fixes import order according to https://medium.com/visual-development/how-to-fix-nasty-circular-dependency-issues-once-and-for-all-in-javascript-typescript-a04c987cf0de

src/domain/session/leftpanel/LeftPanelViewModel.js

@@ -20,7 +20,7 @@ import {RoomTileViewModel} from "./RoomTileViewModel.js";
 import {InviteTileViewModel} from "./InviteTileViewModel.js";
 import {RoomBeingCreatedTileViewModel} from "./RoomBeingCreatedTileViewModel.js";
 import {RoomFilter} from "./RoomFilter.js";
-import {ApplyMap} from "../../../observable/map/ApplyMap";
+import {ApplyMap} from "../../../observable";
 import {addPanelIfNeeded} from "../../navigation";
 
 export class LeftPanelViewModel extends ViewModel {

src/lib.ts

@@ -78,8 +78,7 @@ export {
     MappedList,
     AsyncMappedList,
     ConcatList,
-    ObservableMap
+} from "./observable";
-} from "./observable/index";
 export {
     BaseObservableValue,
     ObservableValue,

src/observable/index.ts

@@ -16,7 +16,7 @@ limitations under the License.
 
 
 // re-export "root" (of chain) collection
-export { ObservableMap } from "./map/ObservableMap";
+export { ObservableMap, ApplyMap, FilteredMap, JoinedMap, LogMap, MappedMap } from "./map";
 export { ObservableArray } from "./list/ObservableArray";
 export { SortedArray } from "./list/SortedArray";
 export { MappedList } from "./list/MappedList";

src/observable/map/ApplyMap.ts

@@ -14,11 +14,15 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import {BaseObservableMap} from "./BaseObservableMap";
+import {BaseObservableMap} from "./index";
 import {SubscriptionHandle} from "../BaseObservable";
-import {BaseObservableMapTransformers} from "./BaseObservableMapTransformers";
 
 
+/*
+This class MUST never be imported directly from here.
+Instead, it MUST be imported from index.ts. See the
+top level comment in index.ts for details.
+*/
 export class ApplyMap<K, V> extends BaseObservableMap<K, V> {
     private _source: BaseObservableMap<K, V>;
     private _subscription?: SubscriptionHandle;
@@ -26,7 +30,7 @@ export class ApplyMap<K, V> extends BaseObservableMap<K, V> {
 
 
     constructor(source: BaseObservableMap<K, V>, apply?: Apply<K, V>) {
-        super(new BaseObservableMapTransformers<K, V>());
+        super();
         this._source = source;
         this._apply = apply;
     }

src/observable/map/BaseObservableMap.ts

@@ -15,11 +15,10 @@ limitations under the License.
 */
 
 import {BaseObservable} from "../BaseObservable";
-import {JoinedMap} from "../map/JoinedMap";
+import {JoinedMap} from "./index";
-import {MappedMap} from "../map/MappedMap";
+import {MappedMap} from "./index";
-import {FilteredMap} from "../map/FilteredMap";
+import {FilteredMap} from "./index";
 import {SortedMapList} from "../list/SortedMapList.js";
-import type {BaseObservableMapTransformers, Mapper, Updater, Comparator, Filter} from "./BaseObservableMapTransformers";
 
 
 export interface IMapObserver<K, V> {
@@ -29,12 +28,15 @@ export interface IMapObserver<K, V> {
     onRemove(key: K, value: V): void
 }
 
+/*
+This class MUST never be imported directly from here.
+Instead, it MUST be imported from index.ts. See the
+top level comment in index.ts for details.
+*/
 export abstract class BaseObservableMap<K, V> extends BaseObservable<IMapObserver<K, V>> {
-    private _defaults: BaseObservableMapTransformers<K, V>;
 
-    constructor(defaults: BaseObservableMapTransformers<K, V>) {
+    constructor() {
         super();
-        this._defaults = defaults;
     }
 
     emitReset(): void {
@@ -63,23 +65,33 @@ export abstract class BaseObservableMap<K, V> extends BaseObservable<IMapObserve
     }
 
     join(...otherMaps: Array<typeof this>): JoinedMap<K, V> {
-        return this._defaults.join(this, ...otherMaps);
+        return new JoinedMap([this].concat(otherMaps));
      }
 
      mapValues<MappedV>(mapper: Mapper<V, MappedV>, updater?: Updater<V, MappedV>): MappedMap<K, V, MappedV> {
-        return this._defaults.mapValues(this, mapper, updater);
+         return new MappedMap(this, mapper, updater);
      }
 
      sortValues(comparator: Comparator<V>): SortedMapList {
-        return this._defaults.sortValues(this, comparator);
+         return new SortedMapList(this, comparator);
      }
 
      filterValues(filter: Filter<K, V>): FilteredMap<K, V> {
-        return this._defaults.filterValues(this, filter);
+         return new FilteredMap(this, filter);
      }
 
-
     abstract [Symbol.iterator](): Iterator<[K, V]>;
     abstract get size(): number;
     abstract get(key: K): V | undefined;
 }
+
+export type Mapper<V, MappedV> = (
+    value: V,
+    emitSpontaneousUpdate: any,
+) => MappedV;
+
+export type Updater<V, MappedV> = (params: any, mappedValue?: MappedV, value?: V) => void;
+
+export type Comparator<V> = (a: V, b: V) => number;
+
+export type Filter<K, V> = (v: V, k: K) => boolean;

src/observable/map/BaseObservableMapTransformers.ts

@@ -1,69 +0,0 @@
-/*
-Copyright 2022 Isaiah Becker-Mayer <ibeckermayer@gmail.com>
-
-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 type {BaseObservableMap} from "./BaseObservableMap";
-import {FilteredMap} from "./FilteredMap";
-import {MappedMap} from "./MappedMap";
-import {JoinedMap} from "./JoinedMap";
-import {SortedMapList} from "../list/SortedMapList.js";
-
-
-// This class provides implementations of functions that transform one BaseObservableMap
-// to another type of Map. It's methods are effectively default implementations of the
-// methods by the same name on BaseObservableMap.
-//
-// It is kept as its own class in its own file in order to avoid circular dependencies
-// which would occur if these method implementations were defined on BaseObservableMap
-// itself. For example, if we attmpted to do the following on BaseObservableMap:
-//
-// class BaseObservableMap<K, V> extends BaseObservable<IMapObserver<K, V>> {
-//   join(...otherMaps: Array<BaseObservableMap<K, V>>): JoinedMap<K, V> {
-//      return new JoinedMap(this.concat(otherMaps));
-//   }
-// }
-//
-// we would end up with a circular dependency between BaseObservableMap and JoinedMap,
-// since BaseObservableMap would need to import JoinedMap for the
-// `return new JoinedMap(this.concat(otherMaps))`, and
-// JoinedMap would need to import BaseObservableMap to do
-// `JoinedMap<K, V> extends BaseObservableMap<K, V>`.
-export class BaseObservableMapTransformers<K, V> {
-    join(_this: BaseObservableMap<K, V>, ...otherMaps: Array<BaseObservableMap<K, V>>): JoinedMap<K, V> {
-       return new JoinedMap([_this].concat(otherMaps));
-    }
-
-    mapValues<MappedV>(_this: BaseObservableMap<K, V>, mapper: Mapper<V, MappedV>, updater?: Updater<V, MappedV>): MappedMap<K, V, MappedV> {
-        return new MappedMap(_this, mapper, updater);
-    }
-
-    sortValues(_this: BaseObservableMap<K, V>, comparator: Comparator<V>): SortedMapList {
-        return new SortedMapList(_this, comparator);
-    }
-
-    filterValues(_this: BaseObservableMap<K, V>, filter: Filter<K, V>): FilteredMap<K, V> {
-        return new FilteredMap(_this, filter);
-    }
-}
-
-export type Mapper<V, MappedV> = (
-    value: V,
-    emitSpontaneousUpdate: any,
-) => MappedV;
-
-export type Updater<V, MappedV> = (params: any, mappedValue?: MappedV, value?: V) => void;
-
-export type Comparator<V> = (a: V, b: V) => number;
-
-export type Filter<K, V> = (v: V, k: K) => boolean;

src/observable/map/FilteredMap.ts

@@ -14,11 +14,15 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import {BaseObservableMap} from "./BaseObservableMap";
+import {BaseObservableMap, Filter} from "./index";
 import {SubscriptionHandle} from "../BaseObservable";
-import {BaseObservableMapTransformers, Filter} from "./BaseObservableMapTransformers";
 
 
+/*
+This class MUST never be imported directly from here.
+Instead, it MUST be imported from index.ts. See the
+top level comment in index.ts for details.
+*/
 export class FilteredMap<K, V> extends BaseObservableMap<K, V> {
     private _source: BaseObservableMap<K, V>;
     private _filter: Filter<K, V>;
@@ -26,7 +30,7 @@ export class FilteredMap<K, V> extends BaseObservableMap<K, V> {
     private _subscription?: SubscriptionHandle;
 
     constructor(source: BaseObservableMap<K, V>, filter: Filter<K, V>) {
-        super(new BaseObservableMapTransformers<K, V>());
+        super();
         this._source = source;
         this._filter = filter;
     }

src/observable/map/JoinedMap.ts

@@ -14,17 +14,21 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import {BaseObservableMap} from "./BaseObservableMap";
+import {BaseObservableMap} from ".";
-import {BaseObservableMapTransformers} from "./BaseObservableMapTransformers";
 import {SubscriptionHandle} from "../BaseObservable";
 
 
+/*
+This class MUST never be imported directly from here.
+Instead, it MUST be imported from index.ts. See the
+top level comment in index.ts for details.
+*/
 export class JoinedMap<K, V> extends BaseObservableMap<K, V> {
     protected _sources: BaseObservableMap<K, V>[];
     private _subscriptions?: SourceSubscriptionHandler<K, V>[];
 
     constructor(sources: BaseObservableMap<K, V>[]) {
-        super(new BaseObservableMapTransformers<K, V>());
+        super();
         this._sources = sources;
     }
 

src/observable/map/LogMap.ts

@@ -14,20 +14,24 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import {BaseObservableMap} from "./BaseObservableMap";
+import {BaseObservableMap} from "./index";
-import {BaseObservableMapTransformers} from "./BaseObservableMapTransformers";
 import {SubscriptionHandle} from "../BaseObservable";
 import {ILogItem, LabelOrValues} from "../../logging/types";
 import {LogLevel} from "../../logging/LogFilter";
 
 
+/*
+This class MUST never be imported directly from here.
+Instead, it MUST be imported from index.ts. See the
+top level comment in index.ts for details.
+*/
 export class LogMap<K, V> extends BaseObservableMap<K, V> {
     private _source: BaseObservableMap<K, V>;
     private _subscription?: SubscriptionHandle;
     private _log: ILogItem;
 
     constructor(source: BaseObservableMap<K, V>, log: ILogItem) {
-        super(new BaseObservableMapTransformers<K, V>());
+        super();
         this._source = source;
         this._log = log;
     }

src/observable/map/MappedMap.ts

@@ -14,8 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import {BaseObservableMap} from "./BaseObservableMap";
+import {BaseObservableMap, Mapper, Updater} from "./index";
-import {BaseObservableMapTransformers, Mapper, Updater} from "./BaseObservableMapTransformers";
 import {SubscriptionHandle} from "../BaseObservable";
 
 
@@ -23,6 +22,11 @@ import {SubscriptionHandle} from "../BaseObservable";
 so a mapped value can emit updates on it's own with this._emitSpontaneousUpdate that is passed in the mapping function
 how should the mapped value be notified of an update though? and can it then decide to not propagate the update?
 */
+/*
+This class MUST never be imported directly from here.
+Instead, it MUST be imported from index.ts. See the
+top level comment in index.ts for details.
+*/
 export class MappedMap<K, V, MappedV> extends BaseObservableMap<K, MappedV> {
     private _source: BaseObservableMap<K, V>;
     private _mapper: Mapper<V, MappedV>;
@@ -36,7 +40,7 @@ export class MappedMap<K, V, MappedV> extends BaseObservableMap<K, MappedV> {
         mapper: Mapper<V, MappedV>,
         updater?: Updater<V, MappedV>
     ) {
-        super(new BaseObservableMapTransformers<K, MappedV>());
+        super();
         this._source = source;
         this._mapper = mapper;
         this._updater = updater;

src/observable/map/ObservableMap.ts

@@ -14,15 +14,19 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import {BaseObservableMap} from "./BaseObservableMap";
+import {BaseObservableMap} from "./index";
-import {BaseObservableMapTransformers} from "./BaseObservableMapTransformers";
 
 
+/*
+This class MUST never be imported directly from here.
+Instead, it MUST be imported from index.ts. See the
+top level comment in index.ts for details.
+*/
 export class ObservableMap<K, V> extends BaseObservableMap<K, V> {
     private readonly _values: Map<K, V>;
 
     constructor(initialValues?: (readonly [K, V])[]) {
-        super(new BaseObservableMapTransformers<K, V>());
+        super();
         this._values = new Map(initialValues);
     }
 

src/observable/map/index.ts

@@ -0,0 +1,16 @@
+// In order to avoid a circular dependency problem at runtime between BaseObservableMap
+// and the classes that extend it, it's important that:
+//
+// 1) It always remain the first module exported below.
+// 2) Anything that imports any of the classes in this module
+//    ONLY import them from this index.ts file.
+//
+// See https://medium.com/visual-development/how-to-fix-nasty-circular-dependency-issues-once-and-for-all-in-javascript-typescript-a04c987cf0de
+// for more on why this discipline is necessary.
+export {BaseObservableMap, Mapper, Updater, Comparator, Filter} from './BaseObservableMap';
+export {ApplyMap} from './ApplyMap';
+export {FilteredMap} from './FilteredMap';
+export {JoinedMap} from './JoinedMap';
+export {LogMap} from './LogMap';
+export {MappedMap} from './MappedMap';
+export {ObservableMap} from './ObservableMap';