bevy_ecs/system/
exclusive_system_param.rs1use crate::{
2 prelude::{FromWorld, QueryState},
3 query::{QueryData, QueryFilter},
4 system::{Local, SystemMeta, SystemParam, SystemState},
5 world::World,
6};
7use bevy_utils::all_tuples;
8use bevy_utils::synccell::SyncCell;
9use std::marker::PhantomData;
10
11#[diagnostic::on_unimplemented(
14 message = "`{Self}` can not be used as a parameter for an exclusive system",
15 label = "invalid system parameter"
16)]
17pub trait ExclusiveSystemParam: Sized {
18 type State: Send + Sync + 'static;
20 type Item<'s>: ExclusiveSystemParam<State = Self::State>;
23
24 fn init(world: &mut World, system_meta: &mut SystemMeta) -> Self::State;
26
27 fn get_param<'s>(state: &'s mut Self::State, system_meta: &SystemMeta) -> Self::Item<'s>;
31}
32
33pub type ExclusiveSystemParamItem<'s, P> = <P as ExclusiveSystemParam>::Item<'s>;
36
37impl<'a, D: QueryData + 'static, F: QueryFilter + 'static> ExclusiveSystemParam
38 for &'a mut QueryState<D, F>
39{
40 type State = QueryState<D, F>;
41 type Item<'s> = &'s mut QueryState<D, F>;
42
43 fn init(world: &mut World, _system_meta: &mut SystemMeta) -> Self::State {
44 QueryState::new(world)
45 }
46
47 fn get_param<'s>(state: &'s mut Self::State, _system_meta: &SystemMeta) -> Self::Item<'s> {
48 state
49 }
50}
51
52impl<'a, P: SystemParam + 'static> ExclusiveSystemParam for &'a mut SystemState<P> {
53 type State = SystemState<P>;
54 type Item<'s> = &'s mut SystemState<P>;
55
56 fn init(world: &mut World, _system_meta: &mut SystemMeta) -> Self::State {
57 SystemState::new(world)
58 }
59
60 fn get_param<'s>(state: &'s mut Self::State, _system_meta: &SystemMeta) -> Self::Item<'s> {
61 state
62 }
63}
64
65impl<'_s, T: FromWorld + Send + 'static> ExclusiveSystemParam for Local<'_s, T> {
66 type State = SyncCell<T>;
67 type Item<'s> = Local<'s, T>;
68
69 fn init(world: &mut World, _system_meta: &mut SystemMeta) -> Self::State {
70 SyncCell::new(T::from_world(world))
71 }
72
73 fn get_param<'s>(state: &'s mut Self::State, _system_meta: &SystemMeta) -> Self::Item<'s> {
74 Local(state.get())
75 }
76}
77
78impl<S: ?Sized> ExclusiveSystemParam for PhantomData<S> {
79 type State = ();
80 type Item<'s> = PhantomData<S>;
81
82 fn init(_world: &mut World, _system_meta: &mut SystemMeta) -> Self::State {}
83
84 fn get_param<'s>(_state: &'s mut Self::State, _system_meta: &SystemMeta) -> Self::Item<'s> {
85 PhantomData
86 }
87}
88
89macro_rules! impl_exclusive_system_param_tuple {
90 ($($param: ident),*) => {
91 #[allow(unused_variables)]
92 #[allow(non_snake_case)]
93 impl<$($param: ExclusiveSystemParam),*> ExclusiveSystemParam for ($($param,)*) {
94 type State = ($($param::State,)*);
95 type Item<'s> = ($($param::Item<'s>,)*);
96
97 #[inline]
98 fn init(_world: &mut World, _system_meta: &mut SystemMeta) -> Self::State {
99 (($($param::init(_world, _system_meta),)*))
100 }
101
102 #[inline]
103 #[allow(clippy::unused_unit)]
104 fn get_param<'s>(
105 state: &'s mut Self::State,
106 system_meta: &SystemMeta,
107 ) -> Self::Item<'s> {
108
109 let ($($param,)*) = state;
110 ($($param::get_param($param, system_meta),)*)
111 }
112 }
113 };
114}
115
116all_tuples!(impl_exclusive_system_param_tuple, 0, 16, P);
117
118#[cfg(test)]
119mod tests {
120 use crate as bevy_ecs;
121 use crate::schedule::Schedule;
122 use crate::system::Local;
123 use crate::world::World;
124 use bevy_ecs_macros::Resource;
125 use std::marker::PhantomData;
126
127 #[test]
128 fn test_exclusive_system_params() {
129 #[derive(Resource, Default)]
130 struct Res {
131 test_value: u32,
132 }
133
134 fn my_system(world: &mut World, mut local: Local<u32>, _phantom: PhantomData<Vec<u32>>) {
135 assert_eq!(world.resource::<Res>().test_value, *local);
136 *local += 1;
137 world.resource_mut::<Res>().test_value += 1;
138 }
139
140 let mut schedule = Schedule::default();
141 schedule.add_systems(my_system);
142
143 let mut world = World::default();
144 world.init_resource::<Res>();
145
146 schedule.run(&mut world);
147 schedule.run(&mut world);
148
149 assert_eq!(2, world.get_resource::<Res>().unwrap().test_value);
150 }
151}