signal-desktop/ts/backbone/reliable_trigger.ts

// Copyright 2017 Signal Messenger, LLC
// SPDX-License-Identifier: AGPL-3.0-only

import type * as Backbone from 'backbone';

type InternalBackboneEvent = {
  callback: (...args: Array<unknown>) => unknown;
  ctx: unknown;
};

/* eslint-disable */

// This file was taken from Backbone and then modified. It does not conform to this
//   project's standards.

// Note: this is all the code required to customize Backbone's trigger() method to make
//   it resilient to exceptions thrown by event handlers. Indentation and code styles
//   were kept inline with the Backbone implementation for easier diffs.

// The changes are:
//   1. added 'name' parameter to triggerEvents to give it access to the
//      current event name
//   2. added try/catch handlers to triggerEvents with error logging inside
//      every while loop

// And of course, we update the prototypes of Backbone.Model/Backbone.View as well as
//   Backbone.Events itself

// Regular expression used to split event strings.
const eventSplitter = /\s+/;

// Implement fancy features of the Events API such as multiple event
// names `"change blur"` and jQuery-style event maps `{change: action}`
// in terms of the existing API.
const eventsApi = function (
  obj: Backbone.Events,
  name: string | Record<string, unknown>,
  rest: ReadonlyArray<unknown>
) {
  if (!name) return true;

  // Handle event maps.
  if (typeof name === 'object') {
    for (const key in name) {
      obj.trigger(key, name[key], ...rest);
    }
    return false;
  }

  // Handle space separated event names.
  if (eventSplitter.test(name)) {
    const names = name.split(eventSplitter);
    for (let i = 0, l = names.length; i < l; i++) {
      obj.trigger(names[i], ...rest);
    }
    return false;
  }

  return true;
};

// A difficult-to-believe, but optimized internal dispatch function for
// triggering events. Tries to keep the usual cases speedy (most internal
// Backbone events have 3 arguments).
const triggerEvents = function (
  events: ReadonlyArray<InternalBackboneEvent>,
  name: string,
  args: Array<unknown>
) {
  let ev,
    i = -1,
    l = events.length,
    a1 = args[0],
    a2 = args[1],
    a3 = args[2];
  const logError = function (error: unknown) {
    window.SignalContext.log.error(
      'Model caught error triggering',
      name,
      'event:',
      error && error instanceof Error && error.stack ? error.stack : error
    );
  };
  switch (args.length) {
    case 0:
      while (++i < l) {
        try {
          (ev = events[i]).callback.call(ev.ctx);
        } catch (error) {
          logError(error);
        }
      }
      return;
    case 1:
      while (++i < l) {
        try {
          (ev = events[i]).callback.call(ev.ctx, a1);
        } catch (error) {
          logError(error);
        }
      }
      return;
    case 2:
      while (++i < l) {
        try {
          (ev = events[i]).callback.call(ev.ctx, a1, a2);
        } catch (error) {
          logError(error);
        }
      }
      return;
    case 3:
      while (++i < l) {
        try {
          (ev = events[i]).callback.call(ev.ctx, a1, a2, a3);
        } catch (error) {
          logError(error);
        }
      }
      return;
    default:
      while (++i < l) {
        try {
          (ev = events[i]).callback.apply(ev.ctx, args);
        } catch (error) {
          logError(error);
        }
      }
  }
};

// Trigger one or many events, firing all bound callbacks. Callbacks are
// passed the same arguments as `trigger` is, apart from the event name
// (unless you're listening on `"all"`, which will cause your callback to
// receive the true name of the event as the first argument).
function trigger<
  T extends Backbone.Events & {
    _events: undefined | Record<string, ReadonlyArray<InternalBackboneEvent>>;
  },
>(this: T, name: string, ...args: Array<unknown>): T {
  if (!this._events) return this;
  if (!eventsApi(this, name, args)) return this;
  const events = this._events[name];
  const allEvents = this._events.all;
  if (events) triggerEvents(events, name, args);
  if (allEvents) triggerEvents(allEvents, name, [...arguments]);
  return this;
}

[
  window.Backbone.Model.prototype,
  window.Backbone.Collection.prototype,
  window.Backbone.Events,
].forEach(proto => {
  Object.assign(proto, { trigger });
});