1:- module(tidylog_number_decimal, [decimal//1]).    2
    3% Define Prolog decimal format
    4
    5:- use_module(library(tidylog/common), [ parsing//0
    6                                       , when_generating//1
    7                                       , when_parsing//1
    8                                       ]).    9
   10
   11decimal(N) -->
   12    parsing,
   13    !,
   14    ( "-", decimal_(M), { N is -M }
   15    ; decimal_(N)
   16    ).
   17decimal(N) -->
   18    % generating
   19    { integer(N) },
   20    ( { N < 0 }, "-", { M is -N }, decimal_(M)
   21    ; decimal_(N)
   22    ).
   23
   24% positive decimal integer
   25decimal_(N) -->
   26    when_generating(decimal_codes(N,[Code|Codes])),
   27
   28    digit(Code),
   29    digits(Codes),
   30
   31    when_parsing(decimal_codes(N,[Code|Codes])).
   32
   33
   34digit(C) -->
   35    [C],
   36    { between(0'0,0'9,C) }.
   37
   38
   39digits([Sep,Code|Codes]) -->
   40    separator(Sep),
   41    digit(Code),
   42    digits(Codes).
   43digits([Code|Codes]) -->
   44    digit(Code),
   45    digits(Codes).
   46digits([]) -->
   47    [].

 decimal_codes(?N:integer, ?Code:list) is det

True if integer N, in decimal notation, is represented as list of Codes. When generating Codes from N, underscore characters are inserted every 3 digits.

   55decimal_codes(N,Codes) :-
   56    integer(N),
   57    !,
   58    format(codes(Codes),"~3I",[N]).
   59decimal_codes(N,Codes) :-
   60    nonvar(Codes),
   61    name(N,Codes),
   62    integer(N).
   63
   64
   65separator(C) -->
   66    [C],
   67    { separator_char(C) }.
   68
   69
   70separator_char(0'_).
   71separator_char(0'\s)