/**

• callbag-to-mobx

• ---

• Convert a listenable callbag source to a mobx observable and back.
• yarn install callbag-to-mobx
• Example:
• const { interval } = require('callbag-basics');
• const { asObservable, fromExpression } = require('callbag-to-mobx');
• // from callbag to mobx
• const value = asObservable(interval(1000), -1)
• autorun(() => console.log(value.current())); // -1, 0, 1, 2, 3
• // from mobx to callbag
• pipe(

• fromExpression(() => value.current()),

• forEach(value => console.log(value)) // -1, 0, 1, 2, 3

• );
• Conversion is lazy; if not observed no work is done. */

const { reaction } = require("mobx"); const { fromResource } = require("mobx-utils");

const asObservable = function(source, initialValue = undefined) { let talkback; return fromResource( function(sink) { source(0, function(t, d) { if (t === 0) talkback = d; if (t === 1) sink(d); if (t === 1 || t === 0) talkback(1); }); }, function() { talkback(2); }, initialValue ); };

const fromExpression = function(expression, fireImmediately = true) { let disposer;

return function(start, sink) { if (start !== 0) return; sink(0, function(t) { if (t === 2) { disposer(); } }); disposer = reaction( expression, function(value) { sink(1, value); }, { fireImmediately } ); }; };

module.exports = { asObservable, fromExpression };