swi-prolog-nox 5.10.4-3ubuntu1 / usr / lib / swi-prolog / boot / writef.pl

/*  $Id$

    Part of SWI-Prolog

    Author:        Jan Wielemaker
    E-mail:        jan@swi.psy.uva.nl
    WWW:           http://www.swi-prolog.org
    Copyright (C): 1985-2002, University of 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  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('$writef',
	  [ writeln/1
	  , writef/1
	  , writef/2
	  , swritef/2
	  , swritef/3
	  ]).

%   Copied from Edinburgh C-Prolog. Original version by Byrd, changed
%   many times since then.
%
%   Changes for version 1.3.0:
%
%	- Format can be of type string.
%	- Adjustment now allowed for arbitrary types.
%	- Uses more appropriate SWI-Prolog built-in predicates.
%	- Uses 0'<letter> to specify ascii values (more readable).
%
%   Changes for version 4.1.1
%
%	- renamed write_ln(X) into writeln(X) for better compatibility
%	- Fixed fileheader

writeln(X) :-
	write(X), nl.

writef(Format) :-
	writef(Format, []).

writef([F|String], List) :-
	'$writefs'([F|String], List),
	fail.				% clean up global stack
writef(String, List) :-
	string(String),
	string_to_list(String, Fstring),
	'$writefs'(Fstring, List),
	fail.				% clean up global stack
writef(Format, List) :-
	atom(Format),
	name(Format, Fstring),
	'$writefs'(Fstring, List),
	fail.				% clean up global stack
writef(_, _).

swritef(String, Format, Arguments) :-
	with_output_to(string(String), writef(Format, Arguments)).
swritef(String, Format) :-
	with_output_to(string(String), writef(Format)).

			% Formatted write for a string (i.e. a list of
			% character codes).

'$writefs'([], _).
'$writefs'([0'%, A|Rest], List) :-	%   %<$action'>
	'$action'(A, List, More), !,
	'$writefs'(Rest, More).
'$writefs'([0'%, D|Rest], [Head|Tail]) :-	%   %<columns><just>
	between(0'0, 0'9, D),
	'$getpad'(Size, Just, [D|Rest], More),  !,
	'$padout'(Head, Size, Just),
	'$writefs'(More, Tail).
'$writefs'([0'\\, C|Rest], List) :-	%   \<special>
	'$special'(C, Char), !,
	put(Char),
	'$writefs'(Rest, List).
'$writefs'([0'\\|Rest], List) :-	%   \<character code in decimal>
	'$getcode'(Char, Rest, More), !,
	put(Char),
	'$writefs'(More, List).
'$writefs'([Char|Rest], List) :-	%   <ordinary character>
	put(Char),
	'$writefs'(Rest, List).


'$action'(0't, [Head|Tail], Tail) :-	%   Term
	print(Head).
'$action'(0'd, [Head|Tail], Tail) :-	%   Display
	write_canonical(Head).
'$action'(0'w, [Head|Tail], Tail) :-	%   Write
	write(Head).
'$action'(0'q, [Head|Tail], Tail) :-	%   Quoted
	writeq(Head).
'$action'(0'p,  [Head|Tail], Tail) :-	%   Print
	print(Head).
'$action'(0'f, List, List) :-		%   Flush
	ttyflush.
'$action'(0'n, [Char|Tail], Tail) :-	%   iNteger (character)
	put(Char).
'$action'(0'r, [Thing, Times|Tail], Tail) :-	%   Repeatedly
	'$writelots'(Times, Thing).
'$action'(0's, [Head|Tail], Tail) :-	%   String
	'$padout'(Head).

'$special'(0'n, 10).		/*  n  */
'$special'(0'l, 10).		/*  l  */
'$special'(0'r, 10).		/*  r  */
'$special'(0't,  9).		/*  t  */
'$special'(0'\\, 0'\\).		/*  \  */
'$special'(0'%, 0'%).		/*  %  */

'$getcode'(Char, In, Out) :-
	'$getdigits'(3, Digits, In, Out),
	Digits = [_|_],
	name(Char, Digits),
	Char < 128.

'$getdigits'(Limit, [Digit|Digits], [Digit|Out0], Out) :-
	Limit > 0,
	between(0'0, 0'9, Digit),
	Fewer is Limit - 1, !,
	'$getdigits'(Fewer, Digits, Out0, Out).
'$getdigits'(_, [], Out, Out).

'$writelots'(N, T) :-
	N > 0, !,
	write(T),
	M is N - 1,
	'$writelots'(M, T).
'$writelots'(_, _).

/*  The new formats are %nC, %nL, and %nR for centered, left, and right
    justified output of atoms, integers, and strings.  This is meant to
    simplify the production of tabular output when it is appropriate.
    At least one space will always precede/follow the item written.
*/

'$getpad'(Size, Just, In, Out) :-
	'$getdigits'(3, Digits, In, [Out1|Out]),
	name(Size, Digits),
	'$getpad'(Out1, Just).

'$getpad'(0'r, r).		%  right justified
'$getpad'(0'l, l).		%  left justified
'$getpad'(0'c, c).		%  centered
'$getpad'(0'R, r).		%  right justified
'$getpad'(0'L, l).		%  left justified
'$getpad'(0'C, c).		%  centered


				%   '$padout'(A, S, J) writes the item A in a
				%   field of S or more characters, Justified.

'$padout'(String, Size, Just) :-
	'$string'(String), !,
	name(Atom, String),
	'$padout'(Atom, Size, Just).
'$padout'(Term, Size, Just) :-
	term_to_atom(Term, Atom),
	atom_length(Atom, Length),
	'$padout'(Just, Size, Length, Left, Right),
	tab(Left),
	write(Atom),
	tab(Right).

'$string'(0) :- !, fail.
'$string'([]) :- !.
'$string'([H|T]) :-
	'$print'(H), !,
	'$string'(T).

'$print'(10).			% newline
'$print'(9).			% tab
'$print'(X) :-
	integer(X),
	between(32, 0'~, X).


				%   '$padout'(Just, Size, Length, Left, Right)
				%   calculates the number of spaces to put
				%   on the Left and Right of an item needing
				%   Length characters in a field of Size.

'$padout'(l, Size, Length, 0, Right) :- !,
	Right is max(1, Size-Length).
'$padout'(r, Size, Length, Left, 0) :- !,
	Left is max(1, Size-Length).
'$padout'(c, Size, Length, Left, Right) :-
	Left is max(1, round((Size - Length)/2)),
	Right is max(1, Size - Length - Left).

				%   '$padout'(Str) writes a string.

'$padout'([Head|Tail]) :- !,
	put(Head),
	'$padout'(Tail).
'$padout'([]).