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use std::marker::PhantomData;
use crate::{component::ComponentId, prelude::*};
use super::{FilteredAccess, QueryData, QueryFilter};
/// Builder struct to create [`QueryState`] instances at runtime.
///
/// ```
/// # use bevy_ecs::prelude::*;
/// #
/// # #[derive(Component)]
/// # struct A;
/// #
/// # #[derive(Component)]
/// # struct B;
/// #
/// # #[derive(Component)]
/// # struct C;
/// #
/// let mut world = World::new();
/// let entity_a = world.spawn((A, B)).id();
/// let entity_b = world.spawn((A, C)).id();
///
/// // Instantiate the builder using the type signature of the iterator you will consume
/// let mut query = QueryBuilder::<(Entity, &B)>::new(&mut world)
/// // Add additional terms through builder methods
/// .with::<A>()
/// .without::<C>()
/// .build();
///
/// // Consume the QueryState
/// let (entity, b) = query.single(&world);
///```
pub struct QueryBuilder<'w, D: QueryData = (), F: QueryFilter = ()> {
access: FilteredAccess<ComponentId>,
world: &'w mut World,
or: bool,
first: bool,
_marker: PhantomData<(D, F)>,
}
impl<'w, D: QueryData, F: QueryFilter> QueryBuilder<'w, D, F> {
/// Creates a new builder with the accesses required for `Q` and `F`
pub fn new(world: &'w mut World) -> Self {
let fetch_state = D::init_state(world);
let filter_state = F::init_state(world);
let mut access = FilteredAccess::default();
D::update_component_access(&fetch_state, &mut access);
// Use a temporary empty FilteredAccess for filters. This prevents them from conflicting with the
// main Query's `fetch_state` access. Filters are allowed to conflict with the main query fetch
// because they are evaluated *before* a specific reference is constructed.
let mut filter_access = FilteredAccess::default();
F::update_component_access(&filter_state, &mut filter_access);
// Merge the temporary filter access with the main access. This ensures that filter access is
// properly considered in a global "cross-query" context (both within systems and across systems).
access.extend(&filter_access);
Self {
access,
world,
or: false,
first: false,
_marker: PhantomData,
}
}
/// Returns a reference to the world passed to [`Self::new`].
pub fn world(&self) -> &World {
self.world
}
/// Returns a mutable reference to the world passed to [`Self::new`].
pub fn world_mut(&mut self) -> &mut World {
self.world
}
/// Adds access to self's underlying [`FilteredAccess`] respecting [`Self::or`] and [`Self::and`]
pub fn extend_access(&mut self, mut access: FilteredAccess<ComponentId>) {
if self.or {
if self.first {
access.required.clear();
self.access.extend(&access);
self.first = false;
} else {
self.access.append_or(&access);
}
} else {
self.access.extend(&access);
}
}
/// Adds accesses required for `T` to self.
pub fn data<T: QueryData>(&mut self) -> &mut Self {
let state = T::init_state(self.world);
let mut access = FilteredAccess::default();
T::update_component_access(&state, &mut access);
self.extend_access(access);
self
}
/// Adds filter from `T` to self.
pub fn filter<T: QueryFilter>(&mut self) -> &mut Self {
let state = T::init_state(self.world);
let mut access = FilteredAccess::default();
T::update_component_access(&state, &mut access);
self.extend_access(access);
self
}
/// Adds [`With<T>`] to the [`FilteredAccess`] of self.
pub fn with<T: Component>(&mut self) -> &mut Self {
self.filter::<With<T>>();
self
}
/// Adds [`With<T>`] to the [`FilteredAccess`] of self from a runtime [`ComponentId`].
pub fn with_id(&mut self, id: ComponentId) -> &mut Self {
let mut access = FilteredAccess::default();
access.and_with(id);
self.extend_access(access);
self
}
/// Adds [`Without<T>`] to the [`FilteredAccess`] of self.
pub fn without<T: Component>(&mut self) -> &mut Self {
self.filter::<Without<T>>();
self
}
/// Adds [`Without<T>`] to the [`FilteredAccess`] of self from a runtime [`ComponentId`].
pub fn without_id(&mut self, id: ComponentId) -> &mut Self {
let mut access = FilteredAccess::default();
access.and_without(id);
self.extend_access(access);
self
}
/// Adds `&T` to the [`FilteredAccess`] of self.
pub fn ref_id(&mut self, id: ComponentId) -> &mut Self {
self.with_id(id);
self.access.add_read(id);
self
}
/// Adds `&mut T` to the [`FilteredAccess`] of self.
pub fn mut_id(&mut self, id: ComponentId) -> &mut Self {
self.with_id(id);
self.access.add_write(id);
self
}
/// Takes a function over mutable access to a [`QueryBuilder`], calls that function
/// on an empty builder and then adds all accesses from that builder to self as optional.
pub fn optional(&mut self, f: impl Fn(&mut QueryBuilder)) -> &mut Self {
let mut builder = QueryBuilder::new(self.world);
f(&mut builder);
self.access.extend_access(builder.access());
self
}
/// Takes a function over mutable access to a [`QueryBuilder`], calls that function
/// on an empty builder and then adds all accesses from that builder to self.
///
/// Primarily used when inside a [`Self::or`] closure to group several terms.
pub fn and(&mut self, f: impl Fn(&mut QueryBuilder)) -> &mut Self {
let mut builder = QueryBuilder::new(self.world);
f(&mut builder);
let access = builder.access().clone();
self.extend_access(access);
self
}
/// Takes a function over mutable access to a [`QueryBuilder`], calls that function
/// on an empty builder, all accesses added to that builder will become terms in an or expression.
///
/// ```
/// # use bevy_ecs::prelude::*;
/// #
/// # #[derive(Component)]
/// # struct A;
/// #
/// # #[derive(Component)]
/// # struct B;
/// #
/// # let mut world = World::new();
/// #
/// QueryBuilder::<Entity>::new(&mut world).or(|builder| {
/// builder.with::<A>();
/// builder.with::<B>();
/// });
/// // is equivalent to
/// QueryBuilder::<Entity>::new(&mut world).filter::<Or<(With<A>, With<B>)>>();
/// ```
pub fn or(&mut self, f: impl Fn(&mut QueryBuilder)) -> &mut Self {
let mut builder = QueryBuilder::new(self.world);
builder.or = true;
builder.first = true;
f(&mut builder);
self.access.extend(builder.access());
self
}
/// Returns a reference to the [`FilteredAccess`] that will be provided to the built [`Query`].
pub fn access(&self) -> &FilteredAccess<ComponentId> {
&self.access
}
/// Transmute the existing builder adding required accesses.
/// This will maintain all existing accesses.
///
/// If including a filter type see [`Self::transmute_filtered`]
pub fn transmute<NewD: QueryData>(&mut self) -> &mut QueryBuilder<'w, NewD> {
self.transmute_filtered::<NewD, ()>()
}
/// Transmute the existing builder adding required accesses.
/// This will maintain all existing accesses.
pub fn transmute_filtered<NewD: QueryData, NewF: QueryFilter>(
&mut self,
) -> &mut QueryBuilder<'w, NewD, NewF> {
let mut fetch_state = NewD::init_state(self.world);
let filter_state = NewF::init_state(self.world);
NewD::set_access(&mut fetch_state, &self.access);
let mut access = FilteredAccess::default();
NewD::update_component_access(&fetch_state, &mut access);
NewF::update_component_access(&filter_state, &mut access);
self.extend_access(access);
// SAFETY:
// - We have included all required accesses for NewQ and NewF
// - The layout of all QueryBuilder instances is the same
unsafe { std::mem::transmute(self) }
}
/// Create a [`QueryState`] with the accesses of the builder.
///
/// Takes `&mut self` to access the innner world reference while initializing
/// state for the new [`QueryState`]
pub fn build(&mut self) -> QueryState<D, F> {
QueryState::<D, F>::from_builder(self)
}
}
#[cfg(test)]
mod tests {
use crate as bevy_ecs;
use crate::prelude::*;
use crate::world::FilteredEntityRef;
#[derive(Component, PartialEq, Debug)]
struct A(usize);
#[derive(Component, PartialEq, Debug)]
struct B(usize);
#[derive(Component, PartialEq, Debug)]
struct C(usize);
#[test]
fn builder_with_without_static() {
let mut world = World::new();
let entity_a = world.spawn((A(0), B(0))).id();
let entity_b = world.spawn((A(0), C(0))).id();
let mut query_a = QueryBuilder::<Entity>::new(&mut world)
.with::<A>()
.without::<C>()
.build();
assert_eq!(entity_a, query_a.single(&world));
let mut query_b = QueryBuilder::<Entity>::new(&mut world)
.with::<A>()
.without::<B>()
.build();
assert_eq!(entity_b, query_b.single(&world));
}
#[test]
fn builder_with_without_dynamic() {
let mut world = World::new();
let entity_a = world.spawn((A(0), B(0))).id();
let entity_b = world.spawn((A(0), C(0))).id();
let component_id_a = world.init_component::<A>();
let component_id_b = world.init_component::<B>();
let component_id_c = world.init_component::<C>();
let mut query_a = QueryBuilder::<Entity>::new(&mut world)
.with_id(component_id_a)
.without_id(component_id_c)
.build();
assert_eq!(entity_a, query_a.single(&world));
let mut query_b = QueryBuilder::<Entity>::new(&mut world)
.with_id(component_id_a)
.without_id(component_id_b)
.build();
assert_eq!(entity_b, query_b.single(&world));
}
#[test]
fn builder_or() {
let mut world = World::new();
world.spawn((A(0), B(0)));
world.spawn(B(0));
world.spawn(C(0));
let mut query_a = QueryBuilder::<Entity>::new(&mut world)
.or(|builder| {
builder.with::<A>();
builder.with::<B>();
})
.build();
assert_eq!(2, query_a.iter(&world).count());
let mut query_b = QueryBuilder::<Entity>::new(&mut world)
.or(|builder| {
builder.with::<A>();
builder.without::<B>();
})
.build();
dbg!(&query_b.component_access);
assert_eq!(2, query_b.iter(&world).count());
let mut query_c = QueryBuilder::<Entity>::new(&mut world)
.or(|builder| {
builder.with::<A>();
builder.with::<B>();
builder.with::<C>();
})
.build();
assert_eq!(3, query_c.iter(&world).count());
}
#[test]
fn builder_transmute() {
let mut world = World::new();
world.spawn(A(0));
world.spawn((A(1), B(0)));
let mut query = QueryBuilder::<()>::new(&mut world)
.with::<B>()
.transmute::<&A>()
.build();
query.iter(&world).for_each(|a| assert_eq!(a.0, 1));
}
#[test]
fn builder_static_components() {
let mut world = World::new();
let entity = world.spawn((A(0), B(1))).id();
let mut query = QueryBuilder::<FilteredEntityRef>::new(&mut world)
.data::<&A>()
.data::<&B>()
.build();
let entity_ref = query.single(&world);
assert_eq!(entity, entity_ref.id());
let a = entity_ref.get::<A>().unwrap();
let b = entity_ref.get::<B>().unwrap();
assert_eq!(0, a.0);
assert_eq!(1, b.0);
}
#[test]
fn builder_dynamic_components() {
let mut world = World::new();
let entity = world.spawn((A(0), B(1))).id();
let component_id_a = world.init_component::<A>();
let component_id_b = world.init_component::<B>();
let mut query = QueryBuilder::<FilteredEntityRef>::new(&mut world)
.ref_id(component_id_a)
.ref_id(component_id_b)
.build();
let entity_ref = query.single(&world);
assert_eq!(entity, entity_ref.id());
let a = entity_ref.get_by_id(component_id_a).unwrap();
let b = entity_ref.get_by_id(component_id_b).unwrap();
// SAFETY: We set these pointers to point to these components
unsafe {
assert_eq!(0, a.deref::<A>().0);
assert_eq!(1, b.deref::<B>().0);
}
}
}