twitst4tz

twitter statistics web application
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iterate.js (1794B)


      1 var async = require('./async.js')
      2   , abort = require('./abort.js')
      3   ;
      4 
      5 // API
      6 module.exports = iterate;
      7 
      8 /**
      9  * Iterates over each job object
     10  *
     11  * @param {array|object} list - array or object (named list) to iterate over
     12  * @param {function} iterator - iterator to run
     13  * @param {object} state - current job status
     14  * @param {function} callback - invoked when all elements processed
     15  */
     16 function iterate(list, iterator, state, callback)
     17 {
     18   // store current index
     19   var key = state['keyedList'] ? state['keyedList'][state.index] : state.index;
     20 
     21   state.jobs[key] = runJob(iterator, key, list[key], function(error, output)
     22   {
     23     // don't repeat yourself
     24     // skip secondary callbacks
     25     if (!(key in state.jobs))
     26     {
     27       return;
     28     }
     29 
     30     // clean up jobs
     31     delete state.jobs[key];
     32 
     33     if (error)
     34     {
     35       // don't process rest of the results
     36       // stop still active jobs
     37       // and reset the list
     38       abort(state);
     39     }
     40     else
     41     {
     42       state.results[key] = output;
     43     }
     44 
     45     // return salvaged results
     46     callback(error, state.results);
     47   });
     48 }
     49 
     50 /**
     51  * Runs iterator over provided job element
     52  *
     53  * @param   {function} iterator - iterator to invoke
     54  * @param   {string|number} key - key/index of the element in the list of jobs
     55  * @param   {mixed} item - job description
     56  * @param   {function} callback - invoked after iterator is done with the job
     57  * @returns {function|mixed} - job abort function or something else
     58  */
     59 function runJob(iterator, key, item, callback)
     60 {
     61   var aborter;
     62 
     63   // allow shortcut if iterator expects only two arguments
     64   if (iterator.length == 2)
     65   {
     66     aborter = iterator(item, async(callback));
     67   }
     68   // otherwise go with full three arguments
     69   else
     70   {
     71     aborter = iterator(item, key, async(callback));
     72   }
     73 
     74   return aborter;
     75 }