Type Alias freya::prelude::AccessibilityIdCounter
source · pub type AccessibilityIdCounter = Rc<RefCell<u64>, Global>;
Aliased Type§
struct AccessibilityIdCounter { /* private fields */ }
Implementations§
source§impl<T> Rc<T, Global>
impl<T> Rc<T, Global>
1.60.0 · sourcepub fn new_cyclic<F>(data_fn: F) -> Rc<T, Global>where
F: FnOnce(&Weak<T, Global>) -> T,
pub fn new_cyclic<F>(data_fn: F) -> Rc<T, Global>where F: FnOnce(&Weak<T, Global>) -> T,
Constructs a new Rc<T>
while giving you a Weak<T>
to the allocation,
to allow you to construct a T
which holds a weak pointer to itself.
Generally, a structure circularly referencing itself, either directly or
indirectly, should not hold a strong reference to itself to prevent a memory leak.
Using this function, you get access to the weak pointer during the
initialization of T
, before the Rc<T>
is created, such that you can
clone and store it inside the T
.
new_cyclic
first allocates the managed allocation for the Rc<T>
,
then calls your closure, giving it a Weak<T>
to this allocation,
and only afterwards completes the construction of the Rc<T>
by placing
the T
returned from your closure into the allocation.
Since the new Rc<T>
is not fully-constructed until Rc<T>::new_cyclic
returns, calling upgrade
on the weak reference inside your closure will
fail and result in a None
value.
Panics
If data_fn
panics, the panic is propagated to the caller, and the
temporary Weak<T>
is dropped normally.
Examples
use std::rc::{Rc, Weak};
struct Gadget {
me: Weak<Gadget>,
}
impl Gadget {
/// Construct a reference counted Gadget.
fn new() -> Rc<Self> {
// `me` is a `Weak<Gadget>` pointing at the new allocation of the
// `Rc` we're constructing.
Rc::new_cyclic(|me| {
// Create the actual struct here.
Gadget { me: me.clone() }
})
}
/// Return a reference counted pointer to Self.
fn me(&self) -> Rc<Self> {
self.me.upgrade().unwrap()
}
}
sourcepub fn new_uninit() -> Rc<MaybeUninit<T>, Global>
🔬This is a nightly-only experimental API. (new_uninit
)
pub fn new_uninit() -> Rc<MaybeUninit<T>, Global>
new_uninit
)Constructs a new Rc
with uninitialized contents.
Examples
#![feature(new_uninit)]
#![feature(get_mut_unchecked)]
use std::rc::Rc;
let mut five = Rc::<u32>::new_uninit();
// Deferred initialization:
Rc::get_mut(&mut five).unwrap().write(5);
let five = unsafe { five.assume_init() };
assert_eq!(*five, 5)
sourcepub fn new_zeroed() -> Rc<MaybeUninit<T>, Global>
🔬This is a nightly-only experimental API. (new_uninit
)
pub fn new_zeroed() -> Rc<MaybeUninit<T>, Global>
new_uninit
)Constructs a new Rc
with uninitialized contents, with the memory
being filled with 0
bytes.
See MaybeUninit::zeroed
for examples of correct and
incorrect usage of this method.
Examples
#![feature(new_uninit)]
use std::rc::Rc;
let zero = Rc::<u32>::new_zeroed();
let zero = unsafe { zero.assume_init() };
assert_eq!(*zero, 0)
sourcepub fn try_new(value: T) -> Result<Rc<T, Global>, AllocError>
🔬This is a nightly-only experimental API. (allocator_api
)
pub fn try_new(value: T) -> Result<Rc<T, Global>, AllocError>
allocator_api
)Constructs a new Rc<T>
, returning an error if the allocation fails
Examples
#![feature(allocator_api)]
use std::rc::Rc;
let five = Rc::try_new(5);
sourcepub fn try_new_uninit() -> Result<Rc<MaybeUninit<T>, Global>, AllocError>
🔬This is a nightly-only experimental API. (allocator_api
)
pub fn try_new_uninit() -> Result<Rc<MaybeUninit<T>, Global>, AllocError>
allocator_api
)Constructs a new Rc
with uninitialized contents, returning an error if the allocation fails
Examples
#![feature(allocator_api, new_uninit)]
#![feature(get_mut_unchecked)]
use std::rc::Rc;
let mut five = Rc::<u32>::try_new_uninit()?;
// Deferred initialization:
Rc::get_mut(&mut five).unwrap().write(5);
let five = unsafe { five.assume_init() };
assert_eq!(*five, 5);
sourcepub fn try_new_zeroed() -> Result<Rc<MaybeUninit<T>, Global>, AllocError>
🔬This is a nightly-only experimental API. (allocator_api
)
pub fn try_new_zeroed() -> Result<Rc<MaybeUninit<T>, Global>, AllocError>
allocator_api
)Constructs a new Rc
with uninitialized contents, with the memory
being filled with 0
bytes, returning an error if the allocation fails
See MaybeUninit::zeroed
for examples of correct and
incorrect usage of this method.
Examples
#![feature(allocator_api, new_uninit)]
use std::rc::Rc;
let zero = Rc::<u32>::try_new_zeroed()?;
let zero = unsafe { zero.assume_init() };
assert_eq!(*zero, 0);
source§impl<T, A> Rc<T, A>where
A: Allocator,
impl<T, A> Rc<T, A>where A: Allocator,
sourcepub fn allocator(this: &Rc<T, A>) -> &A
🔬This is a nightly-only experimental API. (allocator_api
)
pub fn allocator(this: &Rc<T, A>) -> &A
allocator_api
)Returns a reference to the underlying allocator.
Note: this is an associated function, which means that you have
to call it as Rc::allocator(&r)
instead of r.allocator()
. This
is so that there is no conflict with a method on the inner type.
sourcepub fn new_in(value: T, alloc: A) -> Rc<T, A>
🔬This is a nightly-only experimental API. (allocator_api
)
pub fn new_in(value: T, alloc: A) -> Rc<T, A>
allocator_api
)Constructs a new Rc
in the provided allocator.
Examples
#![feature(allocator_api)]
use std::rc::Rc;
use std::alloc::System;
let five = Rc::new_in(5, System);
sourcepub fn new_uninit_in(alloc: A) -> Rc<MaybeUninit<T>, A>
🔬This is a nightly-only experimental API. (allocator_api
)
pub fn new_uninit_in(alloc: A) -> Rc<MaybeUninit<T>, A>
allocator_api
)Constructs a new Rc
with uninitialized contents in the provided allocator.
Examples
#![feature(new_uninit)]
#![feature(get_mut_unchecked)]
#![feature(allocator_api)]
use std::rc::Rc;
use std::alloc::System;
let mut five = Rc::<u32, _>::new_uninit_in(System);
let five = unsafe {
// Deferred initialization:
Rc::get_mut_unchecked(&mut five).as_mut_ptr().write(5);
five.assume_init()
};
assert_eq!(*five, 5)
sourcepub fn new_zeroed_in(alloc: A) -> Rc<MaybeUninit<T>, A>
🔬This is a nightly-only experimental API. (allocator_api
)
pub fn new_zeroed_in(alloc: A) -> Rc<MaybeUninit<T>, A>
allocator_api
)Constructs a new Rc
with uninitialized contents, with the memory
being filled with 0
bytes, in the provided allocator.
See MaybeUninit::zeroed
for examples of correct and
incorrect usage of this method.
Examples
#![feature(new_uninit)]
#![feature(allocator_api)]
use std::rc::Rc;
use std::alloc::System;
let zero = Rc::<u32, _>::new_zeroed_in(System);
let zero = unsafe { zero.assume_init() };
assert_eq!(*zero, 0)
sourcepub fn try_new_in(value: T, alloc: A) -> Result<Rc<T, A>, AllocError>
🔬This is a nightly-only experimental API. (allocator_api
)
pub fn try_new_in(value: T, alloc: A) -> Result<Rc<T, A>, AllocError>
allocator_api
)Constructs a new Rc<T>
in the provided allocator, returning an error if the allocation
fails
Examples
#![feature(allocator_api)]
use std::rc::Rc;
use std::alloc::System;
let five = Rc::try_new_in(5, System);
sourcepub fn try_new_uninit_in(alloc: A) -> Result<Rc<MaybeUninit<T>, A>, AllocError>
🔬This is a nightly-only experimental API. (allocator_api
)
pub fn try_new_uninit_in(alloc: A) -> Result<Rc<MaybeUninit<T>, A>, AllocError>
allocator_api
)Constructs a new Rc
with uninitialized contents, in the provided allocator, returning an
error if the allocation fails
Examples
#![feature(allocator_api, new_uninit)]
#![feature(get_mut_unchecked)]
use std::rc::Rc;
use std::alloc::System;
let mut five = Rc::<u32, _>::try_new_uninit_in(System)?;
let five = unsafe {
// Deferred initialization:
Rc::get_mut_unchecked(&mut five).as_mut_ptr().write(5);
five.assume_init()
};
assert_eq!(*five, 5);
sourcepub fn try_new_zeroed_in(alloc: A) -> Result<Rc<MaybeUninit<T>, A>, AllocError>
🔬This is a nightly-only experimental API. (allocator_api
)
pub fn try_new_zeroed_in(alloc: A) -> Result<Rc<MaybeUninit<T>, A>, AllocError>
allocator_api
)Constructs a new Rc
with uninitialized contents, with the memory
being filled with 0
bytes, in the provided allocator, returning an error if the allocation
fails
See MaybeUninit::zeroed
for examples of correct and
incorrect usage of this method.
Examples
#![feature(allocator_api, new_uninit)]
use std::rc::Rc;
use std::alloc::System;
let zero = Rc::<u32, _>::try_new_zeroed_in(System)?;
let zero = unsafe { zero.assume_init() };
assert_eq!(*zero, 0);
sourcepub fn pin_in(value: T, alloc: A) -> Pin<Rc<T, A>>
🔬This is a nightly-only experimental API. (allocator_api
)
pub fn pin_in(value: T, alloc: A) -> Pin<Rc<T, A>>
allocator_api
)Constructs a new Pin<Rc<T>>
in the provided allocator. If T
does not implement Unpin
, then
value
will be pinned in memory and unable to be moved.
1.4.0 · sourcepub fn try_unwrap(this: Rc<T, A>) -> Result<T, Rc<T, A>>
pub fn try_unwrap(this: Rc<T, A>) -> Result<T, Rc<T, A>>
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 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);
1.70.0 · sourcepub fn into_inner(this: Rc<T, A>) -> Option<T>
pub fn into_inner(this: Rc<T, A>) -> Option<T>
Returns the inner value, if the Rc
has exactly one strong reference.
Otherwise, None
is returned and the Rc
is dropped.
This will succeed even if there are outstanding weak references.
If Rc::into_inner
is called on every clone of this Rc
,
it is guaranteed that exactly one of the calls returns the inner value.
This means in particular that the inner value is not dropped.
This is equivalent to Rc::try_unwrap(this).ok()
. (Note that these are not equivalent for
Arc
, due to race conditions that do not apply to Rc
.)
source§impl<T> Rc<T, Global>where
T: ?Sized,
impl<T> Rc<T, Global>where T: ?Sized,
1.17.0 · sourcepub unsafe fn from_raw(ptr: *const T) -> Rc<T, Global>
pub unsafe fn from_raw(ptr: *const T) -> Rc<T, Global>
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 raw pointer must point to a block of memory allocated by the global allocator
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 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!
1.53.0 · sourcepub unsafe fn increment_strong_count(ptr: *const T)
pub unsafe fn increment_strong_count(ptr: *const T)
Increments the strong reference count on the Rc<T>
associated with the
provided pointer by one.
Safety
The pointer must have been obtained through Rc::into_raw
, the
associated Rc
instance must be valid (i.e. the strong count must be at
least 1) for the duration of this method, and ptr
must point to a block of memory
allocated by the global allocator.
Examples
use std::rc::Rc;
let five = Rc::new(5);
unsafe {
let ptr = Rc::into_raw(five);
Rc::increment_strong_count(ptr);
let five = Rc::from_raw(ptr);
assert_eq!(2, Rc::strong_count(&five));
}
1.53.0 · sourcepub unsafe fn decrement_strong_count(ptr: *const T)
pub unsafe fn decrement_strong_count(ptr: *const T)
Decrements the strong reference count on the Rc<T>
associated with the
provided pointer by one.
Safety
The pointer must have been obtained through Rc::into_raw
, the
associated Rc
instance must be valid (i.e. the strong count must be at
least 1) when invoking this method, and ptr
must point to a block of memory
allocated by the global allocator. This method can be used to release the final Rc
and
backing storage, but should not be called after the final Rc
has been released.
Examples
use std::rc::Rc;
let five = Rc::new(5);
unsafe {
let ptr = Rc::into_raw(five);
Rc::increment_strong_count(ptr);
let five = Rc::from_raw(ptr);
assert_eq!(2, Rc::strong_count(&five));
Rc::decrement_strong_count(ptr);
assert_eq!(1, Rc::strong_count(&five));
}
source§impl<T, A> Rc<T, A>where
A: Allocator,
T: ?Sized,
impl<T, A> Rc<T, A>where A: Allocator, T: ?Sized,
1.17.0 · sourcepub fn into_raw(this: Rc<T, A>) -> *const T
pub fn into_raw(this: Rc<T, A>) -> *const T
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");
1.45.0 · sourcepub fn as_ptr(this: &Rc<T, A>) -> *const T
pub fn as_ptr(this: &Rc<T, A>) -> *const T
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 std::rc::Rc;
let x = Rc::new("hello".to_owned());
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 }, "hello");
sourcepub unsafe fn from_raw_in(ptr: *const T, alloc: A) -> Rc<T, A>
🔬This is a nightly-only experimental API. (allocator_api
)
pub unsafe fn from_raw_in(ptr: *const T, alloc: A) -> Rc<T, A>
allocator_api
)Constructs an Rc<T, A>
from a raw pointer in the provided allocator.
The raw pointer must have been previously returned by a call to
Rc<U, A>::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 raw pointer must point to a block of memory allocated by alloc
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
#![feature(allocator_api)]
use std::rc::Rc;
use std::alloc::System;
let x = Rc::new_in("hello".to_owned(), System);
let x_ptr = Rc::into_raw(x);
unsafe {
// Convert back to an `Rc` to prevent leak.
let x = Rc::from_raw_in(x_ptr, System);
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!
1.15.0 · sourcepub fn weak_count(this: &Rc<T, A>) -> usize
pub fn weak_count(this: &Rc<T, A>) -> usize
1.15.0 · sourcepub fn strong_count(this: &Rc<T, A>) -> usize
pub fn strong_count(this: &Rc<T, A>) -> usize
Gets the number of strong (Rc
) pointers to this allocation.
Examples
use std::rc::Rc;
let five = Rc::new(5);
let _also_five = Rc::clone(&five);
assert_eq!(2, Rc::strong_count(&five));
sourcepub unsafe fn increment_strong_count_in(ptr: *const T, alloc: A)where
A: Clone,
🔬This is a nightly-only experimental API. (allocator_api
)
pub unsafe fn increment_strong_count_in(ptr: *const T, alloc: A)where A: Clone,
allocator_api
)Increments the strong reference count on the Rc<T>
associated with the
provided pointer by one.
Safety
The pointer must have been obtained through Rc::into_raw
, the
associated Rc
instance must be valid (i.e. the strong count must be at
least 1) for the duration of this method, and ptr
must point to a block of memory
allocated by alloc
Examples
#![feature(allocator_api)]
use std::rc::Rc;
use std::alloc::System;
let five = Rc::new_in(5, System);
unsafe {
let ptr = Rc::into_raw(five);
Rc::increment_strong_count_in(ptr, System);
let five = Rc::from_raw_in(ptr, System);
assert_eq!(2, Rc::strong_count(&five));
}
sourcepub unsafe fn decrement_strong_count_in(ptr: *const T, alloc: A)
🔬This is a nightly-only experimental API. (allocator_api
)
pub unsafe fn decrement_strong_count_in(ptr: *const T, alloc: A)
allocator_api
)Decrements the strong reference count on the Rc<T>
associated with the
provided pointer by one.
Safety
The pointer must have been obtained through Rc::into_raw
, the
associated Rc
instance must be valid (i.e. the strong count must be at
least 1) when invoking this method, and ptr
must point to a block of memory
allocated by alloc
. This method can be used to release the final Rc
and backing storage,
but should not be called after the final Rc
has been released.
Examples
#![feature(allocator_api)]
use std::rc::Rc;
use std::alloc::System;
let five = Rc::new_in(5, System);
unsafe {
let ptr = Rc::into_raw(five);
Rc::increment_strong_count_in(ptr, System);
let five = Rc::from_raw_in(ptr, System);
assert_eq!(2, Rc::strong_count(&five));
Rc::decrement_strong_count_in(ptr, System);
assert_eq!(1, Rc::strong_count(&five));
}
1.4.0 · sourcepub fn get_mut(this: &mut Rc<T, A>) -> Option<&mut T>
pub fn get_mut(this: &mut Rc<T, A>) -> Option<&mut T>
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 Rc
pointers.
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());
sourcepub unsafe fn get_mut_unchecked(this: &mut Rc<T, A>) -> &mut T
🔬This is a nightly-only experimental API. (get_mut_unchecked
)
pub unsafe fn get_mut_unchecked(this: &mut Rc<T, A>) -> &mut T
get_mut_unchecked
)Returns a mutable reference into the given Rc
,
without any check.
See also get_mut
, which is safe and does appropriate checks.
Safety
If any other Rc
or Weak
pointers to the same allocation exist, then
they must not be dereferenced or have active borrows for the duration
of the returned borrow, and their inner type must be exactly the same as the
inner type of this Rc (including lifetimes). This is trivially the case if no
such pointers exist, for example immediately after Rc::new
.
Examples
#![feature(get_mut_unchecked)]
use std::rc::Rc;
let mut x = Rc::new(String::new());
unsafe {
Rc::get_mut_unchecked(&mut x).push_str("foo")
}
assert_eq!(*x, "foo");
Other Rc
pointers to the same allocation must be to the same type.
#![feature(get_mut_unchecked)]
use std::rc::Rc;
let x: Rc<str> = Rc::from("Hello, world!");
let mut y: Rc<[u8]> = x.clone().into();
unsafe {
// this is Undefined Behavior, because x's inner type is str, not [u8]
Rc::get_mut_unchecked(&mut y).fill(0xff); // 0xff is invalid in UTF-8
}
println!("{}", &*x); // Invalid UTF-8 in a str
Other Rc
pointers to the same allocation must be to the exact same type, including lifetimes.
#![feature(get_mut_unchecked)]
use std::rc::Rc;
let x: Rc<&str> = Rc::new("Hello, world!");
{
let s = String::from("Oh, no!");
let mut y: Rc<&str> = x.clone().into();
unsafe {
// this is Undefined Behavior, because x's inner type
// is &'long str, not &'short str
*Rc::get_mut_unchecked(&mut y) = &s;
}
}
println!("{}", &*x); // Use-after-free
1.17.0 · sourcepub fn ptr_eq(this: &Rc<T, A>, other: &Rc<T, A>) -> bool
pub fn ptr_eq(this: &Rc<T, A>, other: &Rc<T, A>) -> bool
Returns true
if the two Rc
s point to the same allocation in a vein similar to
ptr::eq
. This function ignores the metadata of dyn Trait
pointers.
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));
source§impl<T, A> Rc<T, A>where
T: Clone,
A: Allocator + Clone,
impl<T, A> Rc<T, A>where T: Clone, A: Allocator + Clone,
1.4.0 · sourcepub fn make_mut(this: &mut Rc<T, A>) -> &mut T
pub fn make_mut(this: &mut Rc<T, A>) -> &mut T
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.
However, if there are no other Rc
pointers to this allocation, but some Weak
pointers, then the Weak
pointers will be disassociated and the inner value will not
be cloned.
See also get_mut
, which will fail rather than cloning the inner value
or disassociating Weak
pointers.
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 allocations.
assert_eq!(*data, 8);
assert_eq!(*other_data, 12);
Weak
pointers will be disassociated:
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());
sourcepub fn unwrap_or_clone(this: Rc<T, A>) -> T
🔬This is a nightly-only experimental API. (arc_unwrap_or_clone
)
pub fn unwrap_or_clone(this: Rc<T, A>) -> T
arc_unwrap_or_clone
)If we have the only reference to T
then unwrap it. Otherwise, clone T
and return the
clone.
Assuming rc_t
is of type Rc<T>
, this function is functionally equivalent to
(*rc_t).clone()
, but will avoid cloning the inner value where possible.
Examples
#![feature(arc_unwrap_or_clone)]
let inner = String::from("test");
let ptr = inner.as_ptr();
let rc = Rc::new(inner);
let inner = Rc::unwrap_or_clone(rc);
// The inner value was not cloned
assert!(ptr::eq(ptr, inner.as_ptr()));
let rc = Rc::new(inner);
let rc2 = rc.clone();
let inner = Rc::unwrap_or_clone(rc);
// Because there were 2 references, we had to clone the inner value.
assert!(!ptr::eq(ptr, inner.as_ptr()));
// `rc2` is the last reference, so when we unwrap it we get back
// the original `String`.
let inner = Rc::unwrap_or_clone(rc2);
assert!(ptr::eq(ptr, inner.as_ptr()));
Trait Implementations§
1.69.0 · source§impl<T> AsFd for Rc<T, Global>where
T: AsFd,
impl<T> AsFd for Rc<T, Global>where T: AsFd,
source§fn as_fd(&self) -> BorrowedFd<'_>
fn as_fd(&self) -> BorrowedFd<'_>
§impl<T> AsRawXcbConnection for Rc<T, Global>where
T: AsRawXcbConnection + ?Sized,
impl<T> AsRawXcbConnection for Rc<T, Global>where T: AsRawXcbConnection + ?Sized,
§fn as_raw_xcb_connection(&self) -> *mut xcb_connection_t
fn as_raw_xcb_connection(&self) -> *mut xcb_connection_t
1.0.0 · source§impl<T, A> Clone for Rc<T, A>where
A: Allocator + Clone,
T: ?Sized,
impl<T, A> Clone for Rc<T, A>where A: Allocator + Clone, T: ?Sized,
source§fn clone(&self) -> Rc<T, A>
fn clone(&self) -> Rc<T, A>
Makes a clone of the Rc
pointer.
This creates another pointer to the same allocation, increasing the strong reference count.
Examples
use std::rc::Rc;
let five = Rc::new(5);
let _ = Rc::clone(&five);
1.0.0 · source§fn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
source
. Read more§impl<C> Connection for Rc<C, Global>where
C: Connection + ?Sized,
impl<C> Connection for Rc<C, Global>where C: Connection + ?Sized,
§fn wait_for_event(&self) -> Result<Event, ConnectionError>
fn wait_for_event(&self) -> Result<Event, ConnectionError>
§fn wait_for_raw_event(
&self
) -> Result<<Rc<C, Global> as RequestConnection>::Buf, ConnectionError>
fn wait_for_raw_event( &self ) -> Result<<Rc<C, Global> as RequestConnection>::Buf, ConnectionError>
§fn wait_for_event_with_sequence(&self) -> Result<(Event, u64), ConnectionError>
fn wait_for_event_with_sequence(&self) -> Result<(Event, u64), ConnectionError>
§fn wait_for_raw_event_with_sequence(
&self
) -> Result<(<Rc<C, Global> as RequestConnection>::Buf, u64), ConnectionError>
fn wait_for_raw_event_with_sequence( &self ) -> Result<(<Rc<C, Global> as RequestConnection>::Buf, u64), ConnectionError>
§fn poll_for_event(&self) -> Result<Option<Event>, ConnectionError>
fn poll_for_event(&self) -> Result<Option<Event>, ConnectionError>
§fn poll_for_raw_event(
&self
) -> Result<Option<<Rc<C, Global> as RequestConnection>::Buf>, ConnectionError>
fn poll_for_raw_event( &self ) -> Result<Option<<Rc<C, Global> as RequestConnection>::Buf>, ConnectionError>
§fn poll_for_event_with_sequence(
&self
) -> Result<Option<(Event, u64)>, ConnectionError>
fn poll_for_event_with_sequence( &self ) -> Result<Option<(Event, u64)>, ConnectionError>
§fn poll_for_raw_event_with_sequence(
&self
) -> Result<Option<(<Rc<C, Global> as RequestConnection>::Buf, u64)>, ConnectionError>
fn poll_for_raw_event_with_sequence( &self ) -> Result<Option<(<Rc<C, Global> as RequestConnection>::Buf, u64)>, ConnectionError>
§fn generate_id(&self) -> Result<u32, ReplyOrIdError>
fn generate_id(&self) -> Result<u32, ReplyOrIdError>
1.0.0 · source§impl<T, A> Drop for Rc<T, A>where
A: Allocator,
T: ?Sized,
impl<T, A> Drop for Rc<T, A>where A: Allocator, T: ?Sized,
source§fn drop(&mut self)
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 = Rc::clone(&foo);
drop(foo); // Doesn't print anything
drop(foo2); // Prints "dropped!"
1.45.0 · source§impl<'a, B> From<Cow<'a, B>> for Rc<B, Global>where
B: ToOwned + ?Sized,
Rc<B, Global>: From<&'a B> + From<<B as ToOwned>::Owned>,
impl<'a, B> From<Cow<'a, B>> for Rc<B, Global>where B: ToOwned + ?Sized, Rc<B, Global>: From<&'a B> + From<<B as ToOwned>::Owned>,
§impl<H> HasDisplayHandle for Rc<H, Global>where
H: HasDisplayHandle + ?Sized,
impl<H> HasDisplayHandle for Rc<H, Global>where H: HasDisplayHandle + ?Sized,
§fn display_handle(&self) -> Result<DisplayHandle<'_>, HandleError>
fn display_handle(&self) -> Result<DisplayHandle<'_>, HandleError>
§impl<H> HasDisplayHandle for Rc<H, Global>where
H: HasDisplayHandle + ?Sized,
impl<H> HasDisplayHandle for Rc<H, Global>where H: HasDisplayHandle + ?Sized,
§fn display_handle(&self) -> Result<DisplayHandle<'_>, HandleError>
fn display_handle(&self) -> Result<DisplayHandle<'_>, HandleError>
§impl<T> HasRawDisplayHandle for Rc<T, Global>where
T: HasRawDisplayHandle + ?Sized,
impl<T> HasRawDisplayHandle for Rc<T, Global>where T: HasRawDisplayHandle + ?Sized,
fn raw_display_handle(&self) -> RawDisplayHandle
§impl<T> HasRawWindowHandle for Rc<T, Global>where
T: HasRawWindowHandle + ?Sized,
impl<T> HasRawWindowHandle for Rc<T, Global>where T: HasRawWindowHandle + ?Sized,
fn raw_window_handle(&self) -> RawWindowHandle
§impl<H> HasWindowHandle for Rc<H, Global>where
H: HasWindowHandle + ?Sized,
impl<H> HasWindowHandle for Rc<H, Global>where H: HasWindowHandle + ?Sized,
§fn window_handle(&self) -> Result<WindowHandle<'_>, HandleError>
fn window_handle(&self) -> Result<WindowHandle<'_>, HandleError>
§impl<H> HasWindowHandle for Rc<H, Global>where
H: HasWindowHandle + ?Sized,
impl<H> HasWindowHandle for Rc<H, Global>where H: HasWindowHandle + ?Sized,
§fn window_handle(&self) -> Result<WindowHandle<'_>, HandleError>
fn window_handle(&self) -> Result<WindowHandle<'_>, HandleError>
1.0.0 · source§impl<T, A> Ord for Rc<T, A>where
T: Ord + ?Sized,
A: Allocator,
impl<T, A> Ord for Rc<T, A>where T: Ord + ?Sized, A: Allocator,
source§fn cmp(&self, other: &Rc<T, A>) -> Ordering
fn cmp(&self, other: &Rc<T, A>) -> 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)));
1.21.0 · source§fn max(self, other: Self) -> Selfwhere
Self: Sized,
fn max(self, other: Self) -> Selfwhere Self: Sized,
1.0.0 · source§impl<T, A> PartialEq<Rc<T, A>> for Rc<T, A>where
T: PartialEq<T> + ?Sized,
A: Allocator,
impl<T, A> PartialEq<Rc<T, A>> for Rc<T, A>where T: PartialEq<T> + ?Sized, A: Allocator,
source§fn eq(&self, other: &Rc<T, A>) -> bool
fn eq(&self, other: &Rc<T, A>) -> bool
Equality for two Rc
s.
Two Rc
s are equal if their inner values are equal, even if they are
stored in different allocation.
If T
also implements Eq
(implying reflexivity of equality),
two Rc
s that point to the same allocation are
always equal.
Examples
use std::rc::Rc;
let five = Rc::new(5);
assert!(five == Rc::new(5));
source§fn ne(&self, other: &Rc<T, A>) -> bool
fn ne(&self, other: &Rc<T, A>) -> bool
Inequality for two Rc
s.
Two Rc
s are not equal if their inner values are not equal.
If T
also implements Eq
(implying reflexivity of equality),
two Rc
s that point to the same allocation are
always equal.
Examples
use std::rc::Rc;
let five = Rc::new(5);
assert!(five != Rc::new(6));
1.0.0 · source§impl<T, A> PartialOrd<Rc<T, A>> for Rc<T, A>where
T: PartialOrd<T> + ?Sized,
A: Allocator,
impl<T, A> PartialOrd<Rc<T, A>> for Rc<T, A>where T: PartialOrd<T> + ?Sized, A: Allocator,
source§fn partial_cmp(&self, other: &Rc<T, A>) -> Option<Ordering>
fn partial_cmp(&self, other: &Rc<T, A>) -> 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)));
source§fn lt(&self, other: &Rc<T, A>) -> bool
fn lt(&self, other: &Rc<T, A>) -> 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));
source§fn le(&self, other: &Rc<T, A>) -> bool
fn le(&self, other: &Rc<T, A>) -> 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));