[SPARK-19254][SQL] Support Seq, Map, and Struct in functions.lit

## What changes were proposed in this pull request?
This pr is to support Seq, Map, and Struct in functions.lit; it adds a new IF named `lit2` with `TypeTag` for avoiding type erasure.

## How was this patch tested?
Added tests in `LiteralExpressionSuite`

Author: Takeshi Yamamuro <yamamuro@apache.org>
Author: Takeshi YAMAMURO <linguin.m.s@gmail.com>

Closes #16610 from maropu/SPARK-19254.

1 files changed, 17 insertions, 8 deletions

diff --git a/sql/core/src/main/scala/org/apache/spark/sql/functions.scala b/sql/core/src/main/scala/org/apache/spark/sql/functions.scala
index 24ed906d33..2247010ac3 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/functions.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/functions.scala
@@ -91,15 +91,24 @@ object functions {
    * @group normal_funcs
    * @since 1.3.0
    */
-  def lit(literal: Any): Column = {
-    literal match {
-      case c: Column => return c
-      case s: Symbol => return new ColumnName(literal.asInstanceOf[Symbol].name)
-      case _ =>  // continue
-    }
+  def lit(literal: Any): Column = typedLit(literal)
 
-    val literalExpr = Literal(literal)
-    Column(literalExpr)
+  /**
+   * Creates a [[Column]] of literal value.
+   *
+   * The passed in object is returned directly if it is already a [[Column]].
+   * If the object is a Scala Symbol, it is converted into a [[Column]] also.
+   * Otherwise, a new [[Column]] is created to represent the literal value.
+   * The difference between this function and [[lit]] is that this function
+   * can handle parameterized scala types e.g.: List, Seq and Map.
+   *
+   * @group normal_funcs
+   * @since 2.2.0
+   */
+  def typedLit[T : TypeTag](literal: T): Column = literal match {
+    case c: Column => c
+    case s: Symbol => new ColumnName(s.name)
+    case _ => Column(Literal.create(literal))
   }
 
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