Support for product types (#251)

build.sbt

@@ -128,6 +128,7 @@ lazy val core = project
       "org.apache.spark" %% "spark-sql" % sparkVersion.value % "provided", // scala-steward:off
       "org.typelevel" %% "cats-core"  % catsVersion(sparkVersion.value),
       "com.lihaoyi"   %% "sourcecode" % "0.3.0",
+      "com.chuusai"   %% "shapeless"  % "2.3.9",
       "com.github.mrpowers" %% "spark-fast-tests" % "1.3.0"  % "test",
       "org.scalatest"       %% "scalatest"        % "3.2.12" % "test"
     ),

core/src/main/scala/doric/DoricColumn.scala

@@ -39,17 +39,13 @@ case class LiteralDoricColumn[T] private[doric] (
 ) extends DoricColumn[T]
 
 object LiteralDoricColumn {
-  def apply[T: SparkType: LiteralSparkType](value: T): LiteralDoricColumn[T] = {
-    val colLit: Doric[Column] = new Column(
-      Literal(
-        CatalystTypeConverters.createToCatalystConverter(SparkType[T].dataType)(
-          LiteralSparkType[T].literalTo(value)
-        ),
-        SparkType[T].dataType
-      )
-    ).pure[Doric]
-    LiteralDoricColumn(colLit, value)
-  }
+  def apply[T: SparkType: LiteralSparkType](
+      value: T
+  )(implicit l: Location): LiteralDoricColumn[T] =
+    LiteralDoricColumn(
+      Kleisli { _ => LiteralSparkType[T].literal(value) },
+      value
+    )
 
   implicit class LiteralGetter[T](litCol: LiteralDoricColumn[T]) {
     def getColumnValueAsSparkValue(implicit

core/src/main/scala/doric/sem/Errors.scala

@@ -161,6 +161,12 @@ case class SparkErrorWrapper(sparkCause: Throwable)(implicit
   }
 }
 
+case class GenDoricError(
+    val message: String
+)(implicit
+    val location: Location
+) extends DoricSingleError(None)
+
 object Location {
   implicit def location(implicit
       line: sourcecode.Line,

core/src/main/scala/doric/syntax/DStructs.scala

@@ -8,10 +8,11 @@ import cats.evidence.Is
 import cats.implicits._
 import doric.sem.{ColumnTypeError, Location, SparkErrorWrapper}
 import doric.types.SparkType
-
 import org.apache.spark.sql.{Column, Dataset, Row}
 import org.apache.spark.sql.catalyst.expressions.ExtractValue
 import org.apache.spark.sql.functions.{struct => sparkStruct}
+import shapeless.labelled.FieldType
+import shapeless.{::, HList, LabelledGeneric, Witness}
 
 private[syntax] trait DStructs {
 
@@ -26,7 +27,9 @@ private[syntax] trait DStructs {
   def struct(cols: DoricColumn[_]*): RowColumn =
     cols.map(_.elem).toList.sequence.map(c => sparkStruct(c: _*)).toDC
 
-  implicit class DStructOps(private val col: RowColumn) {
+  implicit class DStructOps[T](private val col: DoricColumn[T])(implicit
+      st: SparkType.Custom[T, Row]
+  ) {
 
     /**
       * Retreaves the child row of the Struct column
@@ -83,15 +86,22 @@ private[syntax] trait DStructs {
         .toDC
     }
   }
-  trait DynamicFieldAccessor[T] extends Dynamic { self: DoricColumn[T] =>
+
+  trait DynamicFieldAccessor[T] extends Dynamic {
+    self: DoricColumn[T] =>
 
     /**
       * Allows for accessing fields of struct columns using the syntax `rowcol.name[T]`.
       * This expression stands for `rowcol.getChild[T](name)`.
       *
+      * @param name
+      * @param location
+      * @param st
+      * @tparam A
       * @return The column which refers to the given field
       * @throws doric.sem.ColumnTypeError if the parent column is not a struct
       */
+
     def selectDynamic[A](name: String)(implicit
         location: Location,
         st: SparkType[A],
@@ -100,4 +110,43 @@ private[syntax] trait DStructs {
       w.lift[DoricColumn].coerce(self).getChild[A](name)
   }
 
+  @annotation.implicitNotFound(msg = "No field ${K} in record ${L}")
+  trait SelectorWithSparkType[L <: HList, K <: Symbol] {
+    type V
+    val st: SparkType[V]
+  }
+
+  object SelectorWithSparkType extends SelectorLPI {
+    type Aux[L <: HList, K <: Symbol, _V] = SelectorWithSparkType[L, K] {
+      type V = _V
+    }
+
+    implicit def Found[K <: Symbol, _V: SparkType, T <: HList] =
+      new SelectorWithSparkType[FieldType[K, _V] :: T, K] {
+        type V = _V
+        val st = SparkType[_V]
+      }
+  }
+
+  trait SelectorLPI {
+    implicit def KeepFinding[K1, V1, T <: HList, K <: Symbol](implicit
+        T: SelectorWithSparkType[T, K]
+    ) =
+      new SelectorWithSparkType[FieldType[K1, V1] :: T, K] {
+        type V = T.V
+        val st = T.st
+      }
+  }
+
+  implicit class StructOps[T, L <: HList](dc: DoricColumn[T])(implicit
+      lg: LabelledGeneric.Aux[T, L],
+      st: SparkType.Custom[T, Row]
+  ) {
+    def getChildSafe[K <: Symbol](k: Witness.Aux[K])(implicit
+        S: SelectorWithSparkType[L, K],
+        location: Location
+    ): DoricColumn[S.V] =
+      new DStructOps(dc).getChild[S.V](k.value.name)(S.st, location)
+  }
+
 }

core/src/main/scala/doric/syntax/LiteralConversions.scala

@@ -1,6 +1,7 @@
 package doric
 package syntax
 
+import doric.sem.Location
 import doric.types.{LiteralSparkType, SparkType}
 
 private[syntax] trait LiteralConversions {
@@ -16,7 +17,9 @@ private[syntax] trait LiteralConversions {
     * A doric column that represent the literal value and the same type as the
     * value.
     */
-  def lit[L: SparkType: LiteralSparkType](litv: L): LiteralDoricColumn[L] = {
+  def lit[L: SparkType: LiteralSparkType](
+      litv: L
+  )(implicit l: Location): LiteralDoricColumn[L] = {
     LiteralDoricColumn(litv)
   }
 
@@ -29,7 +32,9 @@ private[syntax] trait LiteralConversions {
       * a literal with the same type.
       */
     @inline
-    def lit: LiteralDoricColumn[L] = LiteralDoricColumn(litv)
+    def lit(implicit l: Location): LiteralDoricColumn[L] = LiteralDoricColumn(
+      litv
+    )
   }
 
 }