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yap-6.3/library/stringutils.yap
2008-03-13 17:38:24 +00:00

35 lines
663 B
Prolog

:- module(string_utils,
[string/1,
upcase_string/2,
downcase_string/2,
string_length/2,
concat_strings/3
]).
:- use_module(library(lists),
[append/3]).
string([]).
string([A|Cs]) :-
integer(A),
A > 0, % no EOF allowed
A < 0x3ffffff, % UNICODE characters, strictly not yet required.
string(Cs).
upcase_string([], []).
upcase_string([C|Cs], [NC|NCs]) :-
code_type(C,to_lower(NC)),
upcase_string(Cs, NCs).
downcase_string([], []).
downcase_string([C|Cs], [NC|NCs]) :-
code_type(C,to_upper(NC)),
downcase_string(Cs, NCs).
string_length(S, Length) :-
length(S, Length).
concat_strings(S1, S2, New) :-
append(S1, S2, New).