pub struct BarState {
open_menu: MenuRootManager,
}
Expand description
What is saved between frames.
Fields§
Implementations§
Methods from Deref<Target = MenuRootManager>§
Methods from Deref<Target = Option<MenuRoot>>§
1.0.0 · sourcepub fn as_ref(&self) -> Option<&T>
pub fn as_ref(&self) -> Option<&T>
Converts from &Option<T>
to Option<&T>
.
§Examples
Calculates the length of an Option<String>
as an Option<usize>
without moving the String
. The map
method takes the self
argument by value,
consuming the original, so this technique uses as_ref
to first take an Option
to a
reference to the value inside the original.
let text: Option<String> = Some("Hello, world!".to_string());
// First, cast `Option<String>` to `Option<&String>` with `as_ref`,
// then consume *that* with `map`, leaving `text` on the stack.
let text_length: Option<usize> = text.as_ref().map(|s| s.len());
println!("still can print text: {text:?}");
1.0.0 · sourcepub fn as_mut(&mut self) -> Option<&mut T>
pub fn as_mut(&mut self) -> Option<&mut T>
Converts from &mut Option<T>
to Option<&mut T>
.
§Examples
let mut x = Some(2);
match x.as_mut() {
Some(v) => *v = 42,
None => {},
}
assert_eq!(x, Some(42));
1.75.0 · sourcepub fn as_slice(&self) -> &[T]
pub fn as_slice(&self) -> &[T]
Returns a slice of the contained value, if any. If this is None
, an
empty slice is returned. This can be useful to have a single type of
iterator over an Option
or slice.
Note: Should you have an Option<&T>
and wish to get a slice of T
,
you can unpack it via opt.map_or(&[], std::slice::from_ref)
.
§Examples
assert_eq!(
[Some(1234).as_slice(), None.as_slice()],
[&[1234][..], &[][..]],
);
The inverse of this function is (discounting
borrowing) [_]::first
:
for i in [Some(1234_u16), None] {
assert_eq!(i.as_ref(), i.as_slice().first());
}
1.75.0 · sourcepub fn as_mut_slice(&mut self) -> &mut [T]
pub fn as_mut_slice(&mut self) -> &mut [T]
Returns a mutable slice of the contained value, if any. If this is
None
, an empty slice is returned. This can be useful to have a
single type of iterator over an Option
or slice.
Note: Should you have an Option<&mut T>
instead of a
&mut Option<T>
, which this method takes, you can obtain a mutable
slice via opt.map_or(&mut [], std::slice::from_mut)
.
§Examples
assert_eq!(
[Some(1234).as_mut_slice(), None.as_mut_slice()],
[&mut [1234][..], &mut [][..]],
);
The result is a mutable slice of zero or one items that points into
our original Option
:
let mut x = Some(1234);
x.as_mut_slice()[0] += 1;
assert_eq!(x, Some(1235));
The inverse of this method (discounting borrowing)
is [_]::first_mut
:
assert_eq!(Some(123).as_mut_slice().first_mut(), Some(&mut 123))
1.40.0 · sourcepub fn as_deref(&self) -> Option<&<T as Deref>::Target>where
T: Deref,
pub fn as_deref(&self) -> Option<&<T as Deref>::Target>where
T: Deref,
Converts from Option<T>
(or &Option<T>
) to Option<&T::Target>
.
Leaves the original Option in-place, creating a new one with a reference
to the original one, additionally coercing the contents via Deref
.
§Examples
let x: Option<String> = Some("hey".to_owned());
assert_eq!(x.as_deref(), Some("hey"));
let x: Option<String> = None;
assert_eq!(x.as_deref(), None);
1.40.0 · sourcepub fn as_deref_mut(&mut self) -> Option<&mut <T as Deref>::Target>where
T: DerefMut,
pub fn as_deref_mut(&mut self) -> Option<&mut <T as Deref>::Target>where
T: DerefMut,
Converts from Option<T>
(or &mut Option<T>
) to Option<&mut T::Target>
.
Leaves the original Option
in-place, creating a new one containing a mutable reference to
the inner type’s Deref::Target
type.
§Examples
let mut x: Option<String> = Some("hey".to_owned());
assert_eq!(x.as_deref_mut().map(|x| {
x.make_ascii_uppercase();
x
}), Some("HEY".to_owned().as_mut_str()));
1.0.0 · sourcepub fn iter(&self) -> Iter<'_, T>
pub fn iter(&self) -> Iter<'_, T>
Returns an iterator over the possibly contained value.
§Examples
let x = Some(4);
assert_eq!(x.iter().next(), Some(&4));
let x: Option<u32> = None;
assert_eq!(x.iter().next(), None);
1.0.0 · sourcepub fn iter_mut(&mut self) -> IterMut<'_, T>
pub fn iter_mut(&mut self) -> IterMut<'_, T>
Returns a mutable iterator over the possibly contained value.
§Examples
let mut x = Some(4);
match x.iter_mut().next() {
Some(v) => *v = 42,
None => {},
}
assert_eq!(x, Some(42));
let mut x: Option<u32> = None;
assert_eq!(x.iter_mut().next(), None);
1.53.0 · sourcepub fn insert(&mut self, value: T) -> &mut T
pub fn insert(&mut self, value: T) -> &mut T
Inserts value
into the option, then returns a mutable reference to it.
If the option already contains a value, the old value is dropped.
See also Option::get_or_insert
, which doesn’t update the value if
the option already contains Some
.
§Example
let mut opt = None;
let val = opt.insert(1);
assert_eq!(*val, 1);
assert_eq!(opt.unwrap(), 1);
let val = opt.insert(2);
assert_eq!(*val, 2);
*val = 3;
assert_eq!(opt.unwrap(), 3);
1.20.0 · sourcepub fn get_or_insert(&mut self, value: T) -> &mut T
pub fn get_or_insert(&mut self, value: T) -> &mut T
Inserts value
into the option if it is None
, then
returns a mutable reference to the contained value.
See also Option::insert
, which updates the value even if
the option already contains Some
.
§Examples
let mut x = None;
{
let y: &mut u32 = x.get_or_insert(5);
assert_eq!(y, &5);
*y = 7;
}
assert_eq!(x, Some(7));
sourcepub fn get_or_insert_default(&mut self) -> &mut Twhere
T: Default,
🔬This is a nightly-only experimental API. (option_get_or_insert_default
)
pub fn get_or_insert_default(&mut self) -> &mut Twhere
T: Default,
option_get_or_insert_default
)1.20.0 · sourcepub fn get_or_insert_with<F>(&mut self, f: F) -> &mut Twhere
F: FnOnce() -> T,
pub fn get_or_insert_with<F>(&mut self, f: F) -> &mut Twhere
F: FnOnce() -> T,
1.80.0 · sourcepub fn take_if<P>(&mut self, predicate: P) -> Option<T>
pub fn take_if<P>(&mut self, predicate: P) -> Option<T>
Takes the value out of the option, but only if the predicate evaluates to
true
on a mutable reference to the value.
In other words, replaces self
with None
if the predicate returns true
.
This method operates similar to Option::take
but conditional.
§Examples
let mut x = Some(42);
let prev = x.take_if(|v| if *v == 42 {
*v += 1;
false
} else {
false
});
assert_eq!(x, Some(43));
assert_eq!(prev, None);
let prev = x.take_if(|v| *v == 43);
assert_eq!(x, None);
assert_eq!(prev, Some(43));
1.31.0 · sourcepub fn replace(&mut self, value: T) -> Option<T>
pub fn replace(&mut self, value: T) -> Option<T>
Replaces the actual value in the option by the value given in parameter,
returning the old value if present,
leaving a Some
in its place without deinitializing either one.
§Examples
let mut x = Some(2);
let old = x.replace(5);
assert_eq!(x, Some(5));
assert_eq!(old, Some(2));
let mut x = None;
let old = x.replace(3);
assert_eq!(x, Some(3));
assert_eq!(old, None);