/* Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@vu.nl
WWW: http://www.swi-prolog.org
Copyright (c) 2010-2018, University of Amsterdam
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in
the documentation and/or other materials provided with the
distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
*/
:- module(xml_result,
[ xml_write_result_table/3, % +Out, +Rows, +Options
xml_read_result_table/3, % +In, -Rows, -VarNames
xml_to_result_table/3 % +XML, -Rows, -VarNames
]).
:- use_module(library(assoc)).
:- use_module(library('semweb/rdf_db')).
:- use_module(library(sgml)).
:- multifile
rdf_io:write_table/4.
/*******************************
* WRITING *
*******************************/
%! write_table(+Format, +Serialization, +Rows, +Options)
%
% Write a result table in Sesame compliant XML format.
%
% @param Format Must be =xml=
rdf_io:write_table(xml, _, Rows, Options) :-
format('Transfer-encoding: chunked~n'),
format('Content-type: text/xml; charset=UTF-8~n~n'),
xml_write_result_table(current_output, Rows, Options).
xml_write_result_table(Out, Rows, Options) :-
format(Out, '~n~n', []),
format(Out, '~n', []),
header(Out, Options),
tuples(Out, Rows),
format(Out, '~n', []).
%! header(+Out, +Options) is det.
%
% Write the column-names obtained from the variables(+Vars)
% option. Vars is either a list of atoms or a term holding the
% comlumn names as arguments (as in v('Name', 'Age')).
header(Out, Options) :-
memberchk(variables(Vars), Options),
!,
( is_list(Vars)
-> Names = Vars
; Vars =.. [_|Names]
),
format(Out, ' ~n', []),
column_names(Names, Out),
format(Out, ' ~n', []).
header(_, _).
column_names([], _).
column_names([H|T], Out) :-
format(Out, ' ~w~n', [H]),
column_names(T, Out).
tuples(Out, Rows) :-
empty_assoc(Map), % URL --> BnodeID
tuples(Rows, Out, 1, Map).
tuples([], _, _, _).
tuples([H|T], Out, BN0, Map0) :-
H =.. [_|Columns],
format(Out, ' ~n', []),
columns(Columns, Out, BN0, BN, Map0, Map),
format(Out, ' ~n', []),
tuples(T, Out, BN, Map).
columns([], _, BN, BN, Map, Map).
columns([H|T], Out, BN0, BN, Map0, Map) :-
column(H, Out, BN0, BN1, Map0, Map1),
columns(T, Out, BN1, BN, Map1, Map).
column(Var, Out, BN, BN, Map, Map) :-
var(Var),
!,
format(Out, ' ~n', []).
column('$null$', Out, BN, BN, Map, Map) :-
!,
format(Out, ' ~n', []).
column(literal(L), Out, BN, BN, Map, Map) :-
!,
literal(L, Out).
column(Anon, Out, BN, BN, Map, Map) :-
get_assoc(Anon, Map, BNode),
!,
format(Out, ' ~w~n', [BNode]).
column(Anon, Out, BN0, BN, Map0, Map) :-
rdf_is_bnode(Anon),
!,
BN is BN0 + 1,
atom_concat(node, BN, BNode),
format(Out, ' ~w~n', [BNode]),
put_assoc(Anon, Map0, BNode, Map).
column(URI, Out, BN, BN, Map, Map) :-
xml_quote_cdata(URI, QURI, utf8),
format(Out, ' ~w~n', [QURI]).
literal(type(Type, String), Out) :-
!,
xml_quote_cdata(String, QString, utf8),
format(Out, ' ~w~n',
[Type, QString]).
literal(lang(Lang, String), Out) :-
!,
xml_quote_cdata(String, QString, utf8),
format(Out, ' ~w~n', [Lang, QString]).
literal(String, Out) :-
!,
xml_quote_cdata(String, QString, utf8),
format(Out, ' ~w~n', [QString]).
/*******************************
* READING *
*******************************/
%! xml_read_result_table(+In, -Rows, -VarNames)
%
% Read an XML document from In and return the rows and variable
% names in there.
xml_read_result_table(In, Rows, VarNames) :-
load_structure(stream(In), XML,
[ dialect(xml),
space(remove)
]),
xml_to_result_table(XML, Rows, VarNames).
%! xml_to_result_table(+XML, -Rows, -VarNames)
%
% Convert a parsed XML document into a list of rows and a column
% name (variable name) term of the format names(Col1, Col2, ...).
xml_to_result_table([XML], Rows, VarNames) :-
!,
xml_to_result_table(XML, Rows, VarNames).
xml_to_result_table(element(tableQueryResult, _, Content), Rows, VarNames) :-
phrase(result_table(Rows, VarNames), Content).
result_table(Rows, VarNames) -->
result_header(VarNames),
result_rows(Rows).
result_header(VarNames) -->
[ element(header, _, Content)
],
!,
{ phrase(column_names(Columns), Content),
VarNames =.. [names|Columns]
}.
result_header(names) -->
[].
column_names([]) -->
[].
column_names([Name|T]) -->
[ element(columnName, _, [Name])
],
column_names(T).
result_rows([Row|Rows]) -->
[ element(tuple, _, Content)
],
{ phrase(columns(Columns), Content),
Row =.. [row|Columns]
},
result_rows(Rows).
result_rows([]) -->
[].
columns([H|T]) -->
column(H),
!,
columns(T).
columns([]) -->
[].
column(URI) -->
[ element(uri, _, [URI])
],
!.
column(Bnode) -->
[ element(bNode, _, [Bnode])
],
!.
column(literal(Literal)) -->
[ element(literal, A, [String]) ],
{ memberchk(datatype=Type, A)
-> Literal = type(Type, String)
; memberchk('xml:lang'=Lang, A)
-> Literal = lang(Lang, String)
; Literal = String
}.
column('$null$') -->
[ element(null, _, [])
],
!.