Trait specs::saveload::Marker [−][src]
pub trait Marker: Clone + Component + Debug + Eq + Hash + DeserializeOwned + Serialize { type Identifier; type Allocator: MarkerAllocator<Self>; fn id(&self) -> Self::Identifier; fn update(&mut self, new_revision: Self) { ... } }
Expand description
This trait should be implemented by a component which is going to be used as
marker. This marker should be set to entity that should be serialized.
If serialization strategy needs to set marker to some entity
then it should use newly allocated marker from Marker::Allocator
.
Example
extern crate specs; #[macro_use] extern crate serde; use std::{collections::HashMap, ops::Range}; use specs::{ prelude::*, saveload::{MarkedBuilder, Marker, MarkerAllocator}, world::EntitiesRes, }; // Marker for entities that should be synced over network #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq, Serialize, Deserialize)] struct NetMarker { id: u64, seq: u64, } impl Component for NetMarker { type Storage = DenseVecStorage<Self>; } impl Marker for NetMarker { type Allocator = NetNode; type Identifier = u64; fn id(&self) -> u64 { self.id } // Updates sequence id. // Entities with too old sequence id get deleted. fn update(&mut self, update: Self) { assert_eq!(self.id, update.id); self.seq = update.seq; } } // Each client and server has one // Contains id range and `NetMarker -> Entity` mapping struct NetNode { range: Range<u64>, mapping: HashMap<u64, Entity>, } impl MarkerAllocator<NetMarker> for NetNode { fn allocate(&mut self, entity: Entity, id: Option<u64>) -> NetMarker { let id = id.unwrap_or_else(|| { self.range .next() .expect("Id range must be virtually endless") }); let marker = NetMarker { id, seq: 0 }; self.mapping.insert(id, entity); marker } fn retrieve_entity_internal(&self, id: u64) -> Option<Entity> { self.mapping.get(&id).cloned() } fn maintain(&mut self, entities: &EntitiesRes, storage: &ReadStorage<NetMarker>) { self.mapping = (entities, storage) .join() .map(|(e, m)| (m.id(), e)) .collect(); } } fn main() { let mut world = World::new(); world.register::<NetMarker>(); world.insert(NetNode { range: 0..100, mapping: HashMap::new(), }); let entity = world.create_entity().marked::<NetMarker>().build(); let storage = &mut world.write_storage::<NetMarker>(); let marker = storage.get(entity).unwrap().clone(); assert_eq!( world .write_resource::<NetNode>() .retrieve_entity(marker, storage, &world.entities()), entity ); }
Associated Types
type Identifier
[src]
type Identifier
[src]Id of the marker
type Allocator: MarkerAllocator<Self>
[src]
type Allocator: MarkerAllocator<Self>
[src]Allocator for this Marker
Required methods
fn id(&self) -> Self::Identifier
[src]
fn id(&self) -> Self::Identifier
[src]Get this marker internal id. The value of this method should be constant.
Provided methods
This gets called when an entity is deserialized by
DeserializeComponents
. It can be used to update internal data that
is not used for identification.
Contract
This function may assume that self.id() == new_revision.id()
.
However, it must not exhibit undefined behavior in such a case.
Panics
May panic if self.id()
!= new_revision.id()
.
Default implementation
The default implementation just sets self
to new_revision
.
Examples
#[derive(Clone, Debug, Deserialize, Eq, Hash, Serialize)] struct MyMarker { id: u64, last_modified: String, } impl Marker for MyMarker { type Identifier = u64; fn id(&self) -> u64 { self.id } fn update(&self, new: Self) { self.last_modified = new.last_modified; } }
Now, the marker always contains the name of the client who updated the entity associated with this marker.