01cce9b11c
# Objective `ParamSetBuilder` is supposed to be used as a tuple constructor, but the field was not marked `pub` so it's not actually usable outside of its module. ## Solution Mark the field `pub`. Realize one advantage of doc tests over unit tests is that they test the public API. Add a doc test example that uses the field so that this would have been caught.
386 lines
13 KiB
Rust
386 lines
13 KiB
Rust
use bevy_utils::{all_tuples, synccell::SyncCell};
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use crate::{
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prelude::QueryBuilder,
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query::{QueryData, QueryFilter, QueryState},
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system::{
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system_param::{Local, ParamSet, SystemParam},
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Query, SystemMeta,
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},
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world::{FromWorld, World},
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};
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use std::fmt::Debug;
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use super::{init_query_param, Res, ResMut, Resource, SystemState};
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/// A builder that can create a [`SystemParam`]
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///
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/// ```
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/// # use bevy_ecs::prelude::*;
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/// # use bevy_ecs_macros::SystemParam;
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/// # use bevy_ecs::system::{RunSystemOnce, ParamBuilder, LocalBuilder, QueryParamBuilder};
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/// #
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/// # #[derive(Component)]
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/// # struct A;
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/// #
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/// # #[derive(Component)]
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/// # struct B;
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/// #
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/// # #[derive(Resource)]
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/// # struct R;
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/// #
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/// # #[derive(SystemParam)]
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/// # struct MyParam;
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/// #
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/// # let mut world = World::new();
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/// # world.insert_resource(R);
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/// #
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/// fn my_system(res: Res<R>, query: Query<&A>, param: MyParam) {
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/// // ...
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/// }
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///
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/// // To build a system, create a tuple of `SystemParamBuilder`s with a builder for each param.
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/// // `ParamBuilder` can be used to build a parameter using its default initialization,
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/// // and has helper methods to create typed builders.
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/// let system = (
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/// ParamBuilder,
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/// ParamBuilder::query::<&A>(),
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/// ParamBuilder::of::<MyParam>(),
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/// )
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/// .build_state(&mut world)
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/// .build_system(my_system);
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///
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/// // Other implementations of `SystemParamBuilder` can be used to configure the parameters.
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/// let system = (
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/// ParamBuilder,
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/// QueryParamBuilder::new::<&A, ()>(|builder| {
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/// builder.with::<B>();
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/// }),
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/// ParamBuilder,
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/// )
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/// .build_state(&mut world)
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/// .build_system(my_system);
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///
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/// fn single_parameter_system(local: Local<u64>) {
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/// // ...
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/// }
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///
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/// // Note that the builder for a system must be a tuple, even if there is only one parameter.
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/// let system = (LocalBuilder(2),)
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/// .build_state(&mut world)
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/// .build_system(single_parameter_system);
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///
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/// world.run_system_once(system);
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///```
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///
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/// # Safety
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///
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/// The implementor must ensure the following is true.
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/// - [`SystemParamBuilder::build`] correctly registers all [`World`] accesses used
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/// by [`SystemParam::get_param`] with the provided [`system_meta`](SystemMeta).
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/// - None of the world accesses may conflict with any prior accesses registered
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/// on `system_meta`.
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///
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/// Note that this depends on the implementation of [`SystemParam::get_param`],
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/// so if `Self` is not a local type then you must call [`SystemParam::init_state`]
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/// or another [`SystemParamBuilder::build`]
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pub unsafe trait SystemParamBuilder<P: SystemParam>: Sized {
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/// Registers any [`World`] access used by this [`SystemParam`]
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/// and creates a new instance of this param's [`State`](SystemParam::State).
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fn build(self, world: &mut World, meta: &mut SystemMeta) -> P::State;
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/// Create a [`SystemState`] from a [`SystemParamBuilder`].
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/// To create a system, call [`SystemState::build_system`] on the result.
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fn build_state(self, world: &mut World) -> SystemState<P> {
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SystemState::from_builder(world, self)
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}
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}
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/// A [`SystemParamBuilder`] for any [`SystemParam`] that uses its default initialization.
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#[derive(Default, Debug, Copy, Clone)]
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pub struct ParamBuilder;
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// SAFETY: Calls `SystemParam::init_state`
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unsafe impl<P: SystemParam> SystemParamBuilder<P> for ParamBuilder {
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fn build(self, world: &mut World, meta: &mut SystemMeta) -> P::State {
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P::init_state(world, meta)
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}
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}
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impl ParamBuilder {
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/// Creates a [`SystemParamBuilder`] for any [`SystemParam`] that uses its default initialization.
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pub fn of<T: SystemParam>() -> impl SystemParamBuilder<T> {
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Self
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}
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/// Helper method for reading a [`Resource`] as a param, equivalent to `of::<Res<T>>()`
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pub fn resource<'w, T: Resource>() -> impl SystemParamBuilder<Res<'w, T>> {
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Self
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}
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/// Helper method for mutably accessing a [`Resource`] as a param, equivalent to `of::<ResMut<T>>()`
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pub fn resource_mut<'w, T: Resource>() -> impl SystemParamBuilder<ResMut<'w, T>> {
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Self
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}
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/// Helper method for adding a [`Local`] as a param, equivalent to `of::<Local<T>>()`
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pub fn local<'s, T: FromWorld + Send + 'static>() -> impl SystemParamBuilder<Local<'s, T>> {
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Self
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}
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/// Helper method for adding a [`Query`] as a param, equivalent to `of::<Query<D>>()`
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pub fn query<'w, 's, D: QueryData + 'static>() -> impl SystemParamBuilder<Query<'w, 's, D, ()>>
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{
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Self
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}
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/// Helper method for adding a filtered [`Query`] as a param, equivalent to `of::<Query<D, F>>()`
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pub fn query_filtered<'w, 's, D: QueryData + 'static, F: QueryFilter + 'static>(
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) -> impl SystemParamBuilder<Query<'w, 's, D, F>> {
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Self
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}
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}
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// SAFETY: Calls `init_query_param`, just like `Query::init_state`.
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unsafe impl<'w, 's, D: QueryData + 'static, F: QueryFilter + 'static>
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SystemParamBuilder<Query<'w, 's, D, F>> for QueryState<D, F>
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{
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fn build(self, world: &mut World, system_meta: &mut SystemMeta) -> QueryState<D, F> {
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self.validate_world(world.id());
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init_query_param(world, system_meta, &self);
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self
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}
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}
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/// A [`SystemParamBuilder`] for a [`Query`].
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pub struct QueryParamBuilder<T>(T);
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impl<T> QueryParamBuilder<T> {
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/// Creates a [`SystemParamBuilder`] for a [`Query`] that accepts a callback to configure the [`QueryBuilder`].
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pub fn new<D: QueryData, F: QueryFilter>(f: T) -> Self
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where
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T: FnOnce(&mut QueryBuilder<D, F>),
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{
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Self(f)
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}
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}
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impl<'a, D: QueryData, F: QueryFilter>
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QueryParamBuilder<Box<dyn FnOnce(&mut QueryBuilder<D, F>) + 'a>>
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{
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/// Creates a [`SystemParamBuilder`] for a [`Query`] that accepts a callback to configure the [`QueryBuilder`].
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/// This boxes the callback so that it has a common type and can be put in a `Vec`.
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pub fn new_box(f: impl FnOnce(&mut QueryBuilder<D, F>) + 'a) -> Self {
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Self(Box::new(f))
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}
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}
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// SAFETY: Calls `init_query_param`, just like `Query::init_state`.
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unsafe impl<
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'w,
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's,
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D: QueryData + 'static,
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F: QueryFilter + 'static,
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T: FnOnce(&mut QueryBuilder<D, F>),
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> SystemParamBuilder<Query<'w, 's, D, F>> for QueryParamBuilder<T>
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{
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fn build(self, world: &mut World, system_meta: &mut SystemMeta) -> QueryState<D, F> {
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let mut builder = QueryBuilder::new(world);
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(self.0)(&mut builder);
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let state = builder.build();
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init_query_param(world, system_meta, &state);
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state
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}
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}
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macro_rules! impl_system_param_builder_tuple {
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($(($param: ident, $builder: ident)),*) => {
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// SAFETY: implementors of each `SystemParamBuilder` in the tuple have validated their impls
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unsafe impl<$($param: SystemParam,)* $($builder: SystemParamBuilder<$param>,)*> SystemParamBuilder<($($param,)*)> for ($($builder,)*) {
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fn build(self, _world: &mut World, _meta: &mut SystemMeta) -> <($($param,)*) as SystemParam>::State {
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#[allow(non_snake_case)]
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let ($($builder,)*) = self;
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#[allow(clippy::unused_unit)]
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($($builder.build(_world, _meta),)*)
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}
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}
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};
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}
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all_tuples!(impl_system_param_builder_tuple, 0, 16, P, B);
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/// A [`SystemParamBuilder`] for a [`ParamSet`].
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/// To build a [`ParamSet`] with a tuple of system parameters, pass a tuple of matching [`SystemParamBuilder`]s.
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/// To build a [`ParamSet`] with a `Vec` of system parameters, pass a `Vec` of matching [`SystemParamBuilder`]s.
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pub struct ParamSetBuilder<T>(pub T);
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macro_rules! impl_param_set_builder_tuple {
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($(($param: ident, $builder: ident, $meta: ident)),*) => {
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// SAFETY: implementors of each `SystemParamBuilder` in the tuple have validated their impls
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unsafe impl<'w, 's, $($param: SystemParam,)* $($builder: SystemParamBuilder<$param>,)*> SystemParamBuilder<ParamSet<'w, 's, ($($param,)*)>> for ParamSetBuilder<($($builder,)*)> {
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#[allow(non_snake_case)]
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fn build(self, _world: &mut World, _system_meta: &mut SystemMeta) -> <($($param,)*) as SystemParam>::State {
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let ParamSetBuilder(($($builder,)*)) = self;
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// Note that this is slightly different from `init_state`, which calls `init_state` on each param twice.
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// One call populates an empty `SystemMeta` with the new access, while the other runs against a cloned `SystemMeta` to check for conflicts.
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// Builders can only be invoked once, so we do both in a single call here.
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// That means that any `filtered_accesses` in the `component_access_set` will get copied to every `$meta`
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// and will appear multiple times in the final `SystemMeta`.
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$(
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let mut $meta = _system_meta.clone();
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let $param = $builder.build(_world, &mut $meta);
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)*
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// Make the ParamSet non-send if any of its parameters are non-send.
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if false $(|| !$meta.is_send())* {
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_system_meta.set_non_send();
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}
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$(
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_system_meta
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.component_access_set
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.extend($meta.component_access_set);
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_system_meta
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.archetype_component_access
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.extend(&$meta.archetype_component_access);
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)*
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#[allow(clippy::unused_unit)]
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($($param,)*)
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}
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}
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};
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}
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all_tuples!(impl_param_set_builder_tuple, 1, 8, P, B, meta);
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/// A [`SystemParamBuilder`] for a [`Local`].
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/// The provided value will be used as the initial value of the `Local`.
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pub struct LocalBuilder<T>(pub T);
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// SAFETY: `Local` performs no world access.
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unsafe impl<'s, T: FromWorld + Send + 'static> SystemParamBuilder<Local<'s, T>>
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for LocalBuilder<T>
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{
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fn build(
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self,
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_world: &mut World,
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_meta: &mut SystemMeta,
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) -> <Local<'s, T> as SystemParam>::State {
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SyncCell::new(self.0)
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}
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}
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#[cfg(test)]
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mod tests {
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use crate as bevy_ecs;
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use crate::prelude::{Component, Query};
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use crate::system::{Local, RunSystemOnce};
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use super::*;
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#[derive(Component)]
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struct A;
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#[derive(Component)]
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struct B;
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#[derive(Component)]
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struct C;
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fn local_system(local: Local<u64>) -> u64 {
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*local
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}
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fn query_system(query: Query<()>) -> usize {
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query.iter().count()
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}
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fn multi_param_system(a: Local<u64>, b: Local<u64>) -> u64 {
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*a + *b + 1
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}
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#[test]
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fn local_builder() {
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let mut world = World::new();
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let system = (LocalBuilder(10),)
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.build_state(&mut world)
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.build_system(local_system);
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let result = world.run_system_once(system);
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assert_eq!(result, 10);
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}
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#[test]
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fn query_builder() {
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let mut world = World::new();
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world.spawn(A);
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world.spawn_empty();
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let system = (QueryParamBuilder::new(|query| {
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query.with::<A>();
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}),)
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.build_state(&mut world)
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.build_system(query_system);
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let result = world.run_system_once(system);
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assert_eq!(result, 1);
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}
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#[test]
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fn query_builder_state() {
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let mut world = World::new();
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world.spawn(A);
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world.spawn_empty();
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let state = QueryBuilder::new(&mut world).with::<A>().build();
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let system = (state,).build_state(&mut world).build_system(query_system);
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let result = world.run_system_once(system);
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assert_eq!(result, 1);
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}
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#[test]
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fn multi_param_builder() {
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let mut world = World::new();
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world.spawn(A);
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world.spawn_empty();
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let system = (LocalBuilder(0), ParamBuilder)
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.build_state(&mut world)
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.build_system(multi_param_system);
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let result = world.run_system_once(system);
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assert_eq!(result, 1);
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}
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#[test]
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fn param_set_builder() {
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let mut world = World::new();
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world.spawn((A, B, C));
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world.spawn((A, B));
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world.spawn((A, C));
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world.spawn((A, C));
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world.spawn_empty();
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let system = (ParamSetBuilder((
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QueryParamBuilder::new(|builder| {
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builder.with::<B>();
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}),
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QueryParamBuilder::new(|builder| {
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builder.with::<C>();
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}),
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)),)
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.build_state(&mut world)
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.build_system(|mut params: ParamSet<(Query<&mut A>, Query<&mut A>)>| {
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params.p0().iter().count() + params.p1().iter().count()
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});
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let result = world.run_system_once(system);
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assert_eq!(result, 5);
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}
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}
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