fix: parse a bracketed operand at the start of a PARTITION BY list (#2878)

`SELECT SUM(x) OVER (PARTITION BY (1 + a) / 2) FROM t` failed with a
ParseException at the `/`. The four PARTITION BY sites chose between
`LOOKAHEAD(3) ComplexExpressionList()` and a bracketed list
`"(" ComplexExpressionList() ")"`. The probe scans into `Expression()`,
whose binary operators live in a Java loop the scan cannot see, so it
failed on `( 1 +`, the bracketed alternative won, parsed `(1 + a)` as the
whole list and then met `/`.

The bracketed alternative only won when the probe failed, and the parse
then failed too, so dropping it changes nothing that parsed before. All
four sites now call `ComplexExpressionList()` directly.

Author: knutwannheden

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

@@ -9477,7 +9477,6 @@ PlainSelect PlainSelect() #PlainSelect:
     OracleHierarchicalExpression oracleHierarchicalQueryClause = null;
     PreferringClause preferringClause = null;
     ExpressionList expressionList = null;
-    boolean partitionByBrackets = false;
     List<Table> intoTables = null;
     MySqlSelectIntoClause mySqlSelectIntoClause = null;
     MySqlProcedureAnalyse mySqlProcedureAnalyse = null;
@@ -9583,13 +9582,9 @@ PlainSelect PlainSelect() #PlainSelect:
     [ LOOKAHEAD(2) oracleHierarchicalQueryClause=OracleHierarchicalQueryClause() { plainSelect.setOracleHierarchical(oracleHierarchicalQueryClause); } ]
     [ LOOKAHEAD(2) preferringClause=PreferringClause() { plainSelect.setPreferringClause(preferringClause); }
         [LOOKAHEAD(2) <K_PARTITION> <K_BY>
-            (
-                LOOKAHEAD(2) expressionList=ComplexExpressionList()
-                |
-                "(" {partitionByBrackets = true;} expressionList=ComplexExpressionList() ")"
-            )
+            expressionList=ComplexExpressionList()
             {
-                preferringClause.setPartitionExpressionList(expressionList, partitionByBrackets);
+                preferringClause.setPartitionExpressionList(expressionList, false);
             }
         ]
     ]
@@ -14467,7 +14462,6 @@ JsonAggregateFunction JsonAggregateFunction() : {
     ExpressionList expressionList = null;
     List<OrderByElement> olist = null;
     WindowElement windowElement = null;
-    boolean partitionByBrackets = false;
 }
 {
     (
@@ -14554,13 +14548,12 @@ JsonAggregateFunction JsonAggregateFunction() : {
             <K_OVER> {result.setAnalyticType(AnalyticType.OVER);}
             "("
             [<K_PARTITION> <K_BY>
-                (LOOKAHEAD(3) expressionList=ComplexExpressionList()
-                | "(" {partitionByBrackets = true;} expressionList=ComplexExpressionList() ")" )
+                expressionList=ComplexExpressionList()
             ]
             [olist=OrderByElements() ]
             [windowElement = WindowElement() ]
             {
-                result.setPartitionExpressionList(expressionList, partitionByBrackets);
+                result.setPartitionExpressionList(expressionList, false);
                 result.setOrderByElements(olist);
                 result.setWindowElement(windowElement);
             }
@@ -14702,7 +14695,6 @@ KeepExpression KeepExpression() : {
 
 void windowFun(AnalyticExpression retval):{
      ExpressionList expressionList = null;
-     boolean partitionByBrackets = false;
      String windowName = null;
      WindowDefinition winDef;
 } {
@@ -14726,10 +14718,9 @@ void windowFun(AnalyticExpression retval):{
         [
             LOOKAHEAD(2) <K_OVER> "("
             [   <K_PARTITION> <K_BY>
-                    (LOOKAHEAD(3) expressionList=ComplexExpressionList()
-                    | "(" {partitionByBrackets = true;} expressionList=ComplexExpressionList() ")" )
+                    expressionList=ComplexExpressionList()
             ]
-            ")" { winDef.setPartitionExpressionList(expressionList, partitionByBrackets); retval.setType(AnalyticType.WITHIN_GROUP_OVER); }
+            ")" { winDef.setPartitionExpressionList(expressionList, false); retval.setType(AnalyticType.WITHIN_GROUP_OVER); }
         ]
     )
 }
@@ -14738,7 +14729,6 @@ WindowDefinition windowDefinition() : {
     ExpressionList expressionList = null;
     List<OrderByElement> olist = null;
     WindowElement windowElement = null;
-    boolean partitionByBrackets = false;
     WindowDefinition winDef = new WindowDefinition();
     String baseWindowName;
 } {
@@ -14752,13 +14742,12 @@ WindowDefinition windowDefinition() : {
         {}
     )
     [<K_PARTITION> <K_BY>
-        (LOOKAHEAD(3) expressionList=ComplexExpressionList()
-        | "(" {partitionByBrackets = true;} expressionList=ComplexExpressionList() ")" )
+        expressionList=ComplexExpressionList()
     ]
     [olist=OrderByElements() ]
     [windowElement = WindowElement() ]
     {
-        winDef.setPartitionExpressionList(expressionList, partitionByBrackets);
+        winDef.setPartitionExpressionList(expressionList, false);
         winDef.setOrderByElements(olist);
         winDef.setWindowElement(windowElement);
     }

src/test/java/net/sf/jsqlparser/expression/AnalyticExpressionTest.java

@@ -43,4 +43,23 @@ void testDatabricks() throws JSQLParserException {
 
         TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr, true);
     }
+
+    @Test
+    void testPartitionByBracketedOperand() throws JSQLParserException {
+        TestUtils.assertSqlCanBeParsedAndDeparsed(
+                "SELECT SUM(x) OVER (PARTITION BY (1 + a) / 2 ORDER BY b) FROM t", true);
+
+        TestUtils.assertSqlCanBeParsedAndDeparsed(
+                "SELECT SUM(x) OVER w FROM t WINDOW w AS (PARTITION BY (1 + a) / 2)", true);
+
+        TestUtils.assertSqlCanBeParsedAndDeparsed(
+                "SELECT LISTAGG(x, ',') WITHIN GROUP (ORDER BY y) OVER (PARTITION BY (1 + a) / 2) FROM t",
+                true);
+
+        TestUtils.assertSqlCanBeParsedAndDeparsed(
+                "SELECT * FROM t PREFERRING HIGH x PARTITION BY (1 + a) / 2", true);
+
+        TestUtils.assertSqlCanBeParsedAndDeparsed(
+                "SELECT SUM(x) OVER (PARTITION BY (a, b), c) FROM t", true);
+    }
 }