Mailspring/src/serializable-registry.es6

/**
 * Public: This keeps track of constructors so we know how to inflate
 * serialized objects.
 *
 * We map constructor string names with factory functions that will return
 * the actual constructor itself.
 *
 * The reason we have an extra function call to return a constructor is so
 * we don't need to `require` all constructors at once on load. We are
 * wasting a very large amount of time on bootup requiring files that may
 * never be used or only used way down the line.
 *
 * If 3rd party packages want to register new inflatable models, they can
 * use `register` and pass the constructor generator along with the name.
 *
 * Note that there is one registry per window.
 */
export default class SerializableRegistry {
  constructor() {
    this._constructorFactories = {}
  }

  get(name) {
    return this._constructorFactories[name].call(null)
  }

  getAllConstructors() {
    const constructors = []
    for (const name of Object.keys(this._constructorFactories)) {
      constructors.push(this.get(name))
    }
    return constructors;
  }

  isInRegistry(name) {
    return !!this._constructorFactories[name]
  }

  deserialize(name, dataJSON) {
    let data = dataJSON;
    if (typeof data === "string") {
      data = JSON.parse(dataJSON)
    }

    const constructor = this.get(name)

    if (typeof constructor !== "function") {
      throw new Error(`Unsure of how to inflate ${JSON.stringify(data)}. \
Your constructor factory must return a class constructor.`);
    }

    const object = new constructor()
    object.fromJSON(data)

    return object
  }

  register(name, constructorFactory) {
    this._constructorFactories[name] = constructorFactory
  }

  unregister(name) {
    delete this._constructorFactories[name]
  }
}