1.0.0[][src]Struct rustc_data_structures::sync::MappedReadGuard

pub struct MappedReadGuard<'b, T> where
    T: 'b + ?Sized
{ value: &'b T, borrow: BorrowRef<'b>, }

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.

Fields

value: &'b Tborrow: BorrowRef<'b>

Methods

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]

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)

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
1.35.0[src]

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]);

Trait Implementations

impl<'b, T, U> CoerceUnsized<Ref<'b, U>> for Ref<'b, T> where
    T: Unsize<U> + ?Sized,
    U: ?Sized
[src]

impl<'_, T> Debug for Ref<'_, T> where
    T: Debug + ?Sized
[src]

impl<'_, T> Deref for Ref<'_, T> where
    T: ?Sized
[src]

type Target = T

The resulting type after dereferencing.

impl<'_, T> Display for Ref<'_, T> where
    T: Display + ?Sized
1.20.0[src]

impl<'a, T> StableDeref for Ref<'a, T> where
    T: ?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> Any for T where
    T: 'static + ?Sized
[src]

impl<T> Borrow<T> for T where
    T: ?Sized
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impl<T> BorrowMut<T> for T where
    T: ?Sized
[src]

impl<'a, T> Captures<'a> for T where
    T: ?Sized
[src]

impl<T> Erased for T[src]

impl<T> From<T> for T[src]

impl<T, U> Into<U> for T where
    U: From<T>, 
[src]

impl<E> SpecializationError for E[src]

impl<T> ToString for T where
    T: Display + ?Sized
[src]

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 
[src]

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 
[src]

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

The type returned in the event of a conversion error.