1 | import {Transform, ingest} from 'vega-dataflow';
|
2 | import {array, inherits} from 'vega-util';
|
3 |
|
4 |
|
5 |
|
6 |
|
7 |
|
8 |
|
9 |
|
10 |
|
11 |
|
12 | export default function Load(params) {
|
13 | Transform.call(this, [], params);
|
14 | this._pending = null;
|
15 | }
|
16 |
|
17 | var prototype = inherits(Load, Transform);
|
18 |
|
19 | prototype.transform = function(_, pulse) {
|
20 | const df = pulse.dataflow;
|
21 |
|
22 | if (this._pending) {
|
23 |
|
24 | return output(this, pulse, this._pending);
|
25 | }
|
26 |
|
27 | if (stop(_)) return pulse.StopPropagation;
|
28 |
|
29 | if (_.values) {
|
30 |
|
31 | return output(this, pulse, df.parse(_.values, _.format));
|
32 | } else if (_.async) {
|
33 |
|
34 | const p = df.request(_.url, _.format).then(res => {
|
35 | this._pending = array(res.data);
|
36 | return df => df.touch(this);
|
37 | });
|
38 | return {async: p};
|
39 | } else {
|
40 |
|
41 | return df.request(_.url, _.format)
|
42 | .then(res => output(this, pulse, array(res.data)));
|
43 | }
|
44 | };
|
45 |
|
46 | function stop(_) {
|
47 | return _.modified('async') && !(
|
48 | _.modified('values') || _.modified('url') || _.modified('format')
|
49 | );
|
50 | }
|
51 |
|
52 | function output(op, pulse, data) {
|
53 | data.forEach(ingest);
|
54 | const out = pulse.fork(pulse.NO_FIELDS & pulse.NO_SOURCE);
|
55 | out.rem = op.value;
|
56 | op.value = out.source = out.add = data;
|
57 | op._pending = null;
|
58 | return out;
|
59 | }
|