categorizing-stream

categorizing-stream

Writable stream that categorizes incoming data

Explanation

A category stream is a writable stream. As you write items to the stream, the stream categorizes those items and emits events on channels named after the categories. If the item belongs to no category, then the item is emitted to the "noCategory" channel.

var stream = categorizeStream({
  categoryA: function (item, next/* , extraArgsPassedByNext...*/) {
    return next(null, matchesA(item), 'extraArg1ForNextCategory', 'extraArg2');
  }
, categoryB: function (item, next/* , extraArgsPassedByNext...*/) {
    var extraArg1ForNextCategory = arguments[2];
    var extraArg2 = arguments[3];
    if (matchesB(item, extraArg1ForNextCategory, extraArg2)) {
      // {halt: true} stops passing the item along the sequence of categories,
      // so the item is never considered for any subsequent categories.
      next(null, true, {halt: true});
    } else {
      next(null, false);
    }
  }
});

stream.on('categoryA', function (item) {
});

stream.on('categoryB', function (item) {
});

An item is considered against each category sequentially (in the order specified by the argument ordering of categorizeStream). If there is a match, then the item will be emitted on an event channel named after the category.

Events

• 'noCategory' - Emitted for items that have no category

  stream.on('noCategory', function (item) {
  });
  

• 'itemCompletelyCategorized' - Always run per item after all analysis is done on that item.

  stream.on('itemCompletelyCategorized', function (item) {
  });
  

MIT License

Copyright (c) 2013 by Brian Noguchi

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.