1/*  Part of ClioPatria
    2
    3    Author:        Jan Wielemaker
    4    E-mail:        J.Wielemaker@vu.nl
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (c)  2013-2018, VU University Amsterdam
    7    All rights reserved.
    8
    9    Redistribution and use in source and binary forms, with or without
   10    modification, are permitted provided that the following conditions
   11    are met:
   12
   13    1. Redistributions of source code must retain the above copyright
   14       notice, this list of conditions and the following disclaimer.
   15
   16    2. Redistributions in binary form must reproduce the above copyright
   17       notice, this list of conditions and the following disclaimer in
   18       the documentation and/or other materials provided with the
   19       distribution.
   20
   21    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   22    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   23    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   24    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   25    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   26    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   27    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   28    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   29    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   31    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   32    POSSIBILITY OF SUCH DAMAGE.
   33*/
   34
   35:- module(sparql_csv_result,
   36          [ sparql_write_csv_result/3   % +Out, +Result, +Options
   37          ]).   38:- use_module(library(csv)).   39:- use_module(library(assoc)).   40:- use_module(library(option)).   41:- use_module(library(sgml_write)).   42:- use_module(library(semweb/rdf_db)).   43:- if(exists_source(library(semweb/rdf11))).   44:- use_module(library(semweb/rdf11),
   45              [ rdf_lexical_form/2
   46              ]).   47:- endif.

   54sparql_csv_mime_type('text/tab-separated-values; charset=UTF-8').

 sparql_write_csv_result(+Out:stream, +Result, +Options) is det

Emit results from a SPARQL SELECT query as CSV. Options:

bnode_state(State0-State)

Maintain blank node mapping accross multiple calls. State0 is either a variable or a state returned by a previous call.

http_header(+Boolean)

if true (default), emit an HTTP Content-type header.

header_row(+Boolean)

if true (default), emit header row with binding names.

See also

- http://www.w3.org/TR/rdf-sparql-json-res/

   70sparql_write_csv_result(Out, select(VarTerm, Rows), Options) :-
   71    !,
   72    option(bnode_state(BNodes0-BNodes), Options, _),
   73    (   var(BNodes0)
   74    ->  empty_assoc(BNodeDict),
   75        BNodes0 = bnode(1, BNodeDict)
   76    ;   true
   77    ),
   78    rows_to_csv(Rows, CSVRows, BNodes0, BNodes),
   79    (   option(http_header(true), Options, true)
   80    ->  sparql_csv_mime_type(ContentType),
   81        format('Content-type: ~w~n~n', [ContentType])
   82    ;   true
   83    ),
   84    (   option(header_row(true), Options, true)
   85    ->  csv_write_stream(Out, [VarTerm|CSVRows], [])
   86    ;   csv_write_stream(Out, CSVRows, [])
   87    ).
   88sparql_write_csv_result(_Out, Result, _Options) :-
   89    !,
   90    domain_error(csv_sparql_result, Result).
   91
   92rows_to_csv([], [], BNodeDict, BNodeDict).
   93rows_to_csv([H0|T0], [H|T], BNodeDict0, BNodeDict) :-
   94    row_to_csv(H0, H, BNodeDict0, BNodeDict1),
   95    rows_to_csv(T0, T, BNodeDict1, BNodeDict).
   96
   97row_to_csv(RDF, CSV, BNodeDict0, BNodeDict) :-
   98    RDF =.. [_|RDFFields],
   99    fields_to_csv(RDFFields, CSVFields, BNodeDict0, BNodeDict),
  100    CSV =.. [row|CSVFields].
  101
  102fields_to_csv([], [], BNodeDict, BNodeDict).
  103fields_to_csv([H0|T0], [H|T], BNodeDict0, BNodeDict) :-
  104    field_to_csv(H0, H, BNodeDict0, BNodeDict1),
  105    fields_to_csv(T0, T, BNodeDict1, BNodeDict).
  106
  107field_to_csv(Var, '', BNodeDict, BNodeDict) :-
  108    (   var(Var)
  109    ->  true
  110    ;   Var == '$null$'
  111    ),
  112    !.
  113field_to_csv(literal(Literal), Text, BNodeDict, BNodeDict) :-
  114    literal_text(Literal, Text),
  115    !.
  116field_to_csv(@(LangString,Lang), Text, BNodeDict, BNodeDict) :-
  117    literal_text(@(LangString,Lang), Text),
  118    !.
  119field_to_csv(^^(Lexical,Type), Text, BNodeDict, BNodeDict) :-
  120    literal_text(^^(Lexical,Type), Text),
  121    !.
  122field_to_csv(Resource, BNode, BNodeDict0, BNodeDict) :-
  123    rdf_is_bnode(Resource),
  124    !,
  125    BNodeDict0 = bnode(N0, Dict0),
  126    (   get_assoc(Resource, Dict0, BNode)
  127    ->  BNodeDict = BNodeDict0
  128    ;   succ(N0, N),
  129        atomic_list_concat(['_:node', N], BNode),
  130        put_assoc(Resource, Dict0, BNode, Dict),
  131        BNodeDict = bnode(N, Dict)
  132    ).
  133field_to_csv(Atomic, Atomic, BNodeDict, BNodeDict) :-
  134    atomic(Atomic),
  135    !.
  136field_to_csv(Term, String, BNodeDict, BNodeDict) :-
  137    term_string(Term, String).

 literal_text(+Literal, -Value) is semidet

  141literal_text(type(Type, Value), Text) :-
  142    !,
  143    atom(Type),
  144    (   rdf_equal(Type, rdf:'XMLLiteral')
  145    ->  with_output_to(string(Text),
  146                       xml_write(Value, [header(false)]))
  147    ;   atomic(Value)
  148    ->  Text = Value
  149    ;   term_string(Value, Text)
  150    ).
  151literal_text(lang(Lang, LangText), Text) :-
  152    !,
  153    atom(Lang),
  154    literal_text(LangText, Text).
  155literal_text(@(LangText, Lang), Text) :-
  156    !,
  157    atom(Lang),
  158    literal_text(LangText, Text).
  159:- if(current_predicate(rdf_lexical_form/2)).  160literal_text(^^(Lexical, Type), Text) :-
  161    !,
  162    rdf_lexical_form(^^(Lexical,Type), ^^(Text,_)).
  163:- endif.  164literal_text(Text, Text) :-
  165    atom(Text),
  166    !.
  167literal_text(Text, Text) :-
  168    string(Text),
  169    !.
  170
  171
  172                 /*******************************
  173                 *   INTERACTIVE QUERY RESULT   *
  174                 *******************************/
  175
  176:- multifile
  177    rdf_io:write_table/4.  178
  179rdf_io:write_table(csv, _, Rows, Options) :-
  180    memberchk(variables(Vars), Options),
  181    !,
  182    (   is_list(Vars)
  183    ->  VarTerm =.. [vars|Vars]
  184    ;   VarTerm = Vars
  185    ),
  186    sparql_write_csv_result(current_output, select(VarTerm, Rows),
  187                            [ content_type(text/plain),
  188                              Options
  189                            ])