fix: #464 order by + expression

Author: liuxy0551

src/grammar/flink/FlinkSqlLexer.g4

@@ -171,6 +171,7 @@ KW_FILTER              : 'FILTER';
 KW_FIRST_VALUE         : 'FIRST_VALUE';
 KW_FLOAT               : 'FLOAT';
 KW_FLOOR               : 'FLOOR';
+KW_FOLLOWING           : 'FOLLOWING';
 KW_FOR                 : 'FOR';
 KW_FOREIGN             : 'FOREIGN';
 KW_FRAME_ROW           : 'FRAME_ROW';
@@ -428,6 +429,7 @@ KW_TRUNCATE            : 'TRUNCATE';
 KW_TRY_CAST            : 'TRY_CAST';
 KW_TUESDAY             : 'TUESDAY';
 KW_UESCAPE             : 'UESCAPE';
+KW_UNBOUNDED           : 'UNBOUNDED';
 KW_UNION               : 'UNION';
 KW_UNIQUE              : 'UNIQUE';
 KW_UNKNOWN             : 'UNKNOWN';

src/grammar/flink/FlinkSqlParser.g4

@@ -496,8 +496,8 @@ projectItemDefinition
     ;
 
 overWindowItem
-    : primaryExpression KW_OVER windowSpec KW_AS identifier
-    | primaryExpression KW_OVER errorCapturingIdentifier KW_AS identifier
+    : primaryExpression KW_OVER windowSpec (KW_AS identifier)?
+    | primaryExpression KW_OVER errorCapturingIdentifier (KW_AS identifier)?
     ;
 
 fromClause
@@ -644,7 +644,9 @@ orderByClause
     ;
 
 orderItemDefinition
-    : columnName ordering=(KW_ASC | KW_DESC)? (KW_NULLS nullOrder=(KW_LAST | KW_FIRST))?
+    : (columnName | valueExpression) ordering=(KW_ASC | KW_DESC)? (
+        KW_NULLS nullOrder=(KW_LAST | KW_FIRST)
+    )?
     ;
 
 limitClause
@@ -694,13 +696,26 @@ patternVariablesDefinition
 
 windowFrame
     : KW_RANGE KW_BETWEEN timeIntervalExpression frameBound
+    | (KW_ROWS | KW_RANGE) KW_BETWEEN frameStart KW_AND frameEnd
     | KW_ROWS KW_BETWEEN DIG_LITERAL frameBound
     ;
 
 frameBound
     : KW_PRECEDING KW_AND KW_CURRENT KW_ROW
     ;
 
+frameStart
+    : KW_UNBOUNDED KW_PRECEDING
+    | DIG_LITERAL KW_PRECEDING
+    | KW_CURRENT KW_ROW
+    ;
+
+frameEnd
+    : KW_CURRENT KW_ROW
+    | DIG_LITERAL KW_FOLLOWING
+    | KW_UNBOUNDED KW_FOLLOWING
+    ;
+
 withinClause
     : KW_WITHIN timeIntervalExpression
     ;