Avoid generating anonymous classes (#142)

build.sbt

@@ -15,7 +15,7 @@ lazy val `teleproto` = project
   .settings(Project.inConfig(Test)(sbtprotoc.ProtocPlugin.protobufConfigSettings): _*)
   .settings(
     name := "teleproto",
-    version := "1.12.1",
+    version := "1.13.0",
     versionScheme := Some("early-semver"),
     libraryDependencies ++= Seq(
       library.scalaPB            % "protobuf;compile",

src/main/scala/io/moia/protos/teleproto/FormatImpl.scala

@@ -37,8 +37,8 @@ trait FormatImpl {
   def error(message: String, pos: Position = c.enclosingPosition): Unit    = c.error(pos, message)
   def abort(message: String, pos: Position = c.enclosingPosition): Nothing = c.abort(pos, message)
 
-  private[teleproto] val mapping =
-    q"io.moia.protos.teleproto"
+  protected def objectRef[T: TypeTag]: Symbol =
+    typeOf[T].termSymbol
 
   /** A `oneof` proto definition is mapped to a `sealed trait` in Scala.
     * Each variant of the `oneof` definition is mapped to a `case class` with exactly one field `value`

src/main/scala/io/moia/protos/teleproto/Reader.scala

@@ -43,39 +43,40 @@ trait Reader[-P, +M] {
     * Transforms successfully read results.
     */
   def map[N](f: M => N): Reader[P, N] =
-    read(_).map(f)
+    Reader.instance(read(_).map(f))
 
   /**
     * Transforms the protobuf before reading.
     */
   final def contramap[Q](f: Q => P): Reader[Q, M] =
-    protobuf => read(f(protobuf))
+    Reader.instance(protobuf => read(f(protobuf)))
 
   /**
     * Transforms successfully read results with the option to fail.
     */
   final def pbmap[N](f: M => PbResult[N]): Reader[P, N] =
-    read(_).flatMap(f)
+    Reader.instance(read(_).flatMap(f))
 
   @deprecated("Use a function that returns a Reader with flatMap or one that returns a PbResult with emap", "1.8.0")
   protected def flatMap[N](f: M => PbSuccess[N]): Reader[P, N] =
-    read(_).flatMap(f)
+    Reader.instance(read(_).flatMap(f))
 
   /**
     * Transforms successfully read results by stacking another reader on top of the original protobuf.
     */
   final def flatMap[Q <: P, N](f: M => Reader[Q, N])(implicit dummy: DummyImplicit): Reader[Q, N] =
-    protobuf => read(protobuf).flatMap(f(_).read(protobuf))
+    Reader.instance(protobuf => read(protobuf).flatMap(f(_).read(protobuf)))
 
   /**
     * Combines two readers with a specified function.
     */
   final def zipWith[Q <: P, N, O](that: Reader[Q, N])(f: (M, N) => O): Reader[Q, O] =
-    protobuf =>
+    Reader.instance { protobuf =>
       for {
         m <- this.read(protobuf)
         n <- that.read(protobuf)
       } yield f(m, n)
+    }
 
   /**
     * Combines two readers into a reader of a tuple.
@@ -87,7 +88,7 @@ trait Reader[-P, +M] {
     * Chain `that` reader after `this` one.
     */
   final def andThen[N](that: Reader[M, N]): Reader[P, N] =
-    read(_).flatMap(that.read)
+    Reader.instance(read(_).flatMap(that.read))
 
   /**
     * Chain `this` reader after `that` one.
@@ -100,6 +101,8 @@ object Reader extends LowPriorityReads {
 
   def apply[P, M](implicit reader: Reader[P, M]): Reader[P, M] = reader
 
+  def instance[P, M](f: P => PbResult[M]): Reader[P, M] = f(_)
+
   /* Combinators */
 
   def transform[PV, MV](protobuf: PV, path: String)(implicit valueReader: Reader[PV, MV]): PbResult[MV] =
@@ -111,17 +114,17 @@ object Reader extends LowPriorityReads {
   def required[PV, MV](protobuf: Option[PV], path: String)(implicit valueReader: Reader[PV, MV]): PbResult[MV] =
     protobuf.map(valueReader.read).getOrElse(PbFailure("Value is required.")).withPathPrefix(path)
 
-  def sequence[F[_], PV, MV](protobufs: Seq[PV], path: String)(implicit factory: Factory[MV, F[MV]],
-                                                               valueReader: Reader[PV, MV]): PbResult[F[MV]] = {
+  def sequence[F[_], PV, MV](protobufs: Seq[PV], path: String)(
+      implicit factory: Factory[MV, F[MV]],
+      valueReader: Reader[PV, MV]
+  ): PbResult[F[MV]] = {
     val results = protobufs.map(valueReader.read).zipWithIndex
-
-    val errors =
-      results.flatMap {
-        case (PbFailure(innerErrors), index) =>
-          PbFailure(innerErrors).withPathPrefix(s"$path($index)").errors
-        case _ =>
-          Seq.empty
-      }
+    val errors = results.flatMap {
+      case (PbFailure(innerErrors), index) =>
+        PbFailure(innerErrors).withPathPrefix(s"$path($index)").errors
+      case _ =>
+        Seq.empty
+    }
 
     if (errors.nonEmpty)
       PbFailure(errors)
@@ -209,18 +212,21 @@ object Reader extends LowPriorityReads {
     * Tries to read a map of Protobuf key/values to a sorted map of Scala key/values if reader exists between both types
     * and an ordering is defined on the Scala key.
     */
-  implicit def treeMapReader[PK, PV, MK, MV](implicit keyReader: Reader[PK, MK],
-                                             valueReader: Reader[PV, MV],
-                                             ordering: Ordering[MK]): Reader[Map[PK, PV], TreeMap[MK, MV]] =
-    (protobuf: Map[PK, PV]) => mapReader(keyReader, valueReader).read(protobuf).map(entries => TreeMap[MK, MV](entries.toSeq: _*))
+  implicit def treeMapReader[PK, PV, MK, MV](
+      implicit keyReader: Reader[PK, MK],
+      valueReader: Reader[PV, MV],
+      ordering: Ordering[MK]
+  ): Reader[Map[PK, PV], TreeMap[MK, MV]] = instance { protobuf =>
+    mapReader(keyReader, valueReader).read(protobuf).map(entries => TreeMap[MK, MV](entries.toSeq: _*))
+  }
 
   /**
     * A reader that gives access to the inner [[PbResult]].
     * Use this if you want to allow failures in nested structures and therefore get back a partial result, for example
     * to always deserialize an event to an `Envelope[PbResult[A]]` even if the actual payload of type `A` fails to parse.
     */
   implicit def pbResultReader[PB <: GeneratedMessage, A](implicit reader: Reader[PB, A]): Reader[PB, PbResult[A]] =
-    pb => PbSuccess(reader.read(pb))
+    instance(pb => PbSuccess(reader.read(pb)))
 }
 
 private[teleproto] trait LowPriorityReads extends LowestPriorityReads {
@@ -229,31 +235,25 @@ private[teleproto] trait LowPriorityReads extends LowestPriorityReads {
     * Tries to read a map of Protobuf key/values to a sorted map of Scala key/values if reader exists between both types
     * and an ordering is defined on the Scala key.
     */
-  implicit def mapReader[PK, PV, MK, MV](implicit keyReader: Reader[PK, MK],
-                                         valueReader: Reader[PV, MV]): Reader[Map[PK, PV], Map[MK, MV]] =
-    (protobuf: Map[PK, PV]) => {
-      val modelResults =
-        for ((protoKey, protoValue) <- protobuf.toSeq)
-          yield {
-            for {
-              key   <- keyReader.read(protoKey).withPathPrefix(s"/$protoKey")
-              value <- valueReader.read(protoValue).withPathPrefix(s"/$key")
-            } yield {
-              (key, value)
-            }
-          }
-
-      val errors =
-        modelResults.flatMap {
-          case PbFailure(innerErrors) => innerErrors
-          case _                      => Seq.empty
-        }
-
-      if (errors.nonEmpty)
-        PbFailure(errors)
-      else
-        PbSuccess(Map[MK, MV](modelResults.map(_.get): _*))
+  implicit def mapReader[PK, PV, MK, MV](
+      implicit keyReader: Reader[PK, MK],
+      valueReader: Reader[PV, MV]
+  ): Reader[Map[PK, PV], Map[MK, MV]] = Reader.instance { protobuf =>
+    val modelResults = for ((protoKey, protoValue) <- protobuf.toSeq) yield {
+      for {
+        key   <- keyReader.read(protoKey).withPathPrefix(s"/$protoKey")
+        value <- valueReader.read(protoValue).withPathPrefix(s"/$key")
+      } yield (key, value)
+    }
+
+    val errors = modelResults.flatMap {
+      case PbFailure(innerErrors) => innerErrors
+      case _                      => Seq.empty
     }
+
+    if (errors.nonEmpty) PbFailure(errors)
+    else PbSuccess(Map[MK, MV](modelResults.map(_.get): _*))
+  }
 }
 
 private[teleproto] trait LowestPriorityReads {
@@ -262,5 +262,5 @@ private[teleproto] trait LowestPriorityReads {
     * Keeps a value of same type in protobuf and model.
     */
   implicit def identityReader[T]: Reader[T, T] =
-    (value: T) => PbSuccess(value)
+    Reader.instance(PbSuccess.apply)
 }

src/main/scala/io/moia/protos/teleproto/ReaderImpl.scala

@@ -22,6 +22,10 @@ import scala.reflect.macros.blackbox
 class ReaderImpl(val c: blackbox.Context) extends FormatImpl {
   import c.universe._
 
+  private[this] val readerObj    = objectRef[Reader.type]
+  private[this] val pbSuccessObj = objectRef[PbSuccess.type]
+  private[this] val pbFailureObj = objectRef[PbFailure.type]
+
   def reader_impl[P: WeakTypeTag, M: WeakTypeTag]: Expr[Reader[P, M]] =
     c.Expr(compile[P, M])
 
@@ -107,56 +111,53 @@ class ReaderImpl(val c: blackbox.Context) extends FormatImpl {
     */
   private def compileClassMapping(protobufType: Type, modelType: Type): Compiled = {
     val modelCompanion = modelType.typeSymbol.companion
-
-    val protobufCons = protobufType.member(termNames.CONSTRUCTOR).asMethod
-    val modelCons    = modelType.member(termNames.CONSTRUCTOR).asMethod
-
+    val protobufCons   = protobufType.member(termNames.CONSTRUCTOR).asMethod
+    val modelCons      = modelType.member(termNames.CONSTRUCTOR).asMethod
     val protobufParams = protobufCons.paramLists.headOption.getOrElse(Nil).map(_.asTerm)
     val modelParams    = modelCons.paramLists.headOption.getOrElse(Nil).map(_.asTerm)
 
-    val mapping = q"io.moia.protos.teleproto"
-
     /*
      * For each parameter creates a value assignment with the name of the parameter, e.g.
      * `val targetParameter = transformationExpression`
      */
-    def valueDefinitions(parameters: List[(TermSymbol, MatchingParam)]): List[Compiled] = {
+    def valueDefinitions(protobuf: TermName, parameters: List[(TermSymbol, MatchingParam)]): List[Compiled] = {
       parameters.flatMap {
-        case (termSymbol, matchingParam) =>
-          val path = q""""/"+${termSymbol.name.decodedName.toString}"""
+        case (paramSym, matchingParam) =>
+          val param = paramSym.name
+          val path  = q""""/"+${param.decodedName.toString}"""
 
           def assign(compiled: Compiled): Compiled =
-            (q"val ${termSymbol.name} = ${compiled._1}", compiled._2)
+            (q"val $param = ${compiled._1}", compiled._2)
 
           matchingParam match {
             case TransformParam(from, to) if from <:< to =>
-              Some(q"val ${termSymbol.name} = protobuf.${termSymbol.name}" -> Compatibility.full)
+              Some(q"val $param = $protobuf.$param" -> Compatibility.full)
             case TransformParam(from, to) if from <:< weakTypeOf[Option[_]] && !(to <:< weakTypeOf[Option[_]]) =>
               val innerFrom = innerType(from)
-              Some(assign(withImplicitReader(innerFrom, to) { readerExpr =>
-                q"""$mapping.Reader.required[$innerFrom, $to](protobuf.${termSymbol.name}, $path)($readerExpr)"""
+              Some(assign(withImplicitReader(innerFrom, to) { reader =>
+                q"$readerObj.required[$innerFrom, $to]($protobuf.$param, $path)($reader)"
               }))
             case TransformParam(from, to) if from <:< weakTypeOf[Option[_]] && (to <:< weakTypeOf[Option[_]]) =>
               val innerFrom = innerType(from)
               val innerTo   = innerType(to)
-              Some(assign(withImplicitReader(innerFrom, innerTo) { readerExpr =>
-                q"""$mapping.Reader.optional[$innerFrom, $innerTo](protobuf.${termSymbol.name}, $path)($readerExpr)"""
+              Some(assign(withImplicitReader(innerFrom, innerTo) { reader =>
+                q"$readerObj.optional[$innerFrom, $innerTo]($protobuf.$param, $path)($reader)"
               }))
 
             case TransformParam(from, to) if from <:< weakTypeOf[Seq[_]] && to <:< weakTypeOf[Iterable[_]] =>
               val innerFrom = innerType(from)
               val innerTo   = innerType(to)
-              Some(assign(withImplicitReader(innerFrom, innerTo) { readerExpr =>
+              Some(assign(withImplicitReader(innerFrom, innerTo) { reader =>
                 // sequence also needs an implicit collection generator which must be looked up since the implicit for the value reader is passed explicitly
                 val canBuildFrom = VersionSpecific.lookupFactory(c)(innerTo, to)
-                q"""$mapping.Reader.sequence[${to.typeConstructor}, $innerFrom, $innerTo](protobuf.${termSymbol.name}, $path)($canBuildFrom, $readerExpr)"""
+                q"$readerObj.sequence[${to.typeConstructor}, $innerFrom, $innerTo]($protobuf.$param, $path)($canBuildFrom, $reader)"
               }))
             case TransformParam(from, to) =>
-              Some(assign(withImplicitReader(from, to) { readerExpr =>
-                q"""$mapping.Reader.transform[$from, $to](protobuf.${termSymbol.name}, $path)($readerExpr)"""
+              Some(assign(withImplicitReader(from, to) { reader =>
+                q"$readerObj.transform[$from, $to]($protobuf.$param, $path)($reader)"
               }))
             case ExplicitDefaultParam(expr) =>
-              Some(q"val ${termSymbol.name} = $expr" -> Compatibility.full)
+              Some(q"val $param = $expr" -> Compatibility.full)
             case SkippedDefaultParam =>
               Option.empty[Compiled]
           }
@@ -200,7 +201,7 @@ class ReaderImpl(val c: blackbox.Context) extends FormatImpl {
             Some(termSymbol.name)
         }
 
-      q"$mapping.PbFailure.combine(..$convertedValues)"
+      q"$pbFailureObj.combine(..$convertedValues)"
     }
 
     def transformation(parameters: Seq[MatchingParam], ownCompatibility: Compatibility): Compiled = {
@@ -216,23 +217,15 @@ class ReaderImpl(val c: blackbox.Context) extends FormatImpl {
             case (param, _)               => Some(q"${param.name} = ${param.name}")
           })
 
-      val (valDefs, parameterCompatibilities) = valueDefinitions(matchedParameters).unzip
+      val protobuf                            = c.freshName(TermName("protobuf"))
+      val (valDefs, parameterCompatibilities) = valueDefinitions(protobuf, matchedParameters).unzip
 
       // expression that constructs the successful result: `PbSuccess(ModelClass(transformedParameter..))`
-      val cons = q"""$mapping.PbSuccess[$modelType](${modelCompanion.asTerm}.apply(..$passedArgumentNames))"""
-
-      val errorsHandled = q"""val result = ${forLoop(matchedParameters, cons)}; result.orElse(${combineErrors(matchedParameters)})"""
-
-      val transformed = valDefs.foldRight(errorsHandled)((t1, t2) => q"$t1; $t2")
-
+      val cons                   = q"$pbSuccessObj[$modelType](${modelCompanion.asTerm}.apply(..$passedArgumentNames))"
+      val errorsHandled          = q"${forLoop(matchedParameters, cons)}.orElse(${combineErrors(matchedParameters)})"
+      val transformed            = valDefs.foldRight(errorsHandled)((t1, t2) => q"$t1; $t2")
       val parameterCompatibility = parameterCompatibilities.fold(Compatibility.full)(_ merge _)
-
-      val result =
-        q"""
-          new $mapping.Reader[$protobufType, $modelType] {
-            def read(protobuf: $protobufType) = $transformed
-          }"""
-
+      val result                 = q"$readerObj.instance[$protobufType, $modelType] { case $protobuf => $transformed }"
       (result, ownCompatibility.merge(parameterCompatibility))
     }
 
@@ -366,15 +359,11 @@ class ReaderImpl(val c: blackbox.Context) extends FormatImpl {
 
     val (cases, compatibility) = subTypes.unzip
     val emptyCase = for (protobufClass <- protobufSubClasses.get(EmptyOneOf) if !modelSubclasses.contains(EmptyOneOf))
-      yield cq"""_: ${objectReferenceTo(protobufClass)}.type => $mapping.PbFailure("Oneof field is empty!")"""
+      yield cq"""_: ${objectReferenceTo(protobufClass)}.type => $pbFailureObj("Oneof field is empty!")"""
 
-    val reader = c.freshName(TermName("reader"))
-    val result = q"""{
-      val $reader: $mapping.Reader[$protobufType, $modelType] = {
-        case ..$cases
-        case ..${emptyCase.toList}
-      }
-      $reader
+    val result = q"""$readerObj.instance[$protobufType, $modelType] {
+      case ..$cases
+      case ..${emptyCase.toList}
     }"""
 
     (result, compatibility.fold(ownCompatibility)(_ merge _))
@@ -419,23 +408,19 @@ class ReaderImpl(val c: blackbox.Context) extends FormatImpl {
     val cases = for {
       (optionName, modelOption) <- modelOptions.toList
       protobufOption            <- protobufOptions.get(optionName)
-    } yield cq"_: ${objectReferenceTo(protobufOption)}.type => $mapping.PbSuccess(${objectReferenceTo(modelOption)})"
+    } yield cq"_: ${objectReferenceTo(protobufOption)}.type => $pbSuccessObj(${objectReferenceTo(modelOption)})"
 
     val invalidCase = for (protobufOption <- protobufOptions.get(InvalidEnum) if !modelOptions.contains(InvalidEnum)) yield {
       val reference = objectReferenceTo(protobufOption)
-      cq"""_: $reference.type => $mapping.PbFailure(s"Enumeration value $${$reference} is invalid!")"""
+      cq"""_: $reference.type => $pbFailureObj(s"Enumeration value $${$reference} is invalid!")"""
     }
 
-    val reader = c.freshName(TermName("reader"))
     val other  = c.freshName(TermName("other"))
-    val result = q"""{
-      val $reader: $mapping.Reader[$protobufType, $modelType] = {
-        case ..$cases
-        case ..${invalidCase.toList}
-        case ${protobufCompanion.asTerm}.Unrecognized($other) =>
-          $mapping.PbFailure(s"Enumeration value $${$other} is unrecognized!")
-      }
-      $reader
+    val result = q"""$readerObj.instance[$protobufType, $modelType] {
+      case ..$cases
+      case ..${invalidCase.toList}
+      case ${protobufCompanion.asTerm}.Unrecognized($other) =>
+        $pbFailureObj(s"Enumeration value $${$other} is unrecognized!")
     }"""
 
     (result, compatibility)