6c003ef794
Fixes #18623, allowing `add_state_scoped_event` to work with computed states. As a side note, should state scoped events be updated to match the recently changed [state scoped entities](https://github.com/bevyengine/bevy/blob/main/release-content/migration-guides/rename_StateScoped.md)?
113 lines
3.3 KiB
Rust
113 lines
3.3 KiB
Rust
use alloc::vec::Vec;
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use core::marker::PhantomData;
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use bevy_app::{App, SubApp};
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use bevy_ecs::{
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event::{Event, EventReader, Events},
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resource::Resource,
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system::Commands,
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world::World,
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};
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use bevy_platform::collections::HashMap;
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use crate::state::{OnExit, StateTransitionEvent, States};
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fn clear_event_queue<E: Event>(w: &mut World) {
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if let Some(mut queue) = w.get_resource_mut::<Events<E>>() {
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queue.clear();
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}
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}
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#[derive(Resource)]
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struct StateScopedEvents<S: States> {
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cleanup_fns: HashMap<S, Vec<fn(&mut World)>>,
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}
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impl<S: States> StateScopedEvents<S> {
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fn add_event<E: Event>(&mut self, state: S) {
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self.cleanup_fns
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.entry(state)
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.or_default()
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.push(clear_event_queue::<E>);
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}
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fn cleanup(&self, w: &mut World, state: S) {
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let Some(fns) = self.cleanup_fns.get(&state) else {
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return;
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};
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for callback in fns {
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(*callback)(w);
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}
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}
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}
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impl<S: States> Default for StateScopedEvents<S> {
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fn default() -> Self {
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Self {
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cleanup_fns: HashMap::default(),
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}
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}
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}
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fn cleanup_state_scoped_event<S: States>(
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mut c: Commands,
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mut transitions: EventReader<StateTransitionEvent<S>>,
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) {
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let Some(transition) = transitions.read().last() else {
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return;
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};
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if transition.entered == transition.exited {
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return;
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}
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let Some(exited) = transition.exited.clone() else {
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return;
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};
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c.queue(move |w: &mut World| {
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w.resource_scope::<StateScopedEvents<S>, ()>(|w, events| {
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events.cleanup(w, exited);
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});
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});
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}
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fn add_state_scoped_event_impl<E: Event, S: States>(
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app: &mut SubApp,
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_p: PhantomData<E>,
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state: S,
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) {
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if !app.world().contains_resource::<StateScopedEvents<S>>() {
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app.init_resource::<StateScopedEvents<S>>();
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}
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app.add_event::<E>();
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app.world_mut()
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.resource_mut::<StateScopedEvents<S>>()
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.add_event::<E>(state.clone());
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app.add_systems(OnExit(state), cleanup_state_scoped_event::<S>);
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}
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/// Extension trait for [`App`] adding methods for registering state scoped events.
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pub trait StateScopedEventsAppExt {
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/// Adds an [`Event`] that is automatically cleaned up when leaving the specified `state`.
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///
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/// Note that event cleanup is ordered ambiguously relative to [`DespawnOnEnterState`](crate::prelude::DespawnOnEnterState)
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/// and [`DespawnOnExitState`](crate::prelude::DespawnOnExitState) entity
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/// cleanup and the [`OnExit`] schedule for the target state. All of these (state scoped
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/// entities and events cleanup, and `OnExit`) occur within schedule [`StateTransition`](crate::prelude::StateTransition)
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/// and system set `StateTransitionSystems::ExitSchedules`.
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fn add_state_scoped_event<E: Event>(&mut self, state: impl States) -> &mut Self;
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}
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impl StateScopedEventsAppExt for App {
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fn add_state_scoped_event<E: Event>(&mut self, state: impl States) -> &mut Self {
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add_state_scoped_event_impl(self.main_mut(), PhantomData::<E>, state);
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self
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}
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}
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impl StateScopedEventsAppExt for SubApp {
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fn add_state_scoped_event<E: Event>(&mut self, state: impl States) -> &mut Self {
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add_state_scoped_event_impl(self, PhantomData::<E>, state);
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self
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}
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}
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