feat: Nested WithItem allows FromQuery

- fixes #2168

Signed-off-by: Andreas Reichel <andreas@manticore-projects.com>

Author: manticore-projects

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

@@ -2316,6 +2316,13 @@ Select Select() #Select:
 }
 {
     (
+
+        //@todo: avoid this expensive semantic look ahead
+        LOOKAHEAD( [ WithList() ] FromQuery()) (
+            [ with=WithList() ]
+            select = FromQuery()
+        )
+        |
         (
             [ with=WithList() ]
             (
@@ -2335,8 +2342,6 @@ Select Select() #Select:
             [ LOOKAHEAD(<K_FETCH>) fetch = Fetch() { select.setFetch(fetch);} ]
             [ LOOKAHEAD(<K_WITH> <K_ISOLATION>) withIsolation = WithIsolation() { select.setIsolation(withIsolation);} ]
         )
-        |
-        select = FromQuery()
     )
     {
         linkAST(select, jjtThis);
@@ -3166,7 +3171,8 @@ List<WithItem<?>> WithList():
     WithItem with = null;
 }
 {
-    <K_WITH> with=WithItem() { withItemsList.add(with); } ("," with=WithItem() { withItemsList.add(with); } )*
+    <K_WITH> with=WithItem() { withItemsList.add(with); }
+    ( LOOKAHEAD(3) "," with=WithItem() { withItemsList.add(with); } )*
 
      { return withItemsList; }
 }

src/test/java/net/sf/jsqlparser/statement/piped/FromQueryTest.java

@@ -231,4 +231,17 @@ void testParseAndDeparseIssue74() throws JSQLParserException {
         // formatter:on
         TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr, true);
     }
+
+    @Test
+    void testParseAndDeparseNestedWithIssue2168() throws JSQLParserException {
+        // formatter:off
+        String sqlStr =
+                "with b as (\n" +
+                        "    with a as (select 1)\n" +
+                        "    from a )\n" +
+                        "from b\n" +
+                        ";";
+        // formatter:on
+        TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr, true);
+    }
 }