64 lines
2 KiB
JavaScript
64 lines
2 KiB
JavaScript
import {BaseObservableMap} from "./BaseObservableMap.js";
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/*
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so a mapped value can emit updates on it's own with this._updater that is passed in the mapping function
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how should the mapped value be notified of an update though? and can it then decide to not propagate the update?
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*/
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export class MappedMap extends BaseObservableMap {
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constructor(source, mapper) {
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super();
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this._source = source;
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this._mapper = mapper;
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this._mappedValues = new Map();
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this._updater = (key, params) => { // this should really be (value, params) but can't make that work for now
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const value = this._mappedValues.get(key);
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this.onUpdate(key, value, params);
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};
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}
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onAdd(key, value) {
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const mappedValue = this._mapper(value, this._updater);
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this._mappedValues.set(key, mappedValue);
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this.emitAdd(key, mappedValue);
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}
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onRemove(key, _value) {
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const mappedValue = this._mappedValues.get(key);
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if (this._mappedValues.delete(key)) {
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this.emitRemove(key, mappedValue);
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}
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}
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onUpdate(key, value, params) {
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const mappedValue = this._mappedValues.get(key);
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if (mappedValue !== undefined) {
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const newParams = this._updater(value, params);
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// if (newParams !== undefined) {
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this.emitUpdate(key, mappedValue, newParams);
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// }
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}
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}
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onSubscribeFirst() {
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this._subscription = this._source.subscribe(this);
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for (let [key, value] of this._source) {
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const mappedValue = this._mapper(value, this._updater);
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this._mappedValues.set(key, mappedValue);
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}
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super.onSubscribeFirst();
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}
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onUnsubscribeLast() {
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this._subscription = this._subscription();
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this._mappedValues.clear();
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}
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onReset() {
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this._mappedValues.clear();
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this.emitReset();
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}
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[Symbol.iterator]() {
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return this._mappedValues.entries();
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}
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}
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