xstate/es/scheduler.js

Finite State Machines and Statecharts for the Modern Web.

import { __assign } from './_virtual/_tslib.js';

var defaultOptions = {
  deferEvents: false
};

var Scheduler =
/*#__PURE__*/

/** @class */
function () {
  function Scheduler(options) {
    this.processingEvent = false;
    this.queue = [];
    this.initialized = false;
    this.options = __assign(__assign({}, defaultOptions), options);
  }

  Scheduler.prototype.initialize = function (callback) {
    this.initialized = true;

    if (callback) {
      if (!this.options.deferEvents) {
        this.schedule(callback);
        return;
      }

      this.process(callback);
    }

    this.flushEvents();
  };

  Scheduler.prototype.schedule = function (task) {
    if (!this.initialized || this.processingEvent) {
      this.queue.push(task);
      return;
    }

    if (this.queue.length !== 0) {
      throw new Error('Event queue should be empty when it is not processing events');
    }

    this.process(task);
    this.flushEvents();
  };

  Scheduler.prototype.clear = function () {
    this.queue = [];
  };

  Scheduler.prototype.flushEvents = function () {
    var nextCallback = this.queue.shift();

    while (nextCallback) {
      this.process(nextCallback);
      nextCallback = this.queue.shift();
    }
  };

  Scheduler.prototype.process = function (callback) {
    this.processingEvent = true;

    try {
      callback();
    } catch (e) {
      // there is no use to keep the future events
      // as the situation is not anymore the same
      this.clear();
      throw e;
    } finally {
      this.processingEvent = false;
    }
  };

  return Scheduler;
}();

export { Scheduler };