Add support for Hive dialect GROUPING SETS. (#1539)

* Add support for Hive GROUPING SETS dialect `GROUP BY a, b, c GROUPING SETS ((a, b), (a, c))`

* Simplify HiveTest::testGroupByGroupingSets.

Author: qzchenwl

src/main/java/net/sf/jsqlparser/statement/select/GroupByElement.java

@@ -95,7 +95,14 @@ public String toString() {
             if (groupByExpressions.isUsingBrackets()) {
                 b.append(" )");
             }
-        } else if (groupingSets.size() > 0) {
+        } else if (groupByExpressions.isUsingBrackets()) {
+            b.append("()");
+        }
+
+        if (groupingSets.size() > 0) {
+            if (b.charAt(b.length() - 1) != ' ') {
+                b.append(' ');
+            }
             b.append("GROUPING SETS (");
             boolean first = true;
             for (Object o : groupingSets) {
@@ -112,10 +119,6 @@ public String toString() {
                 }
             }
             b.append(")");
-        } else {
-            if (groupByExpressions.isUsingBrackets()) {
-                b.append("()");
-            }
         }
 
         return b.toString();

src/main/java/net/sf/jsqlparser/util/deparser/GroupByDeParser.java

@@ -51,6 +51,9 @@ public void deParse(GroupByElement groupBy) {
             buffer.append(" )");
         }
         if (!groupBy.getGroupingSets().isEmpty()) {
+            if (buffer.charAt(buffer.length() - 1) != ' ') {
+                buffer.append(' ');
+            }
             buffer.append("GROUPING SETS (");
             boolean first = true;
             for (Object o : groupBy.getGroupingSets()) {

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -2747,6 +2747,19 @@ GroupByElement GroupByColumnReferences():
     <K_GROUP> <K_BY>
     (     LOOKAHEAD(2) (
               "(" ")" { groupBy.withUsingBrackets(true); }
+              (
+                LOOKAHEAD(2) (
+                  <K_GROUPING> <K_SETS> "("
+                      ( LOOKAHEAD(2) "(" ")" { groupBy.addGroupingSet(new ExpressionList()); }
+                          | LOOKAHEAD(3) "(" list = SimpleExpressionList(true) ")" { groupBy.addGroupingSet(list); }
+                          | expr = SimpleExpression() { groupBy.addGroupingSet(expr); } )
+
+                      ( "," ( LOOKAHEAD(2) "(" ")" { groupBy.addGroupingSet(new ExpressionList()); }
+                          | LOOKAHEAD(3) "(" list = SimpleExpressionList(true) ")" { groupBy.addGroupingSet(list); }
+                          | expr = SimpleExpression() { groupBy.addGroupingSet(expr); } ) )*
+                  ")"
+                )
+              )?
           )
           |
           LOOKAHEAD(2) ( 
@@ -2763,6 +2776,19 @@ GroupByElement GroupByColumnReferences():
           |
           LOOKAHEAD(2) (  
             list = ComplexExpressionList() { groupBy.setGroupByExpressionList(list.withUsingBrackets(false)); }
+            (
+              LOOKAHEAD(2) (
+                <K_GROUPING> <K_SETS> "("
+                    ( LOOKAHEAD(2) "(" ")" { groupBy.addGroupingSet(new ExpressionList()); }
+                        | LOOKAHEAD(3) "(" list = SimpleExpressionList(true) ")" { groupBy.addGroupingSet(list); }
+                        | expr = SimpleExpression() { groupBy.addGroupingSet(expr); } )
+
+                    ( "," ( LOOKAHEAD(2) "(" ")" { groupBy.addGroupingSet(new ExpressionList()); }
+                        | LOOKAHEAD(3) "(" list = SimpleExpressionList(true) ")" { groupBy.addGroupingSet(list); }
+                        | expr = SimpleExpression() { groupBy.addGroupingSet(expr); } ) )*
+                ")"
+              )
+            )?
           )
     )
     {

src/test/java/net/sf/jsqlparser/statement/select/HiveTest.java

@@ -46,4 +46,14 @@ public void testLeftSemiJoin() throws Exception {
 
         assertSqlCanBeParsedAndDeparsed(sql, true);
     }
+
+    @Test
+    public void testGroupByGroupingSets() throws Exception {
+        String sql = "SELECT\n"
+            + "    C1, C2, C3, MAX(Value)\n"
+            + "FROM\n"
+            + "    Sometable\n"
+            + "GROUP BY C1, C2, C3 GROUPING SETS ((C1, C2), (C1, C2, C3), ())";
+        assertSqlCanBeParsedAndDeparsed(sql, true);
+    }
 }