diff --git a/src/observable/map/ObservableValueMap.ts b/src/observable/map/ObservableValueMap.ts new file mode 100644 index 00000000..2108d8ce --- /dev/null +++ b/src/observable/map/ObservableValueMap.ts @@ -0,0 +1,53 @@ +/* +Copyright 2022 The Matrix.org Foundation C.I.C. + +Licensed under the Apache License, Version 2.0 (the "License"); +you may not use this file except in compliance with the License. +You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, software +distributed under the License is distributed on an "AS IS" BASIS, +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +See the License for the specific language governing permissions and +limitations under the License. +*/ + +import {BaseObservableMap} from "./BaseObservableMap"; +import {BaseObservableValue} from "../value/BaseObservableValue"; +import {SubscriptionHandle} from "../BaseObservable"; + +export class ObservableValueMap extends BaseObservableMap { + private subscription?: SubscriptionHandle; + + constructor(private readonly key: K, private readonly observableValue: BaseObservableValue) { + super(); + } + + onSubscribeFirst() { + this.subscription = this.observableValue.subscribe(value => { + this.emitUpdate(this.key, value, undefined); + }); + super.onSubscribeFirst(); + } + + onUnsubscribeLast() { + this.subscription!(); + super.onUnsubscribeLast(); + } + + *[Symbol.iterator](): Iterator<[K, V]> { + yield [this.key, this.observableValue.get()]; + } + + get size(): number { + return 1; + } + + get(key: K): V | undefined { + if (key == this.key) { + return this.observableValue.get(); + } + } +}