Struct Optional 

pub struct Optional<T>(pub T);

Allows iteration over a component that may be absent.

Example:

use shipyard::{Component, IntoIter, View, World};

#[derive(Component, PartialEq, Eq, Debug)]
struct A(u32);

#[derive(Component, PartialEq, Eq, Debug)]
struct B(u32);

let mut world = World::new();

world.add_entity((A(0),));
world.add_entity((A(1), B(10)));

let (a, b) = world.borrow::<(View<A>, View<B>)>().unwrap();
let mut iter = (&a, b.as_optional()).iter();

assert_eq!(iter.next(), Some((&A(0), None)));
assert_eq!(iter.next(), Some((&A(1), Some(&B(10)))));

Tuple Fields

0: T

Trait Implementations

impl<T: Clone> Clone for Optional<T>

fn clone(&self) -> Optional<T>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<'tmp, 'v: 'tmp, T: Component> IntoShiperator for Optional<&'tmp View<'v, T>>

type Shiperator = Optional<FullRawWindow<'tmp, T>>

fn into_shiperator( self, storage_ids: &mut ShipHashSet<StorageId>, ) -> (Self::Shiperator, usize, RawEntityIdAccess)

Returns the Shiperator, its maximum length and RawEntityIdAccess.

fn can_captain() -> bool

Returns true if the Shiperator can be a captain.

fn can_sailor() -> bool

Returns true if the Shiperator can be a sailor.

impl<'tmp, 'v: 'tmp, T: Component, Track: Tracking> IntoShiperator for Optional<&'tmp ViewMut<'v, T, Track>>

type Shiperator = Optional<FullRawWindow<'tmp, T>>

fn into_shiperator( self, storage_ids: &mut ShipHashSet<StorageId>, ) -> (Self::Shiperator, usize, RawEntityIdAccess)

Returns the Shiperator, its maximum length and RawEntityIdAccess.

fn can_captain() -> bool

Returns true if the Shiperator can be a captain.

fn can_sailor() -> bool

Returns true if the Shiperator can be a sailor.

impl<'tmp, 'v: 'tmp, T: Component, Track: Tracking> IntoShiperator for Optional<&'tmp mut ViewMut<'v, T, Track>>

type Shiperator = Optional<FullRawWindowMut<'tmp, T, Track>>

fn into_shiperator( self, storage_ids: &mut ShipHashSet<StorageId>, ) -> (Self::Shiperator, usize, RawEntityIdAccess)

Returns the Shiperator, its maximum length and RawEntityIdAccess.

fn can_captain() -> bool

Returns true if the Shiperator can be a captain.

fn can_sailor() -> bool

Returns true if the Shiperator can be a sailor.

impl<'tmp, T: Component> ShiperatorCaptain for Optional<FullRawWindow<'tmp, T>>

unsafe fn get_captain_data(&self, _index: usize) -> Self::Out

Returns the component at index.

fn next_slice(&mut self)

Shiperators might iterate multiple splices of EntityIds.
This function is called on the switch to the next slice.

fn sail_time(&self) -> usize

Approximation of how much time iterating this Shiperator will take.
This helps pick the fastest Shiperator when iterating multiple storages.

fn is_exact_sized(&self) -> bool

true when this Shiperator cannot return None.

fn unpick(&mut self)

By default into_shiperator returns Shiperators that thinks they are captains.
This function is called on the ones that end up not being picked.

impl<'tmp, T: Component, Track> ShiperatorCaptain for Optional<FullRawWindowMut<'tmp, T, Track>>

where Optional<FullRawWindowMut<'tmp, T, Track>>: ShiperatorOutput, FullRawWindowMut<'tmp, T, Track>: ShiperatorCaptain,

unsafe fn get_captain_data(&self, _index: usize) -> Self::Out

Returns the component at index.

fn next_slice(&mut self)

Shiperators might iterate multiple splices of EntityIds.
This function is called on the switch to the next slice.

fn sail_time(&self) -> usize

Approximation of how much time iterating this Shiperator will take.
This helps pick the fastest Shiperator when iterating multiple storages.

fn is_exact_sized(&self) -> bool

true when this Shiperator cannot return None.

fn unpick(&mut self)

By default into_shiperator returns Shiperators that thinks they are captains.
This function is called on the ones that end up not being picked.

impl<'tmp, T: Component> ShiperatorOutput for Optional<FullRawWindow<'tmp, T>>

type Out = Option<&'tmp T>

The type returned by the Shiperator.

impl<'tmp, T: Component, Track> ShiperatorOutput for Optional<FullRawWindowMut<'tmp, T, Track>>

where FullRawWindowMut<'tmp, T, Track>: ShiperatorOutput,

type Out = Option<<FullRawWindowMut<'tmp, T, Track> as ShiperatorOutput>::Out>

The type returned by the Shiperator.

impl<'tmp, T: Component> ShiperatorSailor for Optional<FullRawWindow<'tmp, T>>

type Index = Option<usize>

Type this Shiperator is indexed with.
This is often usize or a tuple of usize for multiple storages.

unsafe fn get_sailor_data(&self, index: Self::Index) -> Self::Out

Returns the component at index.

fn indices_of(&self, entity_id: EntityId, index: usize) -> Option<Self::Index>

Returns the index of the component with id entity_id.

fn index_from_usize(_index: usize) -> Self::Index

When a Mixed iterator flags a storage as captain, it can skip indices_of and directly use index for this one Shiperator.
But at the type level there is no way to express this since the captain is picked at runtime.

impl<'tmp, T: Component, Track> ShiperatorSailor for Optional<FullRawWindowMut<'tmp, T, Track>>

where Optional<FullRawWindowMut<'tmp, T, Track>>: ShiperatorOutput<Out = Option<<FullRawWindowMut<'tmp, T, Track> as ShiperatorOutput>::Out>>, FullRawWindowMut<'tmp, T, Track>: ShiperatorSailor<Index = usize>,

type Index = Option<usize>

Type this Shiperator is indexed with.
This is often usize or a tuple of usize for multiple storages.

unsafe fn get_sailor_data(&self, index: Self::Index) -> Self::Out

Returns the component at index.

fn indices_of(&self, entity_id: EntityId, index: usize) -> Option<Self::Index>

Returns the index of the component with id entity_id.

fn index_from_usize(_index: usize) -> Self::Index

When a Mixed iterator flags a storage as captain, it can skip indices_of and directly use index for this one Shiperator.
But at the type level there is no way to express this since the captain is picked at runtime.