swi-prolog-nox 6.6.4-2ubuntu1 / usr / lib / swi-prolog / library / writef.pl

/*  $Id$

    Part of SWI-Prolog

    Author:        Jan Wielemaker
    E-mail:        J.Wielemaker@cs.vu.nl
    WWW:           http://www.swi-prolog.org
    Copyright (C): 1985-2011, 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 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(writef,
	  [ writef/1,			% +Format
	    writef/2,			% +Format, +Args
	    swritef/2,			% -String, +Format
	    swritef/3			% -String, +Format, +Args
	  ]).
:- set_prolog_flag(generate_debug_info, false).

/** <module> Old-style formatted write

This library provides writef/1 and   friends. These predicates originate
from Edinburgh C-Prolog and and provided for compatibility purposes. New
code should use format/1, format/2  and   friends,  which  are currently
supported by more Prolog implementations.

The   writef-family   of   predicates   conflicts    with   the   modern
_|character-esacapes|_ flag about  the   interpretation  of \-sequences.
This can be avoided by

  1. Disable character escapes (not recommended unless one wants to
  run really outdated code unmodified).
  2. Double the \ for conflicting interpretations
  3. Use ISO compliant alternatives for conflicting interpretations

@copyright	Copied from Edinburgh C-Prolog. Original version by Byrd,
		changed many times since.
*/

%%	writef(+Format) is det.
%%	writef(+Format, +Arguments) is det.
%
%	Formatted write to the  =current_output=.   Format  is  a format
%	specifier. Some escape sequences require  arguments that must be
%	provided in the list Arguments. There   are  two types of escape
%	sequences: special characters  start  with   =|\|=  and  include
%	arguments start with =|%|=. The special character sequences are:
%
%	    | =|\n|= | Output a newline character |
%	    | =|\l|= | Output a line separator (same as =|\n|=) |
%	    | =|\r|= | Output a carriage-return character (ASCII 13) |
%	    | =|\r|= | Output a TAB character (ASCII 9) |
%	    | =|\\|= | Output =|\|= |
%	    | =|\%|= | Output =|%|= |
%	    | =|\nnn|= | Output character <nnn>. <nnn> is a 1-3 decimal number |
%
%	Escape sequences to include arguments  from Arguments. Each time
%	a %-escape sequence is found in   Format  the next argument from
%	Arguments is formatted according to the specification.
%
%	    | =|%t|= | print/1 the next item (mnemonic: term) |
%	    | =|%w|= | write/1 the next item |
%	    | =|%q|= | writeq/1 the next item  |
%	    | =|%d|= | display/1 the next item |
%	    | =|%n|= | Put the next item as a character |
%	    | =|%r|= | Write the next item N times where N is the second item (an integer) |
%	    | =|%s|= | Write the next item as a String (so it must be a list of characters) |
%	    | =|%f|= |Perform a ttyflush/0 (no items used) |
%	    | =|%Nc|= | Write the next item Centered in N columns. |
%	    | =|%Nl|= | Write the next item Left justified in N columns. |
%	    | =|%Nr|= | Write the next item Right justified in N columns. |
%
%	@deprecated New code should use format/1, format/2, etc.

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

writef([F|String], List) :-
	'$writefs'([F|String], List),
	fail.				% clean up global stack
writef(String, List) :-
	string(String),
	string_codes(String, Fstring),
	'$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) is det.
%%	swritef(-String, +Format, +Arguments) is det.
%
%	Use writef/1 or writef/2 and  write   the  result to a _string_.
%	Note that this is a  string   in  the sense of string_codes/2,
%	_not_ a list of character(-code)s.
%
%	@deprecated.  See format/2,3 and/or with_output_to/2.

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) :-
	format(string(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'([]).