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node_modules/asynckit/serialOrdered.js 1.71 KB
aaac7fed   liuqimichale   add
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  var iterate    = require('./lib/iterate.js')
    , initState  = require('./lib/state.js')
    , terminator = require('./lib/terminator.js')
    ;
  
  // Public API
  module.exports = serialOrdered;
  // sorting helpers
  module.exports.ascending  = ascending;
  module.exports.descending = descending;
  
  /**
   * Runs iterator over provided sorted array elements in series
   *
   * @param   {array|object} list - array or object (named list) to iterate over
   * @param   {function} iterator - iterator to run
   * @param   {function} sortMethod - custom sort function
   * @param   {function} callback - invoked when all elements processed
   * @returns {function} - jobs terminator
   */
  function serialOrdered(list, iterator, sortMethod, callback)
  {
    var state = initState(list, sortMethod);
  
    iterate(list, iterator, state, function iteratorHandler(error, result)
    {
      if (error)
      {
        callback(error, result);
        return;
      }
  
      state.index++;
  
      // are we there yet?
      if (state.index < (state['keyedList'] || list).length)
      {
        iterate(list, iterator, state, iteratorHandler);
        return;
      }
  
      // done here
      callback(null, state.results);
    });
  
    return terminator.bind(state, callback);
  }
  
  /*
   * -- Sort methods
   */
  
  /**
   * sort helper to sort array elements in ascending order
   *
   * @param   {mixed} a - an item to compare
   * @param   {mixed} b - an item to compare
   * @returns {number} - comparison result
   */
  function ascending(a, b)
  {
    return a < b ? -1 : a > b ? 1 : 0;
  }
  
  /**
   * sort helper to sort array elements in descending order
   *
   * @param   {mixed} a - an item to compare
   * @param   {mixed} b - an item to compare
   * @returns {number} - comparison result
   */
  function descending(a, b)
  {
    return -1 * ascending(a, b);
  }