com.softwaremill.macwire.InstanceLookup.scala Maven / Gradle / Ivy

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package com.softwaremill.macwire

import com.softwaremill.macwire.Wired.InstanceFactoryMap

private[macwire] trait InstanceLookup {
  private lazy val lookupMap = prepareLookupMap

  def lookup[T](cls: Class[T]): List[T] = {
    lookupMap.getOrElse(cls, Nil).map(_().asInstanceOf[T])
  }

  def lookupSingleOrThrow[T](cls: Class[T]) = lookup(cls) match {
    case Nil     => throw new RuntimeException(s"Cannot find implementations of class $cls!")
    case List(i) => i
    case l       => throw new RuntimeException(s"Found multiple implementations of class $cls: $l!")
  }

  private def prepareLookupMap: Map[Class[_], List[() => AnyRef]] = {
    instanceFactoryMap.toList
      .flatMap { case (startingCls, impl) =>
        def allSuperClasses(cls: Class[_]): List[Class[_]] = {
          if (cls == null) {
            Nil
          } else {
            (cls :: allSuperClasses(cls.getSuperclass)) ++ cls.getInterfaces.flatMap(allSuperClasses)
          }
        }

        allSuperClasses(startingCls).map(_ -> impl)
      }
      .groupBy(_._1)
      .map { case (cls, clsAndImpls) => cls -> clsAndImpls.map(_._2) }
      .toMap
  }

  protected def instanceFactoryMap: InstanceFactoryMap
}