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      1 // Copyright (C) 2018 The Android Open Source Project
      2 //
      3 // Licensed under the Apache License, Version 2.0 (the "License");
      4 // you may not use this file except in compliance with the License.
      5 // You may obtain a copy of the License at
      6 //
      7 //      http://www.apache.org/licenses/LICENSE-2.0
      8 //
      9 // Unless required by applicable law or agreed to in writing, software
     10 // distributed under the License is distributed on an "AS IS" BASIS,
     11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     12 // See the License for the specific language governing permissions and
     13 // limitations under the License.
     14 
     15 export interface HasKind { kind: string; }
     16 
     17 export class Registry<T extends HasKind> {
     18   private registry: Map<string, T>;
     19 
     20   constructor() {
     21     this.registry = new Map<string, T>();
     22   }
     23 
     24   register(registrant: T) {
     25     const kind = registrant.kind;
     26     if (this.registry.has(kind)) {
     27       throw new Error(`Registrant ${kind} already exists in the registry`);
     28     }
     29     this.registry.set(kind, registrant);
     30   }
     31 
     32   has(kind: string): boolean {
     33     return this.registry.has(kind);
     34   }
     35 
     36   get(kind: string): T {
     37     const registrant = this.registry.get(kind);
     38     if (registrant === undefined) {
     39       throw new Error(`${kind} has not been registered.`);
     40     }
     41     return registrant;
     42   }
     43 
     44   unregisterAllForTesting(): void {
     45     this.registry.clear();
     46   }
     47 }
     48