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use core::any::TypeId;
use core::fmt::{self, Debug, Display, Formatter};
use core::marker::PhantomData;
use core::ops::{Deref, DerefMut, FnOnce};
use core::ptr::NonNull;
use crate::archetype::Archetype;
use crate::{
ArchetypeColumn, ArchetypeColumnMut, Component, Entity, Fetch, MissingComponent, Query,
QueryOne,
};
/// Handle to an entity with any component types
#[derive(Copy, Clone)]
pub struct EntityRef<'a> {
archetype: &'a Archetype,
entity: Entity,
index: u32,
}
impl<'a> EntityRef<'a> {
pub(crate) unsafe fn new(archetype: &'a Archetype, entity: Entity, index: u32) -> Self {
Self {
archetype,
entity,
index,
}
}
/// Get the [`Entity`] handle associated with this entity
#[inline]
pub fn entity(&self) -> Entity {
self.entity
}
/// Determine whether this entity would satisfy the query `Q` without borrowing any components
pub fn satisfies<Q: Query>(&self) -> bool {
Q::Fetch::access(self.archetype).is_some()
}
/// Determine whether this entity has a `T` component without borrowing it
///
/// Equivalent to [`satisfies::<&T>`](Self::satisfies)
pub fn has<T: Component>(&self) -> bool {
self.archetype.has::<T>()
}
/// Borrow a single component, if it exists
///
/// `T` must be a shared or unique reference to a component type.
///
/// # Example
/// ```
/// # use hecs::*;
/// let mut world = World::new();
/// let a = world.spawn((42, "abc"));
/// let e = world.entity(a).unwrap();
/// *e.get::<&mut i32>().unwrap() = 17;
/// assert_eq!(*e.get::<&i32>().unwrap(), 17);
/// ```
///
/// Panics if `T` is a unique reference and the component is already borrowed, or if the
/// component is already uniquely borrowed.
pub fn get<T: ComponentRef<'a>>(&self) -> Option<T::Ref> {
T::get_component(*self)
}
/// Run a query against this entity
///
/// Equivalent to invoking [`World::query_one`](crate::World::query_one) on the entity. May
/// outlive `self`.
///
/// # Example
/// ```
/// # use hecs::*;
/// let mut world = World::new();
/// let a = world.spawn((123, true, "abc"));
/// // The returned query must outlive the borrow made by `get`
/// let mut query = world.entity(a).unwrap().query::<(&mut i32, &bool)>();
/// let (number, flag) = query.get().unwrap();
/// if *flag { *number *= 2; }
/// assert_eq!(*number, 246);
/// ```
pub fn query<Q: Query>(&self) -> QueryOne<'a, Q> {
unsafe { QueryOne::new(self.archetype, self.index) }
}
/// Enumerate the types of the entity's components
///
/// Convenient for dispatching component-specific logic for a single entity. For example, this
/// can be combined with a `HashMap<TypeId, Box<dyn Handler>>` where `Handler` is some
/// user-defined trait with methods for serialization, or to be called after spawning or before
/// despawning to maintain secondary indices.
pub fn component_types(&self) -> impl Iterator<Item = TypeId> + 'a {
self.archetype.types().iter().map(|ty| ty.id())
}
/// Number of components in this entity
pub fn len(&self) -> usize {
self.archetype.types().len()
}
/// Shorthand for `self.len() == 0`
pub fn is_empty(&self) -> bool {
self.len() == 0
}
}
unsafe impl<'a> Send for EntityRef<'a> {}
unsafe impl<'a> Sync for EntityRef<'a> {}
/// Shared borrow of an entity's component
pub struct Ref<'a, T: ?Sized> {
borrow: ComponentBorrow<'a>,
target: NonNull<T>,
_phantom: PhantomData<&'a T>,
}
impl<'a, T: Component> Ref<'a, T> {
pub(crate) unsafe fn new(
archetype: &'a Archetype,
index: u32,
) -> Result<Self, MissingComponent> {
let (target, borrow) = ComponentBorrow::for_component::<T>(archetype, index)?;
Ok(Self {
borrow,
target,
_phantom: PhantomData,
})
}
}
unsafe impl<T: ?Sized + Sync> Send for Ref<'_, T> {}
unsafe impl<T: ?Sized + Sync> Sync for Ref<'_, T> {}
impl<'a, T: ?Sized> Ref<'a, T> {
/// Transform the `Ref<'_, T>` to point to a part of the borrowed data, e.g.
/// a struct field.
///
/// The `Ref<'_, T>` is already borrowed, so this cannot fail.
///
/// # Examples
///
/// ```no_run
/// # use hecs::{EntityRef, Ref};
/// struct Component {
/// member: i32,
/// }
///
/// # fn example(entity_ref: EntityRef<'_>) {
/// let component_ref = entity_ref.get::<&Component>()
/// .expect("Entity does not contain an instance of \"Component\"");
/// let member_ref = Ref::map(component_ref, |component| &component.member);
/// println!("member = {:?}", *member_ref);
/// # }
/// ```
pub fn map<U: ?Sized, F>(orig: Ref<'a, T>, f: F) -> Ref<'a, U>
where
F: FnOnce(&T) -> &U,
{
let target = NonNull::from(f(&*orig));
Ref {
borrow: orig.borrow,
target,
_phantom: PhantomData,
}
}
}
impl<'a, T: ?Sized> Deref for Ref<'a, T> {
type Target = T;
fn deref(&self) -> &T {
unsafe { self.target.as_ref() }
}
}
impl<'a, T: ?Sized + Debug> Debug for Ref<'a, T> {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
Debug::fmt(self.deref(), f)
}
}
impl<'a, T: ?Sized + Display> Display for Ref<'a, T> {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
Display::fmt(self.deref(), f)
}
}
impl<'a, T: ?Sized> Clone for Ref<'a, T> {
fn clone(&self) -> Self {
Self {
borrow: self.borrow.clone(),
target: self.target,
_phantom: self._phantom,
}
}
}
/// Unique borrow of an entity's component
pub struct RefMut<'a, T: ?Sized> {
borrow: ComponentBorrowMut<'a>,
target: NonNull<T>,
_phantom: PhantomData<&'a mut T>,
}
impl<'a, T: Component> RefMut<'a, T> {
pub(crate) unsafe fn new(
archetype: &'a Archetype,
index: u32,
) -> Result<Self, MissingComponent> {
let (target, borrow) = ComponentBorrowMut::for_component::<T>(archetype, index)?;
Ok(Self {
borrow,
target,
_phantom: PhantomData,
})
}
}
unsafe impl<T: ?Sized + Send> Send for RefMut<'_, T> {}
unsafe impl<T: ?Sized + Sync> Sync for RefMut<'_, T> {}
impl<'a, T: ?Sized> RefMut<'a, T> {
/// Transform the `RefMut<'_, T>` to point to a part of the borrowed data, e.g.
/// a struct field.
///
/// The `RefMut<'_, T>` is already mutably borrowed, so this cannot fail.
///
/// # Examples
///
/// ```no_run
/// # use hecs::{EntityRef, RefMut};
/// struct Component {
/// member: i32,
/// }
///
/// # fn example(entity_ref: EntityRef<'_>) {
/// let component_ref = entity_ref.get::<&mut Component>()
/// .expect("Entity does not contain an instance of \"Component\"");
/// let mut member_ref = RefMut::map(component_ref, |component| &mut component.member);
/// *member_ref = 21;
/// println!("member = {:?}", *member_ref);
/// # }
/// ```
pub fn map<U: ?Sized, F>(mut orig: RefMut<'a, T>, f: F) -> RefMut<'a, U>
where
F: FnOnce(&mut T) -> &mut U,
{
let target = NonNull::from(f(&mut *orig));
RefMut {
borrow: orig.borrow,
target,
_phantom: PhantomData,
}
}
}
impl<'a, T: ?Sized> Deref for RefMut<'a, T> {
type Target = T;
fn deref(&self) -> &T {
unsafe { self.target.as_ref() }
}
}
impl<'a, T: ?Sized> DerefMut for RefMut<'a, T> {
fn deref_mut(&mut self) -> &mut T {
unsafe { self.target.as_mut() }
}
}
impl<'a, T: ?Sized + Debug> Debug for RefMut<'a, T> {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
Debug::fmt(self.deref(), f)
}
}
impl<'a, T: ?Sized + Display> Display for RefMut<'a, T> {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
Display::fmt(self.deref(), f)
}
}
/// `&T` or `&mut T` where `T` is some component type
///
/// The interface of this trait is a private implementation detail.
pub trait ComponentRef<'a> {
/// Smart pointer to a component of the referenced type
#[doc(hidden)]
type Ref;
/// Smart pointer to a column of the referenced type in an [`Archetype`](crate::Archetype)
#[doc(hidden)]
type Column;
/// Component type referenced by `Ref`
#[doc(hidden)]
type Component: Component;
/// Fetch the component from `entity`
#[doc(hidden)]
fn get_component(entity: EntityRef<'a>) -> Option<Self::Ref>;
/// Construct from a raw pointer
///
/// # Safety
///
/// Dereferencing `raw` for lifetime `'a` must be sound
#[doc(hidden)]
unsafe fn from_raw(raw: *mut Self::Component) -> Self;
/// Borrow a column from an archetype
#[doc(hidden)]
fn get_column(archetype: &'a Archetype) -> Option<Self::Column>;
}
impl<'a, T: Component> ComponentRef<'a> for &'a T {
type Ref = Ref<'a, T>;
type Column = ArchetypeColumn<'a, T>;
type Component = T;
fn get_component(entity: EntityRef<'a>) -> Option<Self::Ref> {
Some(unsafe { Ref::new(entity.archetype, entity.index).ok()? })
}
unsafe fn from_raw(raw: *mut Self::Component) -> Self {
&*raw
}
fn get_column(archetype: &'a Archetype) -> Option<Self::Column> {
ArchetypeColumn::new(archetype)
}
}
impl<'a, T: Component> ComponentRef<'a> for &'a mut T {
type Ref = RefMut<'a, T>;
type Column = ArchetypeColumnMut<'a, T>;
type Component = T;
fn get_component(entity: EntityRef<'a>) -> Option<Self::Ref> {
Some(unsafe { RefMut::new(entity.archetype, entity.index).ok()? })
}
unsafe fn from_raw(raw: *mut Self::Component) -> Self {
&mut *raw
}
fn get_column(archetype: &'a Archetype) -> Option<Self::Column> {
ArchetypeColumnMut::new(archetype)
}
}
/// `&T` where `T` is some component type
///
/// Used when consistency demands that references to component types, rather than component types
/// themselves, be supplied as a type parameter to a function that cannot operate on unique
/// references.
pub trait ComponentRefShared<'a>: ComponentRef<'a> {}
impl<'a, T: Component> ComponentRefShared<'a> for &'a T {}
struct ComponentBorrow<'a> {
archetype: &'a Archetype,
/// State index for the borrowed component in the `archetype`.
state: usize,
}
impl<'a> ComponentBorrow<'a> {
// This method is unsafe as if the `index` is out of bounds,
// then this will cause undefined behavior as the returned
// `target` will point to undefined memory.
unsafe fn for_component<T: Component>(
archetype: &'a Archetype,
index: u32,
) -> Result<(NonNull<T>, Self), MissingComponent> {
let state = archetype
.get_state::<T>()
.ok_or_else(MissingComponent::new::<T>)?;
let target =
NonNull::new_unchecked(archetype.get_base::<T>(state).as_ptr().add(index as usize));
archetype.borrow::<T>(state);
Ok((target, Self { archetype, state }))
}
}
impl<'a> Clone for ComponentBorrow<'a> {
fn clone(&self) -> Self {
unsafe {
self.archetype.borrow_raw(self.state);
}
Self {
archetype: self.archetype,
state: self.state,
}
}
}
impl<'a> Drop for ComponentBorrow<'a> {
fn drop(&mut self) {
unsafe {
self.archetype.release_raw(self.state);
}
}
}
struct ComponentBorrowMut<'a> {
archetype: &'a Archetype,
/// State index for the borrowed component in the `archetype`.
state: usize,
}
impl<'a> ComponentBorrowMut<'a> {
// This method is unsafe as if the `index` is out of bounds,
// then this will cause undefined behavior as the returned
// `target` will point to undefined memory.
unsafe fn for_component<T: Component>(
archetype: &'a Archetype,
index: u32,
) -> Result<(NonNull<T>, Self), MissingComponent> {
let state = archetype
.get_state::<T>()
.ok_or_else(MissingComponent::new::<T>)?;
let target =
NonNull::new_unchecked(archetype.get_base::<T>(state).as_ptr().add(index as usize));
archetype.borrow_mut::<T>(state);
Ok((target, Self { archetype, state }))
}
}
impl<'a> Drop for ComponentBorrowMut<'a> {
fn drop(&mut self) {
unsafe {
self.archetype.release_raw_mut(self.state);
}
}
}