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[Merged by Bors] - Redo State architecture #1424

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[Merged by Bors] - Redo State architecture #1424

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a9d4f55
Implement StateSet
TheRawMeatball Feb 9, 2021
4c4f795
ci fix
TheRawMeatball Feb 10, 2021
ff6ed69
Improve API and remove StateStage
TheRawMeatball Feb 11, 2021
ca54b6e
Fix bevy_app
TheRawMeatball Feb 11, 2021
f1073f5
Minor cleanup
TheRawMeatball Feb 12, 2021
49adf8e
Major improvements
TheRawMeatball Feb 15, 2021
5c756a8
Fix startup bug
TheRawMeatball Feb 16, 2021
bf78a9e
Add InStackUpdate
TheRawMeatball Feb 16, 2021
a515a97
Fix unit test
TheRawMeatball Feb 16, 2021
79f68ee
Arbitrarily typed states
TheRawMeatball Feb 19, 2021
2bc0e30
Removed redundant allow
TheRawMeatball Feb 19, 2021
b659cec
Merge branch 'main' into state-set-v2
TheRawMeatball Mar 5, 2021
c1f6079
Update State
TheRawMeatball Mar 5, 2021
12a98e5
hotfix
TheRawMeatball Mar 5, 2021
d0065f2
Finalize
TheRawMeatball Mar 5, 2021
f493d32
Finish
TheRawMeatball Mar 5, 2021
2f5cac9
Update crates/bevy_ecs/src/schedule/state.rs
TheRawMeatball Mar 5, 2021
0616037
Remove unnecessary /**/
TheRawMeatball Mar 5, 2021
e71dc64
Improve API ergonomics
TheRawMeatball Mar 6, 2021
3da119f
Hotfix
TheRawMeatball Mar 6, 2021
b8b0081
Fix same-state transitions
TheRawMeatball Mar 13, 2021
1c6beed
Cut down on explicit ordering
TheRawMeatball Mar 14, 2021
07cb8fe
Merge branch 'main' into state-set-v2
TheRawMeatball Mar 14, 2021
eb37b9a
cargo fmt
TheRawMeatball Mar 14, 2021
1f4a4fb
Remove unnecessary println!
TheRawMeatball Mar 15, 2021
e67bab1
Final issues
TheRawMeatball Mar 15, 2021
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195 changes: 171 additions & 24 deletions crates/bevy_ecs/src/schedule/state.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,6 @@

use std::{
any::TypeId,
marker::PhantomData,
mem::{discriminant, Discriminant},
};

Expand All @@ -12,6 +11,13 @@ use crate::{
};
use thiserror::Error;

/// ### Stack based state machine
/// Important: `T` must be an enum!
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///
/// This state machine has three operations: Next, Pop, and Push.
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/// * Push pushes a new state to the state stack, pausing the previous state
/// * Pop removes the current state, and unpauses the last paused state.
/// * Next unwinds the state stack, and replaces the entire stack with a single new state
#[derive(Debug)]
pub struct State<T: Clone> {
transition: Option<StateTransition<T>>,
Expand Down Expand Up @@ -61,6 +67,9 @@ impl<T: Clone + Resource> State<T> {
Wrapper::<T, OnExit>::new(discriminant(&d))
}

/// Creates a driver set for the State.
///
/// Important note: this set must be inserted **before** all other state-dependant sets to work properly!
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This is unfortunate, but I don't think this can be avoided until #1375 or some stop-gap measure that lets us order run criteria evaluation.

pub fn make_driver() -> SystemSet {
SystemSet::default().with_run_criteria(state_cleaner::<T>.system())
}
Expand Down Expand Up @@ -165,24 +174,37 @@ pub enum StateError {
}

trait Comparer<T: Clone> {
fn compare(d: Discriminant<T>, s: &State<T>) -> bool;
fn compare(&mut self, d: Discriminant<T>, s: &State<T>) -> bool;
}

#[derive(Default)]
struct OnUpdate;
impl<T: Clone> Comparer<T> for OnUpdate {
fn compare(d: Discriminant<T>, s: &State<T>) -> bool {
fn compare(&mut self, d: Discriminant<T>, s: &State<T>) -> bool {
discriminant(s.stack.last().unwrap()) == d && s.transition.is_none()
}
}
struct OnInactiveUpdate;
#[derive(Default)]
struct OnInactiveUpdate(bool /*tracks if the relevant state has been entered*/);
impl<T: Clone> Comparer<T> for OnInactiveUpdate {
fn compare(d: Discriminant<T>, s: &State<T>) -> bool {
s.stack.iter().map(discriminant).any(|s| s == d) && s.transition.is_none()
fn compare(&mut self, d: Discriminant<T>, s: &State<T>) -> bool {
match &s.transition {
Some(StateTransition::Pausing(ref relevant, _))
| Some(StateTransition::Resuming(_, ref relevant)) => {
if discriminant(relevant) == d {
self.0 = !self.0;
}
false
}
Some(_) => false,
None => self.0,
}
}
}
#[derive(Default)]
struct OnEnter;
impl<T: Clone> Comparer<T> for OnEnter {
fn compare(d: Discriminant<T>, s: &State<T>) -> bool {
fn compare(&mut self, d: Discriminant<T>, s: &State<T>) -> bool {
s.transition
.as_ref()
.map_or(false, |transition| match transition {
Expand All @@ -192,9 +214,10 @@ impl<T: Clone> Comparer<T> for OnEnter {
})
}
}
#[derive(Default)]
struct OnExit;
impl<T: Clone> Comparer<T> for OnExit {
fn compare(d: Discriminant<T>, s: &State<T>) -> bool {
fn compare(&mut self, d: Discriminant<T>, s: &State<T>) -> bool {
s.transition
.as_ref()
.map_or(false, |transition| match transition {
Expand All @@ -204,9 +227,10 @@ impl<T: Clone> Comparer<T> for OnExit {
})
}
}
#[derive(Default)]
struct OnPause;
impl<T: Clone> Comparer<T> for OnPause {
fn compare(d: Discriminant<T>, s: &State<T>) -> bool {
fn compare(&mut self, d: Discriminant<T>, s: &State<T>) -> bool {
s.transition
.as_ref()
.map_or(false, |transition| match transition {
Expand All @@ -215,9 +239,10 @@ impl<T: Clone> Comparer<T> for OnPause {
})
}
}
#[derive(Default)]
struct OnResume;
impl<T: Clone> Comparer<T> for OnResume {
fn compare(d: Discriminant<T>, s: &State<T>) -> bool {
fn compare(&mut self, d: Discriminant<T>, s: &State<T>) -> bool {
s.transition
.as_ref()
.map_or(false, |transition| match transition {
Expand All @@ -227,7 +252,7 @@ impl<T: Clone> Comparer<T> for OnResume {
}
}

impl<T: Clone + Resource, C: Comparer<T>> Wrapper<T, C> {
impl<T: Clone + Resource, C: Comparer<T> + Default> Wrapper<T, C> {
fn new(discriminant: Discriminant<T>) -> Self {
let mut resource_access = TypeAccess::default();
resource_access.add_read(std::any::TypeId::of::<State<T>>());
Expand All @@ -238,22 +263,22 @@ impl<T: Clone + Resource, C: Comparer<T>> Wrapper<T, C> {
id: SystemId::new(),
archetype_access: Default::default(),
component_access: Default::default(),
marker: Default::default(),
comparer: Default::default(),
}
}
}

struct Wrapper<T: Clone + Resource, C: Comparer<T>> {
struct Wrapper<T: Clone + Resource, C: Comparer<T> + Default> {
discriminant: Discriminant<T>,
exit_flag: bool,
resource_access: TypeAccess<TypeId>,
id: SystemId,
archetype_access: TypeAccess<ArchetypeComponent>,
component_access: TypeAccess<TypeId>,
marker: PhantomData<C>,
comparer: C,
}

impl<T: Clone + Resource, C: Comparer<T> + Resource> System for Wrapper<T, C> {
impl<T: Clone + Resource, C: Comparer<T> + Resource + Default> System for Wrapper<T, C> {
type In = ();
type Out = ShouldRun;

Expand Down Expand Up @@ -299,7 +324,7 @@ impl<T: Clone + Resource, C: Comparer<T> + Resource> System for Wrapper<T, C> {
Some(ShouldRun::No)
} else {
self.exit_flag = true;
Some(if C::compare(self.discriminant, state) {
Some(if self.comparer.compare(self.discriminant, state) {
ShouldRun::YesAndCheckAgain
} else {
ShouldRun::NoAndCheckAgain
Expand Down Expand Up @@ -364,28 +389,150 @@ fn state_cleaner<T: Clone + Resource>(mut state: ResMut<State<T>>) -> ShouldRun
mod test {
use crate::prelude::*;

#[derive(Clone, Copy)]
enum StateEnum {
#[derive(Clone, Copy, PartialEq, Eq)]
enum MyState {
S1,
S2,
S3,
S4,
S5,
S6,
Final,
}

#[test]
fn state_test() {
let mut world = World::default();
let mut resources = Resources::default();

resources.insert(Vec::<i32>::new());
resources.insert(Vec::<&'static str>::new());
resources.insert(State::new(MyState::S1));

let mut stage = SystemStage::parallel();

stage.add_system_set(State::<StateEnum>::make_driver());
stage.add_system_set(
SystemSet::default().with_run_criteria(State::<StateEnum>::on_update(StateEnum::S1)),
);
stage.add_system_set(State::<MyState>::make_driver());
stage
.add_system_set(
SystemSet::default()
.with_system(
(|mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
r.push("update S1");
s.overwrite_next(MyState::S2).unwrap();
})
.system(),
)
.with_run_criteria(State::<MyState>::on_update(MyState::S1)),
)
.add_system_set(
SystemSet::default()
.with_system((|mut r: ResMut<Vec<&'static str>>| r.push("enter S2")).system())
.with_run_criteria(State::<MyState>::on_enter(MyState::S2)),
)
.add_system_set(
SystemSet::default()
.with_system(
(|mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
r.push("update S2");
s.overwrite_next(MyState::S3).unwrap();
})
.system(),
)
.with_run_criteria(State::<MyState>::on_update(MyState::S2)),
)
.add_system_set(
SystemSet::default()
.with_system((|mut r: ResMut<Vec<&'static str>>| r.push("exit S2")).system())
.with_run_criteria(State::<MyState>::on_exit(MyState::S2)),
)
.add_system_set(
SystemSet::default()
.with_system((|mut r: ResMut<Vec<&'static str>>| r.push("enter S3")).system())
.with_run_criteria(State::<MyState>::on_enter(MyState::S3)),
)
.add_system_set(
SystemSet::default()
.with_system(
(|mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
r.push("update S3");
s.overwrite_push(MyState::S4).unwrap();
})
.system(),
)
.with_run_criteria(State::<MyState>::on_update(MyState::S3)),
)
.add_system_set(
SystemSet::default()
.with_system((|mut r: ResMut<Vec<&'static str>>| r.push("pause S3")).system())
.with_run_criteria(State::<MyState>::on_pause(MyState::S3)),
)
.add_system_set(
SystemSet::default()
.with_system(
(|mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
r.push("update S4");
s.overwrite_push(MyState::S5).unwrap();
})
.system(),
)
.with_run_criteria(State::<MyState>::on_update(MyState::S4)),
)
.add_system_set(
SystemSet::default()
.with_system(
(|mut r: ResMut<Vec<&'static str>>| r.push("inactive S4")).system(),
)
.with_run_criteria(State::<MyState>::on_inactive_update(MyState::S4)),
)
.add_system_set(
SystemSet::default()
.with_system(
(|mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
r.push("update S5");
s.overwrite_push(MyState::S6).unwrap();
})
.system(),
)
.with_run_criteria(State::<MyState>::on_update(MyState::S5)),
)
.add_system_set(
SystemSet::default()
.with_system(
(|mut r: ResMut<Vec<&'static str>>| r.push("inactive S5")).system(),
)
.with_run_criteria(State::<MyState>::on_inactive_update(MyState::S5)),
)
.add_system_set(
SystemSet::default()
.with_system(
(|mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
r.push("update S6");
s.overwrite_push(MyState::Final).unwrap();
})
.system(),
)
.with_run_criteria(State::<MyState>::on_update(MyState::S6)),
)
.add_system_set(
SystemSet::default()
.with_system((|mut r: ResMut<Vec<&'static str>>| r.push("resume S4")).system())
.with_run_criteria(State::<MyState>::on_resume(MyState::S4)),
)
.add_system_set(
SystemSet::default()
.with_system((|mut r: ResMut<Vec<&'static str>>| r.push("exit S4")).system())
.with_run_criteria(State::<MyState>::on_exit(MyState::S4)),
);

loop {
println!("new run!");
stage.run(&mut world, &mut resources);
for s in resources.get_mut::<Vec<&'static str>>().unwrap().drain(..) {
println!("{}", s);
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}

stage.run(&mut world, &mut resources);
if resources.get::<State<MyState>>().unwrap().current() == &MyState::Final {
break;
}
}
}
}