implemented scala 3 basic derivation based on mirrors

modules/core/src/main/scala-2.12/tethys/derivation/JsonReaderDerivation.scala

@@ -0,0 +1,6 @@
+package tethys.derivation
+
+
+private [tethys] trait JsonReaderDerivation {
+
+}

modules/core/src/main/scala-2.12/tethys/derivation/JsonWriterDerivation.scala

@@ -0,0 +1,6 @@
+package tethys.derivation
+
+
+private [tethys] trait JsonWriterDerivation {
+
+}

modules/core/src/main/scala-2.13+/tethys/derivation/JsonReaderDerivation.scala

@@ -0,0 +1,6 @@
+package tethys.derivation
+
+
+private [tethys] trait JsonReaderDerivation {
+
+}

modules/core/src/main/scala-2.13+/tethys/derivation/JsonWriterDerivation.scala

@@ -0,0 +1,6 @@
+package tethys.derivation
+
+
+private [tethys] trait JsonWriterDerivation {
+
+}

modules/core/src/main/scala-3/tethys/OrdinalEnumReader.scala

@@ -0,0 +1,18 @@
+package tethys
+
+import tethys.readers.{FieldName, ReaderError}
+import tethys.readers.tokens.TokenIterator
+
+trait OrdinalEnumReader[A] extends JsonReader[A]
+
+object OrdinalEnumReader:
+  inline def derived[A <: scala.reflect.Enum]: OrdinalEnumReader[A] =
+    new OrdinalEnumReader[A]:
+      def read(it: TokenIterator)(implicit fieldName: FieldName): A =
+        if it.currentToken().isNumberValue then
+          val res = it.int()
+          it.next()
+          derivation.EnumCompanion.getByOrdinal[A](res)
+        else
+          ReaderError.wrongJson(s"Expected int value but found: ${it.currentToken()}")
+

modules/core/src/main/scala-3/tethys/OrdinalEnumWriter.scala

@@ -0,0 +1,16 @@
+package tethys
+import tethys.writers.tokens.TokenWriter
+
+
+trait OrdinalEnumWriter[A] extends JsonWriter[A]
+
+object OrdinalEnumWriter:
+  inline def derived[A <: scala.reflect.Enum]: OrdinalEnumWriter[A] =
+    (value: A, tokenWriter: TokenWriter) => tokenWriter.writeNumber(value.ordinal)
+
+  inline def withLabel[A <: scala.reflect.Enum](label: String): JsonObjectWriter[A] =
+    (value: A, tokenWriter: writers.tokens.TokenWriter) =>
+      tokenWriter.writeFieldName(label)
+      tokenWriter.writeNumber(value.ordinal)
+
+

modules/core/src/main/scala-3/tethys/StringEnumReader.scala

@@ -0,0 +1,18 @@
+package tethys
+import tethys.readers.{FieldName, ReaderError}
+import tethys.readers.tokens.TokenIterator
+
+trait StringEnumReader[A] extends JsonReader[A]
+
+object StringEnumReader:
+  inline def derived[A <: scala.reflect.Enum]: StringEnumReader[A] =
+    new StringEnumReader[A]:
+      def read(it: TokenIterator)(implicit fieldName: FieldName): A =
+        if it.currentToken().isStringValue then
+          val res = it.string()
+          it.next()
+          derivation.EnumCompanion.getByName[A](res)
+        else
+          ReaderError.wrongJson(s"Expected string value but found: ${it.currentToken()}")
+
+

modules/core/src/main/scala-3/tethys/StringEnumWriter.scala

@@ -0,0 +1,14 @@
+package tethys
+import tethys.writers.tokens.TokenWriter
+
+trait StringEnumWriter[A] extends JsonWriter[A]
+
+object StringEnumWriter:
+  inline def derived[A <: scala.reflect.Enum]: StringEnumWriter[A] = 
+    (value: A, tokenWriter: TokenWriter) => tokenWriter.writeString(value.toString)
+
+  inline def withLabel[A <: scala.reflect.Enum](label: String): JsonObjectWriter[A] =
+    (value: A, tokenWriter: writers.tokens.TokenWriter) =>
+      tokenWriter.writeFieldName(label)
+      tokenWriter.writeString(value.toString)
+

modules/core/src/main/scala-3/tethys/derivation/Defaults.scala

@@ -0,0 +1,31 @@
+package tethys.derivation
+
+
+private[tethys]
+object Defaults:
+  inline def collectFrom[T]: Map[Int, Any] = ${ DefaultsMacro.collect[T] }
+
+
+private[derivation]
+object DefaultsMacro:
+  import scala.quoted.*
+
+  def collect[T: Type](using quotes: Quotes): Expr[Map[Int, Any]] =
+    import quotes.reflect.*
+    val typeSymbol = TypeRepr.of[T].typeSymbol
+
+    val res = typeSymbol.caseFields.zipWithIndex.flatMap {
+      case (sym, idx) if sym.flags.is(Flags.HasDefault) =>
+        val defaultValueMethodSym =
+          typeSymbol.companionClass
+            .declaredMethod(s"$$lessinit$$greater$$default$$${idx + 1}")
+            .headOption
+            .getOrElse(report.errorAndAbort(s"Error while extracting default value for field '${sym.name}'"))
+
+        Some(Expr.ofTuple(Expr(idx) -> Ref(typeSymbol.companionModule).select(defaultValueMethodSym).asExprOf[Any]))
+      case _ =>
+        None
+    }
+
+    '{ Map(${ Varargs(res) }: _*) }
+

modules/core/src/main/scala-3/tethys/derivation/EnumCompanion.scala

@@ -0,0 +1,28 @@
+package tethys.derivation
+
+private[tethys]
+object EnumCompanion:
+  inline def getByName[T](name: String): T =
+    ${ EnumCompanionMacro.getByName[T]('{ name }) }
+
+  inline def getByOrdinal[T](ordinal: Int): T =
+    ${ EnumCompanionMacro.getByOrdinal[T]('{ ordinal }) }
+
+
+private[derivation]
+object EnumCompanionMacro:
+  import scala.quoted.*
+  def getByName[T: scala.quoted.Type](name: Expr[String])(using quotes: Quotes): Expr[T] =
+    import quotes.reflect.*
+    Select.unique(Ref(TypeRepr.of[T].typeSymbol.companionModule), "valueOf")
+      .appliedToArgs(List(name.asTerm))
+      .asExprOf[T]
+
+
+  def getByOrdinal[T: scala.quoted.Type](ordinal: Expr[Int])(using quotes: Quotes): Expr[T] =
+    import quotes.reflect.*
+    Select.unique(Ref(TypeRepr.of[T].typeSymbol.companionModule), "fromOrdinal")
+      .appliedToArgs(List(ordinal.asTerm))
+      .asExprOf[T]
+
+

modules/core/src/main/scala-3/tethys/derivation/JsonReaderDerivation.scala

@@ -0,0 +1,90 @@
+package tethys.derivation
+
+import tethys.readers.{FieldName, ReaderError}
+import tethys.readers.tokens.TokenIterator
+import tethys.JsonReader
+
+import scala.deriving.Mirror
+import scala.compiletime.{erasedValue, summonInline, constValue, constValueTuple, summonFrom}
+
+
+private [tethys] trait JsonReaderDerivation:
+  inline def derived[A](using mirror: Mirror.ProductOf[A]): JsonReader[A] =
+    new JsonReader[A]:
+      override def read(it: TokenIterator)(implicit fieldName: FieldName) =
+        if !it.currentToken().isObjectStart then
+          ReaderError.wrongJson("Expected object start but found: " + it.currentToken().toString)
+        else
+          it.nextToken()
+          val labels = constValueTuple[mirror.MirroredElemLabels].toArray.collect { case s: String => s }
+          val readersByLabels = labels.zip(summonJsonReaders[A, mirror.MirroredElemTypes].zipWithIndex).toMap
+          val defaults = getOptionsByIndex[mirror.MirroredElemTypes](0).toMap ++ Defaults.collectFrom[A]
+          val optionalLabels = defaults.keys.map(labels(_))
+
+          val collectedValues = scala.collection.mutable.Map.from[Int, Any](defaults)
+          val missingFields = scala.collection.mutable.Set.from(labels) -- optionalLabels
+
+          while (!it.currentToken().isObjectEnd)
+            val jsonName = it.fieldName()
+            it.nextToken()
+            val currentIt = it.collectExpression()
+            readersByLabels.get(jsonName).foreach { (reader, idx) =>
+              val value: Any = reader.read(currentIt.copy())(fieldName.appendFieldName(jsonName))
+              collectedValues += idx -> value
+              missingFields -= jsonName
+            }
+
+          it.nextToken()
+
+          if (missingFields.nonEmpty)
+            ReaderError.wrongJson("Can not extract fields from json: " + missingFields.mkString(", "))
+          else
+            mirror.fromProduct:
+              new Product:
+                override def productArity = labels.length
+                override def productElement(n: Int) = collectedValues(n)
+                override def canEqual(that: Any) =
+                  that match
+                    case that: Product if that.productArity == productArity => true
+                    case _ => false
+
+  private inline def summonJsonReaders[T, Elems <: Tuple]: List[JsonReader[?]] =
+    inline erasedValue[Elems] match
+      case _: EmptyTuple =>
+        Nil
+      case _: (elem *: elems) =>
+        deriveOrSummon[T, elem] :: summonJsonReaders[T, elems]
+
+  private inline def deriveOrSummon[T, Elem]: JsonReader[Elem] =
+    inline erasedValue[Elem] match
+      case _: T =>
+        deriveRec[T, Elem]
+      case _ =>
+        summonInline[JsonReader[Elem]]
+
+  private inline def deriveRec[T, Elem]: JsonReader[Elem] =
+    inline erasedValue[T] match
+      case _: Elem =>
+        scala.compiletime.error("Recursive derivation is not possible")
+      case value =>
+        JsonReader.derived[Elem](using summonInline[Mirror.ProductOf[Elem]])
+
+
+  private inline def getLabels[T <: Tuple]: List[String] =
+    inline erasedValue[T] match
+      case EmptyTuple => Nil
+      case _: (t *: ts) =>
+        constValue[t].asInstanceOf[String] :: getLabels[ts]
+
+
+  private inline def getOptionsByIndex[Elems <: Tuple](idx: Int): List[(Int, Option[?])] =
+    inline erasedValue[Elems] match
+      case _: EmptyTuple =>
+        Nil
+      case _: (elem *: elems) =>
+        inline erasedValue[elem] match
+          case _: Option[_] =>
+            idx -> None :: getOptionsByIndex[elems](idx + 1)
+          case _ =>
+            getOptionsByIndex[elems](idx + 1)
+

modules/core/src/main/scala-3/tethys/derivation/JsonWriterDerivation.scala

@@ -0,0 +1,59 @@
+package tethys.derivation
+
+import tethys.{JsonObjectWriter, JsonWriter}
+import tethys.writers.tokens.TokenWriter
+
+import scala.deriving.Mirror
+import scala.compiletime.{summonInline, erasedValue, summonFrom}
+
+private[tethys] trait JsonWriterDerivation:
+  inline def derived[A](using mirror: Mirror.Of[A]): JsonObjectWriter[A] =
+    new JsonObjectWriter[A]:
+      override def writeValues(value: A, tokenWriter: TokenWriter): Unit =
+        inline mirror match
+          case m: Mirror.ProductOf[A] =>
+            val product = summonInline[A <:< Product](value)
+            product.productElementNames
+              .zip(product.productIterator)
+              .zip(summonJsonWriters[A, m.MirroredElemTypes])
+              .foreach { case ((name, value), writer) =>
+                writer.write(name, value.asInstanceOf, tokenWriter)
+              }
+
+          case m: Mirror.SumOf[A] =>
+            summonJsonWriters[A, m.MirroredElemTypes](m.ordinal(value))
+              .asInstanceOf[JsonObjectWriter[A]]
+              .writeValues(value, tokenWriter)
+
+
+  private inline def summonJsonWriters[T, Elems <: Tuple]: List[JsonWriter[?]] =
+    inline erasedValue[Elems] match
+      case _: EmptyTuple =>
+        Nil
+      case _: (elem *: elems) =>
+        deriveOrSummon[T, elem] :: summonJsonWriters[T, elems]
+
+  private inline def deriveOrSummon[T, Elem]: JsonWriter[Elem] =
+    summonFrom[scala.util.NotGiven[Elem =:= T]] {
+      case found: scala.util.NotGiven[_] =>
+        summonFrom[JsonWriter[Elem]] {
+          case writer: JsonWriter[Elem] =>
+            writer
+          case _ =>
+            deriveRec[T, Elem]
+        }
+      case _ =>
+        inline erasedValue[Elem] match
+          case _: T =>
+            deriveRec[T, Elem]
+          case _ =>
+            summonInline[JsonWriter[Elem]]
+
+    }
+
+  private inline def deriveRec[T, Elem]: JsonWriter[Elem] =
+    inline erasedValue[T] match
+      case _: Elem =>
+        scala.compiletime.error("Recursive derivation is not possible")
+      case value =>
+        JsonWriter.derived[Elem](using summonInline[Mirror.Of[Elem]])

modules/core/src/main/scala/tethys/JsonObjectWriter.scala

@@ -29,7 +29,7 @@ trait JsonObjectWriter[A] extends JsonWriter[A] {
   }
 }
 
-object JsonObjectWriter extends LowPriorityJsonObjectWriters {
+object JsonObjectWriter extends LowPriorityJsonObjectWriters with derivation.JsonWriterDerivation {
   def apply[A](implicit jsonObjectWriter: JsonObjectWriter[A]): JsonObjectWriter[A] = jsonObjectWriter
 }
 

modules/core/src/main/scala/tethys/JsonReader.scala

@@ -20,7 +20,7 @@ trait JsonReader[@specialized(specializations) A] {
   }
 }
 
-object JsonReader extends AllJsonReaders {
+object JsonReader extends AllJsonReaders with derivation.JsonReaderDerivation {
   def apply[A](implicit jsonReader: JsonReader[A]): JsonReader[A] = jsonReader
 
   val builder: JsonReaderBuilder.type = JsonReaderBuilder

modules/core/src/main/scala/tethys/JsonWriter.scala

@@ -26,7 +26,8 @@ trait JsonWriter[@specialized(specializations) A] {
   }
 }
 
-object JsonWriter extends AllJsonWriters {
+object JsonWriter extends AllJsonWriters with derivation.JsonWriterDerivation {
+
   def apply[A](implicit jsonWriter: JsonWriter[A]): JsonWriter[A] = jsonWriter
 
   def obj[A]: SimpleJsonObjectWriter[A] = SimpleJsonObjectWriter[A]