Struct RcCell

pub struct RcCell<T>(/* private fields */);

Wrapper for Rc<RefCell<T>>.

Implementations

impl<T> RcCell<T>

pub fn new(value: T) -> Self

Constructs a new RcCell<T>.

Examples

use rccell::RcCell;

let x = RcCell::new(1);

pub fn try_unwrap(self) -> Result<T, Self>

Similar to Rc::try_unwrap. Returns the inner value if the RefCell has only one strong reference. Otherwise, it returns an Err with the same RefCell that was passed in. Note that this function success even if there are multiple weak references.

Examples

use rccell::RcCell;

let x = RcCell::new(1);
assert_eq!(RcCell::try_unwrap(x), Ok(1));

let x = RcCell::new(2);
let _y = RcCell::clone(&x);
assert!(RcCell::try_unwrap(x).is_err());

pub fn unwrap(self) -> T

Returns the inner value if the RefCell has only one strong reference. Otherwise, it panics. Note that this function success even if there are multiple weak references.

Examples

use rccell::RcCell;

let x = RcCell::new(1);
assert_eq!(RcCell::unwrap(x), 1);

let x = RcCell::new(2);
let _y = RcCell::clone(&x);
// assert_eq!(RcCell::unwrap(x), 2);  // This will panic, as there are two RcCells

pub fn downgrade(&self) -> WeakCell<T>

Similar to Rc::downgrade. Creates a new WeakCell pointer to this allocation.

Examples

use rccell::RcCell;

let x = RcCell::new(1);
let weak_five = x.downgrade();

pub fn weak_count(this: &Self) -> usize

Similar to Rc::weak_count. Gets the number of WeakCell pointers to this allocation.

Examples

use rccell::RcCell;

let x = RcCell::new(1);
let weak_five = x.downgrade();

assert_eq!(RcCell::weak_count(&x), 1);

pub fn strong_count(this: &Self) -> usize

Similar to Rc::strong_count. Gets the number of strong (RcCell) pointers to this allocation.

Examples

use rccell::RcCell;

let x = RcCell::new(1);
let _y = x.clone();

assert_eq!(RcCell::strong_count(&x), 2);

pub fn ptr_eq(this: &Self, other: &Self) -> bool

Similar to Rc::ptr_eq. Returns true if two RcCells point to the same allocation.

Examples

use rccell::RcCell;

let x = RcCell::new(1);
let xx = x.clone();
let y = RcCell::new(1);

assert!(RcCell::ptr_eq(&x, &xx));
assert!(!RcCell::ptr_eq(&x, &y));

pub fn try_borrow(&self) -> Result<Ref<'_, T>, BorrowError>

Similar to RefCell::try_borrow. Returns a Ref to the inner value if there is no RefMut pointing to the same allocation. Otherwise, it returns a BorrowError.

Examples

use rccell::RcCell;

let x = RcCell::new(1);

let x_ref = x.try_borrow();
assert!(x_ref.is_ok());

pub fn try_borrow_mut(&self) -> Result<RefMut<'_, T>, BorrowMutError>

Similar to RefCell::try_borrow_mut. Returns a RefMut to the inner value if there is no RefMut nor Ref pointing to the same allocation. Otherwise, it returns a BorrowMutError.

Examples

use rccell::RcCell;

let x = RcCell::new(1);

let mut x_ref = x.try_borrow_mut();
assert!(x_ref.is_ok());

pub fn borrow(&self) -> Ref<'_, T>

Similar to RefCell::borrow. Returns a Ref to the inner value if there is no RefMut pointing to the same allocation. Otherwise, it panics.

Examples

use rccell::RcCell;

let x = RcCell::new(1);
let x_ref = x.borrow();

pub fn borrow_mut(&self) -> RefMut<'_, T>

Similar to RefCell::borrow_mut. Returns a RefMut to the inner value if there is no RefMut nor Ref pointing to the same allocation. Otherwise, it panics.

Examples

use rccell::RcCell;

let x = RcCell::new(1);
let x_ref = x.borrow_mut();

impl<T: Unpin> RcCell<T>

pub fn pin(value: T) -> Pin<Self>

Constructs a new Pin<RcCell<T>>. It is only implemented if T implements Unpin.

Methods from Deref<Target = RefCell<T>>

pub fn replace(&self, t: T) -> T

Replaces the wrapped value with a new one, returning the old value, without deinitializing either one.

This function corresponds to std::mem::replace.

Panics

Panics if the value is currently borrowed.

Examples

use std::cell::RefCell;
let cell = RefCell::new(5);
let old_value = cell.replace(6);
assert_eq!(old_value, 5);
assert_eq!(cell, RefCell::new(6));

pub fn replace_with<F>(&self, f: F) -> T

where F: FnOnce(&mut T) -> T,

Replaces the wrapped value with a new one computed from f, returning the old value, without deinitializing either one.

Panics

Panics if the value is currently borrowed.

Examples

use std::cell::RefCell;
let cell = RefCell::new(5);
let old_value = cell.replace_with(|&mut old| old + 1);
assert_eq!(old_value, 5);
assert_eq!(cell, RefCell::new(6));

pub fn swap(&self, other: &RefCell<T>)

Swaps the wrapped value of self with the wrapped value of other, without deinitializing either one.

This function corresponds to std::mem::swap.

Panics

Panics if the value in either RefCell is currently borrowed, or if self and other point to the same RefCell.

Examples

use std::cell::RefCell;
let c = RefCell::new(5);
let d = RefCell::new(6);
c.swap(&d);
assert_eq!(c, RefCell::new(6));
assert_eq!(d, RefCell::new(5));

pub fn borrow(&self) -> Ref<'_, T>

Immutably borrows the wrapped value.

The borrow lasts until the returned Ref exits scope. Multiple immutable borrows can be taken out at the same time.

Panics

Panics if the value is currently mutably borrowed. For a non-panicking variant, use try_borrow.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);

let borrowed_five = c.borrow();
let borrowed_five2 = c.borrow();

An example of panic:

use std::cell::RefCell;

let c = RefCell::new(5);

let m = c.borrow_mut();
let b = c.borrow(); // this causes a panic

pub fn try_borrow(&self) -> Result<Ref<'_, T>, BorrowError>

Immutably borrows the wrapped value, returning an error if the value is currently mutably borrowed.

The borrow lasts until the returned Ref exits scope. Multiple immutable borrows can be taken out at the same time.

This is the non-panicking variant of borrow.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);

{
    let m = c.borrow_mut();
    assert!(c.try_borrow().is_err());
}

{
    let m = c.borrow();
    assert!(c.try_borrow().is_ok());
}

pub fn borrow_mut(&self) -> RefMut<'_, T>

Mutably borrows the wrapped value.

The borrow lasts until the returned RefMut or all RefMuts derived from it exit scope. The value cannot be borrowed while this borrow is active.

Panics

Panics if the value is currently borrowed. For a non-panicking variant, use try_borrow_mut.

Examples

use std::cell::RefCell;

let c = RefCell::new("hello".to_owned());

*c.borrow_mut() = "bonjour".to_owned();

assert_eq!(&*c.borrow(), "bonjour");

An example of panic:

use std::cell::RefCell;

let c = RefCell::new(5);
let m = c.borrow();

let b = c.borrow_mut(); // this causes a panic

pub fn try_borrow_mut(&self) -> Result<RefMut<'_, T>, BorrowMutError>

Mutably borrows the wrapped value, returning an error if the value is currently borrowed.

The borrow lasts until the returned RefMut or all RefMuts derived from it exit scope. The value cannot be borrowed while this borrow is active.

This is the non-panicking variant of borrow_mut.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);

{
    let m = c.borrow();
    assert!(c.try_borrow_mut().is_err());
}

assert!(c.try_borrow_mut().is_ok());

pub fn as_ptr(&self) -> *mut T

Returns a raw pointer to the underlying data in this cell.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);

let ptr = c.as_ptr();

pub unsafe fn try_borrow_unguarded(&self) -> Result<&T, BorrowError>

Immutably borrows the wrapped value, returning an error if the value is currently mutably borrowed.

Safety

Unlike RefCell::borrow, this method is unsafe because it does not return a Ref, thus leaving the borrow flag untouched. Mutably borrowing the RefCell while the reference returned by this method is alive is undefined behavior.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);

{
    let m = c.borrow_mut();
    assert!(unsafe { c.try_borrow_unguarded() }.is_err());
}

{
    let m = c.borrow();
    assert!(unsafe { c.try_borrow_unguarded() }.is_ok());
}

pub fn take(&self) -> T

Takes the wrapped value, leaving Default::default() in its place.

Panics

Panics if the value is currently borrowed.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);
let five = c.take();

assert_eq!(five, 5);
assert_eq!(c.into_inner(), 0);

Trait Implementations

impl<T> Clone for RcCell<T>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for RcCell<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: Default> Default for RcCell<T>

fn default() -> RcCell<T>

Returns the “default value” for a type.

impl<T> Deref for RcCell<T>

RefCell<T> does not implement Deref, and borrowing its inner value can cause a lot of panic errors. Therefore, Deref::deref will return a reference to the inner RefCell<T>.

type Target = RefCell<T>

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<T> Hash for RcCell<T>

RefCell<T> does not implement PartialEq, and borrowing its inner value can cause a lot of panic errors. Therefore, Hash will only use the value of the Rc pointer inside RefCell<T>.

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

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

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<T> PartialEq for RcCell<T>

RefCell<T> does not implement PartialEq, and borrowing its inner value can cause a lot of panic errors. Therefore, PartialEq will check that two RefCell<T> point to the exact same allocation.

fn eq(&self, other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T: Eq> Eq for RcCell<T>