Allows CASE ... ELSE ComplexExpression (#1388)

Fixes #1375

Co-authored-by: Tobias <t.warneke@gmx.net>

Author: manticore-projects

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

@@ -4291,7 +4291,7 @@ Expression CaseWhenExpression() #CaseWhenExpression:
     [ switchExp=Condition() ]
     ( clause=WhenThenSearchCondition() { whenClauses.add(clause); } )+
     [<K_ELSE> (LOOKAHEAD( ["("] CaseWhenExpression() [")"] ( <K_WHEN> | <K_ELSE> | <K_END> ) ) ["("] elseExp=CaseWhenExpression() [")" { ((CaseExpression) elseExp).setUsingBrackets(true); } ] 
-              | elseExp=Condition()
+              | elseExp=Expression()
               )
     ]
     <K_END>  { caseCounter--; }
@@ -4323,21 +4323,6 @@ WhenClause WhenThenSearchCondition():
     }
 }
 
-/*WhenClause WhenThenValue():
-{
-    WhenClause whenThen = new WhenClause();
-    Expression whenExp = null;
-    Expression thenExp = null;
-}
-{
-    <K_WHEN> whenExp=SimpleExpression() <K_THEN> thenExp=SimpleExpression()
-    {
-       whenThen.setWhenExpression(whenExp);
-       whenThen.setThenExpression(thenExp);
-       return whenThen;
-    }
-}*/
-
 RowConstructor RowConstructor(): {
     RowConstructor rowConstructor = new RowConstructor();
     ColumnDefinition columnDefinition = null;

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

@@ -4891,6 +4891,11 @@ public void testCanCallSubSelectOnWithItemEvenIfNotSetIssue1369() {
     }
 
     @Test
+    public void testCaseElseExpressionIssue1375() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed(
+                "SELECT * FROM t1 WHERE CASE WHEN 1 = 1 THEN c1 = 'a' ELSE c2 = 'b' AND c4 = 'd' END", true);
+    }
+  
     public void testComplexInExpressionIssue905() throws JSQLParserException {
         assertSqlCanBeParsedAndDeparsed(
                 "select * " +