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// Copyright 2019 Google LLC // // Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or // http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or // http://opensource.org/licenses/MIT>, at your option. This file may not be // copied, modified, or distributed except according to those terms. use crate::alloc::{vec, vec::Vec}; use core::any::TypeId; use core::borrow::Borrow; use core::convert::TryFrom; use core::{fmt, mem, ptr}; #[cfg(feature = "std")] use std::error::Error; use hashbrown::{HashMap, HashSet}; use crate::alloc::boxed::Box; use crate::archetype::{Archetype, TypeIdMap, TypeInfo}; use crate::entities::{Entities, Location, ReserveEntitiesIterator}; use crate::{ Bundle, ColumnBatch, DynamicBundle, Entity, EntityRef, Fetch, MissingComponent, NoSuchEntity, Query, QueryBorrow, QueryItem, QueryMut, QueryOne, Ref, RefMut, }; /// An unordered collection of entities, each having any number of distinctly typed components /// /// Similar to `HashMap<Entity, Vec<Box<dyn Any>>>` where each `Vec` never contains two of the same /// type, but far more efficient to traverse. /// /// The components of entities who have the same set of component types are stored in contiguous /// runs, allowing for extremely fast, cache-friendly iteration. /// /// There is a maximum number of unique entity IDs, which means that there is a maximum number of live /// entities. When old entities are despawned, their IDs will be reused on a future entity, and /// old `Entity` values with that ID will be invalidated. /// /// ### Collisions /// /// If an entity is despawned and its `Entity` handle is preserved over the course of billions of /// following spawns and despawns, that handle may, in rare circumstances, collide with a /// newly-allocated `Entity` handle. Very long-lived applications should therefore limit the period /// over which they may retain handles of despawned entities. pub struct World { entities: Entities, archetypes: ArchetypeSet, /// Maps statically-typed bundle types to archetypes bundle_to_archetype: TypeIdMap<u32>, } impl World { /// Create an empty world pub fn new() -> Self { Self { entities: Entities::default(), archetypes: ArchetypeSet::new(), bundle_to_archetype: HashMap::default(), } } /// Create an entity with certain components /// /// Returns the ID of the newly created entity. /// /// Arguments can be tuples, structs annotated with [`#[derive(Bundle)]`](macro@Bundle), or the /// result of calling [`build`](crate::EntityBuilder::build) on an /// [`EntityBuilder`](crate::EntityBuilder), which is useful if the set of components isn't /// statically known. To spawn an entity with only one component, use a one-element tuple like /// `(x,)`. /// /// Any type that satisfies `Send + Sync + 'static` can be used as a component. /// /// # Example /// ``` /// # use hecs::*; /// let mut world = World::new(); /// let a = world.spawn((123, "abc")); /// let b = world.spawn((456, true)); /// ``` pub fn spawn(&mut self, components: impl DynamicBundle) -> Entity { // Ensure all entity allocations are accounted for so `self.entities` can realloc if // necessary self.flush(); let entity = self.entities.alloc(); self.spawn_inner(entity, components); entity } /// Create an entity with certain components and a specific [`Entity`] handle. /// /// See [`spawn`](Self::spawn). /// /// Despawns any existing entity with the same [`Entity::id`]. /// /// Useful for easy handle-preserving deserialization. Be cautious resurrecting old `Entity` /// handles in already-populated worlds as it vastly increases the likelihood of collisions. /// /// # Example /// ``` /// # use hecs::*; /// let mut world = World::new(); /// let a = world.spawn((123, "abc")); /// let b = world.spawn((456, true)); /// world.despawn(a); /// assert!(!world.contains(a)); /// // all previous Entity values pointing to 'a' will be live again, instead pointing to the new entity. /// world.spawn_at(a, (789, "ABC")); /// assert!(world.contains(a)); /// ``` pub fn spawn_at(&mut self, handle: Entity, components: impl DynamicBundle) { // Ensure all entity allocations are accounted for so `self.entities` can realloc if // necessary self.flush(); let loc = self.entities.alloc_at(handle); if let Some(loc) = loc { if let Some(moved) = unsafe { self.archetypes.archetypes[loc.archetype as usize].remove(loc.index, true) } { self.entities.meta[moved as usize].location.index = loc.index; } } self.spawn_inner(handle, components); } fn spawn_inner(&mut self, entity: Entity, components: impl DynamicBundle) { let archetype_id = match components.key() { Some(k) => { let archetypes = &mut self.archetypes; *self.bundle_to_archetype.entry(k).or_insert_with(|| { components.with_ids(|ids| archetypes.get(ids, &|| components.type_info())) }) } None => components.with_ids(|ids| self.archetypes.get(ids, &|| components.type_info())), }; let archetype = &mut self.archetypes.archetypes[archetype_id as usize]; unsafe { let index = archetype.allocate(entity.id); components.put(|ptr, ty| { archetype.put_dynamic(ptr, ty.id(), ty.layout().size(), index); }); self.entities.meta[entity.id as usize].location = Location { archetype: archetype_id, index, }; } } /// Efficiently spawn a large number of entities with the same components /// /// Faster than calling [`spawn`](Self::spawn) repeatedly with the same components. /// /// # Example /// ``` /// # use hecs::*; /// let mut world = World::new(); /// let entities = world.spawn_batch((0..1_000).map(|i| (i, "abc"))).collect::<Vec<_>>(); /// for i in 0..1_000 { /// assert_eq!(*world.get::<i32>(entities[i]).unwrap(), i as i32); /// } /// ``` pub fn spawn_batch<I>(&mut self, iter: I) -> SpawnBatchIter<'_, I::IntoIter> where I: IntoIterator, I::Item: Bundle + 'static, { // Ensure all entity allocations are accounted for so `self.entities` can realloc if // necessary self.flush(); let iter = iter.into_iter(); let (lower, upper) = iter.size_hint(); let archetype_id = self.reserve_inner::<I::Item>( u32::try_from(upper.unwrap_or(lower)).expect("iterator too large"), ); SpawnBatchIter { inner: iter, entities: &mut self.entities, archetype_id, archetype: &mut self.archetypes.archetypes[archetype_id as usize], } } /// Super-efficiently spawn the contents of a [`ColumnBatch`] /// /// The fastest, but most specialized, way to spawn large numbers of entities. Useful for high /// performance deserialization. pub fn spawn_column_batch(&mut self, batch: ColumnBatch) -> SpawnColumnBatchIter<'_> { self.flush(); let archetype = batch.0; let entity_count = archetype.len(); // Store component data let (archetype_id, base) = self.archetypes.insert_batch(archetype); let archetype = &mut self.archetypes.archetypes[archetype_id as usize]; let id_alloc = self.entities.alloc_many(entity_count, archetype_id, base); // Fix up entity IDs let mut id_alloc_clone = id_alloc.clone(); let mut index = base as usize; while let Some(id) = id_alloc_clone.next(&self.entities) { archetype.set_entity_id(index, id); index += 1; } // Return iterator over new IDs SpawnColumnBatchIter { pending_end: id_alloc.pending_end, id_alloc, entities: &mut self.entities, } } /// Hybrid of [`spawn_column_batch`](Self::spawn_column_batch) and [`spawn_at`](Self::spawn_at) pub fn spawn_column_batch_at(&mut self, handles: &[Entity], batch: ColumnBatch) { let archetype = batch.0; assert_eq!( handles.len(), archetype.len() as usize, "number of entity IDs {} must match number of entities {}", handles.len(), archetype.len() ); // Drop components of entities that will be replaced for &handle in handles { let loc = self.entities.alloc_at(handle); if let Some(loc) = loc { if let Some(moved) = unsafe { self.archetypes.archetypes[loc.archetype as usize].remove(loc.index, true) } { self.entities.meta[moved as usize].location.index = loc.index; } } } // Store components let (archetype_id, base) = self.archetypes.insert_batch(archetype); // Fix up entity IDs let archetype = &mut self.archetypes.archetypes[archetype_id as usize]; for (&handle, index) in handles.iter().zip(base as usize..) { archetype.set_entity_id(index, handle.id()); } } /// Allocate many entities ID concurrently /// /// Unlike [`spawn`](Self::spawn), this can be called simultaneously to other operations on the /// [`World`] such as queries, but does not immediately create the entities. Reserved entities /// are not visible to queries or world iteration, but can be otherwise operated on /// freely. Operations that uniquely borrow the world, such as `insert` or `despawn`, will cause /// all outstanding reserved entities to become real entities before proceeding. This can also /// be done explicitly by calling `flush`. /// /// Useful for reserving an ID that will later have components attached to it with `insert`. pub fn reserve_entities(&self, count: u32) -> ReserveEntitiesIterator { self.entities.reserve_entities(count) } /// Allocate an entity ID concurrently /// /// See [`reserve_entities`](Self::reserve_entities). pub fn reserve_entity(&self) -> Entity { self.entities.reserve_entity() } /// Destroy an entity and all its components pub fn despawn(&mut self, entity: Entity) -> Result<(), NoSuchEntity> { self.flush(); let loc = self.entities.free(entity)?; if let Some(moved) = unsafe { self.archetypes.archetypes[loc.archetype as usize].remove(loc.index, true) } { self.entities.meta[moved as usize].location.index = loc.index; } Ok(()) } /// Ensure `additional` entities with exact components `T` can be spawned without reallocating pub fn reserve<T: Bundle + 'static>(&mut self, additional: u32) { self.reserve_inner::<T>(additional); } fn reserve_inner<T: Bundle + 'static>(&mut self, additional: u32) -> u32 { self.flush(); self.entities.reserve(additional); let archetypes = &mut self.archetypes; let archetype_id = *self .bundle_to_archetype .entry(TypeId::of::<T>()) .or_insert_with(|| { T::with_static_ids(|ids| archetypes.get(ids, &|| T::static_type_info())) }); self.archetypes.archetypes[archetype_id as usize].reserve(additional); archetype_id } /// Despawn all entities /// /// Preserves allocated storage for reuse. pub fn clear(&mut self) { for x in &mut self.archetypes.archetypes { x.clear(); } self.entities.clear(); } /// Whether `entity` still exists pub fn contains(&self, entity: Entity) -> bool { self.entities.contains(entity) } /// Efficiently iterate over all entities that have certain components, using dynamic borrow /// checking /// /// Prefer [`query_mut`](Self::query_mut) when concurrent access to the [`World`] is not required. /// /// Calling `iter` on the returned value yields `(Entity, Q)` tuples, where `Q` is some query /// type. A query type is `&T`, `&mut T`, a tuple of query types, or an `Option` wrapping a /// query type, where `T` is any component type. Components queried with `&mut` must only appear /// once. Entities which do not have a component type referenced outside of an `Option` will be /// skipped. /// /// Entities are yielded in arbitrary order. /// /// The returned [`QueryBorrow`] can be further transformed with combinator methods; see its /// documentation for details. /// /// Iterating a query will panic if it would violate an existing unique reference or construct /// an invalid unique reference. This occurs when two simultaneously-active queries could expose /// the same entity. Simultaneous queries can access the same component type if and only if the /// world contains no entities that have all components required by both queries, assuming no /// other component borrows are outstanding. /// /// Iterating a query yields references with lifetimes bound to the [`QueryBorrow`] returned /// here. To ensure those are invalidated, the return value of this method must be dropped for /// its dynamic borrows from the world to be released. Similarly, lifetime rules ensure that /// references obtained from a query cannot outlive the [`QueryBorrow`]. /// /// # Example /// ``` /// # use hecs::*; /// let mut world = World::new(); /// let a = world.spawn((123, true, "abc")); /// let b = world.spawn((456, false)); /// let c = world.spawn((42, "def")); /// let entities = world.query::<(&i32, &bool)>() /// .iter() /// .map(|(e, (&i, &b))| (e, i, b)) // Copy out of the world /// .collect::<Vec<_>>(); /// assert_eq!(entities.len(), 2); /// assert!(entities.contains(&(a, 123, true))); /// assert!(entities.contains(&(b, 456, false))); /// ``` pub fn query<Q: Query>(&self) -> QueryBorrow<'_, Q> { QueryBorrow::new(&self.entities.meta, &self.archetypes.archetypes) } /// Query a uniquely borrowed world /// /// Like [`query`](Self::query), but faster because dynamic borrow checks can be skipped. Note /// that, unlike [`query`](Self::query), this returns an `IntoIterator` which can be passed /// directly to a `for` loop. pub fn query_mut<Q: Query>(&mut self) -> QueryMut<'_, Q> { QueryMut::new(&self.entities.meta, &mut self.archetypes.archetypes) } /// Prepare a query against a single entity, using dynamic borrow checking /// /// Prefer [`query_one_mut`](Self::query_one_mut) when concurrent access to the [`World`] is not /// required. /// /// Call [`get`](QueryOne::get) on the resulting [`QueryOne`] to actually execute the query. The /// [`QueryOne`] value is responsible for releasing the dynamically-checked borrow made by /// `get`, so it can't be dropped while references returned by `get` are live. /// /// Handy for accessing multiple components simultaneously. /// /// # 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.query_one::<(&mut i32, &bool)>(a).unwrap(); /// let (number, flag) = query.get().unwrap(); /// if *flag { *number *= 2; } /// assert_eq!(*number, 246); /// ``` pub fn query_one<Q: Query>(&self, entity: Entity) -> Result<QueryOne<'_, Q>, NoSuchEntity> { let loc = self.entities.get(entity)?; Ok(unsafe { QueryOne::new( &self.archetypes.archetypes[loc.archetype as usize], loc.index, ) }) } /// Query a single entity in a uniquely borrow world /// /// Like [`query_one`](Self::query_one), but faster because dynamic borrow checks can be /// skipped. Note that, unlike [`query_one`](Self::query_one), on success this returns the /// query's results directly. pub fn query_one_mut<Q: Query>( &mut self, entity: Entity, ) -> Result<QueryItem<'_, Q>, QueryOneError> { let loc = self.entities.get(entity)?; unsafe { let fetch = Q::Fetch::new(&self.archetypes.archetypes[loc.archetype as usize]) .ok_or(QueryOneError::Unsatisfied)?; Ok(fetch.get(loc.index as usize)) } } /// Borrow the `T` component of `entity` /// /// Panics if the component is already uniquely borrowed from another entity with the same /// components. pub fn get<T: Component>(&self, entity: Entity) -> Result<Ref<'_, T>, ComponentError> { Ok(self .entity(entity)? .get() .ok_or_else(MissingComponent::new::<T>)?) } /// Uniquely borrow the `T` component of `entity` /// /// Panics if the component is already borrowed from another entity with the same components. pub fn get_mut<T: Component>(&self, entity: Entity) -> Result<RefMut<'_, T>, ComponentError> { Ok(self .entity(entity)? .get_mut() .ok_or_else(MissingComponent::new::<T>)?) } /// Access an entity regardless of its component types /// /// Does not immediately borrow any component. pub fn entity(&self, entity: Entity) -> Result<EntityRef<'_>, NoSuchEntity> { let loc = self.entities.get(entity)?; unsafe { Ok(EntityRef::new( &self.archetypes.archetypes[loc.archetype as usize], loc.index, )) } } /// Given an id obtained from [`Entity::id`], reconstruct the still-live [`Entity`]. /// /// # Safety /// /// `id` must correspond to a currently live [`Entity`]. A despawned or never-allocated `id` /// will produce undefined behavior. pub unsafe fn find_entity_from_id(&self, id: u32) -> Entity { self.entities.resolve_unknown_gen(id) } /// Iterate over all entities in the world /// /// Entities are yielded in arbitrary order. Prefer [`query`](Self::query) for better /// performance when components will be accessed in predictable patterns. /// /// # Example /// ``` /// # use hecs::*; /// let mut world = World::new(); /// let a = world.spawn(()); /// let b = world.spawn(()); /// let ids = world.iter().map(|(id, _)| id).collect::<Vec<_>>(); /// assert_eq!(ids.len(), 2); /// assert!(ids.contains(&a)); /// assert!(ids.contains(&b)); /// ``` pub fn iter(&self) -> Iter<'_> { Iter::new(&self.archetypes.archetypes, &self.entities) } /// Add `components` to `entity` /// /// Computational cost is proportional to the number of components `entity` has. If an entity /// already has a component of a certain type, it is dropped and replaced. /// /// When inserting a single component, see [`insert_one`](Self::insert_one) for convenience. /// /// # Example /// ``` /// # use hecs::*; /// let mut world = World::new(); /// let e = world.spawn((123, "abc")); /// world.insert(e, (456, true)); /// assert_eq!(*world.get::<i32>(e).unwrap(), 456); /// assert_eq!(*world.get::<bool>(e).unwrap(), true); /// ``` pub fn insert( &mut self, entity: Entity, components: impl DynamicBundle, ) -> Result<(), NoSuchEntity> { self.flush(); let loc = self.entities.get_mut(entity)?; let target_storage; let target = match components.key() { None => { target_storage = self .archetypes .get_insert_target(loc.archetype, &components); &target_storage } Some(key) => match self.archetypes.insert_edges[loc.archetype as usize].get(&key) { Some(x) => x, None => { let t = self .archetypes .get_insert_target(loc.archetype, &components); self.archetypes.insert_edges[loc.archetype as usize] .entry(key) .or_insert(t) } }, }; unsafe { // Drop the components we're overwriting let source_arch = &mut self.archetypes.archetypes[loc.archetype as usize]; for &ty in &target.replaced { let ptr = source_arch .get_dynamic(ty.id(), ty.layout().size(), loc.index) .unwrap(); ty.drop(ptr.as_ptr()); } if target.index == loc.archetype { // Update components in the current archetype let arch = &mut self.archetypes.archetypes[loc.archetype as usize]; components.put(|ptr, ty| { arch.put_dynamic(ptr, ty.id(), ty.layout().size(), loc.index); }); return Ok(()); } let (source_arch, target_arch) = index2( &mut self.archetypes.archetypes, loc.archetype as usize, target.index as usize, ); // Allocate storage in the archetype and update the entity's location to address it let target_index = target_arch.allocate(entity.id); loc.archetype = target.index; let old_index = mem::replace(&mut loc.index, target_index); // Move the new components components.put(|ptr, ty| { target_arch.put_dynamic(ptr, ty.id(), ty.layout().size(), target_index); }); // Move the components we're keeping for &ty in &target.retained { let src = source_arch .get_dynamic(ty.id(), ty.layout().size(), old_index) .unwrap(); target_arch.put_dynamic(src.as_ptr(), ty.id(), ty.layout().size(), target_index) } // Free storage in the old archetype if let Some(moved) = source_arch.remove(old_index, false) { self.entities.meta[moved as usize].location.index = old_index; } } Ok(()) } /// Add `component` to `entity` /// /// See [`insert`](Self::insert). pub fn insert_one( &mut self, entity: Entity, component: impl Component, ) -> Result<(), NoSuchEntity> { self.insert(entity, (component,)) } /// Remove components from `entity` /// /// Computational cost is proportional to the number of components `entity` has. The entity /// itself is not removed, even if no components remain; use `despawn` for that. If any /// component in `T` is not present in `entity`, no components are removed and an error is /// returned. /// /// When removing a single component, see [`remove_one`](Self::remove_one) for convenience. /// /// # Example /// ``` /// # use hecs::*; /// let mut world = World::new(); /// let e = world.spawn((123, "abc", true)); /// assert_eq!(world.remove::<(i32, &str)>(e), Ok((123, "abc"))); /// assert!(world.get::<i32>(e).is_err()); /// assert!(world.get::<&str>(e).is_err()); /// assert_eq!(*world.get::<bool>(e).unwrap(), true); /// ``` pub fn remove<T: Bundle + 'static>(&mut self, entity: Entity) -> Result<T, ComponentError> { self.flush(); // Gather current metadata let loc = self.entities.get_mut(entity)?; let old_index = loc.index; let source_arch = &self.archetypes.archetypes[loc.archetype as usize]; // Move out of the source archetype, or bail out if a component is missing let bundle = unsafe { T::get(|ty| source_arch.get_dynamic(ty.id(), ty.layout().size(), old_index))? }; // Find the target archetype ID let target = match source_arch.remove_edges.get(&TypeId::of::<T>()) { Some(&x) => x, None => { let removed = T::with_static_ids(|ids| ids.iter().copied().collect::<HashSet<_>>()); let info = source_arch .types() .iter() .cloned() .filter(|x| !removed.contains(&x.id())) .collect::<Vec<_>>(); let elements = info.iter().map(|x| x.id()).collect::<Box<_>>(); let index = self.archetypes.get(&*elements, move || info); self.archetypes.archetypes[loc.archetype as usize] .remove_edges .insert(TypeId::of::<T>(), index); index } }; // Store components to the target archetype and update metadata if loc.archetype != target { // If we actually removed any components, the entity needs to be moved into a new archetype unsafe { let (source_arch, target_arch) = index2( &mut self.archetypes.archetypes, loc.archetype as usize, target as usize, ); let target_index = target_arch.allocate(entity.id); loc.archetype = target; loc.index = target_index; if let Some(moved) = source_arch.move_to(old_index, |src, ty, size| { // Only move the components present in the target archetype, i.e. the non-removed ones. if let Some(dst) = target_arch.get_dynamic(ty, size, target_index) { ptr::copy_nonoverlapping(src, dst.as_ptr(), size); } }) { self.entities.meta[moved as usize].location.index = old_index; } } } Ok(bundle) } /// Remove the `T` component from `entity` /// /// See [`remove`](Self::remove). pub fn remove_one<T: Component>(&mut self, entity: Entity) -> Result<T, ComponentError> { self.remove::<(T,)>(entity).map(|(x,)| x) } /// Borrow the `T` component of `entity` without safety checks /// /// Should only be used as a building block for safe abstractions. /// /// # Safety /// /// `entity` must have been previously obtained from this [`World`], and no unique borrow of the /// same component of `entity` may be live simultaneous to the returned reference. pub unsafe fn get_unchecked<T: Component>(&self, entity: Entity) -> Result<&T, ComponentError> { let loc = self.entities.get(entity)?; if loc.archetype == 0 { return Err(MissingComponent::new::<T>().into()); } Ok(&*self.archetypes.archetypes[loc.archetype as usize] .get_base::<T>() .ok_or_else(MissingComponent::new::<T>)? .as_ptr() .add(loc.index as usize)) } /// Uniquely borrow the `T` component of `entity` without safety checks /// /// Should only be used as a building block for safe abstractions. /// /// # Safety /// /// `entity` must have been previously obtained from this [`World`], and no borrow of the same /// component of `entity` may be live simultaneous to the returned reference. pub unsafe fn get_unchecked_mut<T: Component>( &self, entity: Entity, ) -> Result<&mut T, ComponentError> { let loc = self.entities.get(entity)?; if loc.archetype == 0 { return Err(MissingComponent::new::<T>().into()); } Ok(&mut *self.archetypes.archetypes[loc.archetype as usize] .get_base::<T>() .ok_or_else(MissingComponent::new::<T>)? .as_ptr() .add(loc.index as usize)) } /// Convert all reserved entities into empty entities that can be iterated and accessed /// /// Invoked implicitly by `spawn`, `despawn`, `insert`, and `remove`. pub fn flush(&mut self) { let arch = &mut self.archetypes.archetypes[0]; self.entities .flush(|id, location| location.index = unsafe { arch.allocate(id) }); } /// Inspect the archetypes that entities are organized into /// /// Useful for dynamically scheduling concurrent queries by checking borrows in advance, and for /// efficient serialization. pub fn archetypes(&self) -> impl ExactSizeIterator<Item = &'_ Archetype> + '_ { self.archetypes.archetypes.iter() } /// Returns a distinct value after `archetypes` is changed /// /// Store the current value after deriving information from [`archetypes`](Self::archetypes), /// then check whether the value returned by this function differs before attempting an /// operation that relies on its correctness. Useful for determining whether e.g. a concurrent /// query execution plan is still correct. /// /// The generation may be, but is not necessarily, changed as a result of adding or removing any /// entity or component. /// /// # Example /// ``` /// # use hecs::*; /// let mut world = World::new(); /// let initial_gen = world.archetypes_generation(); /// world.spawn((123, "abc")); /// assert_ne!(initial_gen, world.archetypes_generation()); /// ``` pub fn archetypes_generation(&self) -> ArchetypesGeneration { ArchetypesGeneration(self.archetypes.generation) } /// Number of currently live entities #[inline] pub fn len(&self) -> u32 { self.entities.len() } /// Whether no entities are live #[inline] pub fn is_empty(&self) -> bool { self.len() == 0 } } unsafe impl Send for World {} unsafe impl Sync for World {} impl Default for World { fn default() -> Self { Self::new() } } impl<'a> IntoIterator for &'a World { type IntoIter = Iter<'a>; type Item = (Entity, EntityRef<'a>); fn into_iter(self) -> Iter<'a> { self.iter() } } fn index2<T>(x: &mut [T], i: usize, j: usize) -> (&mut T, &mut T) { assert!(i != j); assert!(i < x.len()); assert!(j < x.len()); let ptr = x.as_mut_ptr(); unsafe { (&mut *ptr.add(i), &mut *ptr.add(j)) } } /// Errors that arise when accessing components #[derive(Debug, Clone, Eq, PartialEq, Hash)] pub enum ComponentError { /// The entity was already despawned NoSuchEntity, /// The entity did not have a requested component MissingComponent(MissingComponent), } #[cfg(feature = "std")] impl Error for ComponentError {} impl fmt::Display for ComponentError { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { use ComponentError::*; match *self { NoSuchEntity => f.write_str("no such entity"), MissingComponent(ref x) => x.fmt(f), } } } impl From<NoSuchEntity> for ComponentError { fn from(NoSuchEntity: NoSuchEntity) -> Self { ComponentError::NoSuchEntity } } impl From<MissingComponent> for ComponentError { fn from(x: MissingComponent) -> Self { ComponentError::MissingComponent(x) } } /// Errors that arise when querying a single entity #[derive(Debug, Clone, Eq, PartialEq, Hash)] pub enum QueryOneError { /// The entity was already despawned NoSuchEntity, /// The entity exists but does not satisfy the query Unsatisfied, } #[cfg(feature = "std")] impl Error for QueryOneError {} impl fmt::Display for QueryOneError { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { use QueryOneError::*; match *self { NoSuchEntity => f.write_str("no such entity"), Unsatisfied => f.write_str("unsatisfied"), } } } impl From<NoSuchEntity> for QueryOneError { fn from(NoSuchEntity: NoSuchEntity) -> Self { QueryOneError::NoSuchEntity } } /// Types that can be components, implemented automatically for all `Send + Sync + 'static` types /// /// This is just a convenient shorthand for `Send + Sync + 'static`, and never needs to be /// implemented manually. pub trait Component: Send + Sync + 'static {} impl<T: Send + Sync + 'static> Component for T {} /// Iterator over all of a world's entities pub struct Iter<'a> { archetypes: core::slice::Iter<'a, Archetype>, entities: &'a Entities, current: Option<&'a Archetype>, index: u32, } impl<'a> Iter<'a> { fn new(archetypes: &'a [Archetype], entities: &'a Entities) -> Self { Self { archetypes: archetypes.iter(), entities, current: None, index: 0, } } } unsafe impl Send for Iter<'_> {} unsafe impl Sync for Iter<'_> {} impl<'a> Iterator for Iter<'a> { type Item = (Entity, EntityRef<'a>); fn next(&mut self) -> Option<Self::Item> { loop { match self.current { None => { self.current = Some(self.archetypes.next()?); self.index = 0; } Some(current) => { if self.index == current.len() as u32 { self.current = None; continue; } let index = self.index; self.index += 1; let id = current.entity_id(index); return Some(( Entity { id, generation: self.entities.meta[id as usize].generation, }, unsafe { EntityRef::new(current, index) }, )); } } } } fn size_hint(&self) -> (usize, Option<usize>) { (self.len(), Some(self.len())) } } impl ExactSizeIterator for Iter<'_> { #[inline] fn len(&self) -> usize { self.entities.len() as usize } } impl<A: DynamicBundle> Extend<A> for World { fn extend<T>(&mut self, iter: T) where T: IntoIterator<Item = A>, { for x in iter { self.spawn(x); } } } impl<A: DynamicBundle> core::iter::FromIterator<A> for World { fn from_iter<I: IntoIterator<Item = A>>(iter: I) -> Self { let mut world = World::new(); world.extend(iter); world } } /// Determines freshness of information derived from [`World::archetypes`] #[derive(Debug, Copy, Clone, Eq, PartialEq)] pub struct ArchetypesGeneration(u64); /// Entity IDs created by [`World::spawn_batch`] pub struct SpawnBatchIter<'a, I> where I: Iterator, I::Item: Bundle, { inner: I, entities: &'a mut Entities, archetype_id: u32, archetype: &'a mut Archetype, } impl<I> Drop for SpawnBatchIter<'_, I> where I: Iterator, I::Item: Bundle, { fn drop(&mut self) { for _ in self {} } } impl<I> Iterator for SpawnBatchIter<'_, I> where I: Iterator, I::Item: Bundle, { type Item = Entity; fn next(&mut self) -> Option<Entity> { let components = self.inner.next()?; let entity = self.entities.alloc(); unsafe { let index = self.archetype.allocate(entity.id); components.put(|ptr, ty| { self.archetype .put_dynamic(ptr, ty.id(), ty.layout().size(), index); }); self.entities.meta[entity.id as usize].location = Location { archetype: self.archetype_id, index, }; } Some(entity) } fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() } } impl<I, T> ExactSizeIterator for SpawnBatchIter<'_, I> where I: ExactSizeIterator<Item = T>, T: Bundle, { fn len(&self) -> usize { self.inner.len() } } /// Iterator over [`Entity`]s spawned by [`World::spawn_column_batch()`] pub struct SpawnColumnBatchIter<'a> { pending_end: usize, id_alloc: crate::entities::AllocManyState, entities: &'a mut Entities, } impl Iterator for SpawnColumnBatchIter<'_> { type Item = Entity; fn next(&mut self) -> Option<Entity> { let id = self.id_alloc.next(&self.entities)?; Some(unsafe { self.entities.resolve_unknown_gen(id) }) } fn size_hint(&self) -> (usize, Option<usize>) { (self.len(), Some(self.len())) } } impl ExactSizeIterator for SpawnColumnBatchIter<'_> { fn len(&self) -> usize { self.id_alloc.len(&self.entities) } } impl Drop for SpawnColumnBatchIter<'_> { fn drop(&mut self) { // Consume used freelist entries self.entities.finish_alloc_many(self.pending_end); } } struct ArchetypeSet { /// Maps sorted component type sets to archetypes index: HashMap<Box<[TypeId]>, u32>, archetypes: Vec<Archetype>, generation: u64, /// Maps static bundle types to the archetype that an entity from this archetype is moved to /// after inserting the components from that bundle. Stored separately from archetypes to avoid /// borrowck difficulties in `World::insert`. insert_edges: Vec<TypeIdMap<InsertTarget>>, } impl ArchetypeSet { fn new() -> Self { // `flush` assumes archetype 0 always exists, representing entities with no components. Self { index: Some((Box::default(), 0)).into_iter().collect(), archetypes: vec![Archetype::new(Vec::new())], generation: 0, insert_edges: vec![HashMap::default()], } } /// Find the archetype ID that has exactly `components` fn get<T: Borrow<[TypeId]> + Into<Box<[TypeId]>>>( &mut self, components: T, info: impl FnOnce() -> Vec<TypeInfo>, ) -> u32 { self.index .get(components.borrow()) .copied() .unwrap_or_else(|| self.insert(components.into(), info())) } fn insert(&mut self, components: Box<[TypeId]>, info: Vec<TypeInfo>) -> u32 { let x = self.archetypes.len() as u32; self.archetypes.push(Archetype::new(info)); let old = self.index.insert(components, x); debug_assert!(old.is_none(), "inserted duplicate archetype"); self.post_insert(); x } /// Returns archetype ID and starting location index fn insert_batch(&mut self, archetype: Archetype) -> (u32, u32) { use hashbrown::hash_map::Entry; let ids = archetype .types() .iter() .map(|info| info.id()) .collect::<Box<_>>(); match self.index.entry(ids) { Entry::Occupied(x) => { // Duplicate of existing archetype let existing = &mut self.archetypes[*x.get() as usize]; let base = existing.len(); unsafe { existing.merge(archetype); } (*x.get(), base) } Entry::Vacant(x) => { // Brand new archetype let id = self.archetypes.len() as u32; self.archetypes.push(archetype); x.insert(id); self.post_insert(); (id, 0) } } } fn post_insert(&mut self) { self.insert_edges.push(HashMap::default()); self.generation += 1; } fn get_insert_target(&mut self, src: u32, components: &impl DynamicBundle) -> InsertTarget { // Assemble Vec<TypeInfo> for the final entity let arch = &mut self.archetypes[src as usize]; let mut info = arch.types().to_vec(); let mut replaced = Vec::new(); // Elements in both archetype.types() and components.type_info() let mut retained = Vec::new(); // Elements in archetype.types() but not components.type_info() // Because both `components.type_info()` and `arch.types()` are // ordered, we can identify elements in one but not the other efficiently with parallel // iteration. let mut src_ty = 0; for ty in components.type_info() { while src_ty < arch.types().len() && arch.types()[src_ty] <= ty { if arch.types()[src_ty] != ty { retained.push(arch.types()[src_ty]); } src_ty += 1; } if arch.has_dynamic(ty.id()) { replaced.push(ty); } else { info.push(ty); } } info.sort_unstable(); retained.extend_from_slice(&arch.types()[src_ty..]); // Find the archetype it'll live in let elements = info.iter().map(|x| x.id()).collect::<Box<_>>(); let index = self.get(elements, move || info); InsertTarget { replaced, retained, index, } } } /// Metadata cached for inserting components into entities from this archetype struct InsertTarget { /// Components from the current archetype that are replaced by the insert replaced: Vec<TypeInfo>, /// Components from the current archetype that are moved by the insert retained: Vec<TypeInfo>, /// ID of the target archetype index: u32, } #[cfg(test)] mod tests { use super::*; #[test] fn reuse_empty() { let mut world = World::new(); let a = world.spawn(()); world.despawn(a).unwrap(); let b = world.spawn(()); assert_eq!(a.id, b.id); assert_ne!(a.generation, b.generation); } #[test] fn spawn_at() { let mut world = World::new(); let a = world.spawn(()); world.despawn(a).unwrap(); let b = world.spawn(()); assert!(world.contains(b)); assert_eq!(a.id, b.id); assert_ne!(a.generation, b.generation); world.spawn_at(a, ()); assert!(!world.contains(b)); assert_eq!(b.id, a.id); assert_ne!(b.generation, a.generation); } #[test] fn reuse_populated() { let mut world = World::new(); let a = world.spawn((42,)); assert_eq!(*world.get::<i32>(a).unwrap(), 42); world.despawn(a).unwrap(); let b = world.spawn((true,)); assert_eq!(a.id, b.id); assert_ne!(a.generation, b.generation); assert!(world.get::<i32>(b).is_err()); assert!(*world.get::<bool>(b).unwrap()); } #[test] fn remove_nothing() { let mut world = World::new(); let a = world.spawn(("abc", 123)); world.remove::<()>(a).unwrap(); } }