bevy/crates/bevy_ecs/src/system/commands/mod.rs
2021-07-24 16:43:37 -07:00

531 lines
15 KiB
Rust

mod command_queue;
use crate::{
bundle::Bundle,
component::Component,
entity::{Entities, Entity},
world::World,
};
use bevy_utils::tracing::debug;
pub use command_queue::CommandQueue;
use std::marker::PhantomData;
/// A [`World`] mutation.
pub trait Command: Send + Sync + 'static {
fn write(self, world: &mut World);
}
/// A list of commands that will be run to modify a [`World`].
pub struct Commands<'a> {
queue: &'a mut CommandQueue,
entities: &'a Entities,
}
impl<'a> Commands<'a> {
/// Create a new `Commands` from a queue and a world.
pub fn new(queue: &'a mut CommandQueue, world: &'a World) -> Self {
Self {
queue,
entities: world.entities(),
}
}
/// Creates a new empty [`Entity`] and returns an [`EntityCommands`] builder for it.
///
/// # Example
///
/// ```
/// use bevy_ecs::prelude::*;
///
/// fn example_system(mut commands: Commands) {
/// // Create a new empty entity and retrieve its id.
/// let empty_entity = commands.spawn().id();
///
/// // Create another empty entity, then add some component to it
/// commands.spawn()
/// // adds a new component bundle to the entity
/// .insert_bundle((1usize, 2u32))
/// // adds a single component to the entity
/// .insert("hello world");
/// }
/// # example_system.system();
/// ```
pub fn spawn(&mut self) -> EntityCommands<'a, '_> {
let entity = self.entities.reserve_entity();
EntityCommands {
entity,
commands: self,
}
}
// TODO: this is a hack to work around the "multiple worlds" limitations:
// Right now Commands must allocate entities from their "scheduled" world, but Commands might be applied to other worlds,
// such as the "render world"
pub fn spawn_and_forget(&mut self, bundle: impl Bundle) {
self.queue.push(Spawn { bundle })
}
/// Creates a new entity with the components contained in `bundle`.
///
/// This returns an [`EntityCommands`] builder, which enables inserting more components and
/// bundles using a "builder pattern".
///
/// Note that `bundle` is a [`Bundle`], which is a collection of components. [`Bundle`] is
/// automatically implemented for tuples of components. You can also create your own bundle
/// types by deriving [`derive@Bundle`].
///
/// # Example
///
/// ```
/// use bevy_ecs::prelude::*;
///
/// struct Component1;
/// struct Component2;
///
/// #[derive(Bundle)]
/// struct ExampleBundle {
/// a: Component1,
/// b: Component2,
/// }
///
/// fn example_system(mut commands: Commands) {
/// // Create a new entity with a component bundle.
/// commands.spawn_bundle(ExampleBundle {
/// a: Component1,
/// b: Component2,
/// });
///
/// commands
/// // Create a new entity with two components using a "tuple bundle".
/// .spawn_bundle((Component1, Component2))
/// // spawn_bundle returns a builder, so you can insert more bundles like this:
/// .insert_bundle((1usize, 2u32))
/// // or insert single components like this:
/// .insert("hello world");
/// }
/// # example_system.system();
/// ```
pub fn spawn_bundle<'b, T: Bundle>(&'b mut self, bundle: T) -> EntityCommands<'a, 'b> {
let mut e = self.spawn();
e.insert_bundle(bundle);
e
}
/// Returns an [`EntityCommands`] builder for the requested [`Entity`].
///
/// # Example
///
/// ```
/// use bevy_ecs::prelude::*;
///
/// fn example_system(mut commands: Commands) {
/// // Create a new, empty entity
/// let entity = commands.spawn().id();
///
/// commands.entity(entity)
/// // adds a new component bundle to the entity
/// .insert_bundle((1usize, 2u32))
/// // adds a single component to the entity
/// .insert("hello world");
/// }
/// # example_system.system();
/// ```
pub fn entity(&mut self, entity: Entity) -> EntityCommands<'a, '_> {
EntityCommands {
entity,
commands: self,
}
}
/// Equivalent to iterating `bundles_iter` and calling [`Self::spawn`] on each bundle, but
/// slightly more performant.
pub fn spawn_batch<I>(&mut self, bundles_iter: I)
where
I: IntoIterator + Send + Sync + 'static,
I::Item: Bundle,
{
self.queue.push(SpawnBatch { bundles_iter });
}
/// See [`World::insert_resource`].
pub fn insert_resource<T: Component>(&mut self, resource: T) {
self.queue.push(InsertResource { resource })
}
/// Queue a resource removal.
pub fn remove_resource<T: Component>(&mut self) {
self.queue.push(RemoveResource::<T> {
phantom: PhantomData,
});
}
/// Adds a command directly to the command list.
pub fn add<C: Command>(&mut self, command: C) {
self.queue.push(command);
}
}
/// A list of commands that will be run to modify an [`Entity`].
pub struct EntityCommands<'a, 'b> {
entity: Entity,
commands: &'b mut Commands<'a>,
}
impl<'a, 'b> EntityCommands<'a, 'b> {
/// Retrieves the current entity's unique [`Entity`] id.
#[inline]
pub fn id(&self) -> Entity {
self.entity
}
/// Adds a [`Bundle`] of components to the current entity.
pub fn insert_bundle(&mut self, bundle: impl Bundle) -> &mut Self {
self.commands.add(InsertBundle {
entity: self.entity,
bundle,
});
self
}
/// Adds a single [`Component`] to the current entity.
///
///
/// # Warning
///
/// It's possible to call this with a bundle, but this is likely not intended and
/// [`Self::insert_bundle`] should be used instead. If `with` is called with a bundle, the
/// bundle itself will be added as a component instead of the bundles' inner components each
/// being added.
///
/// # Example
///
/// `Self::insert` can be chained with [`Commands::spawn`].
///
/// ```
/// use bevy_ecs::prelude::*;
///
/// struct Component1;
/// struct Component2;
///
/// fn example_system(mut commands: Commands) {
/// // Create a new entity with `Component1` and `Component2`
/// commands.spawn()
/// .insert(Component1)
/// .insert(Component2);
///
/// // Psst! These are also equivalent to the expression above!
/// commands.spawn().insert_bundle((Component1, Component2));
/// commands.spawn_bundle((Component1, Component2));
/// }
/// # example_system.system();
/// ```
pub fn insert(&mut self, component: impl Component) -> &mut Self {
self.commands.add(Insert {
entity: self.entity,
component,
});
self
}
/// See [`EntityMut::remove_bundle`](crate::world::EntityMut::remove_bundle).
pub fn remove_bundle<T>(&mut self) -> &mut Self
where
T: Bundle,
{
self.commands.add(RemoveBundle::<T> {
entity: self.entity,
phantom: PhantomData,
});
self
}
/// See [`EntityMut::remove`](crate::world::EntityMut::remove).
pub fn remove<T>(&mut self) -> &mut Self
where
T: Component,
{
self.commands.add(Remove::<T> {
entity: self.entity,
phantom: PhantomData,
});
self
}
/// Despawns only the specified entity, not including its children.
pub fn despawn(&mut self) {
self.commands.add(Despawn {
entity: self.entity,
})
}
/// Returns the underlying `[Commands]`.
pub fn commands(&mut self) -> &mut Commands<'a> {
self.commands
}
}
#[derive(Debug)]
pub struct Spawn<T> {
pub bundle: T,
}
impl<T> Command for Spawn<T>
where
T: Bundle,
{
fn write(self, world: &mut World) {
world.spawn().insert_bundle(self.bundle);
}
}
pub struct SpawnBatch<I>
where
I: IntoIterator,
I::Item: Bundle,
{
pub bundles_iter: I,
}
impl<I> Command for SpawnBatch<I>
where
I: IntoIterator + Send + Sync + 'static,
I::Item: Bundle,
{
fn write(self, world: &mut World) {
world.spawn_batch(self.bundles_iter);
}
}
#[derive(Debug)]
pub struct Despawn {
pub entity: Entity,
}
impl Command for Despawn {
fn write(self, world: &mut World) {
if !world.despawn(self.entity) {
debug!("Failed to despawn non-existent entity {:?}", self.entity);
}
}
}
pub struct InsertBundle<T> {
pub entity: Entity,
pub bundle: T,
}
impl<T> Command for InsertBundle<T>
where
T: Bundle + 'static,
{
fn write(self, world: &mut World) {
world.entity_mut(self.entity).insert_bundle(self.bundle);
}
}
#[derive(Debug)]
pub struct Insert<T> {
pub entity: Entity,
pub component: T,
}
impl<T> Command for Insert<T>
where
T: Component,
{
fn write(self, world: &mut World) {
world.entity_mut(self.entity).insert(self.component);
}
}
#[derive(Debug)]
pub struct Remove<T> {
pub entity: Entity,
pub phantom: PhantomData<T>,
}
impl<T> Command for Remove<T>
where
T: Component,
{
fn write(self, world: &mut World) {
if let Some(mut entity_mut) = world.get_entity_mut(self.entity) {
entity_mut.remove::<T>();
}
}
}
#[derive(Debug)]
pub struct RemoveBundle<T> {
pub entity: Entity,
pub phantom: PhantomData<T>,
}
impl<T> Command for RemoveBundle<T>
where
T: Bundle,
{
fn write(self, world: &mut World) {
if let Some(mut entity_mut) = world.get_entity_mut(self.entity) {
// remove intersection to gracefully handle components that were removed before running
// this command
entity_mut.remove_bundle_intersection::<T>();
}
}
}
pub struct InsertResource<T: Component> {
pub resource: T,
}
impl<T: Component> Command for InsertResource<T> {
fn write(self, world: &mut World) {
world.insert_resource(self.resource);
}
}
pub struct RemoveResource<T: Component> {
pub phantom: PhantomData<T>,
}
impl<T: Component> Command for RemoveResource<T> {
fn write(self, world: &mut World) {
world.remove_resource::<T>();
}
}
#[cfg(test)]
#[allow(clippy::float_cmp, clippy::approx_constant)]
mod tests {
use crate::{
component::{ComponentDescriptor, StorageType},
system::{CommandQueue, Commands},
world::World,
};
use std::sync::{
atomic::{AtomicUsize, Ordering},
Arc,
};
#[derive(Clone, Debug)]
struct DropCk(Arc<AtomicUsize>);
impl DropCk {
fn new_pair() -> (Self, Arc<AtomicUsize>) {
let atomic = Arc::new(AtomicUsize::new(0));
(DropCk(atomic.clone()), atomic)
}
}
impl Drop for DropCk {
fn drop(&mut self) {
self.0.as_ref().fetch_add(1, Ordering::Relaxed);
}
}
#[test]
fn commands() {
let mut world = World::default();
let mut command_queue = CommandQueue::default();
let entity = Commands::new(&mut command_queue, &world)
.spawn_bundle((1u32, 2u64))
.id();
command_queue.apply(&mut world);
assert!(world.entities().len() == 1);
let results = world
.query::<(&u32, &u64)>()
.iter(&world)
.map(|(a, b)| (*a, *b))
.collect::<Vec<_>>();
assert_eq!(results, vec![(1u32, 2u64)]);
// test entity despawn
{
let mut commands = Commands::new(&mut command_queue, &world);
commands.entity(entity).despawn();
commands.entity(entity).despawn(); // double despawn shouldn't panic
}
command_queue.apply(&mut world);
let results2 = world
.query::<(&u32, &u64)>()
.iter(&world)
.map(|(a, b)| (*a, *b))
.collect::<Vec<_>>();
assert_eq!(results2, vec![]);
}
#[test]
fn remove_components() {
let mut world = World::default();
struct DenseDropCk(DropCk);
world
.register_component(ComponentDescriptor::new::<DropCk>(StorageType::SparseSet))
.unwrap();
let mut command_queue = CommandQueue::default();
let (dense_dropck, dense_is_dropped) = DropCk::new_pair();
let dense_dropck = DenseDropCk(dense_dropck);
let (sparse_dropck, sparse_is_dropped) = DropCk::new_pair();
let entity = Commands::new(&mut command_queue, &world)
.spawn()
.insert_bundle((1u32, 2u64, dense_dropck, sparse_dropck))
.id();
command_queue.apply(&mut world);
let results_before = world
.query::<(&u32, &u64)>()
.iter(&world)
.map(|(a, b)| (*a, *b))
.collect::<Vec<_>>();
assert_eq!(results_before, vec![(1u32, 2u64)]);
// test component removal
Commands::new(&mut command_queue, &world)
.entity(entity)
.remove::<u32>()
.remove_bundle::<(u32, u64, DenseDropCk, DropCk)>();
assert_eq!(dense_is_dropped.load(Ordering::Relaxed), 0);
assert_eq!(sparse_is_dropped.load(Ordering::Relaxed), 0);
command_queue.apply(&mut world);
assert_eq!(dense_is_dropped.load(Ordering::Relaxed), 1);
assert_eq!(sparse_is_dropped.load(Ordering::Relaxed), 1);
let results_after = world
.query::<(&u32, &u64)>()
.iter(&world)
.map(|(a, b)| (*a, *b))
.collect::<Vec<_>>();
assert_eq!(results_after, vec![]);
let results_after_u64 = world
.query::<&u64>()
.iter(&world)
.copied()
.collect::<Vec<_>>();
assert_eq!(results_after_u64, vec![]);
}
#[test]
fn remove_resources() {
let mut world = World::default();
let mut queue = CommandQueue::default();
{
let mut commands = Commands::new(&mut queue, &world);
commands.insert_resource(123);
commands.insert_resource(456.0);
}
queue.apply(&mut world);
assert!(world.contains_resource::<i32>());
assert!(world.contains_resource::<f64>());
{
let mut commands = Commands::new(&mut queue, &world);
// test resource removal
commands.remove_resource::<i32>();
}
queue.apply(&mut world);
assert!(!world.contains_resource::<i32>());
assert!(world.contains_resource::<f64>());
}
}