io.fintrospect.parameters.Retrieval.scala Maven / Gradle / Ivy

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Library that adds self-documentation to Finagle server endpoint services

There is a newer version: 12.21.1

package io.fintrospect.parameters

/**
  * Represents the ability to retrieve a value from an enclosing object (request/form etc..)
  */
trait Retrieval[-From, T] {

  /**
    * Extract the value from the target object. Throws on failure, but that shouldn't be a problem as the pre-validation
    * stage for declared parameters and bodies handles the failure before user code is entered.
    */
  def <--(from: From): T

  /**
    * Extract the value from the target object. Throws on failure, but that shouldn't be a problem as the pre-validation
    * stage for declared parameters and bodies handles the failure before user code is entered.
    * User-friendly synonym for <--(), which is why the method is final.
    */
  final def from(from: From): T = <--(from)
}

trait Mandatory[-From, T] extends Retrieval[From, T] with Extractable[From, T] {
  val required = true

  override def <--(from: From): T = extract(from) match {
    case Extracted(t) => t
    case _ => throw new IllegalStateException("Extraction should not have failed")
  }
}

trait Optional[-From, T] extends Retrieval[From, Option[T]] with Extractable[From, T] {
  val required = false

  def <--(from: From): Option[T] = extract(from) match {
    case Extracted(t) => Some(t)
    case NotProvided => None
    case _ => throw new IllegalStateException("Extraction should not have failed")
  }
}