31 lines
No EOL
1.1 KiB
TypeScript
31 lines
No EOL
1.1 KiB
TypeScript
/**
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* Every previously added point is remembered, but new points are added.
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* Data coming from upstream will always overwrite a previous value
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*/
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import FeatureSource from "../FeatureSource";
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import {UIEventSource} from "../../UIEventSource";
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export default class RememberingSource implements FeatureSource {
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public readonly features: UIEventSource<{ feature: any, freshness: Date }[]>;
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public readonly name;
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constructor(source: FeatureSource) {
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const self = this;
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this.name = "RememberingSource of " + source.name;
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const empty = [];
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this.features = source.features.map(features => {
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const oldFeatures = self.features?.data ?? empty;
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if (features === undefined) {
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return oldFeatures;
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}
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// Then new ids
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const ids = new Set<string>(features.map(f => f.feature.properties.id + f.feature.geometry.type));
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// the old data
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const oldData = oldFeatures.filter(old => !ids.has(old.feature.properties.id + old.feature.geometry.type))
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return [...features, ...oldData];
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})
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}
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} |