = RcMut::from_const(5);
do x.with_mut_borrow |_| {} do x.with_mut_borrow |_| {}
do x.with_borrow |_| {} do x.with_borrow |_| {}
} }
@ -332,7 +328,7 @@ mod test_rc_mut {
#[test] #[test]
#[should_fail] #[should_fail]
fn frozen() { fn frozen() {
let x = rc_mut_from_owned(5); let x = RcMut::from_owned(5);
let y = x.clone(); let y = x.clone();
do x.with_borrow |_| { do x.with_borrow |_| {
@ -344,7 +340,7 @@ mod test_rc_mut {
#[test] #[test]
#[should_fail] #[should_fail]
fn mutable_dupe() { fn mutable_dupe() {
let x = rc_mut_from_const(5); let x = RcMut::from_const(5);
let y = x.clone(); let y = x.clone();
do x.with_mut_borrow |_| { do x.with_mut_borrow |_| {
@ -356,7 +352,7 @@ mod test_rc_mut {
#[test] #[test]
#[should_fail] #[should_fail]
fn mutable_freeze() { fn mutable_freeze() {
let x = rc_mut_from_owned(5); let x = RcMut::from_owned(5);
let y = x.clone(); let y = x.clone();
do x.with_mut_borrow |_| { do x.with_mut_borrow |_| {
@ -368,7 +364,7 @@ mod test_rc_mut {
#[test] #[test]
#[should_fail] #[should_fail]
fn restore_freeze() { fn restore_freeze() {
let x = rc_mut_from_const(5); let x = RcMut::from_const(5);
let y = x.clone(); let y = x.clone();
do x.with_borrow |_| { do x.with_borrow |_| {

2
src/test/compile-fail/rcmut-not-const-and-not-owned.rs
View File

@ -14,7 +14,7 @@ fn o<T: Send>(_: &T) {}
fn c<T: Freeze>(_: &T) {} fn c<T: Freeze>(_: &T) {}
fn main() { 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` 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` c(&x); //~ ERROR instantiating a type parameter with an incompatible type `extra::rc::RcMut<int>`, which does not fulfill `Freeze`
} }