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Change State::*_next to *_replace, add proper next (#1676)

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In the current impl, next clears out the entire stack and replaces it with a new state. This PR moves this functionality into a replace method, and changes the behavior of next to only change the top state.

Co-authored-by: Carter Anderson <mcanders1@gmail.com>
This commit is contained in:
TheRawMeatball 2021-03-25 03:28:40 +00:00
parent 621cba4864
commit 78edec2e45
5 changed files with 63 additions and 30 deletions
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81
crates/bevy_ecs/src/schedule/state.rs
View File

@ -11,12 +11,13 @@ use thiserror::Error;
/// ### Stack based state machine
///
/// This state machine has three operations: Push, Pop, and Next.
/// This state machine has four operations: Push, Pop, Next and Replace.
/// * 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
/// * Pop removes the current state, and unpauses the last paused state
/// * Set replaces the active state with a new one
/// * Replace unwinds the state stack, and replaces the entire stack with a single new state
#[derive(Debug)]
pub struct State<T> {
pub struct State<T: Component + Clone + Eq> {
transition: Option<StateTransition<T>>,
stack: Vec<T>,
scheduled: Option<ScheduledOperation<T>>,
@ -24,7 +25,7 @@ pub struct State<T> {
}
#[derive(Debug)]
enum StateTransition<T> {
enum StateTransition<T: Component + Clone + Eq> {
PreStartup,
Startup,
// The parameter order is always (leaving, entering)
@ -36,8 +37,9 @@ enum StateTransition<T> {
}
#[derive(Debug)]
enum ScheduledOperation<T> {
Next(T),
enum ScheduledOperation<T: Component + Clone + Eq> {
Set(T),
Replace(T),
Pop,
Push(T),
}
@ -270,10 +272,10 @@ where
}
}
/// Schedule a state change that replaces the full stack with the given state.
/// Schedule a state change that replaces the active state with the given state.
/// This will fail if there is a scheduled operation, or if the given `state` matches the
/// current state
pub fn set_next(&mut self, state: T) -> Result<(), StateError> {
pub fn set(&mut self, state: T) -> Result<(), StateError> {
if self.stack.last().unwrap() == &state {
return Err(StateError::AlreadyInState);
}
@ -282,23 +284,48 @@ where
return Err(StateError::StateAlreadyQueued);
}
self.scheduled = Some(ScheduledOperation::Next(state));
self.scheduled = Some(ScheduledOperation::Set(state));
Ok(())
}
/// Same as [Self::set_next], but if there is already a next state, it will be overwritten
/// Same as [Self::set], but if there is already a next state, it will be overwritten
/// instead of failing
pub fn overwrite_next(&mut self, state: T) -> Result<(), StateError> {
pub fn overwrite_set(&mut self, state: T) -> Result<(), StateError> {
if self.stack.last().unwrap() == &state {
return Err(StateError::AlreadyInState);
}
self.scheduled = Some(ScheduledOperation::Next(state));
self.scheduled = Some(ScheduledOperation::Set(state));
Ok(())
}
/// Same as [Self::set_next], but does a push operation instead of a next operation
pub fn set_push(&mut self, state: T) -> Result<(), StateError> {
/// Schedule a state change that replaces the full stack with the given state.
/// This will fail if there is a scheduled operation, or if the given `state` matches the current state
pub fn replace(&mut self, state: T) -> Result<(), StateError> {
if self.stack.last().unwrap() == &state {
return Err(StateError::AlreadyInState);
}
if self.scheduled.is_some() {
return Err(StateError::StateAlreadyQueued);
}
self.scheduled = Some(ScheduledOperation::Replace(state));
Ok(())
}
/// Same as [Self::replace], but if there is already a next state, it will be overwritten instead of failing
pub fn overwrite_replace(&mut self, state: T) -> Result<(), StateError> {
if self.stack.last().unwrap() == &state {
return Err(StateError::AlreadyInState);
}
self.scheduled = Some(ScheduledOperation::Replace(state));
Ok(())
}
/// Same as [Self::set], but does a push operation instead of a next operation
pub fn push(&mut self, state: T) -> Result<(), StateError> {
if self.stack.last().unwrap() == &state {
return Err(StateError::AlreadyInState);
}
@ -311,7 +338,7 @@ where
Ok(())
}
/// Same as [Self::set_push], but if there is already a next state, it will be overwritten
/// Same as [Self::push], but if there is already a next state, it will be overwritten
/// instead of failing
pub fn overwrite_push(&mut self, state: T) -> Result<(), StateError> {
if self.stack.last().unwrap() == &state {
@ -322,8 +349,8 @@ where
Ok(())
}
/// Same as [Self::set_next], but does a pop operation instead of a next operation
pub fn set_pop(&mut self) -> Result<(), StateError> {
/// Same as [Self::next], but does a pop operation instead of a set operation
pub fn pop(&mut self) -> Result<(), StateError> {
if self.scheduled.is_some() {
return Err(StateError::StateAlreadyQueued);
}
@ -336,7 +363,7 @@ where
Ok(())
}
/// Same as [Self::set_pop], but if there is already a next state, it will be overwritten
/// Same as [Self::pop], but if there is already a next state, it will be overwritten
/// instead of failing
pub fn overwrite_pop(&mut self) -> Result<(), StateError> {
if self.stack.len() == 1 {
@ -394,14 +421,20 @@ fn state_cleaner<T: Component + Clone + Eq>(
return ShouldRun::No;
}
match state.scheduled.take() {
Some(ScheduledOperation::Next(next)) => {
Some(ScheduledOperation::Set(next)) => {
state.transition = Some(StateTransition::ExitingFull(
state.stack.last().unwrap().clone(),
next,
));
}
Some(ScheduledOperation::Replace(next)) => {
if state.stack.len() <= 1 {
state.transition = Some(StateTransition::ExitingFull(
state.stack.last().unwrap().clone(),
next,
));
} else {
state.scheduled = Some(ScheduledOperation::Next(next));
state.scheduled = Some(ScheduledOperation::Replace(next));
match state.transition.take() {
Some(StateTransition::ExitingToResume(p, n)) => {
state.stack.pop();
@ -429,7 +462,7 @@ fn state_cleaner<T: Component + Clone + Eq>(
None => match state.transition.take() {
Some(StateTransition::ExitingFull(p, n)) => {
state.transition = Some(StateTransition::Entering(p, n.clone()));
state.stack[0] = n;
*state.stack.last_mut().unwrap() = n;
}
Some(StateTransition::Pausing(p, n)) => {
state.transition = Some(StateTransition::Entering(p, n.clone()));
@ -487,7 +520,7 @@ mod test {
State::on_update_set(MyState::S1).with_system(
(|mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
r.push("update S1");
s.overwrite_next(MyState::S2).unwrap();
s.overwrite_replace(MyState::S2).unwrap();
})
.system(),
),
@ -500,7 +533,7 @@ mod test {
State::on_update_set(MyState::S2).with_system(
(|mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
r.push("update S2");
s.overwrite_next(MyState::S3).unwrap();
s.overwrite_replace(MyState::S3).unwrap();
})
.system(),
),

2
examples/2d/texture_atlas.rs
View File

@ -36,7 +36,7 @@ fn check_textures(
if let LoadState::Loaded =
asset_server.get_group_load_state(rpg_sprite_handles.handles.iter().map(|handle| handle.id))
{
state.set_next(AppState::Finished).unwrap();
state.set(AppState::Finished).unwrap();
}
}

2
examples/ecs/state.rs
View File

@ -81,7 +81,7 @@ fn menu(
match *interaction {
Interaction::Clicked => {
*material = button_materials.pressed.clone();
state.set_next(AppState::InGame).unwrap();
state.set(AppState::InGame).unwrap();
}
Interaction::Hovered => {
*material = button_materials.hovered.clone();

4
examples/game/alien_cake_addict.rs
View File

@ -304,7 +304,7 @@ fn spawn_bonus(
commands.entity(entity).despawn_recursive();
game.bonus.entity = None;
if game.score <= -5 {
state.set_next(GameState::GameOver).unwrap();
state.set(GameState::GameOver).unwrap();
return;
}
}
@ -358,7 +358,7 @@ fn scoreboard_system(game: Res<Game>, mut query: Query<&mut Text>) {
// restart the game when pressing spacebar
fn gameover_keyboard(mut state: ResMut<State<GameState>>, keyboard_input: Res<Input<KeyCode>>) {
if keyboard_input.just_pressed(KeyCode::Space) {
state.set_next(GameState::Playing).unwrap();
state.set(GameState::Playing).unwrap();
}
}

4
examples/window/multiple_windows.rs
View File

@ -52,7 +52,7 @@ fn setup_window(
},
});
app_state.set_next(AppState::Setup).unwrap();
app_state.set(AppState::Setup).unwrap();
}
fn setup_pipeline(
@ -207,5 +207,5 @@ fn setup_pipeline(
..Default::default()
});
app_state.set_next(AppState::Done).unwrap();
app_state.set(AppState::Done).unwrap();
}