sttp.client4.wrappers.EitherBackend.scala Maven / Gradle / Ivy

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package sttp.client4.wrappers

import sttp.client4.monad.FunctionK
import sttp.client4.{Backend, StreamBackend, SyncBackend, WebSocketBackend, WebSocketStreamBackend}
import sttp.monad.EitherMonad
import sttp.shared.Identity

/** A synchronous backend that safely wraps exceptions in `Either[Throwable, *]`'s */
object EitherBackend {
  def apply(backend: SyncBackend): Backend[Either[Throwable, *]] =
    MappedEffectBackend(backend, idToEither, eitherToId, EitherMonad)
  def apply(backend: WebSocketBackend[Identity]): WebSocketBackend[Either[Throwable, *]] =
    MappedEffectBackend(backend, idToEither, eitherToId, EitherMonad)
  def apply[S](backend: StreamBackend[Identity, S]): StreamBackend[Either[Throwable, *], S] =
    MappedEffectBackend(backend, idToEither, eitherToId, EitherMonad)
  def apply[S](backend: WebSocketStreamBackend[Identity, S]): WebSocketStreamBackend[Either[Throwable, *], S] =
    MappedEffectBackend(backend, idToEither, eitherToId, EitherMonad)

  private val eitherToId: FunctionK[Either[Throwable, *], Identity] =
    new FunctionK[Either[Throwable, *], Identity] {
      override def apply[A](fa: => Either[Throwable, A]): Identity[A] =
        fa match {
          case Left(e)  => throw e
          case Right(v) => v
        }
    }

  private val idToEither: FunctionK[Identity, Either[Throwable, *]] =
    new FunctionK[Identity, Either[Throwable, *]] {
      override def apply[A](fa: => Identity[A]): Either[Throwable, A] = Right(fa)
    }
}