zlib

packages/zlib/zlib.pl

@@ -0,0 +1,88 @@
+/*  $Id$
+
+    Part of SWI-Prolog
+
+    Author:        Jan Wielemaker
+    E-mail:        wielemak@science.uva.nl
+    WWW:           http://www.swi-prolog.org
+    Copyright (C): 1985-2006, 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 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(zlib,
+	  [ zopen/3,			% +Stream, -ZStream, +Option
+	    gzopen/3,			% +File, +Mode, -Stream
+	    gzopen/4			% +File, +Mode, -Stream, +Options
+	  ]).
+:- use_module(library(shlib)).
+:- use_module(library(error)).
+
+:- expects_dialect(swi).
+:- assert(system:swi_io).
+
+
+/** <module> Zlib wrapper for SWI-Prolog
+
+Read/write compressed data based on the zlib library.
+
+@author Jan Wielemaker
+@see	http://www.zlib.net/
+@see	http://www.swi-prolog.org/packages/zlib.html
+*/
+
+:- use_foreign_library(foreign(zlib4pl)).
+
+%%	gzopen(+File, +Mode, -Stream) is det.
+%%	gzopen(+File, +Mode, -Stream, +Options) is det.
+%
+%	Open a file compatible with the  gzip   program.  Note that if a
+%	file is opened in =append= mode,  a   second  gzip image will be
+%	added to the end of the file.
+%
+%	@tbd	Later versions may actually append to an existing
+%		compressed file.
+
+gzopen(File, Mode, Stream) :-
+	gzopen(File, Mode, Stream, []).
+
+gzopen(File, Mode, Stream, Options) :-
+	must_be(oneof([read,write,append]), Mode),
+	zoptions(Options, ZOptions, OpenOptions),
+	open(File, Mode, Stream0, OpenOptions),
+	zopen(Stream0, Stream,
+	      [ format(gzip),
+		close_parent(true)
+	      | ZOptions
+	      ]).
+
+zoptions([], [], []).
+zoptions([H|T], [H|TZ], TO) :-
+	zoption(H), !,
+	zoptions(T, TZ, TO).
+zoptions([H|T], TZ, [H|TO]) :-
+	zoptions(T, TZ, TO).
+
+zoption(format(_)).
+zoption(level(_)).
+
+:- retract(system:swi_io).