readme.js

July 28, 2018 · View on GitHub

/**

callbag-merge
Callbag factory that merges data from multiple callbag sources. Works well
with listenable sources, and while it may work for some pullable sources,
it is only designed for listenable sources.
npm install callbag-merge
Example:

const interval = require('callbag-interval');

const forEach = require('callbag-for-each');

const merge = require('callbag-merge');

const source = merge(interval(100), interval(350));

forEach(x => console.log(x))(source); // 0

                                      // 1

                                      // 2

                                      // 0

                                      // 3

                                      // 4

                                      // 5

                                      // ...

function merge(...sources) { return (start, sink) => { if (start !== 0) return; const n = sources.length; const sourceTalkbacks = new Array(n); let startCount = 0; let endCount = 0; let ended = false; const talkback = (t, d) => { if (t === 2) ended = true; for (let i = 0; i < n; i++) sourceTalkbacks[i] && sourceTalkbacks[i](t, d); }; for (let i = 0; i < n; i++) { if (ended) return; sources[i](0, (t, d) => { if (t === 0) { sourceTalkbacks[i] = d; if (++startCount === 1) sink(0, talkback); } else if (t === 2 && d) { ended = true; for (let j = 0; j < n; j++) { if (j !== i) sourceTalkbacks[j] && sourceTalkbacksj; } sink(2, d); } else if (t === 2) { sourceTalkbacks[i] = void 0; if (++endCount === n) sink(2); } else sink(t, d); }); } }; }

export default merge;