Struct script::dom::bindings::cell::RefCell

1.0.0 · source ·
pub struct RefCell<T>
where T: ?Sized,
{ borrow: Cell<isize>, value: UnsafeCell<T>, }
Expand description

A mutable memory location with dynamically checked borrow rules

See the module-level documentation for more.

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§borrow: Cell<isize>§value: UnsafeCell<T>

Implementations§

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impl<T> RefCell<T>

1.0.0 (const: 1.24.0) · source

pub const fn new(value: T) -> RefCell<T>

Creates a new RefCell containing value.

§Examples
use std::cell::RefCell;

let c = RefCell::new(5);
1.0.0 (const: unstable) · source

pub fn into_inner(self) -> T

Consumes the RefCell, returning the wrapped value.

§Examples
use std::cell::RefCell;

let c = RefCell::new(5);

let five = c.into_inner();
1.24.0 · source

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));
1.35.0 · source

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));
1.24.0 · source

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));
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impl<T> RefCell<T>
where T: ?Sized,

1.0.0 · source

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
1.13.0 · source

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());
}
1.0.0 · source

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
1.13.0 · source

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());
1.12.0 · source

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();
1.11.0 · source

pub fn get_mut(&mut self) -> &mut T

Returns a mutable reference to the underlying data.

Since this method borrows RefCell mutably, it is statically guaranteed that no borrows to the underlying data exist. The dynamic checks inherent in borrow_mut and most other methods of RefCell are therefore unnecessary.

This method can only be called if RefCell can be mutably borrowed, which in general is only the case directly after the RefCell has been created. In these situations, skipping the aforementioned dynamic borrowing checks may yield better ergonomics and runtime-performance.

In most situations where RefCell is used, it can’t be borrowed mutably. Use borrow_mut to get mutable access to the underlying data then.

§Examples
use std::cell::RefCell;

let mut c = RefCell::new(5);
*c.get_mut() += 1;

assert_eq!(c, RefCell::new(6));
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pub fn undo_leak(&mut self) -> &mut T

🔬This is a nightly-only experimental API. (cell_leak)

Undo the effect of leaked guards on the borrow state of the RefCell.

This call is similar to get_mut but more specialized. It borrows RefCell mutably to ensure no borrows exist and then resets the state tracking shared borrows. This is relevant if some Ref or RefMut borrows have been leaked.

§Examples
#![feature(cell_leak)]
use std::cell::RefCell;

let mut c = RefCell::new(0);
std::mem::forget(c.borrow_mut());

assert!(c.try_borrow().is_err());
c.undo_leak();
assert!(c.try_borrow().is_ok());
1.37.0 · source

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 behaviour.

§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());
}
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impl<T> RefCell<T>
where T: Default,

1.50.0 · source

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§

1.0.0 · source§

impl<T> Clone for RefCell<T>
where T: Clone,

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fn clone(&self) -> RefCell<T>

§Panics

Panics if the value is currently mutably borrowed.

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fn clone_from(&mut self, source: &RefCell<T>)

§Panics

Panics if source is currently mutably borrowed.

1.0.0 · source§

impl<T> Debug for RefCell<T>
where T: Debug + ?Sized,

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

Formats the value using the given formatter. Read more
1.0.0 · source§

impl<T> Default for RefCell<T>
where T: Default,

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fn default() -> RefCell<T>

Creates a RefCell<T>, with the Default value for T.

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impl<'de, T> Deserialize<'de> for RefCell<T>
where T: Deserialize<'de>,

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fn deserialize<D>( deserializer: D, ) -> Result<RefCell<T>, <D as Deserializer<'de>>::Error>
where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer. Read more
1.12.0 · source§

impl<T> From<T> for RefCell<T>

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fn from(t: T) -> RefCell<T>

Creates a new RefCell<T> containing the given value.

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impl<T> MallocSizeOf for RefCell<T>
where T: MallocSizeOf,

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fn size_of(&self, ops: &mut MallocSizeOfOps) -> usize

Measure the heap usage of all descendant heap-allocated structures, but not the space taken up by the value itself.
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impl<T> MallocSizeOf for RefCell<T>
where T: MallocSizeOf,

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fn size_of(&self, ops: &mut MallocSizeOfOps) -> usize

Measure the heap usage of all descendant heap-allocated structures, but not the space taken up by the value itself.
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impl<T> MallocSizeOf for RefCell<T>
where T: MallocSizeOf,

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fn size_of(&self, ops: &mut MallocSizeOfOps) -> usize

Measure the heap usage of all descendant heap-allocated structures, but not the space taken up by the value itself.
1.10.0 · source§

impl<T> Ord for RefCell<T>
where T: Ord + ?Sized,

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fn cmp(&self, other: &RefCell<T>) -> Ordering

§Panics

Panics if the value in either RefCell is currently mutably borrowed.

1.0.0 · source§

impl<T> PartialEq for RefCell<T>
where T: PartialEq + ?Sized,

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fn eq(&self, other: &RefCell<T>) -> bool

§Panics

Panics if the value in either RefCell is currently mutably borrowed.

1.0.0 · source§

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

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
1.10.0 · source§

impl<T> PartialOrd for RefCell<T>
where T: PartialOrd + ?Sized,

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fn partial_cmp(&self, other: &RefCell<T>) -> Option<Ordering>

§Panics

Panics if the value in either RefCell is currently mutably borrowed.

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fn lt(&self, other: &RefCell<T>) -> bool

§Panics

Panics if the value in either RefCell is currently mutably borrowed.

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fn le(&self, other: &RefCell<T>) -> bool

§Panics

Panics if the value in either RefCell is currently mutably borrowed.

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fn gt(&self, other: &RefCell<T>) -> bool

§Panics

Panics if the value in either RefCell is currently mutably borrowed.

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fn ge(&self, other: &RefCell<T>) -> bool

§Panics

Panics if the value in either RefCell is currently mutably borrowed.

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impl<T> Serialize for RefCell<T>
where T: Serialize + ?Sized,

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fn serialize<S>( &self, serializer: S, ) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>
where S: Serializer,

Serialize this value into the given Serde serializer. Read more
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impl<T> Traceable for RefCell<T>
where T: Traceable,

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unsafe fn trace(&self, trc: *mut JSTracer)

Trace self.
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impl<T, U> CoerceUnsized<RefCell<U>> for RefCell<T>
where T: CoerceUnsized<U>,

1.2.0 · source§

impl<T> Eq for RefCell<T>
where T: Eq + ?Sized,

1.0.0 · source§

impl<T> Send for RefCell<T>
where T: Send + ?Sized,

1.0.0 · source§

impl<T> !Sync for RefCell<T>
where T: ?Sized,

Auto Trait Implementations§

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impl<T> !Freeze for RefCell<T>

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impl<T> !RefUnwindSafe for RefCell<T>

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impl<T> Unpin for RefCell<T>
where T: Unpin + ?Sized,

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impl<T> UnwindSafe for RefCell<T>
where T: UnwindSafe + ?Sized,

Blanket Implementations§

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

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<Q, K> Comparable<K> for Q
where Q: Ord + ?Sized, K: Borrow<Q> + ?Sized,

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fn compare(&self, key: &K) -> Ordering

Compare self to key and return their ordering.
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impl<T> Downcast<T> for T

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fn downcast(&self) -> &T

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impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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fn equivalent(&self, key: &K) -> bool

Checks if this value is equivalent to the given key. Read more
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impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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fn equivalent(&self, key: &K) -> bool

Compare self to key and return true if they are equal.
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impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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fn equivalent(&self, key: &K) -> bool

Compare self to key and return true if they are equal.
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impl<T> Filterable for T

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fn filterable( self, filter_name: &'static str, ) -> RequestFilterDataProvider<T, fn(_: DataRequest<'_>) -> bool>

Creates a filterable data provider with the given name for debugging. Read more
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impl<T> From<!> for T

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fn from(t: !) -> T

Converts to this type from the input type.
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> IntoEither for T

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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts self into a Left variant of Either<Self, Self> if into_left(&self) returns true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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impl<T> MaybeBoxed<Box<T>> for T

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fn maybe_boxed(self) -> Box<T>

Convert
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impl<T> MaybeBoxed<T> for T

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fn maybe_boxed(self) -> T

Convert
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impl<T> Pointable for T

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const ALIGN: usize = _

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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impl<R, P> ReadPrimitive<R> for P
where R: Read + ReadEndian<P>, P: Default,

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fn read_from_little_endian(read: &mut R) -> Result<Self, Error>

Read this value from the supplied reader. Same as ReadEndian::read_from_little_endian().
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fn read_from_big_endian(read: &mut R) -> Result<Self, Error>

Read this value from the supplied reader. Same as ReadEndian::read_from_big_endian().
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fn read_from_native_endian(read: &mut R) -> Result<Self, Error>

Read this value from the supplied reader. Same as ReadEndian::read_from_native_endian().
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impl<T> Same for T

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type Output = T

Should always be Self
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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T> Upcast<T> for T

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fn upcast(&self) -> Option<&T>

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impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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fn vzip(self) -> V

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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more
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impl<T> DeserializeOwned for T
where T: for<'de> Deserialize<'de>,

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impl<T> ErasedDestructor for T
where T: 'static,

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impl<T> MaybeSendSync for T

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impl<T> WasmNotSend for T
where T: Send,