1/* $Id$ 2 3 Part of SWI-Prolog 4 5 Author: Jan Wielemaker 6 E-mail: jan@swi.psy.uva.nl 7 WWW: http://www.swi-prolog.org 8 Copyright (C): 1985-2004, University of Amsterdam 9 10 This program is free software; you can redistribute it and/or 11 modify it under the terms of the GNU General Public License 12 as published by the Free Software Foundation; either version 2 13 of the License, or (at your option) any later version. 14 15 This program is distributed in the hope that it will be useful, 16 but WITHOUT ANY WARRANTY; without even the implied warranty of 17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 18 GNU General Public License for more details. 19 20 You should have received a copy of the GNU Lesser General Public 21 License along with this library; if not, write to the Free Software 22 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 23 24 As a special exception, if you link this library with other files, 25 compiled with a Free Software compiler, to produce an executable, this 26 library does not by itself cause the resulting executable to be covered 27 by the GNU General Public License. This exception does not however 28 invalidate any other reasons why the executable file might be covered by 29 the GNU General Public License. 30*/ 31 32:- module(rdf_io, 33 [ write_table/2, % +Row, +Options 34 write_graph/2, % +Triples, +Options 35 get_triples/3 % +Input, -Triples, +Options 36 ]). 37:- use_module(library('semweb/rdf_db')). 38:- use_module(library(rdf_write)). 39:- use_module(library(rdf)). 40:- use_module(library(lists)). 41 42:- multifile 43 write_table/4, % +Format, +Serialization, +Rows, +Options 44 write_graph/4, % +Format, +Serialization, +Triples, +Options 45 get_triples/4. % +Format, +Input, -Triples, +Options 46 47/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 48This module acts as a dispatcher module, allowing other modules to add 49clauses for write_table/4 and write_graph/4 and thus providing 50additional output formats without modifications to the kernel source. 51- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
row(C1, C2, ...). Options specifies additional processing
options. Defined options are:
vars and atom-arguments describing the names
of each subsequent column. For Example:
variables(vars('Name', 'Address'))
The output hooks may support additional options.
82write_table(Rows, Options) :-
83 needed_option(result_format(Format), Options),
84 needed_option(serialization(Serialization), Options),
85 write_table(Format, Serialization, Rows, Options).rdf(S,P,O) triples.
Options:
101write_graph(Triples, Options) :- 102 needed_option(serialization(Serialization), Options), 103 ( Serialization == rdfxml 104 -> ( memberchk(result_format(Format), Options) 105 -> true 106 ; Format = xml 107 ) 108 ; option(result_format(Format), Options) 109 -> true 110 ; Format = Serialization 111 ), 112 write_graph(Format, Serialization, Triples, Options). 113 114 115 /******************************* 116 * READING * 117 *******************************/
124get_triples(Input, Triples, Options0) :-
125 select(data_format(Format), Options0, Options),
126 get_triples(Format, Input, Triples, Options).rdf(S,P,O) for a given
Format. The default implementation supports rdfxml by means of
load_rdf/3.134get_triples(rdfxml, Input, Triples, Options) :- !, 135 load_rdf(Input, Triples, Options). 136 137 138 /******************************* 139 * HOOK * 140 *******************************/
xml and Serialization = rdfxml. It uses
rdf_write_xml/2 to emit the graph.152write_graph(xml, rdfxml, Triples, Options) :- 153 option(mimetype(Type), Options, 'application/rdf+xml'), 154 format('Transfer-encoding: chunked~n'), 155 format('Content-type: Type; charset=UTF-8~n~n', [Type]), 156 rdf_write_xml(current_output, Triples). 157 158 159 /******************************* 160 * UTIL * 161 *******************************/ 162 163needed_option(Term, Options) :- 164 memberchk(Term, Options), !. 165needed_option(Term, _) :- 166 functor(Term, Name, _), 167 throw(error(existence_error(option, Name), _))