95 lines
3.4 KiB
TypeScript
95 lines
3.4 KiB
TypeScript
import { Store, UIEventSource } from "../../UIEventSource"
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import { FeatureSource, IndexedFeatureSource } from "../FeatureSource"
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import { Feature } from "geojson"
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import { Utils } from "../../../Utils"
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import DynamicTileSource from "../TiledFeatureSource/DynamicTileSource"
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/**
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* The featureSourceMerger receives complete geometries from various sources.
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* If multiple sources contain the same object (as determined by 'id'), only one copy of them is retained
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*/
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export default class FeatureSourceMerger<Src extends FeatureSource = FeatureSource> implements IndexedFeatureSource {
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public features: UIEventSource<Feature[]> = new UIEventSource([])
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public readonly featuresById: Store<Map<string, Feature>>
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protected readonly _featuresById: UIEventSource<Map<string, Feature>>
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private readonly _sources: Src[] = []
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/**
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* Merges features from different featureSources.
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* In case that multiple features have the same id, the latest `_version_number` will be used. Otherwise, we will take the last one
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*/
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constructor(...sources: Src[]) {
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this._featuresById = new UIEventSource<Map<string, Feature>>(new Map<string, Feature>())
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this.featuresById = this._featuresById
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const self = this
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sources = Utils.NoNull(sources)
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for (let source of sources) {
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source.features.addCallback(() => {
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self.addDataFromSources(sources)
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})
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}
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this.addDataFromSources(sources)
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this._sources = sources
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}
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public addSource(source: Src) {
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if (!source) {
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return
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}
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this._sources.push(source)
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source.features.addCallbackAndRun(() => {
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this.addDataFromSources(this._sources)
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})
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}
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protected addDataFromSources(sources: Src[]){
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this.addData(sources.map(s => s.features.data))
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}
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protected addData(sources: Feature[][]) {
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sources = Utils.NoNull(sources)
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let somethingChanged = false
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const all: Map<string, Feature> = new Map()
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const unseen = new Set<string>()
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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.properties.id, oldValue)
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unseen.add(oldValue.properties.id)
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}
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for (const features of sources) {
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for (const f of features) {
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const id = f.properties.id
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unseen.delete(id)
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if (!all.has(id)) {
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// This is a new, previously unseen 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 == f) {
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continue
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}
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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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somethingChanged ||= unseen.size > 0
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unseen.forEach((id) => all.delete(id))
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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 = Array.from(all.values())
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this.features.setData(newList)
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this._featuresById.setData(all)
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}
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}
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