Struct caffe2_imports::RefMut
1.0.0 · source · pub struct RefMut<'b, T>where
T: 'b + ?Sized,{ /* private fields */ }
Expand description
A wrapper type for a mutably borrowed value from a RefCell<T>
.
See the module-level documentation for more.
Implementations§
source§impl<'b, T> RefMut<'b, T>where
T: ?Sized,
impl<'b, T> RefMut<'b, T>where T: ?Sized,
1.8.0 · sourcepub fn map<U, F>(orig: RefMut<'b, T>, f: F) -> RefMut<'b, U>where
F: FnOnce(&mut T) -> &mut U,
U: ?Sized,
pub fn map<U, F>(orig: RefMut<'b, T>, f: F) -> RefMut<'b, U>where F: FnOnce(&mut T) -> &mut U, U: ?Sized,
Makes a new RefMut
for a component of the borrowed data, e.g., an enum
variant.
The RefCell
is already mutably borrowed, so this cannot fail.
This is an associated function that needs to be used as
RefMut::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, RefMut};
let c = RefCell::new((5, 'b'));
{
let b1: RefMut<(u32, char)> = c.borrow_mut();
let mut b2: RefMut<u32> = RefMut::map(b1, |t| &mut t.0);
assert_eq!(*b2, 5);
*b2 = 42;
}
assert_eq!(*c.borrow(), (42, 'b'));
1.63.0 · sourcepub fn filter_map<U, F>(
orig: RefMut<'b, T>,
f: F
) -> Result<RefMut<'b, U>, RefMut<'b, T>>where
F: FnOnce(&mut T) -> Option<&mut U>,
U: ?Sized,
pub fn filter_map<U, F>( orig: RefMut<'b, T>, f: F ) -> Result<RefMut<'b, U>, RefMut<'b, T>>where F: FnOnce(&mut T) -> Option<&mut U>, U: ?Sized,
Makes a new RefMut
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 mutably borrowed, so this cannot fail.
This is an associated function that needs to be used as
RefMut::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, RefMut};
let c = RefCell::new(vec![1, 2, 3]);
{
let b1: RefMut<Vec<u32>> = c.borrow_mut();
let mut b2: Result<RefMut<u32>, _> = RefMut::filter_map(b1, |v| v.get_mut(1));
if let Ok(mut b2) = b2 {
*b2 += 2;
}
}
assert_eq!(*c.borrow(), vec![1, 4, 3]);
1.35.0 · sourcepub fn map_split<U, V, F>(
orig: RefMut<'b, T>,
f: F
) -> (RefMut<'b, U>, RefMut<'b, V>)where
F: FnOnce(&mut T) -> (&mut U, &mut V),
U: ?Sized,
V: ?Sized,
pub fn map_split<U, V, F>( orig: RefMut<'b, T>, f: F ) -> (RefMut<'b, U>, RefMut<'b, V>)where F: FnOnce(&mut T) -> (&mut U, &mut V), U: ?Sized, V: ?Sized,
Splits a RefMut
into multiple RefMut
s for different components of the
borrowed data.
The underlying RefCell
will remain mutably borrowed until both
returned RefMut
s go out of scope.
The RefCell
is already mutably borrowed, so this cannot fail.
This is an associated function that needs to be used as
RefMut::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::{RefCell, RefMut};
let cell = RefCell::new([1, 2, 3, 4]);
let borrow = cell.borrow_mut();
let (mut begin, mut end) = RefMut::map_split(borrow, |slice| slice.split_at_mut(2));
assert_eq!(*begin, [1, 2]);
assert_eq!(*end, [3, 4]);
begin.copy_from_slice(&[4, 3]);
end.copy_from_slice(&[2, 1]);
sourcepub fn leak(orig: RefMut<'b, T>) -> &'b mut T
🔬This is a nightly-only experimental API. (cell_leak
)
pub fn leak(orig: RefMut<'b, T>) -> &'b mut T
cell_leak
)Convert into a mutable reference to the underlying data.
The underlying RefCell
can not be borrowed from again and will always appear already
mutably borrowed, making the returned reference the only to the interior.
This is an associated function that needs to be used as
RefMut::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, RefMut};
let cell = RefCell::new(0);
let value = RefMut::leak(cell.borrow_mut());
assert_eq!(*value, 0);
*value = 1;
assert!(cell.try_borrow_mut().is_err());
Trait Implementations§
impl<'b, T, U> CoerceUnsized<RefMut<'b, U>> for RefMut<'b, T>where T: Unsize<U> + ?Sized, U: ?Sized,
impl<'a, T> StableDeref for RefMut<'a, T>where T: ?Sized,
Auto Trait Implementations§
impl<'b, T> !RefUnwindSafe for RefMut<'b, T>
impl<'b, T> !Send for RefMut<'b, T>
impl<'b, T> !Sync for RefMut<'b, T>
impl<'b, T: ?Sized> Unpin for RefMut<'b, T>
impl<'b, T> !UnwindSafe for RefMut<'b, T>
Blanket Implementations§
§impl<T> Pointable for T
impl<T> Pointable for T
§impl<SS, SP> SupersetOf<SS> for SPwhere
SS: SubsetOf<SP>,
impl<SS, SP> SupersetOf<SS> for SPwhere SS: SubsetOf<SP>,
§fn to_subset(&self) -> Option<SS>
fn to_subset(&self) -> Option<SS>
self
from the equivalent element of its
superset. Read more§fn is_in_subset(&self) -> bool
fn is_in_subset(&self) -> bool
self
is actually part of its subset T
(and can be converted to it).§fn to_subset_unchecked(&self) -> SS
fn to_subset_unchecked(&self) -> SS
self.to_subset
but without any property checks. Always succeeds.§fn from_subset(element: &SS) -> SP
fn from_subset(element: &SS) -> SP
self
to the equivalent element of its superset.