Struct serde::lib::core::cell::Ref

1.0.0 · source ·
pub struct Ref<'b, T>where
    T: 'b + ?Sized,
{ value: NonNull<T>, borrow: BorrowRef<'b>, }
Expand description

Wraps a borrowed reference to a value in a RefCell box. A wrapper type for an immutably borrowed value from a RefCell<T>.

See the module-level documentation for more.

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§value: NonNull<T>§borrow: BorrowRef<'b>

Implementations§

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impl<'b, T> Ref<'b, T>where
    T: ?Sized,

1.15.0 · source

pub fn clone(orig: &Ref<'b, T>) -> Ref<'b, T>

Copies a Ref.

The RefCell is already immutably borrowed, so this cannot fail.

This is an associated function that needs to be used as Ref::clone(...). A Clone implementation or a method would interfere with the widespread use of r.borrow().clone() to clone the contents of a RefCell.

1.8.0 · source

pub fn map<U, F>(orig: Ref<'b, T>, f: F) -> Ref<'b, U>where
    F: FnOnce(&T) -> &U,
    U: ?Sized,

Makes a new Ref for a component of the borrowed data.

The RefCell is already immutably borrowed, so this cannot fail.

This is an associated function that needs to be used as Ref::map(...). A method would interfere with methods of the same name on the contents of a RefCell used through Deref.

Examples
use std::cell::{RefCell, Ref};

let c = RefCell::new((5, 'b'));
let b1: Ref<(u32, char)> = c.borrow();
let b2: Ref<u32> = Ref::map(b1, |t| &t.0);
assert_eq!(*b2, 5)
1.63.0 · source

pub fn filter_map<U, F>(orig: Ref<'b, T>, f: F) -> Result<Ref<'b, U>, Ref<'b, T>>where
    F: FnOnce(&T) -> Option<&U>,
    U: ?Sized,

Makes a new Ref for an optional component of the borrowed data. The original guard is returned as an Err(..) if the closure returns None.

The RefCell is already immutably borrowed, so this cannot fail.

This is an associated function that needs to be used as Ref::filter_map(...). A method would interfere with methods of the same name on the contents of a RefCell used through Deref.

Examples
use std::cell::{RefCell, Ref};

let c = RefCell::new(vec![1, 2, 3]);
let b1: Ref<Vec<u32>> = c.borrow();
let b2: Result<Ref<u32>, _> = Ref::filter_map(b1, |v| v.get(1));
assert_eq!(*b2.unwrap(), 2);
1.35.0 · source

pub fn map_split<U, V, F>(orig: Ref<'b, T>, f: F) -> (Ref<'b, U>, Ref<'b, V>)where
    F: FnOnce(&T) -> (&U, &V),
    U: ?Sized,
    V: ?Sized,

Splits a Ref into multiple Refs for different components of the borrowed data.

The RefCell is already immutably borrowed, so this cannot fail.

This is an associated function that needs to be used as Ref::map_split(...). A method would interfere with methods of the same name on the contents of a RefCell used through Deref.

Examples
use std::cell::{Ref, RefCell};

let cell = RefCell::new([1, 2, 3, 4]);
let borrow = cell.borrow();
let (begin, end) = Ref::map_split(borrow, |slice| slice.split_at(2));
assert_eq!(*begin, [1, 2]);
assert_eq!(*end, [3, 4]);
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pub fn leak(orig: Ref<'b, T>) -> &'b T

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

Convert into a reference to the underlying data.

The underlying RefCell can never be mutably borrowed from again and will always appear already immutably borrowed. It is not a good idea to leak more than a constant number of references. The RefCell can be immutably borrowed again if only a smaller number of leaks have occurred in total.

This is an associated function that needs to be used as Ref::leak(...). A method would interfere with methods of the same name on the contents of a RefCell used through Deref.

Examples
#![feature(cell_leak)]
use std::cell::{RefCell, Ref};
let cell = RefCell::new(0);

let value = Ref::leak(cell.borrow());
assert_eq!(*value, 0);

assert!(cell.try_borrow().is_ok());
assert!(cell.try_borrow_mut().is_err());

Trait Implementations§

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impl<T> Debug for Ref<'_, 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
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impl<T> Deref for Ref<'_, T>where
    T: ?Sized,

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type Target = T

The resulting type after dereferencing.
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fn deref(&self) -> &T

Dereferences the value.
1.20.0 · source§

impl<T> Display for Ref<'_, T>where
    T: Display + ?Sized,

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

Formats the value using the given formatter. Read more
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impl<'b, T, U> CoerceUnsized<Ref<'b, U>> for Ref<'b, T>where
    T: Unsize<U> + ?Sized,
    U: ?Sized,

Auto Trait Implementations§

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impl<'b, T> !RefUnwindSafe for Ref<'b, T>

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impl<'b, T> !Send for Ref<'b, T>

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impl<'b, T> !Sync for Ref<'b, T>

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impl<'b, T: ?Sized> Unpin for Ref<'b, T>

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impl<'b, T> !UnwindSafe for Ref<'b, T>

Blanket Implementations§

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impl<T> Any for Twhere
    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 Twhere
    T: ?Sized,

const: unstable · source§

fn borrow(&self) -> &T

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

const: unstable · source§

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

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

const: unstable · source§

fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere
    U: From<T>,

const: unstable · source§

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> ToString for Twhere
    T: Display + ?Sized,

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default fn to_string(&self) -> String

Converts the given value to a String. Read more
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impl<T, U> TryFrom<U> for Twhere
    U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
const: unstable · source§

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 Twhere
    U: TryFrom<T>,

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

The type returned in the event of a conversion error.
const: unstable · source§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.