/* $Id$ 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). /** 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 Disable character escapes (not recommended unless one wants to run really outdated code unmodified). 2.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 . 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). '$writefs'([0'%, D|Rest], [Head|Tail]) :- % % between(0'0, 0'9, D), '$getpad'(Size, Just, [D|Rest], More), !, '$padout'(Head, Size, Just), '$writefs'(More, Tail). '$writefs'([0'\\, C|Rest], List) :- % \ '$special'(C, Char), !, put(Char), '$writefs'(Rest, List). '$writefs'([0'\\|Rest], List) :- % \ '$getcode'(Char, Rest, More), !, put(Char), '$writefs'(More, List). '$writefs'([Char|Rest], List) :- % put(Char), '$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'([]).