-/* Old versions
-# define _rl_to_upper(c) (_rl_lowercase_p(c) ? ((c) - 32) : (c))
-# define _rl_to_lower(c) (_rl_uppercase_p(c) ? ((c) + 32) : (c))
-*/
+/* Some systems define these; we want our definitions. */
+#undef ISPRINT
+
+/* Beware: these only work with single-byte ASCII characters. */
+
+#define ISALNUM(c) (IN_CTYPE_DOMAIN (c) && isalnum (c))
+#define ISALPHA(c) (IN_CTYPE_DOMAIN (c) && isalpha (c))
+#define ISDIGIT(c) (IN_CTYPE_DOMAIN (c) && isdigit (c))
+#define ISLOWER(c) (IN_CTYPE_DOMAIN (c) && islower (c))
+#define ISPRINT(c) (IN_CTYPE_DOMAIN (c) && isprint (c))
+#define ISUPPER(c) (IN_CTYPE_DOMAIN (c) && isupper (c))
+#define ISXDIGIT(c) (IN_CTYPE_DOMAIN (c) && isxdigit (c))
+
+#define _rl_lowercase_p(c) (NON_NEGATIVE(c) && ISLOWER(c))
+#define _rl_uppercase_p(c) (NON_NEGATIVE(c) && ISUPPER(c))
+#define _rl_digit_p(c) ((c) >= '0' && (c) <= '9')
+
+#define _rl_pure_alphabetic(c) (NON_NEGATIVE(c) && ISALPHA(c))
+#define ALPHABETIC(c) (NON_NEGATIVE(c) && ISALNUM(c))