74 lines
No EOL
2.5 KiB
TypeScript
74 lines
No EOL
2.5 KiB
TypeScript
import FeatureSource from "./FeatureSource";
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import {UIEventSource} from "../UIEventSource";
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/**
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* Merges features from different featureSources
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* Uses the freshest feature available in the case multiple sources offer data with the same identifier
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*/
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export default class FeatureSourceMerger implements FeatureSource {
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public features: UIEventSource<{ feature: any; freshness: Date }[]> = new UIEventSource<{ feature: any; freshness: Date }[]>([]);
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public readonly name;
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private readonly _sources: FeatureSource[];
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constructor(sources: FeatureSource[]) {
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this._sources = sources;
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this.name = "SourceMerger of (" + sources.map(s => s.name).join(", ") + ")"
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const self = this;
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for (let i = 0; i < sources.length; i++) {
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let source = sources[i];
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source.features.addCallback(() => {
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self.Update();
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});
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}
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this.Update();
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}
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private Update() {
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let somethingChanged = false;
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const all: Map<string, { feature: any, freshness: Date }> = new Map<string, { feature: any; freshness: Date }>();
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// We seed the dictionary with the previously loaded features
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const oldValues = this.features.data ?? [];
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for (const oldValue of oldValues) {
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all.set(oldValue.feature.id + oldValue.feature._matching_layer_id, oldValue)
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}
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for (const source of this._sources) {
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if (source?.features?.data === undefined) {
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continue;
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}
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for (const f of source.features.data) {
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const id = f.feature.properties.id + f.feature._matching_layer_id;
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if (!all.has(id)) {
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// This is a new feature
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somethingChanged = true;
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all.set(id, f);
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continue;
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}
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// This value has been seen already, either in a previous run or by a previous datasource
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// Let's figure out if something changed
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const oldV = all.get(id);
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if (oldV.freshness < f.freshness) {
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// Jup, this feature is fresher
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all.set(id, f);
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somethingChanged = true;
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}
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}
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}
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if(!somethingChanged){
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// We don't bother triggering an update
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return;
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}
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const newList = [];
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all.forEach((value, key) => {
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newList.push(value)
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})
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this.features.setData(newList);
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}
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} |