/* Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@vu.nl
WWW: http://www.swi-prolog.org
Copyright (C): 1985-2012, University of Amsterdam
VU University Amsterdam
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
As a special exception, if you link this library with other files,
compiled with a Free Software compiler, to produce an executable, this
library does not by itself cause the resulting executable to be covered
by the GNU General Public License. This exception does not however
invalidate any other reasons why the executable file might be covered by
the GNU General Public License.
*/
:- module(ctypes,
[ is_alnum/1,
is_alpha/1,
is_ascii/1,
is_cntrl/1,
is_csym/1,
is_csymf/1,
is_digit/1,
is_digit/3,
is_endfile/1,
is_endline/1,
is_graph/1,
is_lower/1,
is_newline/1,
is_newpage/1,
is_paren/2,
is_period/1,
is_print/1,
is_punct/1,
is_quote/1,
is_space/1,
is_upper/1,
is_white/1,
to_lower/2,
to_upper/2,
upper_lower/2
]).
/** <module> Character code classification
This file implements the functionality of the corresponding Quintus
library based on SWI-Prolog's code_type/2 predicate. Please check the
documentation of this predicate to find the definitions of the classes.
@see code_type/2
@see char_type/2
*/
is_alnum(C) :- code_type(C, alnum).
is_alpha(C) :- code_type(C, alpha).
is_ascii(C) :- code_type(C, ascii).
is_cntrl(C) :- code_type(C, cntrl).
is_csym(C) :- code_type(C, csym).
is_csymf(C) :- code_type(C, csymf).
is_digit(C) :- code_type(C, digit).
is_graph(C) :- code_type(C, graph).
is_lower(C) :- code_type(C, lower).
is_upper(C) :- code_type(C, upper).
is_period(C) :- code_type(C, period).
is_endline(C) :- code_type(C, end_of_line).
is_print(C) :- is_graph(C).
is_punct(C) :- code_type(C, punct).
is_quote(C) :- code_type(C, quote).
is_space(C) :- code_type(C, space).
is_white(C) :- code_type(C, white).
is_endfile(-1).
is_newpage(12). % Control-L
is_newline(10).
%% is_paren(?Open, ?Close) is semidet.
%
% True if Open is the open-parenthesis of Close.
is_paren(0'(, 0')). % Prolog is too good at this
is_paren(0'[, 0']).
is_paren(0'{, 0'}).
%% to_lower(+U, -L) is det.
%
% Downcase a character code. If U is the character code of an
% uppercase character, unify L with the character code of the
% lowercase version. Else unify L with U.
to_lower(U, L) :-
code_type(L, to_lower(U)).
%% to_upper(+L, -U) is det.
%
% Upcase a character code. If L is the character code of a
% lowercase character, unify L with the character code of the
% uppercase version. Else unify U with L.
to_upper(L, U) :-
code_type(U, to_upper(L)).
%% upper_lower(?U, ?L) is det.
%
% True when U is the character code of an uppercase character and
% L is the character code of the corresponding lowercase
% character.
upper_lower(Upper, Lower) :-
nonvar(Upper), !,
code_type(Lower, lower(Upper)).
upper_lower(Upper, Lower) :-
code_type(Upper, upper(Lower)).
%% is_digit(+C, +Base, -Weight) is det.
%% is_digit(-C, +Base, +Weight) is det.
%
% Succeeds if `C' is a digit using `Base' as base and `Weight'
% represents its value. Only the base-10 case is handled by code_type.
is_digit(C, Base, Weight) :-
Base == 10, !,
code_type(C, digit(Weight)).
is_digit(C, Base, Weight) :-
between(2, 36, Base),
succ(X, Base),
between(0, X, Weight),
is_digit(C, Weight).
is_digit(C, Weight) :-
Weight < 10, !,
plus(Weight, 0'0, C).
is_digit(C, Weight) :-
plus(Weight, 87, C), !. /* `a`-10 */
is_digit(C, Weight) :-
plus(Weight, 55, C). /* `A`-10 */