Struct std::cell::Ref 1.0.0[−][src]
pub struct Ref<'b, T> where
T: 'b + ?Sized, { /* fields omitted */ }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.
Implementations
impl<'b, T> Ref<'b, T> where
T: ?Sized, [src]
impl<'b, T> Ref<'b, T> where
T: ?Sized, [src]pub fn clone(orig: &Ref<'b, T>) -> Ref<'b, T>1.15.0[src]
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.
pub fn map<U, F>(orig: Ref<'b, T>, f: F) -> Ref<'b, U> where
F: FnOnce(&T) -> &U,
U: ?Sized, 1.8.0[src]
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)Run
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, [src]
orig: Ref<'b, T>,
f: F
) -> Result<Ref<'b, U>, Ref<'b, T>> where
F: FnOnce(&T) -> Option<&U>,
U: ?Sized,
🔬 This is a nightly-only experimental API. (cell_filter_map #81061)
recently added
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
#![feature(cell_filter_map)] 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);Run
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),
V: ?Sized,
U: ?Sized, 1.35.0[src]
F: FnOnce(&T) -> (&U, &V),
V: ?Sized,
U: ?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]);Run
pub fn leak(orig: Ref<'b, T>) -> &'b TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Future + Unpin + ?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 Rimpl<W: Write + ?Sized> Write for &mut W[src]
Notable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Future + Unpin + ?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 Rimpl<W: Write + ?Sized> Write for &mut WConvert 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());Run
Trait Implementations
impl<'_, T> Deref for Ref<'_, T> where
T: ?Sized, [src]
impl<'_, T> Deref for Ref<'_, T> where
T: ?Sized, [src]type Target = T
The resulting type after dereferencing.
pub fn deref(&self) -> &TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Future + Unpin + ?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 Rimpl<W: Write + ?Sized> Write for &mut W[src]
Notable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Future + Unpin + ?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 Rimpl<W: Write + ?Sized> Write for &mut Wimpl<'b, T, U> CoerceUnsized<Ref<'b, U>> for Ref<'b, T> where
T: Unsize<U> + ?Sized,
U: ?Sized, [src]
T: Unsize<U> + ?Sized,
U: ?Sized,
Auto Trait Implementations
impl<'b, T> !RefUnwindSafe for Ref<'b, T>
impl<'b, T> !Send for Ref<'b, T>
impl<'b, T> !Sync for Ref<'b, T>
impl<'b, T: ?Sized> Unpin for Ref<'b, T>
impl<'b, T> !UnwindSafe for Ref<'b, T>
Blanket Implementations
impl<T> Borrow<T> for T where
T: ?Sized, [src]
impl<T> Borrow<T> for T where
T: ?Sized, [src]pub fn borrow(&self) -> &TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Future + Unpin + ?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 Rimpl<W: Write + ?Sized> Write for &mut W[src]
Notable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Future + Unpin + ?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 Rimpl<W: Write + ?Sized> Write for &mut Wimpl<T> BorrowMut<T> for T where
T: ?Sized, [src]
impl<T> BorrowMut<T> for T where
T: ?Sized, [src]pub fn borrow_mut(&mut self) -> &mut TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Future + Unpin + ?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 Rimpl<W: Write + ?Sized> Write for &mut W[src]
Notable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Future + Unpin + ?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 Rimpl<W: Write + ?Sized> Write for &mut W