ApplyMap, your observable map collection for applying side-effects

src/observable/map/ApplyMap.js

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+/*
+Copyright 2020 Bruno Windels <bruno@windels.cloud>
+
+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.js";
+
+export class ApplyMap extends BaseObservableMap {
+    constructor(source, apply) {
+        super();
+        this._source = source;
+        this._apply = apply;
+        this._subscription = null;
+    }
+
+    setApply(apply) {
+        this._apply = apply;
+        if (apply) {
+            this.applyOnce(this._apply);
+        }
+    }
+
+    applyOnce(apply) {
+        for (const [key, value] of this._source) {
+            apply(key, value);
+        }
+    }
+
+    onAdd(key, value) {
+        if (this._apply) {
+            this._apply(key, value);
+        }
+        this.emitAdd(key, value);
+    }
+
+    onRemove(key, value) {
+        this.emitRemove(key, value);
+    }
+
+    onUpdate(key, value, params) {
+        if (this._apply) {
+            this._apply(key, value, params);
+        }
+        this.emitUpdate(key, value, params);
+    }
+
+    onSubscribeFirst() {
+        this._subscription = this._source.subscribe(this);
+        if (this._apply) {
+            this.applyOnce(this._apply);
+        }
+        super.onSubscribeFirst();
+    }
+
+    onUnsubscribeLast() {
+        super.onUnsubscribeLast();
+        this._subscription = this._subscription();
+    }
+
+    onReset() {
+        if (this._apply) {
+            this.applyOnce(this._apply);
+        }
+        this.emitReset();
+    }
+
+    [Symbol.iterator]() {
+        return this._source[Symbol.iterator]();
+    }
+}