avocado-old/packages/entity/trait/registry.js

let traitId = 0;
const idToTraitMap = new Map();
const traitToIdMap = new Map();
const traitRegistry = new Map();

export function registerTrait(Trait) {
  const hadTrait = traitRegistry.has(Trait.type());
  traitRegistry.set(Trait.type(), Trait);
  if (!hadTrait) {
    traitToIdMap.set(Trait.type(), traitId);
    idToTraitMap.set(traitId, Trait.type());
    traitId += 1;
  }
}

export function hasTrait(type) {
  return traitRegistry.has(type);
}

export function idFromTrait(Trait) {
  return traitToIdMap.get(Trait.type());
}

export function lookupTrait(type) {
  return traitRegistry.get(type);
}

export function traitFromId(id) {
  return lookupTrait(idToTraitMap.get(id));
}