Crate hecs

A handy ECS

hecs provides a high-performance, minimalist entity-component-system (ECS) world. It is a library, not a framework. In place of an explicit "System" abstraction, a World's entities are easily queried from regular code. Organize your application however you like!

In order of importance, hecs pursues:

• fast traversals
• a simple interface
• a small dependency closure
• exclusion of externally-implementable functionality

let mut world = World::new();
// Nearly any type can be used as a component with zero boilerplate
let a = world.spawn((123, true, "abc"));
let b = world.spawn((42, false));
// Systems can be simple for loops
for (id, (number, &flag)) in world.query::<(&mut i32, &bool)>().iter() {
  if flag { *number *= 2; }
}
// Random access is simple and safe
assert_eq!(*world.get::<i32>(a).unwrap(), 246);
assert_eq!(*world.get::<i32>(b).unwrap(), 42);

Structs

Archetype	A collection of entities having the same component types
ArchetypesGeneration	Determines freshness of information derived from World::archetypes
BatchedIter	Batched version of QueryIter
BuiltEntity	The output of an EntityBuilder, suitable for passing to World::spawn or World::insert
Entity	Lightweight unique ID of an entity
EntityBuilder	Helper for incrementally constructing a bundle of components with dynamic component types
EntityRef	Handle to an entity with any component types
Iter	Iterator over all of a world's entities
MissingComponent	Error indicating that an entity did not have a required component
NoSuchEntity	Error indicating that no entity with a particular ID exists
QueryBorrow	A borrow of a World sufficient to execute the query Q
QueryIter	Iterator over the set of entities with the components in Q
QueryOne	A borrow of a World sufficient to execute the query Q on a single entity
Ref	Shared borrow of an entity's component
RefMut	Unique borrow of an entity's component
SpawnBatchIter	Entity IDs created by World::spawn_batch
With	Query transformer skipping entities that do not have a T component
Without	Query transformer skipping entities that have a T component
World	An unordered collection of entities, each having any number of distinctly typed components

Enums

Access	Type of access a Query may have to an Archetype
ComponentError	Errors that arise when accessing components

Traits

Bundle	A statically typed collection of components
Component	Types that can be components, implemented automatically for all Send + Sync + 'static types
DynamicBundle	A dynamically typed collection of components
Query	A collection of component types to fetch from a World

Derive Macros

Bundle

Implement Bundle for a monomorphic struct