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Struct std::rc::Rc

#[lang = "rc"]
pub struct Rc<T> where    T: ?Sized,  { /* fields omitted */ }

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.

Methods

impl<T> Rc<T>[src]

pub fn new(value: T) -> Rc<T>[src]

Constructs a new Rc<T>.

Examples

use std::rc::Rc;

let five = Rc::new(5);

pub fn pin(value: T) -> Pin<Rc<T>>[src]1.33.0

ⓘImportant traits for Pin<P>
impl<P> Future for Pin<P> where
    P: Unpin + DerefMut,
    <P as Deref>::Target: Future, 
    type Output = <<P as Deref>::Target as Future>::Output;

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: Rc<T>) -> Result<T, Rc<T>>[src]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 = Rc::clone(&x);
assert_eq!(*Rc::try_unwrap(x).unwrap_err(), 4);

impl<T> Rc<T> where
    T: ?Sized, [src]

pub fn into_raw(this: Rc<T>) -> *const T[src]1.17.0

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 std::rc::Rc;

let x = Rc::new("hello".to_owned());
let x_ptr = Rc::into_raw(x);
assert_eq!(unsafe { &*x_ptr }, "hello");

pub unsafe fn from_raw(ptr: *const T) -> Rc<T>[src]1.17.0

Constructs an Rc from a raw pointer.

The raw pointer must have been previously returned by a call to a Rc::into_raw.

This function is unsafe because improper use may lead to memory problems. For example, a double-free may occur if the function is called twice on the same raw pointer.

Examples

use std::rc::Rc;

let x = Rc::new("hello".to_owned());
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, "hello");

    // 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 into_raw_non_null(this: Rc<T>) -> NonNull<T>[src]

🔬 This is a nightly-only experimental API. (rc_into_raw_non_null #47336)

Consumes the Rc, returning the wrapped pointer as NonNull<T>.

Examples

#![feature(rc_into_raw_non_null)]

use std::rc::Rc;

let x = Rc::new("hello".to_owned());
let ptr = Rc::into_raw_non_null(x);
let deref = unsafe { ptr.as_ref() };
assert_eq!(deref, "hello");

pub fn downgrade(this: &Rc<T>) -> Weak<T>[src]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);

pub fn weak_count(this: &Rc<T>) -> usize[src]1.15.0

Gets the number of Weak pointers to this value.

Examples

use std::rc::Rc;

let five = Rc::new(5);
let _weak_five = Rc::downgrade(&five);

assert_eq!(1, Rc::weak_count(&five));

pub fn strong_count(this: &Rc<T>) -> usize[src]1.15.0

Gets the number of strong (Rc) pointers to this value.

Examples

use std::rc::Rc;

let five = Rc::new(5);
let _also_five = Rc::clone(&five);

assert_eq!(2, Rc::strong_count(&five));

pub fn get_mut(this: &mut Rc<T>) -> Option<&mut T>[src]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 = Rc::clone(&x);
assert!(Rc::get_mut(&mut x).is_none());

pub fn ptr_eq(this: &Rc<T>, other: &Rc<T>) -> bool[src]1.17.0

Returns true if the two Rcs point to the same value (not just values that compare as equal).

Examples

use std::rc::Rc;

let five = Rc::new(5);
let same_five = Rc::clone(&five);
let other_five = Rc::new(5);

assert!(Rc::ptr_eq(&five, &same_five));
assert!(!Rc::ptr_eq(&five, &other_five));

impl<T> Rc<T> where
    T: Clone, [src]

pub fn make_mut(this: &mut Rc<T>) -> &mut T[src]1.4.0

ⓘImportant traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized, 
    type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized, 
    type Item = <I as Iterator>::Item;
impl<'_, R: Read + ?Sized> Read for &'_ mut R
impl<'_, W: Write + ?Sized> Write for &'_ mut W

Makes a mutable reference into the given Rc.

If there are other Rc pointers to the same value, then make_mut will clone the inner value to ensure unique ownership. This is also referred to as clone-on-write.

If there are no other Rc pointers to this value, then Weak pointers to this value will be dissassociated.

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 = Rc::clone(&data);    // 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);

Weak pointers will be dissassociated:

use std::rc::Rc;

let mut data = Rc::new(75);
let weak = Rc::downgrade(&data);

assert!(75 == *data);
assert!(75 == *weak.upgrade().unwrap());

*Rc::make_mut(&mut data) += 1;

assert!(76 == *data);
assert!(weak.upgrade().is_none());

impl Rc<dyn Any + 'static>[src]

pub fn downcast<T>(self) -> Result<Rc<T>, Rc<dyn Any + 'static>> where
    T: Any, [src]1.29.0

Attempt to downcast the Rc<dyn Any> to a concrete type.

Examples

use std::any::Any;
use std::rc::Rc;

fn print_if_string(value: Rc<dyn Any>) {
    if let Ok(string) = value.downcast::<String>() {
        println!("String ({}): {}", string.len(), string);
    }
}

fn main() {
    let my_string = "Hello World".to_string();
    print_if_string(Rc::new(my_string));
    print_if_string(Rc::new(0i8));
}

Trait Implementations

impl<T> Display for Rc<T> where
    T: Display + ?Sized, [src]

impl<T> !Send for Rc<T> where
    T: ?Sized, [src]

impl<T, U> DispatchFromDyn<Rc<U>> for Rc<T> where
    T: Unsize<U> + ?Sized,
    U: ?Sized, [src]

impl<T> AsRef<T> for Rc<T> where
    T: ?Sized, [src]1.5.0

ⓘImportant traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized, 
    type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized, 
    type Item = <I as Iterator>::Item;
impl<'_, R: Read + ?Sized> Read for &'_ mut R
impl<'_, W: Write + ?Sized> Write for &'_ mut W

impl<T> Hash for Rc<T> where
    T: Hash + ?Sized, [src]

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, [src]1.3.0

Feeds a slice of this type into the given [Hasher]. Read more

impl<T> Eq for Rc<T> where
    T: Eq + ?Sized, [src]

impl From<String> for Rc<str>[src]1.21.0

impl<T> From<Vec<T>> for Rc<[T]>[src]1.21.0

impl<'_> From<&'_ str> for Rc<str>[src]1.21.0

impl<'_, T> From<&'_ [T]> for Rc<[T]> where
    T: Clone, [src]1.21.0

impl<T> From<Box<T>> for Rc<T> where
    T: ?Sized, [src]1.21.0

impl<T> From<T> for Rc<T>[src]1.6.0

impl<T> Ord for Rc<T> where
    T: Ord + ?Sized, [src]

fn cmp(&self, other: &Rc<T>) -> Ordering[src]

Comparison for two Rcs.

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)));

fn max(self, other: Self) -> Self[src]1.21.0

Compares and returns the maximum of two values. Read more

fn min(self, other: Self) -> Self[src]1.21.0

Compares and returns the minimum of two values. Read more

fn clamp(self, min: Self, max: Self) -> Self[src]

🔬 This is a nightly-only experimental API. (clamp #44095)

Restrict a value to a certain interval. Read more

impl<T> Debug for Rc<T> where
    T: Debug + ?Sized, [src]

impl<T, U> CoerceUnsized<Rc<U>> for Rc<T> where
    T: Unsize<U> + ?Sized,
    U: ?Sized, [src]

impl<T> Drop for Rc<T> where
    T: ?Sized, [src]

fn drop(&mut self)[src]

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 = Rc::clone(&foo);

drop(foo);    // Doesn't print anything
drop(foo2);   // Prints "dropped!"

impl<T> PartialEq<Rc<T>> for Rc<T> where
    T: PartialEq<T> + ?Sized, [src]

fn eq(&self, other: &Rc<T>) -> bool[src]

Equality for two Rcs.

Two Rcs are equal if their inner values are equal.

If T also implements Eq, two Rcs that point to the same value are always equal.

Examples

use std::rc::Rc;

let five = Rc::new(5);

assert!(five == Rc::new(5));

fn ne(&self, other: &Rc<T>) -> bool[src]

Inequality for two Rcs.

Two Rcs are unequal if their inner values are unequal.

If T also implements Eq, two Rcs that point to the same value are never unequal.

Examples

use std::rc::Rc;

let five = Rc::new(5);

assert!(five != Rc::new(6));

impl<T> Deref for Rc<T> where
    T: ?Sized, [src]

type Target = T

The resulting type after dereferencing.

ⓘImportant traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized, 
    type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized, 
    type Item = <I as Iterator>::Item;
impl<'_, R: Read + ?Sized> Read for &'_ mut R
impl<'_, W: Write + ?Sized> Write for &'_ mut W

impl<T> Unpin for Rc<T> where
    T: ?Sized, [src]1.33.0

impl<T> Clone for Rc<T> where
    T: ?Sized, [src]

fn clone(&self) -> Rc<T>[src]

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);

let _ = Rc::clone(&five);

fn clone_from(&mut self, source: &Self)[src]

Performs copy-assignment from source. Read more

impl<T> Default for Rc<T> where
    T: Default, [src]

fn default() -> Rc<T>[src]

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> Borrow<T> for Rc<T> where
    T: ?Sized, [src]

ⓘImportant traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized, 
    type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized, 
    type Item = <I as Iterator>::Item;
impl<'_, R: Read + ?Sized> Read for &'_ mut R
impl<'_, W: Write + ?Sized> Write for &'_ mut W

impl<T> Pointer for Rc<T> where
    T: ?Sized, [src]

impl<T> PartialOrd<Rc<T>> for Rc<T> where
    T: PartialOrd<T> + ?Sized, [src]

fn partial_cmp(&self, other: &Rc<T>) -> Option<Ordering>[src]

Partial comparison for two Rcs.

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[src]

Less-than comparison for two Rcs.

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[src]

'Less than or equal to' comparison for two Rcs.

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[src]

Greater-than comparison for two Rcs.

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[src]

'Greater than or equal to' comparison for two Rcs.

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> !Sync for Rc<T> where
    T: ?Sized, [src]

impl<T: RefUnwindSafe + ?Sized> UnwindSafe for Rc<T>[src]1.9.0

impl From<CString> for Rc<CStr>[src]1.24.0

fn from(s: CString) -> Rc<CStr>[src]

Converts a CString into a Rc<CStr> without copying or allocating.

impl<'_> From<&'_ CStr> for Rc<CStr>[src]1.24.0

impl From<OsString> for Rc<OsStr>[src]1.24.0

fn from(s: OsString) -> Rc<OsStr>[src]

Converts a OsString into a Rc<OsStr> without copying or allocating.

impl<'_> From<&'_ OsStr> for Rc<OsStr>[src]1.24.0

impl From<PathBuf> for Rc<Path>[src]1.24.0

fn from(s: PathBuf) -> Rc<Path>[src]

Converts a Path into a Rc by copying the Path data into a new Rc buffer.

impl<'_> From<&'_ Path> for Rc<Path>[src]1.24.0

fn from(s: &Path) -> Rc<Path>[src]

Converts a Path into a Rc by copying the Path data into a new Rc buffer.

Auto Trait Implementations

impl<T> !RefUnwindSafe for Rc<T>

Blanket Implementations

impl<T, U> TryFrom<U> for T where
    U: Into<T>, [src]

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> Into<U> for T where
    U: From<T>, [src]

impl<T> From<T> for T[src]

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, [src]

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

impl<T> Borrow<T> for T where
    T: ?Sized, [src]

ⓘImportant traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized, 
    type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized, 
    type Item = <I as Iterator>::Item;
impl<'_, R: Read + ?Sized> Read for &'_ mut R
impl<'_, W: Write + ?Sized> Write for &'_ mut W

impl<T> BorrowMut<T> for T where
    T: ?Sized, [src]

ⓘImportant traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized, 
    type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized, 
    type Item = <I as Iterator>::Item;
impl<'_, R: Read + ?Sized> Read for &'_ mut R
impl<'_, W: Write + ?Sized> Write for &'_ mut W

impl<T> Any for T where
    T: 'static + ?Sized, [src]

impl<T> ToOwned for T where
    T: Clone, [src]

type Owned = T

The resulting type after obtaining ownership.

impl<T> ToString for T where
    T: Display + ?Sized, [src]

© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/rc/struct.Rc.html