jecs/lib/index.d.ts

type Archetype = {
	id: number,
	edges: {
		[key: number]: {
			add: Archetype,
			remove: Archetype,
		},
	},
	types: Array<number>,
	type: string | number,
	entities: Array<number>,
	columns: Array<Array<unknown>>,
	records: { [key: number]: number },
}

type ArchetypeMap = {
	cache: Array<number>,
	first: ArchetypeMap,
	second: ArchetypeMap,
	parent: ArchetypeMap,
	size: number,
}

type Query<T extends unknown[]> = {
    without: (...components: Entity[]) => Query<T>;
} & IterableFunction<LuaTuple<[Entity, ...T]>>

// Exported due to functions below requiring this type.
export type EntityIndex = {
    dense: {
        [key: number]: number
    };
    sparse: {
        [key: number]: {
			archetype: Archetype,
			row: number,
			dense: number,
			componentRecord: ArchetypeMap,
		}
    }
}

// Utility Types
export type Entity<T = unknown> = number & { __nominal_type_dont_use: T }
export type EntityType<T> = T extends Entity<infer A> ? A : never;
export type InferComponents<A extends Entity[]> = {
    [K in keyof A]: EntityType<A[K]>
};
type Nullable<T extends unknown[]> = {
	[K in keyof T]: T[K] | undefined
}

export class World {

	/**
	 * Creates a new World
	 */
	constructor();

	/**
	 * Creates a new entity
	 * @returns Entity
	 */
    entity(): Entity;

	/**
	 * Creates a new entity located in the first 256 ids.
	 * These should be used for static components for fast access.
	 * @returns Entity<T>
	 */
    component<T = unknown>(): Entity<T>;

	/**
	 * Gets the target of a relationship. For example, when a user calls
	 * `world.target(id, ChildOf(parent))`, you will obtain the parent entity.
	 * @param id Entity
	 * @param relation The Relationship
	 * @returns The Parent Entity if it exists
	 */
    target(id: Entity, relation: Entity): Entity | undefined;

	/**
	 * Deletes an entity and all its related components and relationships.
	 * @param id Entity to be destroyed
	 */
    delete(id: Entity): void;

	/**
	 * Adds a component to the entity with no value
	 * @param id Target Entity
	 * @param component Component
	 */
    add<T>(id: Entity, component: Entity<T>): void;

	/**
	 * Assigns a value to a component on the given entity
	 * @param id Target Entity
	 * @param component Target Component
	 * @param data Component Data
	 */
    set<T>(id: Entity, component: Entity<T>, data: T): void;

	/**
	 * Removes a component from the given entity
	 * @param id Target Entity
	 * @param component Target Component
	 */
    remove(id: Entity, component: Entity): void;

	// Manually typed out get since there is a hard limit.

	/**
	 * Retrieves the value of one component. This value may be undefined.
	 * @param id Target Entity
	 * @param component Target Component
	 * @returns Data associated with the component if it exists
	 */
    get<A>(id: number, component: Entity<A>): A | undefined;

	/**
	 * Retrieves the value of two components. This value may be undefined.
	 * @param id Target Entity
	 * @param component Target Component 1
	 * @param component2 Target Component 2
	 * @returns Data associated with the components if it exists
	 */
    get<A, B>(id: number, component: Entity<A>, component2: Entity<B>): LuaTuple<Nullable<[A, B]>>;

	/**
	 * Retrieves the value of three components. This value may be undefined.
	 * @param id Target Entity
	 * @param component Target Component 1
	 * @param component2 Target Component 2
	 * @param component3 Target Component 3
	 * @returns Data associated with the components if it exists
	 */
    get<A, B, C>(id: number, component: Entity<A>, component2: Entity<B>, component3: Entity<C>): LuaTuple<Nullable<[A, B, C]>>;

	/**
	 * Retrieves the value of four components. This value may be undefined.
	 * @param id Target Entity
	 * @param component Target Component 1
	 * @param component2 Target Component 2
	 * @param component3 Target Component 3
	 * @param component4 Target Component 4
	 * @returns Data associated with the components if it exists
	 */
    get<A, B, C, D>(id: number, component: Entity<A>, component2: Entity<B>, component3: Entity<C>, component4: Entity<D>): LuaTuple<Nullable<[A, B, C, D]>>;
    
	/**
	 * Searches the world for entities that match a given query
	 * @param components Queried Components
	 * @returns Iterable function
	 */
    query<T extends Entity[]>(...components: T): Query<InferComponents<T>>
}

export const pair: (pred: Entity, obj: Entity) => Entity;

export const OnAdd: Entity;
export const OnRemove: Entity;
export const OnSet: Entity;
export const Wildcard: Entity;
export const w: Entity;
export const REST: Entity;

export const IS_PAIR: (e: Entity) => boolean;
export const ECS_ID: (e: Entity) => Entity;
export const ECS_PAIR: (pred: Entity, obj: Entity) => Entity;
export const ECS_GENERATION_INC: (e: Entity) => Entity;
export const ECS_GENERATION: (e: Entity) => Entity;
export const ECS_PAIR_RELATION: <T>(entityIndex: EntityIndex, e: Entity<T>) => Entity;
export const ECS_PAIR_OBJECT: <T>(entityIndex: EntityIndex, e: Entity<T>) => Entity;

export const getAlive: (entityIndex: EntityIndex, id: Entity) => Entity;