callbag-filter

/**

• callbag-filter

• ---

• Callbag operator that conditionally lets data pass through. Works on either
• pullable or listenable sources.
• npm install callbag-filter
• Example:

• const fromIter = require('callbag-from-iter');
  

• const iterate = require('callbag-iterate');
  

• const filter = require('callbag-filter');
  

• const source = filter(x => x % 2)(fromIter([1,2,3,4,5]));
  

• iterate(x => console.log(x))(source); // 1
  

•                                       // 3
  

•                                       // 5
  

*/

const filter = condition => source => (start, sink) => { if (start !== 0) return; let talkback; source(0, (t, d) => { if (t === 0) { talkback = d; sink(t, d); } else if (t === 1) { if (condition(d)) sink(t, d); else talkback(1); } else sink(t, d); }); };

module.exports = filter;