caliban.schema.ObjectFieldResolver.scala Maven / Gradle / Ivy

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package caliban.schema

import caliban.schema.Step.{ NullStep, ObjectStep }

import scala.collection.compat._
import scala.collection.mutable

final private class ObjectFieldResolver[R, A] private (
  name: String,
  fields: mutable.HashMap[String, A => Step[R]]
) {
  import ObjectFieldResolver._

  private def getFieldStep(value: A): String => Step[R] =
    fields.getOrElse(_, nullStepFn)(value)

  def resolve(value: A): Step[R] = ObjectStep(name, getFieldStep(value))
}

private object ObjectFieldResolver {
  def apply[R, A](objectName: String, fields: Iterable[(String, A => Step[R])]): ObjectFieldResolver[R, A] =
    // NOTE: mutable.HashMap is about twice as fast than immutable.HashMap for .get
    new ObjectFieldResolver(objectName, mutable.HashMap.from(fields))

  private val nullStepFn: Any => Step[Any] = _ => NullStep
}