Carbon/src/js/store/SubscribeValue.js

import { Subscribable } from "./Subscribable.js";

class SubscribeValue extends Subscribable {
  constructor() {
    super();
    this.hasData = false;
    this.data = null;
  }

  exists() {
    return this.hasData;
  }

  value() {
    if (this.hasData) return this.data;
    else return null;
  }

  set(data) {
    const exists = this.exists();
    this.data = data;
    this.hasData = true;
    if (exists) {
      this.broadcast("editSelf", this.data);
    } else {
      this.broadcast("addSelf", this.data);
    }
    return this;
  }

  edit(f) {
    if (this.exists()) {
      f(this.data);
      this.set(this.data);
    } else {
      throw new Error("Tried to edit a SubscribeValue that had no value");
    }
  }

  delete() {
    this.hasData = false;
    this.broadcast("removeSelf");
    return this;
  }
}

export { SubscribeValue };