com.softwaremill.macwire.internals.DependencyResolver.scala Maven / Gradle / Ivy

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package com.softwaremill.macwire.internals

import scala.quoted.*
import EligibleValuesFinder.Scope.*

private[macwire] class DependencyResolver[Q <: Quotes, T: Type](using val q: Q)(
    debug: Logger,
    resolutionFallback: q.reflect.TypeRepr => q.reflect.Term
) {
  import q.reflect.*

  private val eligibleValuesFinder = new EligibleValuesFinder[q.type](debug)

  private lazy val eligibleValues = eligibleValuesFinder.find()

  /** Look for a single instance of type `t`. If either no instance or multiple instances are found, a compilation error
    * is reported and `None` is returned.
    */
  def resolve(param: Symbol, t: TypeRepr): Term = {

    eligibleValues.findInFirstScope(t).toList match {
      case Nil          => resolutionFallback(t)
      case (value: Term) :: Nil => value
      case value :: Nil => Ref(value.symbol).changeOwner(Symbol.spliceOwner.owner.owner)
      case values       => report.throwError(s"Found multiple values of type [${showTypeName(t)}]: [$values]")
    }
  }

  /** @return
    *   all the instances of type `t` that are accessible.
    */
  def resolveAll(t: TypeRepr): Iterable[Tree] = {
    eligibleValues.findInAllScope(t).map { 
      case x: Term => x
      case x =>  buildRef(x.symbol) 
  }
  }

  private def buildRef(sym: Symbol): Tree = Ref(sym).changeOwner(Symbol.spliceOwner.owner.owner)
}

object DependencyResolver {
  def throwErrorOnResolutionFailure[Q <: Quotes, T: Type](debug: Logger)(using q: Q) =
    new DependencyResolver[q.type, T](using q)(
      debug,
      tpe => q.reflect.report.throwError(s"Cannot find a value of type: [${showTypeName(tpe)}]")
    )
}