Enum bevy::ecs::world::Entry

pub enum Entry<'w, 'a, T>
where
    T: Component,
{
    Occupied(OccupiedEntry<'w, 'a, T>),
    Vacant(VacantEntry<'w, 'a, T>),
}

A view into a single entity and component in a world, which may either be vacant or occupied.

This enum can only be constructed from the entry method on EntityWorldMut.

Variants

Occupied(OccupiedEntry<'w, 'a, T>)

An occupied entry.

Vacant(VacantEntry<'w, 'a, T>)

A vacant entry.

Implementations

impl<'w, 'a, T> Entry<'w, 'a, T>

where T: Component,

pub fn and_modify<F>(self, f: F) -> Entry<'w, 'a, T>

where F: FnOnce(Mut<'_, T>),

Provides in-place mutable access to an occupied entry.

Examples

#[derive(Component, Default, Clone, Copy, Debug, PartialEq)]
struct Comp(u32);

let mut entity = world.spawn(Comp(0));

entity.entry::<Comp>().and_modify(|mut c| c.0 += 1);
assert_eq!(world.query::<&Comp>().single(&world).0, 1);

pub fn insert_entry(self, component: T) -> OccupiedEntry<'w, 'a, T>

Replaces the component of the entry, and returns an OccupiedEntry.

Examples

#[derive(Component, Default, Clone, Copy, Debug, PartialEq)]
struct Comp(u32);

let mut entity = world.spawn_empty();

let entry = entity.entry().insert_entry(Comp(4));
assert_eq!(entry.get(), &Comp(4));

let entry = entity.entry().insert_entry(Comp(2));
assert_eq!(entry.get(), &Comp(2));

pub fn or_insert(self, default: T) -> Mut<'a, T>

Ensures the entry has this component by inserting the given default if empty, and returns a mutable reference to this component in the entry.

Examples

#[derive(Component, Default, Clone, Copy, Debug, PartialEq)]
struct Comp(u32);

let mut entity = world.spawn_empty();

entity.entry().or_insert(Comp(4));
assert_eq!(world.query::<&Comp>().single(&world).0, 4);

entity.entry().or_insert(Comp(15)).0 *= 2;
assert_eq!(world.query::<&Comp>().single(&world).0, 8);

pub fn or_insert_with<F>(self, default: F) -> Mut<'a, T>

where F: FnOnce() -> T,

Ensures the entry has this component by inserting the result of the default function if empty, and returns a mutable reference to this component in the entry.

Examples

#[derive(Component, Default, Clone, Copy, Debug, PartialEq)]
struct Comp(u32);

let mut entity = world.spawn_empty();

entity.entry().or_insert_with(|| Comp(4));
assert_eq!(world.query::<&Comp>().single(&world).0, 4);

impl<'w, 'a, T> Entry<'w, 'a, T>

where T: Component + Default,

pub fn or_default(self) -> Mut<'a, T>

Ensures the entry has this component by inserting the default value if empty, and returns a mutable reference to this component in the entry.

Examples

#[derive(Component, Default, Clone, Copy, Debug, PartialEq)]
struct Comp(u32);

let mut entity = world.spawn_empty();

entity.entry::<Comp>().or_default();
assert_eq!(world.query::<&Comp>().single(&world).0, 0);