Struct ptr_eq::rc::Rc [−][src]
A single-threaded reference-counting pointer. ‘Rc’ stands for ‘Reference Counted’.
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(&mut value)
instead of
value.get_mut()
. This avoids conflicts with methods of the inner type T
.
Implementations
impl<T: PtrEq> Rc<T>
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pub fn new(value: T) -> Rc<T>
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Constructs a new Rc<T>
.
Examples
use ptr_eq::rc::Rc; use ptr_eq::PtrEq; #[derive(PtrEq)] struct Test(i64); let five = Rc::new(Test(5));
pub fn pin(value: T) -> Pin<Rc<T>>
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Constructs a new Pin<Rc<T>>
. If T
does not implement Unpin
, then
value
will be pinned in memory and unable to be moved.
pub fn try_unwrap(this: Self) -> Result<T, Self>
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Returns the inner 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 ptr_eq::rc::Rc; use ptr_eq::PtrEq; #[derive(PtrEq, Debug)] struct Test(i64); let x = Rc::new(Test(3)); assert_eq!(Rc::try_unwrap(x).unwrap().0, 3); let x = Rc::new(Test(4)); let _y = Rc::clone(&x); assert_eq!(Rc::try_unwrap(x).unwrap_err().0, 4);
impl<T: PtrEq + ?Sized> Rc<T>
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pub fn into_raw(this: Self) -> *const T
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Consumes the Rc
, returning the wrapped pointer.
To avoid a memory leak the pointer must be converted back to an Rc
using
Rc::from_raw
.
Examples
use ptr_eq::rc::Rc; use ptr_eq::PtrEq; #[derive(PtrEq, Debug)] struct Test(i64); let x = Rc::new(Test(42)); let x_ptr = Rc::into_raw(x); assert_eq!(unsafe { &*x_ptr }.0, 42);
pub fn as_ptr(this: &Self) -> *const T
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Provides a raw pointer to the data.
The counts are not affected in any way and the Rc
is not consumed. The pointer is valid
for as long there are strong counts in the Rc
.
Examples
use ptr_eq::rc::Rc; use ptr_eq::PtrEq; #[derive(PtrEq, Debug)] struct Test(i64); let x = Rc::new(Test(42)); let y = Rc::clone(&x); let x_ptr = Rc::as_ptr(&x); assert_eq!(x_ptr, Rc::as_ptr(&y)); assert_eq!(unsafe { &*x_ptr }.0, 42);
pub unsafe fn from_raw(ptr: *const T) -> Self
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Constructs an Rc<T>
from a raw pointer.
The raw pointer must have been previously returned by a call to
Rc<U>::into_raw
where U
must have the same size
and alignment as T
. This is trivially true if U
is T
.
Note that if U
is not T
but has the same size and alignment, this is
basically like transmuting references of different types. See
mem::transmute
for more information on what
restrictions apply in this case.
The user of from_raw
has to make sure a specific value of T
is only
dropped once.
This function is unsafe because improper use may lead to memory unsafety,
even if the returned Rc<T>
is never accessed.
Examples
use ptr_eq::rc::Rc; use ptr_eq::PtrEq; #[derive(PtrEq, Debug)] struct Test(i64); let x = Rc::new(Test(42)); let x_ptr = Rc::into_raw(x); unsafe { // Convert back to an `Rc` to prevent leak. let x = Rc::from_raw(x_ptr); assert_eq!(x.0, 42); // Further calls to `Rc::from_raw(x_ptr)` would be memory-unsafe. } // The memory was freed when `x` went out of scope above, so `x_ptr` is now dangling!
pub fn downgrade(this: &Self) -> Weak<T>
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Creates a new Weak
pointer to this allocation.
Examples
use ptr_eq::rc::Rc; use ptr_eq::PtrEq; #[derive(PtrEq, Debug)] struct Test(i64); let five = Rc::new(Test(5)); let weak_five = Rc::downgrade(&five);
pub fn weak_count(this: &Self) -> usize
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Gets the number of Weak
pointers to this allocation.
Examples
use ptr_eq::rc::Rc; use ptr_eq::PtrEq; #[derive(PtrEq, Debug)] struct Test(i64); let five = Rc::new(Test(5)); let _weak_five = Rc::downgrade(&five); assert_eq!(1, Rc::weak_count(&five));
pub fn strong_count(this: &Self) -> usize
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Gets the number of strong (Rc
) pointers to this allocation.
Examples
use ptr_eq::rc::Rc; use ptr_eq::PtrEq; #[derive(PtrEq, Debug)] struct Test(i64); let five = Rc::new(Test(5)); let _also_five = Rc::clone(&five); assert_eq!(2, Rc::strong_count(&five));
pub fn get_mut(this: &mut Self) -> Option<&mut T>
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Returns a mutable reference into the given Rc
, if there are
no other Rc
or Weak
pointers to the same allocation.
Returns None
otherwise, because it is not safe to
mutate a shared value.
See also make_mut
, which will clone
the inner value when there are other pointers.
Examples
use ptr_eq::rc::Rc; use ptr_eq::PtrEq; #[derive(PtrEq, Debug)] struct Test(i64); let mut x = Rc::new(Test(3)); *Rc::get_mut(&mut x).unwrap() = Test(4); assert_eq!(x.0, 4); let _y = Rc::clone(&x); assert!(Rc::get_mut(&mut x).is_none());
impl<T: PtrEq + Clone> Rc<T>
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pub fn make_mut(this: &mut Self) -> &mut T
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Makes a mutable reference into the given Rc
.
If there are other Rc
pointers to the same allocation, then make_mut
will
clone
the inner value to a new allocation to ensure unique ownership. This is also
referred to as clone-on-write.
If there are no other Rc
pointers to this allocation, then Weak
pointers to this allocation will be disassociated.
See also get_mut
, which will fail rather than cloning.
Examples
use ptr_eq::rc::Rc; use ptr_eq::PtrEq; #[derive(PtrEq, Debug, Clone)] struct Test(i64); let mut data = Rc::new(Test(5)); Rc::make_mut(&mut data).0 += 1; // Won't clone anything let mut other_data = Rc::clone(&data); // Won't clone inner data Rc::make_mut(&mut data).0 += 1; // Clones inner data Rc::make_mut(&mut data).0 += 1; // Won't clone anything Rc::make_mut(&mut other_data).0 *= 2; // Won't clone anything // Now `data` and `other_data` point to different allocations. assert_eq!(data.0, 8); assert_eq!(other_data.0, 12);
Weak
pointers will be disassociated:
use ptr_eq::rc::Rc; use ptr_eq::PtrEq; #[derive(PtrEq, Debug, Clone)] struct Test(i64); let mut data = Rc::new(Test(75)); let weak = Rc::downgrade(&data); assert!(75 == data.0); assert!(75 == weak.upgrade().unwrap().0); Rc::make_mut(&mut data).0 += 1; assert!(76 == data.0); assert!(weak.upgrade().is_none());
Trait Implementations
impl<T: PtrEq + ?Sized> AsRef<T> for Rc<T>
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impl<T: PtrEq + ?Sized> Borrow<T> for Rc<T>
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impl<T: PtrEq + ?Sized> Clone for Rc<T>
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fn clone(&self) -> Rc<T>
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Makes a clone of the Rc
pointer.
This creates another pointer to the same allocation, increasing the strong reference count.
Examples
use ptr_eq::rc::Rc; use ptr_eq::PtrEq; #[derive(PtrEq)] struct Test(i64); let five = Rc::new(Test(5)); let _ = Rc::clone(&five);
pub fn clone_from(&mut self, source: &Self)
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impl<T: Debug + PtrEq + ?Sized> Debug for Rc<T>
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impl<T: PtrEq + Default> Default for Rc<T>
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fn default() -> Rc<T>
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Creates a new Rc<T>
, with the Default
value for T
.
Examples
use ptr_eq::rc::Rc; use ptr_eq::PtrEq; #[derive(PtrEq, Default)] struct Test(i64); let x: Rc<Test> = Default::default(); assert_eq!(x.0, 0);
impl<T: PtrEq + ?Sized> Deref for Rc<T>
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impl<T: PtrEq> From<T> for Rc<T>
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impl<T> From<Vec<T, Global>> for Rc<[T]> where
[T]: PtrEq,
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[T]: PtrEq,
impl<T> FromIterator<T> for Rc<[T]> where
[T]: PtrEq,
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[T]: PtrEq,
impl<T: PtrEq + ?Sized> Pointer for Rc<T>
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Auto Trait Implementations
impl<T> !RefUnwindSafe for Rc<T>
impl<T> !Send for Rc<T>
impl<T> !Sync for Rc<T>
impl<T: ?Sized> Unpin for Rc<T>
impl<T: ?Sized> UnwindSafe for Rc<T> where
T: RefUnwindSafe,
T: RefUnwindSafe,
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut T
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impl<T> From<!> for T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
pub fn to_owned(&self) -> T
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pub fn clone_into(&self, target: &mut T)
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,