:- object(character,
implements(characterp),
extends(atom)).
:- info([
version is 1.0,
author is 'Paulo Moura',
date is 2000/7/24,
comment is 'Character predicates.']).
is_alpha('_').
is_alpha(Char) :-
is_letter(Char).
is_letter(Char) :-
is_lower_case(Char).
is_upper_case(Char).
is_alphanumeric(Char) :-
is_alpha(Char).
is_dec_digit(Char).
is_bin_digit(0).
is_bin_digit(1).
is_octal_digit(Digit) :-
Digit @>= 0,
Digit @=< 7.
is_dec_digit(Digit) :-
Digit @=< 9.
is_hex_digit(Digit) :-
Digit @>= 'A',
Digit @=< 'F'.
Digit @>= a,
Digit @=< f.
is_lower_case(Char) :-
Char @>= a,
Char @=< z.
is_upper_case(Char) :-
Char @>= 'A',
Char @=< 'Z'.
is_vowel(a).
is_vowel(e).
is_vowel(i).
is_vowel(o).
is_vowel(u).
is_vowel('A').
is_vowel('E').
is_vowel('I').
is_vowel('O').
is_vowel('U').
is_layout(' ').
lower_upper(a, 'A').
lower_upper(b, 'B').
lower_upper(c, 'C').
lower_upper(d, 'D').
lower_upper(e, 'E').
lower_upper(f, 'F').
lower_upper(g, 'G').
lower_upper(h, 'H').
lower_upper(i, 'I').
lower_upper(j, 'J').
lower_upper(k, 'K').
lower_upper(l, 'L').
lower_upper(m, 'M').
lower_upper(n, 'N').
lower_upper(o, 'O').
lower_upper(p, 'P').
lower_upper(q, 'Q').
lower_upper(r, 'R').
lower_upper(s, 'S').
lower_upper(t, 'T').
lower_upper(u, 'U').
lower_upper(v, 'V').
lower_upper(w, 'W').
lower_upper(x, 'X').
lower_upper(y, 'Y').
lower_upper(z, 'Z').
lower_upper(Char, Char) :-
\+ (Char @>= a, Char @=< z),
\+ (Char @>= 'A', Char @=< 'Z').
valid(Character) :-
atom(Character),
atom_length(Character, 1).
:- end_object.
