recompact/utils/createChangeEmitter.js

A set of React high order components based on Rx.

"use strict";

exports.__esModule = true;
var createChangeEmitter = function createChangeEmitter() {
  var currentListeners = [];
  var nextListeners = currentListeners;

  function ensureCanMutateNextListeners() {
    if (nextListeners === currentListeners) {
      nextListeners = currentListeners.slice();
    }
  }

  function listen(listener) {
    var isSubscribed = true;

    ensureCanMutateNextListeners();
    nextListeners.push(listener);

    return function () {
      if (!isSubscribed) {
        return;
      }

      isSubscribed = false;

      ensureCanMutateNextListeners();
      var index = nextListeners.indexOf(listener);
      nextListeners.splice(index, 1);
    };
  }

  function emit(value) {
    currentListeners = nextListeners;
    var listeners = currentListeners;
    for (var i = 0; i < listeners.length; i += 1) {
      listeners[i](value);
    }
  }

  return { listen: listen, emit: emit };
};

exports.default = createChangeEmitter;