1/*  Part of SWI-Prolog
   2
   3    Author:        Jan Wielemaker
   4    E-mail:        J.Wielemaker@vu.nl
   5    WWW:           http://www.swi-prolog.org
   6    Copyright (c)  1985-2012, University of Amsterdam
   7                              VU University Amsterdam
   8    All rights reserved.
   9
  10    Redistribution and use in source and binary forms, with or without
  11    modification, are permitted provided that the following conditions
  12    are met:
  13
  14    1. Redistributions of source code must retain the above copyright
  15       notice, this list of conditions and the following disclaimer.
  16
  17    2. Redistributions in binary form must reproduce the above copyright
  18       notice, this list of conditions and the following disclaimer in
  19       the documentation and/or other materials provided with the
  20       distribution.
  21
  22    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  23    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  24    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  25    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  26    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  27    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  28    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  29    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  30    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  32    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  33    POSSIBILITY OF SUCH DAMAGE.
  34*/
  35
  36:- module(ctypes,
  37          [ is_alnum/1,
  38            is_alpha/1,
  39            is_ascii/1,
  40            is_cntrl/1,
  41            is_csym/1,
  42            is_csymf/1,
  43            is_digit/1,
  44            is_digit/3,
  45            is_endfile/1,
  46            is_endline/1,
  47            is_graph/1,
  48            is_lower/1,
  49            is_newline/1,
  50            is_newpage/1,
  51            is_paren/2,
  52            is_period/1,
  53            is_print/1,
  54            is_punct/1,
  55            is_quote/1,
  56            is_space/1,
  57            is_upper/1,
  58            is_white/1,
  59            to_lower/2,
  60            to_upper/2,
  61            upper_lower/2
  62          ]).
  63
  64/** <module> Character code classification
  65
  66This file implements the functionality of the corresponding Quintus
  67library based on SWI-Prolog's code_type/2 predicate. Please check the
  68documentation of this predicate to find the definitions of the classes.
  69
  70@see    code_type/2
  71@see    char_type/2
  72*/
  73
  74is_alnum(C)   :- code_type(C, alnum).
  75is_alpha(C)   :- code_type(C, alpha).
  76is_ascii(C)   :- code_type(C, ascii).
  77is_cntrl(C)   :- code_type(C, cntrl).
  78is_csym(C)    :- code_type(C, csym).
  79is_csymf(C)   :- code_type(C, csymf).
  80is_digit(C)   :- code_type(C, digit).
  81is_graph(C)   :- code_type(C, graph).
  82is_lower(C)   :- code_type(C, lower).
  83is_upper(C)   :- code_type(C, upper).
  84is_period(C)  :- code_type(C, period).
  85is_endline(C) :- code_type(C, end_of_line).
  86is_print(C)   :- is_graph(C).
  87is_punct(C)   :- code_type(C, punct).
  88is_quote(C)   :- code_type(C, quote).
  89is_space(C)   :- code_type(C, space).
  90is_white(C)   :- code_type(C, white).
  91
  92is_endfile(-1).
  93is_newpage(12).                         % Control-L
  94is_newline(10).
  95
  96%!  is_paren(?Open, ?Close) is semidet.
  97%
  98%   True if Open is the open-parenthesis of Close.
  99
 100is_paren(0'(, 0')).                     % Prolog is too good at this
 101is_paren(0'[, 0']).
 102is_paren(0'{, 0'}).
 103
 104%!  to_lower(+U, -L) is det.
 105%
 106%   Downcase a character code. If U  is   the  character  code of an
 107%   uppercase character, unify L with  the   character  code  of the
 108%   lowercase version. Else unify L with U.
 109
 110to_lower(U, L) :-
 111    code_type(L, to_lower(U)).
 112
 113%!  to_upper(+L, -U) is det.
 114%
 115%   Upcase a character code.  If  L  is   the  character  code  of a
 116%   lowercase character, unify L with  the   character  code  of the
 117%   uppercase version. Else unify U with L.
 118
 119to_upper(L, U) :-
 120    code_type(U, to_upper(L)).
 121
 122%!  upper_lower(?U, ?L) is det.
 123%
 124%   True when U is the character code  of an uppercase character and
 125%   L  is  the  character  code    of  the  corresponding  lowercase
 126%   character.
 127
 128upper_lower(Upper, Lower) :-
 129    nonvar(Upper),
 130    !,
 131    code_type(Lower, lower(Upper)).
 132upper_lower(Upper, Lower) :-
 133    code_type(Upper, upper(Lower)).
 134
 135
 136%!  is_digit(+C, +Base, -Weight) is det.
 137%!  is_digit(-C, +Base, +Weight) is det.
 138%
 139%   Succeeds if `C' is a digit using `Base'  as  base  and  `Weight'
 140%   represents its value.  Only the base-10 case is handled by code_type.
 141
 142is_digit(C, Base, Weight) :-
 143    Base == 10,
 144    !,
 145    code_type(C, digit(Weight)).
 146is_digit(C, Base, Weight) :-
 147    between(2, 36, Base),
 148    succ(X, Base),
 149    between(0, X, Weight),
 150    is_digit(C, Weight).
 151
 152is_digit(C, Weight) :-
 153    Weight < 10,
 154    !,
 155    plus(Weight, 0'0, C).
 156is_digit(C, Weight) :-
 157    plus(Weight, 87, C),
 158    !.         /* `a`-10 */
 159is_digit(C, Weight) :-
 160    plus(Weight, 55, C).            /* `A`-10 */