bevy/crates/bevy_ecs/src/system/commands.rs
Carter Anderson b17f8a4bce format comments (#1612)
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2021-03-11 00:27:30 +00:00

478 lines
13 KiB
Rust

use crate::{
bundle::Bundle,
component::Component,
entity::{Entities, Entity},
world::World,
};
use bevy_utils::tracing::debug;
use std::marker::PhantomData;
/// A [World] mutation
pub trait Command: Send + Sync + 'static {
fn write(self: Box<Self>, world: &mut World);
}
#[derive(Default)]
pub struct CommandQueue {
commands: Vec<Box<dyn Command>>,
}
impl CommandQueue {
pub fn apply(&mut self, world: &mut World) {
world.flush();
for command in self.commands.drain(..) {
command.write(world);
}
}
#[inline]
pub fn push(&mut self, command: Box<dyn Command>) {
self.commands.push(command);
}
}
/// A list of commands that will be run to modify a `World`
pub struct Commands<'a> {
queue: &'a mut CommandQueue,
entities: &'a Entities,
current_entity: Option<Entity>,
}
impl<'a> Commands<'a> {
pub fn new(queue: &'a mut CommandQueue, world: &'a World) -> Self {
Self {
queue,
entities: world.entities(),
current_entity: None,
}
}
/// Creates a new entity with the components contained in `bundle`.
///
/// 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`]. If you would like to spawn an entity with a single
/// component, consider wrapping the component in a tuple (which [Bundle] is implemented for).
///
/// See [`Self::set_current_entity`], [`Self::insert`].
///
/// # 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(ExampleBundle {
/// a: Component1,
/// b: Component2,
/// });
///
/// // Create a new entity with a single component.
/// commands.spawn((Component1,));
/// // Create a new entity with two components.
/// commands.spawn((Component1, Component2));
/// }
/// # example_system.system();
/// ```
pub fn spawn(&mut self, bundle: impl Bundle) -> &mut Self {
let entity = self.entities.reserve_entity();
self.set_current_entity(entity);
self.insert_bundle(entity, bundle);
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) -> &mut Self
where
I: IntoIterator + Send + Sync + 'static,
I::Item: Bundle,
{
self.add_command(SpawnBatch { bundles_iter })
}
/// Despawns only the specified entity, not including its children.
pub fn despawn(&mut self, entity: Entity) -> &mut Self {
self.add_command(Despawn { entity })
}
/// Inserts a bundle of components into `entity`.
///
/// See [crate::world::EntityMut::insert_bundle].
pub fn insert_bundle(&mut self, entity: Entity, bundle: impl Bundle) -> &mut Self {
self.add_command(InsertBundle { entity, bundle })
}
/// Inserts a single component into `entity`.
///
/// See [crate::world::EntityMut::insert].
pub fn insert(&mut self, entity: Entity, component: impl Component) -> &mut Self {
self.add_command(Insert { entity, component })
}
/// See [crate::world::EntityMut::remove].
pub fn remove<T>(&mut self, entity: Entity) -> &mut Self
where
T: Component,
{
self.add_command(Remove::<T> {
entity,
phantom: PhantomData,
})
}
/// See [World::insert_resource].
pub fn insert_resource<T: Component>(&mut self, resource: T) -> &mut Self {
self.add_command(InsertResource { resource })
}
/// See [crate::world::EntityMut::remove_bundle].
pub fn remove_bundle<T>(&mut self, entity: Entity) -> &mut Self
where
T: Bundle,
{
self.add_command(RemoveBundle::<T> {
entity,
phantom: PhantomData,
})
}
pub fn remove_resource<T: Component>(&mut self) -> &mut Self {
self.add_command(RemoveResource::<T> {
phantom: PhantomData,
})
}
/// Adds a bundle of components to the current entity.
///
/// See [`Self::with`], [`Self::current_entity`].
pub fn with_bundle(&mut self, bundle: impl Bundle) -> &mut Self {
let current_entity = self.current_entity.expect("Cannot add bundle because the 'current entity' is not set. You should spawn an entity first.");
self.queue.push(Box::new(InsertBundle {
entity: current_entity,
bundle,
}));
self
}
/// Adds a single component to the current entity.
///
/// See [`Self::with_bundle`], [`Self::current_entity`].
///
/// # Warning
///
/// It's possible to call this with a bundle, but this is likely not intended and
/// [`Self::with_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
///
/// `with` can be chained with [`Self::spawn`].
///
/// ```
/// use bevy_ecs::prelude::*;
///
/// struct Component1;
/// struct Component2;
///
/// fn example_system(mut commands: Commands) {
/// // Create a new entity with a `Component1` and `Component2`.
/// commands.spawn((Component1,)).with(Component2);
///
/// // Psst! These are also equivalent to the line above!
/// commands.spawn((Component1, Component2));
/// commands.spawn(()).with(Component1).with(Component2);
/// #[derive(Bundle)]
/// struct ExampleBundle {
/// a: Component1,
/// b: Component2,
/// }
/// commands.spawn(()).with_bundle(ExampleBundle {
/// a: Component1,
/// b: Component2,
/// });
/// }
/// # example_system.system();
/// ```
pub fn with(&mut self, component: impl Component) -> &mut Self {
let current_entity = self.current_entity.expect("Cannot add component because the 'current entity' is not set. You should spawn an entity first.");
self.queue.push(Box::new(Insert {
entity: current_entity,
component,
}));
self
}
/// Adds a command directly to the command list. Prefer this to [`Self::add_command_boxed`] if
/// the type of `command` is statically known.
pub fn add_command<C: Command>(&mut self, command: C) -> &mut Self {
self.queue.push(Box::new(command));
self
}
/// See [`Self::add_command`].
pub fn add_command_boxed(&mut self, command: Box<dyn Command>) -> &mut Self {
self.queue.push(command);
self
}
/// Returns the current entity, set by [`Self::spawn`] or with [`Self::set_current_entity`].
pub fn current_entity(&self) -> Option<Entity> {
self.current_entity
}
pub fn set_current_entity(&mut self, entity: Entity) {
self.current_entity = Some(entity);
}
pub fn clear_current_entity(&mut self) {
self.current_entity = None;
}
pub fn for_current_entity(&mut self, f: impl FnOnce(Entity)) -> &mut Self {
let current_entity = self
.current_entity
.expect("The 'current entity' is not set. You should spawn an entity first.");
f(current_entity);
self
}
}
#[derive(Debug)]
pub(crate) struct Spawn<T> {
bundle: T,
}
impl<T> Command for Spawn<T>
where
T: Bundle,
{
fn write(self: Box<Self>, world: &mut World) {
world.spawn().insert_bundle(self.bundle);
}
}
pub(crate) struct SpawnBatch<I>
where
I: IntoIterator,
I::Item: Bundle,
{
bundles_iter: I,
}
impl<I> Command for SpawnBatch<I>
where
I: IntoIterator + Send + Sync + 'static,
I::Item: Bundle,
{
fn write(self: Box<Self>, world: &mut World) {
world.spawn_batch(self.bundles_iter);
}
}
#[derive(Debug)]
pub(crate) struct Despawn {
entity: Entity,
}
impl Command for Despawn {
fn write(self: Box<Self>, world: &mut World) {
if !world.despawn(self.entity) {
debug!("Failed to despawn non-existent entity {:?}", self.entity);
}
}
}
pub struct InsertBundle<T> {
entity: Entity,
bundle: T,
}
impl<T> Command for InsertBundle<T>
where
T: Bundle + 'static,
{
fn write(self: Box<Self>, world: &mut World) {
world.entity_mut(self.entity).insert_bundle(self.bundle);
}
}
#[derive(Debug)]
pub(crate) struct Insert<T> {
entity: Entity,
component: T,
}
impl<T> Command for Insert<T>
where
T: Component,
{
fn write(self: Box<Self>, world: &mut World) {
world.entity_mut(self.entity).insert(self.component);
}
}
#[derive(Debug)]
pub(crate) struct Remove<T> {
entity: Entity,
phantom: PhantomData<T>,
}
impl<T> Command for Remove<T>
where
T: Component,
{
fn write(self: Box<Self>, world: &mut World) {
if let Some(mut entity_mut) = world.get_entity_mut(self.entity) {
entity_mut.remove::<T>();
}
}
}
#[derive(Debug)]
pub(crate) struct RemoveBundle<T> {
entity: Entity,
phantom: PhantomData<T>,
}
impl<T> Command for RemoveBundle<T>
where
T: Bundle,
{
fn write(self: Box<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> {
resource: T,
}
impl<T: Component> Command for InsertResource<T> {
fn write(self: Box<Self>, world: &mut World) {
world.insert_resource(self.resource);
}
}
pub struct RemoveResource<T: Component> {
phantom: PhantomData<T>,
}
impl<T: Component> Command for RemoveResource<T> {
fn write(self: Box<Self>, world: &mut World) {
world.remove_resource::<T>();
}
}
#[cfg(test)]
#[allow(clippy::float_cmp, clippy::approx_constant)]
mod tests {
use crate::{
system::{CommandQueue, Commands},
world::World,
};
#[test]
fn commands() {
let mut world = World::default();
let mut command_queue = CommandQueue::default();
let entity = Commands::new(&mut command_queue, &world)
.spawn((1u32, 2u64))
.current_entity()
.unwrap();
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
Commands::new(&mut command_queue, &world)
.despawn(entity)
.despawn(entity); // 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();
let mut command_queue = CommandQueue::default();
let entity = Commands::new(&mut command_queue, &world)
.spawn((1u32, 2u64))
.current_entity()
.unwrap();
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)
.remove::<u32>(entity)
.remove_bundle::<(u32, u64)>(entity);
command_queue.apply(&mut world);
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>());
}
}