dynatrace-cordova-outsystems-plugin/node_modules/asynckit/lib/streamify.js

This plugin gives you the ability to use the Dynatrace instrumentation in your hybrid application (Cordova, Ionic, ..). It uses the Mobile Agent, the JavaScript Agent and the Javascript Bridge. The Mobile Agent will give you all device specific values con

var async = require('./async.js');

// API
module.exports = {
  iterator: wrapIterator,
  callback: wrapCallback
};

/**
 * Wraps iterators with long signature
 *
 * @this    ReadableAsyncKit#
 * @param   {function} iterator - function to wrap
 * @returns {function} - wrapped function
 */
function wrapIterator(iterator)
{
  var stream = this;

  return function(item, key, cb)
  {
    var aborter
      , wrappedCb = async(wrapIteratorCallback.call(stream, cb, key))
      ;

    stream.jobs[key] = wrappedCb;

    // it's either shortcut (item, cb)
    if (iterator.length == 2)
    {
      aborter = iterator(item, wrappedCb);
    }
    // or long format (item, key, cb)
    else
    {
      aborter = iterator(item, key, wrappedCb);
    }

    return aborter;
  };
}

/**
 * Wraps provided callback function
 * allowing to execute snitch function before
 * real callback
 *
 * @this    ReadableAsyncKit#
 * @param   {function} callback - function to wrap
 * @returns {function} - wrapped function
 */
function wrapCallback(callback)
{
  var stream = this;

  var wrapped = function(error, result)
  {
    return finisher.call(stream, error, result, callback);
  };

  return wrapped;
}

/**
 * Wraps provided iterator callback function
 * makes sure snitch only called once,
 * but passes secondary calls to the original callback
 *
 * @this    ReadableAsyncKit#
 * @param   {function} callback - callback to wrap
 * @param   {number|string} key - iteration key
 * @returns {function} wrapped callback
 */
function wrapIteratorCallback(callback, key)
{
  var stream = this;

  return function(error, output)
  {
    // don't repeat yourself
    if (!(key in stream.jobs))
    {
      callback(error, output);
      return;
    }

    // clean up jobs
    delete stream.jobs[key];

    return streamer.call(stream, error, {key: key, value: output}, callback);
  };
}

/**
 * Stream wrapper for iterator callback
 *
 * @this  ReadableAsyncKit#
 * @param {mixed} error - error response
 * @param {mixed} output - iterator output
 * @param {function} callback - callback that expects iterator results
 */
function streamer(error, output, callback)
{
  if (error && !this.error)
  {
    this.error = error;
    this.pause();
    this.emit('error', error);
    // send back value only, as expected
    callback(error, output && output.value);
    return;
  }

  // stream stuff
  this.push(output);

  // back to original track
  // send back value only, as expected
  callback(error, output && output.value);
}

/**
 * Stream wrapper for finishing callback
 *
 * @this  ReadableAsyncKit#
 * @param {mixed} error - error response
 * @param {mixed} output - iterator output
 * @param {function} callback - callback that expects final results
 */
function finisher(error, output, callback)
{
  // signal end of the stream
  // only for successfully finished streams
  if (!error)
  {
    this.push(null);
  }

  // back to original track
  callback(error, output);
}