Struct OptionalBusDevice 

pub struct OptionalBusDevice<D, N> {
    pub device: Option<D>,
    pub next_device: N,
}

A pseudo BusDevice allowing for plugging in and out a device at run time.

Fields

device: Option<D>

The device that can be “plugged in”.

next_device: N

The next device in the daisy chain.

Implementations

impl<D, N> OptionalBusDevice<D, N>

where D: BusDevice, N: BusDevice,

pub fn new(device: Option<D>, next_device: N) -> OptionalBusDevice<D, N>

Methods from Deref<Target = Option<D>>

pub fn is_some(&self) -> bool

Returns true if the option is a Some value.

Examples

let x: Option<u32> = Some(2);
assert_eq!(x.is_some(), true);

let x: Option<u32> = None;
assert_eq!(x.is_some(), false);

pub fn is_none(&self) -> bool

Returns true if the option is a None value.

Examples

let x: Option<u32> = Some(2);
assert_eq!(x.is_none(), false);

let x: Option<u32> = None;
assert_eq!(x.is_none(), true);

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:?}");

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));

pub fn as_pin_ref(self: Pin<&Option<T>>) -> Option<Pin<&T>>

Converts from Pin<&Option<T>> to Option<Pin<&T>>.

pub fn as_pin_mut(self: Pin<&mut Option<T>>) -> Option<Pin<&mut T>>

Converts from Pin<&mut Option<T>> to Option<Pin<&mut 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());
}

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))

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);

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()));

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);

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);

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);

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));

pub fn get_or_insert_default(&mut self) -> &mut T

where T: Default,

Inserts the default value into the option if it is None, then returns a mutable reference to the contained value.

Examples

let mut x = None;

{
    let y: &mut u32 = x.get_or_insert_default();
    assert_eq!(y, &0);

    *y = 7;
}

assert_eq!(x, Some(7));

pub fn get_or_insert_with<F>(&mut self, f: F) -> &mut T

where F: FnOnce() -> T,

Inserts a value computed from f into the option if it is None, then returns a mutable reference to the contained value.

Examples

let mut x = None;

{
    let y: &mut u32 = x.get_or_insert_with(|| 5);
    assert_eq!(y, &5);

    *y = 7;
}

assert_eq!(x, Some(7));

pub fn get_or_try_insert_with<'a, R, F>( &'a mut self, f: F, ) -> <<R as Try>::Residual as Residual<&'a mut T>>::TryType

where F: FnOnce() -> R, R: Try<Output = T>, <R as Try>::Residual: Residual<&'a mut T>,

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

If the option is None, calls the closure and inserts its output if successful.

If the closure returns a residual value such as Err or None, that residual value is returned and nothing is inserted.

If the option is Some, nothing is inserted.

Unless a residual is returned, a mutable reference to the value of the option will be output.

Examples

#![feature(option_get_or_try_insert_with)]
let mut o1: Option<u32> = None;
let mut o2: Option<u8> = None;

let number = "12345";

assert_eq!(o1.get_or_try_insert_with(|| number.parse()).copied(), Ok(12345));
assert!(o2.get_or_try_insert_with(|| number.parse()).is_err());
assert_eq!(o1, Some(12345));
assert_eq!(o2, None);

pub fn take(&mut self) -> Option<T>

Takes the value out of the option, leaving a None in its place.

Examples

let mut x = Some(2);
let y = x.take();
assert_eq!(x, None);
assert_eq!(y, Some(2));

let mut x: Option<u32> = None;
let y = x.take();
assert_eq!(x, None);
assert_eq!(y, None);

pub fn take_if<P>(&mut self, predicate: P) -> Option<T>

where P: FnOnce(&mut T) -> bool,

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));

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);

Trait Implementations

impl<D, N> AyAudioBusDevice for Box<OptionalBusDevice<D, N>>

where OptionalBusDevice<D, N>: AyAudioBusDevice + BusDevice,

fn render_ay_audio<L, B>( &mut self, blep: &mut B, end_ts: <Box<OptionalBusDevice<D, N>> as BusDevice>::Timestamp, frame_tstates: i32, chans: [usize; 3], )

where B: Blep, L: AmpLevels<<B as Blep>::SampleDelta>,

Renders square-wave pulses via Blep interface.

impl<D, N> AyAudioBusDevice for OptionalBusDevice<D, N>

where <D as BusDevice>::Timestamp: Into<i32> + Copy, D: AyAudioBusDevice + BusDevice, N: AyAudioBusDevice<Timestamp = <D as BusDevice>::Timestamp> + BusDevice,

fn render_ay_audio<L, B>( &mut self, blep: &mut B, end_ts: <D as BusDevice>::Timestamp, frame_tstates: i32, chans: [usize; 3], )

where B: Blep, L: AmpLevels<<B as Blep>::SampleDelta>,

Note

If a device is being attached to an optional device the call will be forwarded to both: an optional device and to the next bus device.

impl<D, N> BusDevice for OptionalBusDevice<D, N>

where D: BusDevice, N: BusDevice<Timestamp = <D as BusDevice>::Timestamp>, <D as BusDevice>::Timestamp: Copy,

type Timestamp = <D as BusDevice>::Timestamp

A type used as a time-stamp.

type NextDevice = N

A type of the next device in a daisy chain.

fn next_device_mut( &mut self, ) -> &mut <OptionalBusDevice<D, N> as BusDevice>::NextDevice

Returns a mutable reference to the next device.

fn next_device_ref(&self) -> &<OptionalBusDevice<D, N> as BusDevice>::NextDevice

Returns a reference to the next device.

fn into_next_device(self) -> <OptionalBusDevice<D, N> as BusDevice>::NextDevice

Destructs self and returns the instance of the next bus device.

fn reset( &mut self, timestamp: <OptionalBusDevice<D, N> as BusDevice>::Timestamp, )

Resets the device and all devices in this chain.

fn update_timestamp( &mut self, timestamp: <OptionalBusDevice<D, N> as BusDevice>::Timestamp, )

This method should be called near the end of each frame.

fn next_frame( &mut self, timestamp: <OptionalBusDevice<D, N> as BusDevice>::Timestamp, )

This method should be called just before the T-state counter of the control unit is wrapped when preparing for the next frame.

fn read_io( &mut self, port: u16, timestamp: <OptionalBusDevice<D, N> as BusDevice>::Timestamp, ) -> Option<(u8, Option<NonZero<u16>>)>

This method is called by the control unit during an I/O read cycle.

fn write_io( &mut self, port: u16, data: u8, timestamp: <OptionalBusDevice<D, N> as BusDevice>::Timestamp, ) -> Option<u16>

This method is called by the control unit during an I/O write cycle.

fn type_id(&self) -> TypeId

where Self: 'static,

Gets the TypeId of self.

impl<D, N> Clone for OptionalBusDevice<D, N>

where D: Clone, N: Clone,

fn clone(&self) -> OptionalBusDevice<D, N>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<D, N> Debug for OptionalBusDevice<D, N>

where D: Debug, N: Debug,

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

Formats the value using the given formatter.

impl<D, N> Default for OptionalBusDevice<D, N>

where D: Default, N: Default,

fn default() -> OptionalBusDevice<D, N>

Returns the “default value” for a type.

impl<D, N> Deref for OptionalBusDevice<D, N>

type Target = Option<D>

The resulting type after dereferencing.

fn deref(&self) -> &<OptionalBusDevice<D, N> as Deref>::Target

Dereferences the value.

impl<D, N> DerefMut for OptionalBusDevice<D, N>

fn deref_mut(&mut self) -> &mut <OptionalBusDevice<D, N> as Deref>::Target

Mutably dereferences the value.

impl<'de, D, N> Deserialize<'de> for OptionalBusDevice<D, N>

where D: Deserialize<'de> + Default, N: Deserialize<'de> + Default,

fn deserialize<__D>( __deserializer: __D, ) -> Result<OptionalBusDevice<D, N>, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<D, N> Display for OptionalBusDevice<D, N>

where D: Display,

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

Formats the value using the given formatter.

impl<D, N> Serialize for OptionalBusDevice<D, N>

where D: Serialize, N: Serialize,

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.