string manipulation utilities for scripts.

git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@2146 b08c6af1-5177-4d33-ba66-4b1c6b8b522a

library/stringutils.yap

@@ -0,0 +1,34 @@
+:- 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).
+