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// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
/*! Task-local reference-counted boxes (`Rc` type)
The `Rc` type provides shared ownership of an immutable value. Destruction is deterministic, and
will occur as soon as the last owner is gone. It is marked as non-sendable because it avoids the
overhead of atomic reference counting.
*/
use ptr::RawPtr;
use unstable::intrinsics::transmute;
use ops::Drop;
use kinds::{Freeze, Send};
use clone::{Clone, DeepClone};
use cell::RefCell;
use cmp::{Eq, TotalEq, Ord, TotalOrd, Ordering};
struct RcBox<T> {
value: T,
count: uint
}
/// Immutable reference counted pointer type
#[unsafe_no_drop_flag]
#[no_send]
pub struct Rc<T> {
priv ptr: *mut RcBox<T>
}
impl<T: Freeze> Rc<T> {
/// Construct a new reference-counted box from a `Freeze` value
#[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)
}
}
}
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 {
unsafe { &(*self.ptr).value }
}
/// Determine if two reference-counted pointers point to the same object
#[inline]
pub fn ptr_eq(&self, other: &Rc<T>) -> bool {
self.ptr == other.ptr
}
}
impl<T: Eq> Eq for Rc<T> {
#[inline]
fn eq(&self, other: &Rc<T>) -> bool {
unsafe { (*self.ptr).value == (*other.ptr).value }
}
#[inline]
fn ne(&self, other: &Rc<T>) -> bool {
unsafe { (*self.ptr).value != (*other.ptr).value }
}
}
impl<T: TotalEq> TotalEq for Rc<T> {
#[inline]
fn equals(&self, other: &Rc<T>) -> bool {
unsafe { (*self.ptr).value.equals(&(*other.ptr).value) }
}
}
impl<T: Ord> Ord for Rc<T> {
#[inline]
fn lt(&self, other: &Rc<T>) -> bool {
unsafe { (*self.ptr).value < (*other.ptr).value }
}
#[inline]
fn le(&self, other: &Rc<T>) -> bool {
unsafe { (*self.ptr).value <= (*other.ptr).value }
}
#[inline]
fn ge(&self, other: &Rc<T>) -> bool {
unsafe { (*self.ptr).value >= (*other.ptr).value }
}
#[inline]
fn gt(&self, other: &Rc<T>) -> bool {
unsafe { (*self.ptr).value > (*other.ptr).value }
}
}
impl<T: TotalOrd> TotalOrd for Rc<T> {
#[inline]
fn cmp(&self, other: &Rc<T>) -> Ordering {
unsafe { (*self.ptr).value.cmp(&(*other.ptr).value) }
}
}
impl<T> Clone for Rc<T> {
#[inline]
fn clone(&self) -> Rc<T> {
unsafe {
(*self.ptr).count += 1;
Rc{ptr: self.ptr}
}
}
}
impl<T: DeepClone> DeepClone for Rc<T> {
#[inline]
fn deep_clone(&self) -> Rc<T> {
unsafe { Rc::new_unchecked(self.borrow().deep_clone()) }
}
}
#[unsafe_destructor]
impl<T> Drop for Rc<T> {
fn drop(&mut self) {
unsafe {
if self.ptr.is_not_null() {
(*self.ptr).count -= 1;
if (*self.ptr).count == 0 {
let _: ~RcBox<T> = transmute(self.ptr);
}
}
}
}
}
#[cfg(test)]
mod test_rc {
use prelude::*;
use super::*;
use cell::RefCell;
#[test]
fn test_clone() {
let x = Rc::from_send(RefCell::new(5));
let y = x.clone();
x.borrow().with_mut(|inner| {
*inner = 20;
});
assert_eq!(y.borrow().with(|v| *v), 20);
}
#[test]
fn test_deep_clone() {
let x = Rc::from_send(RefCell::new(5));
let y = x.deep_clone();
x.borrow().with_mut(|inner| {
*inner = 20;
});
assert_eq!(y.borrow().with(|v| *v), 5);
}
#[test]
fn test_simple() {
let x = Rc::new(5);
assert_eq!(*x.borrow(), 5);
}
#[test]
fn test_simple_clone() {
let x = Rc::new(5);
let y = x.clone();
assert_eq!(*x.borrow(), 5);
assert_eq!(*y.borrow(), 5);
}
#[test]
fn test_destructor() {
let x = Rc::from_send(~5);
assert_eq!(**x.borrow(), 5);
}
#[test]
fn test_from_mut() {
let a = 10;
let _x = Rc::from_mut(RefCell::new(&a));
}
}
|
