Struct alloc::rc::Rc 1.0.0
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pub struct Rc<T: ?Sized> { /* fields omitted */ }
A single-threaded reference-counting pointer.
See the module-level documentation for more details.
The inherent methods of Rc
are all associated functions, which means
that you have to call them as e.g. Rc::get_mut(&value)
instead of
value.get_mut()
. This avoids conflicts with methods of the inner
type T
.
Methods
impl<T> Rc<T>
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fn new(value: T) -> Rc<T>
fn try_unwrap(this: Self) -> Result<T, Self>
1.4.0
Returns the contained value, if the Rc
has exactly one strong reference.
Otherwise, an Err
is returned with the same Rc
that was
passed in.
This will succeed even if there are outstanding weak references.
Examples
use std::rc::Rc; let x = Rc::new(3); assert_eq!(Rc::try_unwrap(x), Ok(3)); let x = Rc::new(4); let _y = x.clone(); assert_eq!(*Rc::try_unwrap(x).unwrap_err(), 4);
fn would_unwrap(this: &Self) -> bool
Checks whether Rc::try_unwrap
would return
Ok
.
Examples
#![feature(rc_would_unwrap)] use std::rc::Rc; let x = Rc::new(3); assert!(Rc::would_unwrap(&x)); assert_eq!(Rc::try_unwrap(x), Ok(3)); let x = Rc::new(4); let _y = x.clone(); assert!(!Rc::would_unwrap(&x)); assert_eq!(*Rc::try_unwrap(x).unwrap_err(), 4);
impl<T: ?Sized> Rc<T>
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fn downgrade(this: &Self) -> Weak<T>
1.4.0
Creates a new Weak
pointer to this value.
Examples
use std::rc::Rc; let five = Rc::new(5); let weak_five = Rc::downgrade(&five);
fn weak_count(this: &Self) -> usize
Gets the number of Weak
pointers to this value.
Examples
#![feature(rc_counts)] use std::rc::Rc; let five = Rc::new(5); let _weak_five = Rc::downgrade(&five); assert_eq!(1, Rc::weak_count(&five));
fn strong_count(this: &Self) -> usize
Gets the number of strong (Rc
) pointers to this value.
Examples
#![feature(rc_counts)] use std::rc::Rc; let five = Rc::new(5); let _also_five = five.clone(); assert_eq!(2, Rc::strong_count(&five));
fn is_unique(this: &Self) -> bool
Returns true if there are no other Rc
or Weak
pointers to
this inner value.
Examples
#![feature(rc_counts)] use std::rc::Rc; let five = Rc::new(5); assert!(Rc::is_unique(&five));
fn get_mut(this: &mut Self) -> Option<&mut T>
1.4.0
Returns a mutable reference to the inner value, if there are
no other Rc
or Weak
pointers to the same value.
Returns None
otherwise, because it is not safe to
mutate a shared value.
See also make_mut
, which will clone
the inner value when it's shared.
Examples
use std::rc::Rc; let mut x = Rc::new(3); *Rc::get_mut(&mut x).unwrap() = 4; assert_eq!(*x, 4); let _y = x.clone(); assert!(Rc::get_mut(&mut x).is_none());
fn ptr_eq(this: &Self, other: &Self) -> bool
Returns true if the two Rc
s point to the same value (not
just values that compare as equal).
Examples
#![feature(ptr_eq)] use std::rc::Rc; let five = Rc::new(5); let same_five = five.clone(); let other_five = Rc::new(5); assert!(Rc::ptr_eq(&five, &same_five)); assert!(!Rc::ptr_eq(&five, &other_five));
impl<T: Clone> Rc<T>
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fn make_mut(this: &mut Self) -> &mut T
1.4.0
Makes a mutable reference into the given Rc
.
If there are other Rc
or Weak
pointers to the same value,
then make_mut
will invoke clone
on the inner value to
ensure unique ownership. This is also referred to as clone-on-write.
See also get_mut
, which will fail rather than cloning.
Examples
use std::rc::Rc; let mut data = Rc::new(5); *Rc::make_mut(&mut data) += 1; // Won't clone anything let mut other_data = data.clone(); // Won't clone inner data *Rc::make_mut(&mut data) += 1; // Clones inner data *Rc::make_mut(&mut data) += 1; // Won't clone anything *Rc::make_mut(&mut other_data) *= 2; // Won't clone anything // Now `data` and `other_data` point to different values. assert_eq!(*data, 8); assert_eq!(*other_data, 12);
Trait Implementations
impl<T: ?Sized> !Send for Rc<T>
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impl<T: ?Sized> !Sync for Rc<T>
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impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Rc<U>> for Rc<T>
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impl<T: ?Sized> Deref for Rc<T>
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type Target = T
The resulting type after dereferencing
fn deref(&self) -> &T
The method called to dereference a value
impl<T: ?Sized> Drop for Rc<T>
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fn drop(&mut self)
Drops the Rc
.
This will decrement the strong reference count. If the strong reference
count reaches zero then the only other references (if any) are
Weak
, so we drop
the inner value.
Examples
use std::rc::Rc; struct Foo; impl Drop for Foo { fn drop(&mut self) { println!("dropped!"); } } let foo = Rc::new(Foo); let foo2 = foo.clone(); drop(foo); // Doesn't print anything drop(foo2); // Prints "dropped!"
impl<T: ?Sized> Clone for Rc<T>
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fn clone(&self) -> Rc<T>
Makes a clone of the Rc
pointer.
This creates another pointer to the same inner value, increasing the strong reference count.
Examples
use std::rc::Rc; let five = Rc::new(5); five.clone();
fn clone_from(&mut self, source: &Self)
Performs copy-assignment from source
. Read more
impl<T: Default> Default for Rc<T>
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fn default() -> Rc<T>
Creates a new Rc<T>
, with the Default
value for T
.
Examples
use std::rc::Rc; let x: Rc<i32> = Default::default(); assert_eq!(*x, 0);
impl<T: ?Sized + PartialEq> PartialEq for Rc<T>
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fn eq(&self, other: &Rc<T>) -> bool
Equality for two Rc
s.
Two Rc
s are equal if their inner values are equal.
Examples
use std::rc::Rc; let five = Rc::new(5); assert!(five == Rc::new(5));
fn ne(&self, other: &Rc<T>) -> bool
Inequality for two Rc
s.
Two Rc
s are unequal if their inner values are unequal.
Examples
use std::rc::Rc; let five = Rc::new(5); assert!(five != Rc::new(6));
impl<T: ?Sized + Eq> Eq for Rc<T>
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impl<T: ?Sized + PartialOrd> PartialOrd for Rc<T>
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fn partial_cmp(&self, other: &Rc<T>) -> Option<Ordering>
Partial comparison for two Rc
s.
The two are compared by calling partial_cmp()
on their inner values.
Examples
use std::rc::Rc; use std::cmp::Ordering; let five = Rc::new(5); assert_eq!(Some(Ordering::Less), five.partial_cmp(&Rc::new(6)));
fn lt(&self, other: &Rc<T>) -> bool
Less-than comparison for two Rc
s.
The two are compared by calling <
on their inner values.
Examples
use std::rc::Rc; let five = Rc::new(5); assert!(five < Rc::new(6));
fn le(&self, other: &Rc<T>) -> bool
'Less than or equal to' comparison for two Rc
s.
The two are compared by calling <=
on their inner values.
Examples
use std::rc::Rc; let five = Rc::new(5); assert!(five <= Rc::new(5));
fn gt(&self, other: &Rc<T>) -> bool
Greater-than comparison for two Rc
s.
The two are compared by calling >
on their inner values.
Examples
use std::rc::Rc; let five = Rc::new(5); assert!(five > Rc::new(4));
fn ge(&self, other: &Rc<T>) -> bool
'Greater than or equal to' comparison for two Rc
s.
The two are compared by calling >=
on their inner values.
Examples
use std::rc::Rc; let five = Rc::new(5); assert!(five >= Rc::new(5));
impl<T: ?Sized + Ord> Ord for Rc<T>
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fn cmp(&self, other: &Rc<T>) -> Ordering
Comparison for two Rc
s.
The two are compared by calling cmp()
on their inner values.
Examples
use std::rc::Rc; use std::cmp::Ordering; let five = Rc::new(5); assert_eq!(Ordering::Less, five.cmp(&Rc::new(6)));
impl<T: ?Sized + Hash> Hash for Rc<T>
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fn hash<H: Hasher>(&self, state: &mut H)
Feeds this value into the state given, updating the hasher as necessary.
fn hash_slice<H>(data: &[Self], state: &mut H) where H: Hasher
1.3.0
Feeds a slice of this type into the state provided.
impl<T: ?Sized + Display> Display for Rc<T>
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impl<T: ?Sized + Debug> Debug for Rc<T>
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impl<T: ?Sized> Pointer for Rc<T>
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impl<T> From<T> for Rc<T>
1.6.0[src]
fn from(t: T) -> Self
Performs the conversion.
impl<T: ?Sized> Borrow<T> for Rc<T>
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impl<T: ?Sized> AsRef<T> for Rc<T>
1.5.0[src]
fn as_ref(&self) -> &T
Performs the conversion.