Files: 635ea39199988640e918cccefadd0bac2abfdf36 / util.js
1622 bytesRaw
1 | var pull = require('pull-stream') |
2 | var Next = require('pull-next') |
3 | |
4 | function first (list, test) { |
5 | for(var i in list) { |
6 | var value = test(list[i], i, list) |
7 | if(value) return value |
8 | } |
9 | } |
10 | |
11 | function decorate (list, value, caller) { |
12 | caller = caller || function (d,e,v) { return d(e, v) } |
13 | |
14 | return list.reduce(function (element, decorator) { |
15 | return caller(decorator, element, value) || element |
16 | }, null) |
17 | } |
18 | |
19 | function get(obj, path) { |
20 | if(obj == null) return obj |
21 | if('string' === typeof path) return obj[path] |
22 | for(var i = 0; i < path.length; i++) { |
23 | obj = obj[path[i]] |
24 | if(obj == null) return |
25 | } |
26 | return obj |
27 | |
28 | } |
29 | |
30 | exports.first = first |
31 | exports.decorate = decorate |
32 | |
33 | exports.next = function (createStream, opts, property, range) { |
34 | |
35 | range = range || opts.reverse ? 'lt' : 'gt' |
36 | property = property || 'timestamp' |
37 | |
38 | var last = null, count = -1 |
39 | return Next(function () { |
40 | if(last) { |
41 | if(count === 0) return |
42 | var value = opts[range] = get(last, property) |
43 | if(value == null) return |
44 | last = null |
45 | } |
46 | return pull( |
47 | createStream(opts), |
48 | pull.through(function (msg) { |
49 | count ++ |
50 | if(!msg.sync) last = msg |
51 | }, function (err) { |
52 | //retry on errors... |
53 | if(err) return count = -1 |
54 | //end stream if there were no results |
55 | if(last == null) last = {} |
56 | }) |
57 | ) |
58 | }) |
59 | } |
60 | |
61 | exports.firstPlug = function (plugs) { |
62 | if(!Array.isArray(plugs)) throw new Error('plugs must be an array') |
63 | var args = [].slice.call(arguments) |
64 | var plugs = args.shift() |
65 | return exports.first(plugs, function (fn) { |
66 | return fn.apply(null, args) |
67 | }) |
68 | } |
69 | |
70 |
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