[Snowflake]Add new supported syntax in IN clause of PIVOT (#4655)

* Add new IN syntax for pivot clause

* Add "default on null"

Author: MasterKuat

sql/snowflake/SnowflakeParser.g4

@@ -4551,12 +4551,21 @@ match_recognize
     ;
 
 pivot_unpivot
-    : PIVOT LR_BRACKET id_ LR_BRACKET id_ RR_BRACKET FOR id_ IN LR_BRACKET literal (COMMA literal)* RR_BRACKET RR_BRACKET (
-        as_alias column_alias_list_in_brackets?
-    )?
+    : PIVOT LR_BRACKET id_ LR_BRACKET id_ RR_BRACKET FOR id_ IN LR_BRACKET pivot_in_clause RR_BRACKET default_on_null? RR_BRACKET (
+        as_alias column_alias_list_in_brackets?  )?
     | UNPIVOT LR_BRACKET id_ FOR column_name IN LR_BRACKET column_list RR_BRACKET RR_BRACKET
     ;
 
+pivot_in_clause
+    : literal (COMMA literal)*
+    | ANY order_by_clause?
+    | subquery
+    ;
+
+default_on_null
+    : DEFAULT ON NULL_ (expr)
+    ;
+
 column_alias_list_in_brackets
     : LR_BRACKET id_ (COMMA id_)* RR_BRACKET
     ;

sql/snowflake/examples/select.sql

@@ -155,4 +155,14 @@ show warehouses
 SELECT 0 as c
 ->> SELECT c FROM $1
 ->> SELECT c FROM $2
-->> SELECT c FROM $3;
+->> SELECT c FROM $3;
+
+SELECT * FROM t PIVOT(SUM(amount) FOR quarter IN (ANY ORDER BY c1 desc)) ORDER BY empid;
+SELECT * FROM t PIVOT(SUM(amount) FOR quarter IN (ANY));
+SELECT * FROM t PIVOT(SUM(amount) FOR quarter IN (
+      SELECT DISTINCT quarter
+        FROM t2
+        WHERE television = TRUE
+        ORDER BY quarter))
+  ORDER BY empid;
+  SELECT * FROM t PIVOT(SUM(amount) FOR quarter IN (ANY) DEFAULT ON NULL (IFF(c3 % 2 = 0 ,1,-1)));