code: private static boolean isSyntaxChar(int c) {
          return 0x21 <= c && c <= 0x7e &&
                  (c <= 0x2f || (0x3a <= c && c <= 0x40) ||
                  (0x5b <= c && c <= 0x60) || (0x7b <= c));
      }
docs: ASCII [:P:] and [:S:]:
  [\u0021-\u002F \u003A-\u0040 \u005B-\u0060 \u007B-\u007E]