za.co.absa.pramen.api.common.FactoryLoader.scala Maven / Gradle / Ivy

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/*
 * Copyright 2022 ABSA Group Limited
 *
 * 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.
 */

package za.co.absa.pramen.api.common

import scala.reflect.ClassTag
import scala.reflect.runtime.universe
import scala.util.{Failure, Success, Try}

/**
  * Factory utils are used within tha API so that projects with custom logic (sources, transformers, sinks etc) won't
  * need to depend on 'pramen-core', but still able to access globally accessible objects.
  */
object FactoryLoader {
  @throws[IllegalArgumentException]
  def loadSingletonFactoryOfType[T: ClassTag : universe.TypeTag](fullyQualifiedName: String): T = {
    val mirror = universe.runtimeMirror(getClass.getClassLoader)
    Try(mirror.staticModule(fullyQualifiedName)) match {
      case Success(module)    => val reflectiveMirror = mirror.reflectModule(module)
        Try(reflectiveMirror.instance) match {
          case Success(instance)  =>
            instance match {
              case singleton: T => singleton
              case _            => throw new IllegalArgumentException(s"Class '$fullyQualifiedName' is not an instance of '${universe.typeOf[T]}'")
            }
          case Failure(exception) => throw new IllegalArgumentException(s"Class '$fullyQualifiedName' is not a singleton", exception)
        }
      case Failure(exception) => throw new IllegalArgumentException(s"Class '$fullyQualifiedName' could not be found", exception)
    }
  }
}