airbnb/caravel

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

interface ClassInterface<T, Args extends unknown[]> {
  new (...args: Args): T;
}

export default function makeSingleton<T, Args extends unknown[]>(
  BaseClass: ClassInterface<T, Args>,
  ...args: Args
): () => T {
  let singleton: T;

  return function getInstance() {
    if (!singleton) {
      singleton = new BaseClass(...args);
    }

    return singleton;
  };
}