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node_modules/matrix-js-sdk/src/NamespacedValue.ts

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+/*
+Copyright 2021 - 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.
+*/
+
+/**
+ * Represents a simple Matrix namespaced value. This will assume that if a stable prefix
+ * is provided that the stable prefix should be used when representing the identifier.
+ */
+export class NamespacedValue<S extends string, U extends string> {
+    // Stable is optional, but one of the two parameters is required, hence the weird-looking types.
+    // Goal is to to have developers explicitly say there is no stable value (if applicable).
+    public constructor(stable: S, unstable: U);
+    public constructor(stable: S, unstable: U | null);
+    public constructor(stable: null, unstable: U);
+    public constructor(
+        public readonly stable: S | null,
+        public readonly unstable: U | null,
+    ) {
+        if (!this.unstable && !this.stable) {
+            throw new Error("One of stable or unstable values must be supplied");
+        }
+    }
+
+    public get name(): U | S {
+        if (this.stable) {
+            return this.stable;
+        }
+        return this.unstable!;
+    }
+
+    public get altName(): U | S | null | undefined {
+        if (!this.stable) {
+            return null;
+        }
+        return this.unstable;
+    }
+
+    public get names(): (U | S)[] {
+        const names = [this.name];
+        const altName = this.altName;
+        if (altName) names.push(altName);
+        return names;
+    }
+
+    public matches(val: string): boolean {
+        return this.name === val || this.altName === val;
+    }
+
+    // this desperately wants https://github.com/microsoft/TypeScript/pull/26349 at the top level of the class
+    // so we can instantiate `NamespacedValue<string, _, _>` as a default type for that namespace.
+    public findIn<V>(obj: Partial<Record<NonNullable<S | U>, V>>): V | undefined {
+        let val: V | undefined = undefined;
+        if (this.name) {
+            val = obj?.[this.name];
+        }
+        if (!val && this.altName) {
+            val = obj?.[this.altName];
+        }
+        return val;
+    }
+
+    public includedIn(arr: any[]): boolean {
+        let included = false;
+        if (this.name) {
+            included = arr.includes(this.name);
+        }
+        if (!included && this.altName) {
+            included = arr.includes(this.altName);
+        }
+        return included;
+    }
+}
+
+export class ServerControlledNamespacedValue<S extends string, U extends string> extends NamespacedValue<S, U> {
+    private preferUnstable = false;
+
+    public setPreferUnstable(preferUnstable: boolean): void {
+        this.preferUnstable = preferUnstable;
+    }
+
+    public get name(): U | S {
+        if (this.stable && !this.preferUnstable) {
+            return this.stable;
+        }
+        return this.unstable!;
+    }
+}
+
+/**
+ * Represents a namespaced value which prioritizes the unstable value over the stable
+ * value.
+ */
+export class UnstableValue<S extends string, U extends string> extends NamespacedValue<S, U> {
+    // Note: Constructor difference is that `unstable` is *required*.
+    public constructor(stable: S, unstable: U) {
+        super(stable, unstable);
+        if (!this.unstable) {
+            throw new Error("Unstable value must be supplied");
+        }
+    }
+
+    public get name(): U {
+        return this.unstable!;
+    }
+
+    public get altName(): S {
+        return this.stable!;
+    }
+}