emissary/lib/helpers.js

Utility mixins for subscribing to and emitting events.

(function() {
  var Behavior, combineArray, combineWithFunction,
    __slice = [].slice;

  Behavior = require('./behavior');

  exports.combine = function() {
    var args;
    args = 1 <= arguments.length ? __slice.call(arguments, 0) : [];
    if (args.length === 1 && Array.isArray(args[0])) {
      return combineArray(args[0]);
    } else if (typeof args[args.length - 1] === 'function') {
      return combineWithFunction(args);
    } else {
      throw new Error("Invalid object type");
    }
  };

  combineArray = function(array) {
    var behavior;
    return behavior = new Behavior(function() {
      var element, i, outputArray, ready, _i, _len,
        _this = this;
      outputArray = array.slice();
      ready = false;
      for (i = _i = 0, _len = array.length; _i < _len; i = ++_i) {
        element = array[i];
        if (element.constructor.name === 'Behavior') {
          (function(element, i) {
            return _this.subscribe(element.onValue(function(value, metadata) {
              if (ready) {
                outputArray = outputArray.slice();
              }
              outputArray[i] = value;
              if (ready) {
                return _this.emitValue(outputArray, metadata);
              }
            }));
          })(element, i);
        }
      }
      ready = true;
      return this.emitValue(outputArray);
    });
  };

  combineWithFunction = function(args) {
    var fn;
    fn = args.pop();
    return combineArray(args).map(function(argsArray) {
      return fn.apply(null, argsArray);
    });
  };

}).call(this);