Merge pull request #1 from road21/basic_scala3_derivation_fix_collect…

…_defauls fix collect defaults macro
tethys-json · Apr 23, 2024 · ce26657 · ce26657
2 parents 9501a3c + f66ee03
commit ce26657
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Showing 2 changed files with 48 additions and 20 deletions.
diff --git a/modules/core/src/main/scala-3/tethys/derivation/Defaults.scala b/modules/core/src/main/scala-3/tethys/derivation/Defaults.scala
@@ -10,22 +10,36 @@ 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) }: _*) }
-
+  def collect[T: Type](using
+
+      Quotes
+  ): Expr[Map[Int, Any]] =
+    import quotes.reflect._
+
+    val tpe = TypeRepr.of[T].typeSymbol
+    val terms = tpe.primaryConstructor.paramSymss.flatten
+      .filter(_.isValDef)
+      .zipWithIndex
+      .flatMap { case (field, idx) =>
+        val defaultMethodName = s"$$lessinit$$greater$$default$$${idx + 1}"
+        tpe.companionClass
+          .declaredMethod(defaultMethodName)
+          .headOption
+          .map { defaultMethod =>
+            val callDefault = {
+            val base = Ident(tpe.companionModule.termRef).select(defaultMethod)
+            val tParams = defaultMethod.paramSymss.headOption.filter(_.forall(_.isType))
+              tParams match
+                case Some(tParams) => TypeApply(base, tParams.map(TypeTree.ref))
+                case _             => base
+            }
+
+            defaultMethod.tree match {
+              case tree: DefDef => tree.rhs.getOrElse(callDefault)
+              case _            => callDefault
+            }
+          }
+          .map(x => Expr.ofTuple(Expr(idx) -> x.asExprOf[Any]))
+      }
+
+    '{ Map(${ Varargs(terms) }: _*) }
diff --git a/modules/core/src/test/scala-3/tethys/DerivationSpec.scala b/modules/core/src/test/scala-3/tethys/DerivationSpec.scala
@@ -6,6 +6,7 @@ import tethys.commons.TokenNode.obj
 import tethys.commons.{Token, TokenNode}
 import tethys.readers.tokens.QueueIterator
 import tethys.writers.tokens.SimpleTokenWriter.SimpleTokenWriterOps
+import tethys.derivation.Defaults
 
 class DerivationSpec extends AnyFlatSpec with Matchers {
   def read[A: JsonReader](nodes: List[TokenNode]): A = {
@@ -113,5 +114,18 @@ class DerivationSpec extends AnyFlatSpec with Matchers {
     }
   }
 
+  it should "correctly read case classes with default parameters" in {
+    object Mod {
+      case class WithOpt(x: Int, y: Option[String] = Some("default")) derives JsonReader
+    }
+
+    read[Mod.WithOpt](obj("x" -> 5)) shouldBe Mod.WithOpt(5)
+  }
 
-}
+  it should "correctly read case classes with default parameters and type arguments" in {
+    case class WithArg[A](x: Int, y: Option[A] = None) derives JsonReader
+
+    read[WithArg[Int]](obj("x" -> 5)) shouldBe WithArg[Int](5)
+    read[WithArg[String]](obj("x" -> 5, "y" -> "lool")) shouldBe WithArg[String](5, Some("lool"))
+  }
+}