Struct ArchetypeComponentId

pub struct ArchetypeComponentId(/* private fields */);

An opaque unique joint ID for a Component in an Archetype within a World.

A component may be present within multiple archetypes, but each component within each archetype has its own unique ArchetypeComponentId. This is leveraged by the system schedulers to opportunistically run multiple systems in parallel that would otherwise conflict. For example, Query<&mut A, With<B>> and Query<&mut A, Without<B>> can run in parallel as the matched ArchetypeComponentId sets for both queries are disjoint, even though &mut A on both queries point to the same ComponentId.

In SQL terms, these IDs are composite keys on a many-to-many relationship between archetypes and components. Each component type will have only one ComponentId, but may have many ArchetypeComponentIds, one for every archetype the component is present in. Likewise, each archetype will have only one ArchetypeId but may have many ArchetypeComponentIds, one for each component that belongs to the archetype.

Every Resource is also assigned one of these IDs. As resources do not belong to any particular archetype, a resource’s ID uniquely identifies it.

These IDs are only valid within a given World, and are not globally unique. Attempting to use an ID on a world that it wasn’t sourced from will not point to the same archetype nor the same component.

Trait Implementations

impl Clone for ArchetypeComponentId

fn clone(&self) -> ArchetypeComponentId

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for ArchetypeComponentId

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

Formats the value using the given formatter.

impl Hash for ArchetypeComponentId

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for ArchetypeComponentId

fn eq(&self, other: &ArchetypeComponentId) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl SparseSetIndex for ArchetypeComponentId

fn sparse_set_index(&self) -> usize

Gets the sparse set index corresponding to this instance.

fn get_sparse_set_index(value: usize) -> Self

Creates a new instance of this type with the specified index.

impl Copy for ArchetypeComponentId

impl Eq for ArchetypeComponentId

impl StructuralPartialEq for ArchetypeComponentId