fix: stop 0x hex literal from swallowing trailing whitespace (#2435)

HEX_VALUE included a space character, so the "0x" hex literal form
greedily consumed trailing whitespace and any adjacent hex letters
(e.g. the "F" of FROM). Consequently `SELECT 0xFF FROM t` failed with
"Encountered <S_IDENTIFIER> t", while `SELECT 0xFF,1 FROM t` (comma,
no space) parsed fine.

The space is only required by the X'..' form, which deliberately allows
internal whitespace (e.g. X'01 bc 2a', covered by StringValueTest).
Split the shared token: X'..' keeps HEX_VALUE (with space), while the
0x.. form uses a new space-less HEX_DIGIT token.

Signed-off-by: 付典 <fudianchn@gmail.com>

Author: fudianchn

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

@@ -1601,8 +1601,9 @@ TOKEN : /* Numeric Constants */
             )>
   |     < S_LONG: ( <DIGIT> )+ >
   |     < #DIGIT: ["0" - "9"] >
-  |     < S_HEX: ("X" ("'" ( <HEX_VALUE> )* "'" (" ")*)+ | "0x" ( <HEX_VALUE> )+ ) >
+  |     < S_HEX: ("X" ("'" ( <HEX_VALUE> )* "'" (" ")*)+ | "0x" ( <HEX_DIGIT> )+ ) >
   |     < #HEX_VALUE: ["0"-"9","A"-"F", " "]  >
+  |     < #HEX_DIGIT: ["0"-"9","A"-"F"]  >
 }
 
 SPECIAL_TOKEN:

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

@@ -39,4 +39,23 @@ void testHexCode() throws JSQLParserException {
 
         Assertions.assertEquals("'\\xC3\\xBC'", hex3.getBlob().toString());
     }
+
+    @Test
+    void testHexLiteralFollowedByPrimaryKeyword() throws JSQLParserException {
+        // Issue #2435: a "0x"-prefixed hex literal must not greedily consume the
+        // following whitespace nor adjacent hex letters (e.g. the "F" of FROM),
+        // which previously made "SELECT 0xFF FROM t" fail to parse.
+        assertHexSelectItem("SELECT 0xFF FROM t", "FF");
+        assertHexSelectItem("SELECT 0xff FROM t", "ff");
+        assertHexSelectItem("SELECT 0xDEADBEEF FROM t", "DEADBEEF");
+        assertHexSelectItem("SELECT 0xab FROM dual", "ab");
+    }
+
+    private static void assertHexSelectItem(String sql, String expectedDigits)
+            throws JSQLParserException {
+        PlainSelect select = (PlainSelect) CCJSqlParserUtil.parse(sql);
+        Expression expr = select.getSelectItem(0).getExpression();
+        Assertions.assertTrue(expr instanceof HexValue, () -> "Expected HexValue for: " + sql);
+        Assertions.assertEquals(expectedDigits, ((HexValue) expr).getDigits());
+    }
 }