[SPARK-16287][SQL] Implement str_to_map SQL function

## What changes were proposed in this pull request?
This PR adds `str_to_map` SQL function in order to remove Hive fallback.

## How was this patch tested?
Pass the Jenkins tests with newly added.

Author: Sandeep Singh <sandeep@techaddict.me>

Closes #13990 from techaddict/SPARK-16287.

1 files changed, 23 insertions, 0 deletions

diff --git a/sql/core/src/test/scala/org/apache/spark/sql/StringFunctionsSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/StringFunctionsSuite.scala
index f509551b1e..524926e1e9 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/StringFunctionsSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/StringFunctionsSuite.scala
@@ -384,4 +384,27 @@ class StringFunctionsSuite extends QueryTest with SharedSQLContext {
     }.getMessage
     assert(m.contains("Invalid number of arguments for function sentences"))
   }
+
+  test("str_to_map function") {
+    val df1 = Seq(
+      ("a=1,b=2", "y"),
+      ("a=1,b=2,c=3", "y")
+    ).toDF("a", "b")
+
+    checkAnswer(
+      df1.selectExpr("str_to_map(a,',','=')"),
+      Seq(
+        Row(Map("a" -> "1", "b" -> "2")),
+        Row(Map("a" -> "1", "b" -> "2", "c" -> "3"))
+      )
+    )
+
+    val df2 = Seq(("a:1,b:2,c:3", "y")).toDF("a", "b")
+
+    checkAnswer(
+      df2.selectExpr("str_to_map(a)"),
+      Seq(Row(Map("a" -> "1", "b" -> "2", "c" -> "3")))
+    )
+
+  }
 }