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'use strict';
import isArray from 'lodash-es/isArray';
import noop from 'lodash-es/noop';
import once from 'lodash-es/once';
import rest from 'lodash-es/rest';
import ensureAsync from './ensureAsync';
import iterator from './iterator';
export default function(tasks, cb) {
cb = once(cb || noop);
if (!isArray(tasks)) return cb(new Error('First argument to waterfall must be an array of functions'));
if (!tasks.length) return cb();
function wrapIterator(iterator) {
return rest(function(err, args) {
if (err) {
cb.apply(null, [err].concat(args));
} else {
var next = iterator.next();
if (next) {
args.push(wrapIterator(next));
} else {
args.push(cb);
}
ensureAsync(iterator).apply(null, args);
}
});
}
wrapIterator(iterator(tasks))();
}
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