89 lines
2.7 KiB
Prolog
89 lines
2.7 KiB
Prolog
/* $Id$
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Part of SWI-Prolog
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Author: Jan Wielemaker
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E-mail: wielemak@science.uva.nl
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WWW: http://www.swi-prolog.org
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Copyright (C): 1985-2006, University of Amsterdam
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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As a special exception, if you link this library with other files,
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compiled with a Free Software compiler, to produce an executable, this
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library does not by itself cause the resulting executable to be covered
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by the GNU General Public License. This exception does not however
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invalidate any other reasons why the executable file might be covered by
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the GNU General Public License.
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*/
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:- module(zlib,
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[ zopen/3, % +Stream, -ZStream, +Option
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gzopen/3, % +File, +Mode, -Stream
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gzopen/4 % +File, +Mode, -Stream, +Options
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]).
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:- use_module(library(shlib)).
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:- use_module(library(error)).
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:- expects_dialect(swi).
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:- assert(system:swi_io).
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/** <module> Zlib wrapper for SWI-Prolog
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Read/write compressed data based on the zlib library.
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@author Jan Wielemaker
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@see http://www.zlib.net/
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@see http://www.swi-prolog.org/packages/zlib.html
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*/
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:- use_foreign_library(foreign(zlib4pl)).
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%% gzopen(+File, +Mode, -Stream) is det.
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%% gzopen(+File, +Mode, -Stream, +Options) is det.
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%
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% Open a file compatible with the gzip program. Note that if a
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% file is opened in =append= mode, a second gzip image will be
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% added to the end of the file.
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%
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% @tbd Later versions may actually append to an existing
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% compressed file.
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gzopen(File, Mode, Stream) :-
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gzopen(File, Mode, Stream, []).
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gzopen(File, Mode, Stream, Options) :-
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must_be(oneof([read,write,append]), Mode),
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zoptions(Options, ZOptions, OpenOptions),
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open(File, Mode, Stream0, OpenOptions),
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zopen(Stream0, Stream,
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[ format(gzip),
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close_parent(true)
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| ZOptions
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]).
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zoptions([], [], []).
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zoptions([H|T], [H|TZ], TO) :-
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zoption(H), !,
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zoptions(T, TZ, TO).
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zoptions([H|T], TZ, [H|TO]) :-
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zoptions(T, TZ, TO).
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zoption(format(_)).
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zoption(level(_)).
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:- retract(system:swi_io).
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