Introduce functions.litValue

typelevel · Aug 29, 2021 · b346330 · b346330
1 parent 657d0a3
commit b346330
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Showing 2 changed files with 47 additions and 13 deletions.
diff --git a/dataset/src/main/scala/frameless/functions/package.scala b/dataset/src/main/scala/frameless/functions/package.scala
@@ -1,10 +1,16 @@
 package frameless
 
+import scala.reflect.ClassTag
+
+import shapeless._
+import shapeless.labelled.FieldType
+import shapeless.ops.hlist.IsHCons
+import shapeless.ops.record.Values
+
 import org.apache.spark.sql.catalyst.ScalaReflection
 import org.apache.spark.sql.catalyst.expressions.Literal
 
-package object functions
-    extends Udf with UnaryFunctions with LowPriorityFunctions {
+package object functions extends Udf with UnaryFunctions {
 
   object aggregate extends AggregateFunctions
   object nonAggregate extends NonAggregateFunctions
@@ -16,9 +22,6 @@ package object functions
     */
   def litAggr[A: TypedEncoder, T](value: A): TypedAggregate[T, A] =
     new TypedAggregate[T,A](lit(value).expr)
-}
-
-private[frameless] sealed trait LowPriorityFunctions {
 
   /** Creates a [[frameless.TypedColumn]] of literal value. If A is to be encoded using an Injection make
     * sure the injection instance is in scope.
@@ -47,4 +50,40 @@ private[frameless] sealed trait LowPriorityFunctions {
       )
     }
   }
+
+  /** Creates a [[frameless.TypedColumn]] of literal value 
+    * for a Value class `A`.
+    * 
+    * @tparam A the value class
+    * @tparam T the row type
+    */
+  def litValue[A <: AnyVal, T, G <: ::[_, HNil], H <: ::[_ <: FieldType[_ <: Symbol, _], HNil], V, VS <: HList](value: A)(
+    implicit
+      i0: LabelledGeneric.Aux[A, G],
+      i1: DropUnitValues.Aux[G, H],
+      i2: IsHCons.Aux[H, _ <: FieldType[_, V], HNil],
+      i3: Values.Aux[H, VS],
+      i4: IsHCons.Aux[VS, V, HNil],
+      i5: TypedEncoder[V],
+      i6: ClassTag[A]
+  ): TypedColumn[T, A] = {
+    val expr = {
+      val field: H = i1(i0.to(value))
+      val v: V = i4.head(i3(field))
+
+      new Literal(v, i5.jvmRepr)
+    }
+
+    implicit val enc: TypedEncoder[A] =
+      RecordFieldEncoder.valueClass[A, G, H, V].encoder
+
+    new TypedColumn[T, A](
+      new Lit(
+        dataType = i5.catalystRepr,
+        nullable = i5.nullable,
+        toCatalyst = i5.toCatalyst(expr).genCode(_),
+        show = value.toString
+      )
+    )
+  }
 }
diff --git a/dataset/src/test/scala/frameless/LitTests.scala b/dataset/src/test/scala/frameless/LitTests.scala
@@ -1,10 +1,10 @@
 package frameless
 
-import frameless.functions.lit
+import frameless.functions.{ lit, litValue }
 
 import org.scalatest.matchers.should.Matchers
 
-import org.scalacheck.{ Arbitrary, Gen, Prop }, Prop._
+import org.scalacheck.Prop, Prop._
 
 import RecordEncoderTests.Name
 
@@ -51,11 +51,6 @@ class LitTests extends TypedDatasetSuite with Matchers {
 
     check(prop[Food] _)
 
-    implicit def nameArb: Arbitrary[Name] =
-      Arbitrary(Gen.alphaStr.map(new Name(_)))
-
-    check(prop[Name] _)
-
     // doesn't work, object has to be serializable
     // check(prop[frameless.LocalDateTime] _)
   }
@@ -70,7 +65,7 @@ class LitTests extends TypedDatasetSuite with Matchers {
 
     val lorem = new Name("Lorem")
 
-    ds.withColumnReplaced('name, lit(lorem)).
+    ds.withColumnReplaced('name, litValue(lorem)).
       collect.run() shouldBe initial.map(_.copy(name = lorem))
   }