Files: 8ba14ee45feb74b60293b50fd0c6af96edfa2ec9 / junk / next-stepper.js
1233 bytesRaw
| 1 | const pull = require('pull-stream') |
| 2 | const Next = require('pull-next') |
| 3 | |
| 4 | module.exports = nextStepper |
| 5 | |
| 6 | // TODO - this should be another module? |
| 7 | |
| 8 | function nextStepper (createStream, opts, property, range) { |
| 9 | range = range || (opts.reverse ? 'lt' : 'gt') |
| 10 | property = property || 'timestamp' |
| 11 | |
| 12 | var last = null |
| 13 | var count = -1 |
| 14 | |
| 15 | return Next(function () { |
| 16 | if (last) { |
| 17 | if (count === 0) return |
| 18 | var value = opts[range] = get(last, property) |
| 19 | if (value == null) return |
| 20 | last = null |
| 21 | } |
| 22 | return pull( |
| 23 | createStream(clone(opts)), |
| 24 | pull.through(function (msg) { |
| 25 | count++ |
| 26 | if (!msg.sync) { |
| 27 | last = msg |
| 28 | } |
| 29 | }, function (err) { |
| 30 | // retry on errors... |
| 31 | if (err) { |
| 32 | count = -1 |
| 33 | return count |
| 34 | } |
| 35 | // end stream if there were no results |
| 36 | if (last == null) last = {} |
| 37 | }) |
| 38 | ) |
| 39 | }) |
| 40 | } |
| 41 | |
| 42 | function get (obj, path) { |
| 43 | if (!obj) return undefined |
| 44 | if (typeof path === 'string') return obj[path] |
| 45 | if (Array.isArray(path)) { |
| 46 | for (var i = 0; obj && i < path.length; i++) { |
| 47 | obj = obj[path[i]] |
| 48 | } |
| 49 | return obj |
| 50 | } |
| 51 | } |
| 52 | |
| 53 | function clone (obj) { |
| 54 | var _obj = {} |
| 55 | for (var k in obj) _obj[k] = obj[k] |
| 56 | return _obj |
| 57 | } |
| 58 | |
| 59 |
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