120 lines
3.8 KiB
TypeScript
120 lines
3.8 KiB
TypeScript
/*
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Copyright 2020 Bruno Windels <bruno@windels.cloud>
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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import {BaseObservableMap, Mapper, Updater} from "./index";
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import {SubscriptionHandle} from "../BaseObservable";
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/*
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so a mapped value can emit updates on it's own with this._emitSpontaneousUpdate 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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/*
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This class MUST never be imported directly from here.
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Instead, it MUST be imported from index.ts. See the
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top level comment in index.ts for details.
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*/
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export class MappedMap<K, V, MappedV> extends BaseObservableMap<K, MappedV> {
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private _source: BaseObservableMap<K, V>;
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private _mapper: Mapper<V, MappedV>;
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private _updater?: Updater<V, MappedV>;
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private _mappedValues: Map<K, MappedV>;
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private _subscription?: SubscriptionHandle;
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constructor(
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source: BaseObservableMap<K, V>,
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mapper: Mapper<V, MappedV>,
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updater?: Updater<V, MappedV>
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) {
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super();
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this._source = source;
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this._mapper = mapper;
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this._updater = updater;
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this._mappedValues = new Map<K, MappedV>();
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}
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_emitSpontaneousUpdate(key: K, params: any): void {
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const value = this._mappedValues.get(key);
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if (value) {
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this.emitUpdate(key, value, params);
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}
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}
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onAdd(key: K, value: V): void {
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const emitSpontaneousUpdate = this._emitSpontaneousUpdate.bind(this, key);
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const mappedValue = this._mapper(value, emitSpontaneousUpdate);
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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: K/*, _value*/): void {
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const mappedValue = this._mappedValues.get(key);
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if (this._mappedValues.delete(key)) {
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if (mappedValue) {
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this.emitRemove(key, mappedValue);
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}
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}
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}
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onUpdate(key: K, value: V, params: any): void {
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// if an update is emitted while calling source.subscribe() from onSubscribeFirst, ignore it
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if (!this._mappedValues) {
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return;
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}
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const mappedValue = this._mappedValues.get(key);
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if (mappedValue !== undefined) {
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this._updater?.(params, mappedValue, value);
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// TODO: map params somehow if needed?
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this.emitUpdate(key, mappedValue, params);
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}
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}
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onSubscribeFirst(): void {
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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 emitSpontaneousUpdate = this._emitSpontaneousUpdate.bind(this, key);
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const mappedValue = this._mapper(value, emitSpontaneousUpdate);
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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(): void {
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super.onUnsubscribeLast();
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if (this._subscription) {
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this._subscription = this._subscription();
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}
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this._mappedValues.clear();
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}
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onReset(): void {
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this._mappedValues.clear();
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this.emitReset();
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}
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[Symbol.iterator](): IterableIterator<[K, MappedV]> {
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return this._mappedValues.entries();
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}
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get size(): number {
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return this._mappedValues.size;
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}
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get(key: K): MappedV | undefined {
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return this._mappedValues.get(key);
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}
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} |