Struct Fetcher

pub struct Fetcher<'a, Q>
where
    Q: Query,
{ /* private fields */ }

A HandlerParam for accessing data from entities matching a given Query.

For more information, see the relevant tutorial chapter.

Implementations

impl<'a, Q> Fetcher<'a, Q>

where Q: Query,

pub fn get(&self, entity: EntityId) -> Result<<Q as Query>::Item<'_>, GetError>

where Q: ReadOnlyQuery,

Returns the read-only query item for the given entity.

If the entity doesn’t exist or doesn’t match the query, then a GetError is returned.

pub unsafe fn get_unchecked( &self, entity: EntityId, ) -> Result<<Q as Query>::Item<'_>, GetError>

Returns the query item for the given entity without checking borrowing rules.

This is useful when you know the entity IDs are disjoint but can’t prove it to the compiler.

If the entity doesn’t exist or doesn’t match the query, then a GetError is returned.

Safety

You must ensure that all entities that co-occur are disjoint if they contain any mutable references.

pub fn get_mut( &mut self, entity: EntityId, ) -> Result<<Q as Query>::Item<'_>, GetError>

Returns the query item for the given entity.

If the entity doesn’t exist or doesn’t match the query, then a GetError is returned.

pub fn get_many_mut<const N: usize>( &mut self, entities: [EntityId; N], ) -> Result<[<Q as Query>::Item<'_>; N], GetManyMutError>

Returns the query items for the given array of entities.

An error of type GetManyMutError is returned in the following scenarios:

1. AliasedMutability if the given array contains any duplicate EntityIds.
2. NoSuchEntity if any of the entities do not exist.
3. QueryDoesNotMatch if any of the entities do not match the Query of this fetcher.

pub fn iter(&self) -> Iter<'_, Q>

where Q: ReadOnlyQuery,

Returns an iterator over all entities matching the read-only query.

pub fn iter_mut(&mut self) -> Iter<'_, Q>

Returns an iterator over all entities matching the query.

Trait Implementations

impl<'a, Q> Debug for Fetcher<'a, Q>

where Q: Query,

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

Formats the value using the given formatter.

impl<Q> HandlerParam for Fetcher<'_, Q>

where Q: Query + 'static,

type State = FetcherState<Q>

Persistent data stored in the handler.

type This<'a> = Fetcher<'a, Q>

The type produced by this handler param. This must be the type of Self but with the lifetime of 'a.

fn init( world: &mut World, config: &mut HandlerConfig, ) -> Result<<Fetcher<'_, Q> as HandlerParam>::State, InitError>

Initializes the handler using the input World and HandlerConfig.

unsafe fn get<'a>( state: &'a mut <Fetcher<'_, Q> as HandlerParam>::State, _info: &'a HandlerInfo, _event_ptr: EventPtr<'a>, _target_location: EntityLocation, world: UnsafeWorldCell<'a>, ) -> <Fetcher<'_, Q> as HandlerParam>::This<'a>

Obtains a new instance of the handler parameter.

fn refresh_archetype( state: &mut <Fetcher<'_, Q> as HandlerParam>::State, arch: &Archetype, )

Refresh an archetype for this handler param. Called whenever Handler::refresh_archetype is called.

fn remove_archetype( state: &mut <Fetcher<'_, Q> as HandlerParam>::State, arch: &Archetype, )

Remove the given archetype for this handler param. Called whenever Handler::remove_archetype is called.

impl<'a, Q> IntoIterator for &'a Fetcher<'_, Q>

where Q: ReadOnlyQuery,

type Item = <Q as Query>::Item<'a>

The type of the elements being iterated over.

type IntoIter = Iter<'a, Q>

Which kind of iterator are we turning this into?

fn into_iter(self) -> <&'a Fetcher<'_, Q> as IntoIterator>::IntoIter

Creates an iterator from a value.

impl<'a, Q> IntoIterator for &'a mut Fetcher<'_, Q>

where Q: Query,

type Item = <Q as Query>::Item<'a>

The type of the elements being iterated over.

type IntoIter = Iter<'a, Q>

Which kind of iterator are we turning this into?

fn into_iter(self) -> <&'a mut Fetcher<'_, Q> as IntoIterator>::IntoIter

Creates an iterator from a value.

impl<'a, Q> IntoIterator for Fetcher<'a, Q>

where Q: Query,

type Item = <Q as Query>::Item<'a>

The type of the elements being iterated over.

type IntoIter = Iter<'a, Q>

Which kind of iterator are we turning this into?

fn into_iter(self) -> <Fetcher<'a, Q> as IntoIterator>::IntoIter

Creates an iterator from a value.

impl<'a, Q> Send for Fetcher<'a, Q>

where Q: Query, <Q as Query>::Item<'a>: Send,

impl<'a, Q> Sync for Fetcher<'a, Q>

where Q: Query, <Q as Query>::Item<'a>: Sync,