memo

bindParams.scala

import scala.language.experimental.macros
import scala.reflect.macros.blackbox.Context
import skinny.micro.{SkinnyMicroParams, MultiParams}

object bindParams {
  def applyParam_impl[A: c.WeakTypeTag](c: Context)(params: c.Expr[SkinnyMicroParams]) = {
    import c.universe._
    
    val A = weakTypeTag[A].tpe
    val constructor = A.decls.collectFirst { case m: MethodSymbol if m.isPrimaryConstructor => m}.getOrElse {
      c.abort(c.enclosingPosition, s"Could not find the primary constructor for $A. type $A must be a class or case class, not trait or type parameter")
    }
    val constParams = constructor.paramLists.head.map { field =>
      val typOpt = field.typeSignature
      val typ = typOpt.typeArgs.headOption.getOrElse {
        c.abort(c.enclosingPosition, s"Field type must be Option[$typOpt], but $typOpt found.")
      }
      val name = field.name.decodedName.toString
      q"${field.name.toTermName} = $params.getAs[$typ]($name)"
    }
    
    c.Expr[A](q"new ${weakTypeTag[A].tpe}(..$constParams)")
  }

  def apply[A](params: SkinnyMicroParams): A = macro applyParam_impl[A]
}