1 files changed, 33 insertions, 0 deletions
diff --git a/src/main/scala/annotations.scala b/src/main/scala/annotations.scala
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+++ b/src/main/scala/annotations.scala
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+package xyz.driver.json
+
+import scala.annotation.StaticAnnotation
+
+/** Indicator trait of anontations related to JSON formatting. */
+sealed trait JsonAnnotation
+
+/** An annotation that designates that a sealed trait is a generalized algebraic
+  * datatype (GADT), and that a type field containing the serialized childrens'
+  * types should be added to the final JSON objects.
+  *
+  * Note that by default all sealed traits are treated as GADTs, with a type
+  * field called `type`. This annotation enables overriding the name of that
+  * field and is really only useful if a child itself has a field called `type`
+  * that would result in a conflict.
+  *
+  * Example
+  * ```
+  * // the JSON field "kind" will contain the actual type of the serialized child
+  * @gadt("kind") sealed abstract class Keyword(`type`: String)
+  * case class If(`type`: String) extends Keyword(`type`)
+  * ```
+  *
+  * @param typeFieldName the name of the field to inject into a serialized JSON
+  *        object */
+final class gadt(val typeFieldName: String = "type")
+    extends StaticAnnotation
+    with JsonAnnotation
+
+/** An annotation that designates that a sealed trait is an enumeration (all
+  * children are strictly case objects), and that all children should be
+  * serialized as strings. */
+final class enum extends StaticAnnotation with JsonAnnotation