feat: Hex to Long conversion

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

src/main/java/net/sf/jsqlparser/expression/HexValue.java

@@ -46,4 +46,20 @@ public HexValue withValue(String value) {
     public String toString() {
         return value;
     }
+
+    public String getDigits() {
+        return value.toUpperCase().startsWith("0X")
+               ? value.substring(2)
+               : value.substring(2, value.length()-1);
+    }
+
+    public Long getLong() {
+        return Long.parseLong(
+                getDigits()
+                , 16);
+    }
+
+    public LongValue getLongValue() {
+        return new LongValue(getLong());
+    }
 }

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

@@ -0,0 +1,29 @@
+package net.sf.jsqlparser.expression;
+
+import net.sf.jsqlparser.JSQLParserException;
+import net.sf.jsqlparser.parser.CCJSqlParserUtil;
+import net.sf.jsqlparser.statement.select.PlainSelect;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class HexValueTest {
+
+    @Test
+    void testHexCode() throws JSQLParserException {
+        String sqlString = "SELECT 0xF001, X'00A1'";
+        PlainSelect select = (PlainSelect) CCJSqlParserUtil.parse(sqlString);
+
+        HexValue hex1 = (HexValue) select.getSelectItem(0).getExpression();
+        HexValue hex2 = (HexValue) select.getSelectItem(1).getExpression();
+
+        Assertions.assertEquals("F001", hex1.getDigits());
+        Assertions.assertEquals(61441, hex1.getLong());
+        Assertions.assertEquals(61441, hex1.getLongValue().getValue());
+
+        Assertions.assertEquals("00A1", hex2.getDigits());
+        Assertions.assertEquals(161, hex2.getLong());
+        Assertions.assertEquals(161, hex2.getLongValue().getValue());
+    }
+}