/* $Id$
Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@cs.vu.nl
WWW: http://www.swi-prolog.org
Copyright (C): 2002-2009, 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 Lesser 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(rdf_parser,
[ xml_to_plrdf/3, % +XMLTerm, -RDFTerm, +State
element_to_plrdf/3, % +ContentList, -RDFTerm, +State
make_rdf_state/3, % +Options, -State, -RestOptions
rdf_modify_state/3, % +XMLAttrs, +State0, -State
rdf_name_space/1
]).
:- use_module(rewrite).
:- use_module(library(sgml)). % xml_name/1
:- use_module(library(lists)).
:- use_module(library(uri)).
:- use_module(library(record)).
:- op(500, fx, \?). % Optional (attrs)
term_expansion(F, T) :- rew_term_expansion(F, T).
goal_expansion(F, T) :- rew_goal_expansion(F, T).
goal_expansion(attrs(Attrs, List), Goal) :-
translate_attrs(List, Attrs, Goal).
translate_attrs(Var, Attrs, rewrite(Var, Attrs)) :-
var(Var), !.
translate_attrs([], _, true) :- !.
translate_attrs([H], Attrs, Goal) :- !,
( var(H)
-> Goal = rewrite(H, Attrs)
; H = \?Optional
-> Goal = ( member(A, Attrs),
OptRewrite
-> true
; true
),
expand_goal(rewrite(\Optional, A), OptRewrite)
; Goal = ( member(A, Attrs),
Rewrite
-> true
),
expand_goal(rewrite(H, A), Rewrite)
).
translate_attrs([H|T], Attrs0, (G0, G1)) :- !,
( var(H)
-> G0 = rewrite(H, Attrs0),
Attrs1 = Attrs0
; H = \?Optional
-> G0 = ( select(A, Attrs0, Attrs1),
OptRewrite
-> true
; Attrs1 = Attrs0
),
expand_goal(rewrite(\Optional, A), OptRewrite)
; G0 = ( select(A, Attrs0, Attrs1),
Rewrite
),
expand_goal(rewrite(H, A), Rewrite)
),
translate_attrs(T, Attrs1, G1).
translate_attrs(Rule, Attrs, Goal) :-
expand_goal(rewrite(Rule, Attrs), Goal).
:- multifile rdf_name_space/1.
:- dynamic rdf_name_space/1.
%% rdf_name_space(?URL) is nondet.
%
% True if URL must be handled as rdf: Determines special handling
% of rdf:about, rdf:resource, etc.
rdf_name_space('http://www.w3.org/1999/02/22-rdf-syntax-ns#').
rdf_name_space('http://www.w3.org/TR/REC-rdf-syntax').
:- record
rdf_state(base_uri='',
lang='',
ignore_lang=false,
convert_typed_literal).
%% xml_to_plrdf(+RDFElementOrObject, -RDFTerm, +State)
%
% Translate an XML (using namespaces) term into an Prolog term
% representing the RDF data. This term can then be fed into
% rdf_triples/[2,3] to create a list of RDF triples. State is an
% instance of an rdf_state record.
xml_to_plrdf(Element, RDF, State) :-
( is_list(Element)
-> rewrite(\xml_content_objects(RDF, State), Element)
; rewrite(\xml_objects(RDF, State), Element)
).
%% element_to_plrdf(+DOM, -RDFTerm, +State)
%
% Rewrite a single XML element.
element_to_plrdf(Element, RDF, State) :-
rewrite(\nodeElementList(RDF, State), [Element]).
xml_objects(Objects, Options0) ::=
E0,
{ modify_state(E0, Options0, E, Options), !,
rewrite(\xml_objects(Objects, Options), E)
}.
xml_objects(Objects, Options) ::=
element((\rdf('RDF'), !),
_,
\nodeElementList(Objects, Options)),
!.
xml_objects(Objects, Options) ::=
element(_, _, \xml_content_objects(Objects, Options)).
xml_content_objects([], _) ::=
[].
xml_content_objects([H|T], Options) ::=
[ \xml_objects(H, Options)
| \xml_content_objects(T, Options)
].
nodeElementList([], _Options) ::=
[], !.
nodeElementList(L, Options) ::=
[ (\ws, !)
| \nodeElementList(L, Options)
].
nodeElementList([H|T], Options) ::=
[ \nodeElementOrError(H, Options)
| \nodeElementList(T, Options)
].
nodeElementOrError(H, Options) ::=
\nodeElement(H, Options), !.
nodeElementOrError(unparsed(Data), _Options) ::=
Data.
nodeElement(description(Type, About, Properties), Options) ::=
\description(Type, About, Properties, Options).
/*******************************
* DESCRIPTION *
*******************************/
description(Type, About, Properties, Options0) ::=
E0,
{ modify_state(E0, Options0, E, Options), !,
rewrite(\description(Type, About, Properties, Options), E)
}.
description(description, About, Properties, Options) ::=
element(\rdf('Description'),
\attrs([ \?idAboutAttr(About, Options)
| \propAttrs(PropAttrs, Options)
]),
\propertyElts(PropElts, Options)),
{ !, append(PropAttrs, PropElts, Properties)
}.
description(Type, About, Properties, Options) ::=
element(\name_uri(Type, Options),
\attrs([ \?idAboutAttr(About, Options)
| \propAttrs(PropAttrs, Options)
]),
\propertyElts(PropElts, Options)),
{ append(PropAttrs, PropElts, Properties)
}.
propAttrs([], _) ::=
[], !.
propAttrs([H|T], Options) ::=
[ \propAttr(H, Options)
| \propAttrs(T, Options)
].
propAttr(rdf:type = URI, Options) ::=
\rdf_or_unqualified(type) = \value_uri(URI, Options), !.
propAttr(Name = Literal, Options) ::=
Name = Value,
{ mkliteral(Value, Literal, Options)
}.
propertyElts([], _) ::=
[], !.
propertyElts(Elts, Options) ::=
[ (\ws, !)
| \propertyElts(Elts, Options)
].
propertyElts([H|T], Options) ::=
[ \propertyElt(H, Options)
| \propertyElts(T, Options)
].
propertyElt(E, Options) ::=
\propertyElt(Id, Name, Value, Options),
{ mkprop(Name, Value, Prop),
( var(Id)
-> E = Prop
; E = id(Id, Prop)
)
}.
mkprop(NS:Local, Value, rdf:Local = Value) :-
rdf_name_space(NS), !.
mkprop(Name, Value, Name = Value).
propertyElt(Id, Name, Value, Options0) ::=
E0,
{ modify_state(E0, Options0, E, Options), !,
rewrite(\propertyElt(Id, Name, Value, Options), E)
}.
propertyElt(Id, Name, Value, Options) ::=
\literalPropertyElt(Id, Name, Value, Options), !.
% 5.14 emptyPropertyElt
propertyElt(Id, Name, Value, Options) ::=
element(Name, A, \all_ws),
{ !,
rewrite(\emptyPropertyElt(Id, Value, Options), A)
}.
propertyElt(_, Name, description(description, Id, Properties), Options) ::=
element(Name,
\attrs([ \parseResource,
\?idAboutAttr(Id, Options)
]),
\propertyElts(Properties, Options)),
!.
propertyElt(_, Name, Literal, Options) ::=
element(Name,
\attrs([ \parseLiteral
]),
Content),
{ !,
literal_value(Content, Literal, Options)
}.
propertyElt(Id, Name, collection(Elements), Options) ::=
element(Name,
\attrs([ \parseCollection,
\?idAttr(Id, Options)
]),
\nodeElementList(Elements, Options)).
propertyElt(Id, Name, Literal, Options) ::=
element(Name,
\attrs([ \?idAttr(Id, Options)
]),
[ Value ]),
{ atom(Value), !,
mkliteral(Value, Literal, Options)
}.
propertyElt(Id, Name, Value, Options) ::=
element(Name,
\attrs([ \?idAttr(Id, Options)
]),
\an_rdf_object(Value, Options)), !.
propertyElt(Id, Name, unparsed(Value), Options) ::=
element(Name,
\attrs([ \?idAttr(Id, Options)
]),
Value).
literalPropertyElt(Id, Name, Literal, Options) ::=
element(Name,
\attrs([ \typeAttr(Type, Options),
\?idAttr(Id, Options)
]),
Content),
{ typed_literal(Type, Content, Literal, Options)
}.
emptyPropertyElt(Id, Literal, Options) ::=
\attrs([ \?idAttr(Id, Options),
\?parseLiteral
| \noMoreAttrs
]),
{ !,
mkliteral('', Literal, Options)
}.
emptyPropertyElt(Id,
description(description, About, Properties),
Options) ::=
\attrs([ \?idAttr(Id, Options),
\?aboutResourceEmptyElt(About, Options),
\?parseResource
| \propAttrs(Properties, Options)
]), !.
aboutResourceEmptyElt(about(URI), Options) ::=
\resourceAttr(URI, Options), !.
aboutResourceEmptyElt(node(URI), _Options) ::=
\nodeIDAttr(URI).
%% literal_value(+In, -Value, +Options)
%
% Create the literal value for rdf:parseType="Literal" attributes.
% The content is the Prolog XML DOM tree for the literal.
%
% @tbd Note that the specs demand a canonical textual representation
% of the XML data as a Unicode string. For now the user can
% achieve this using the convert_typed_literal hook.
literal_value(Value, literal(type(rdf:'XMLLiteral', Value)), _).
%% mkliteral(+Atom, -Object, +Options)
%
% Translate attribute value Atom into an RDF object using the
% lang(Lang) option from Options.
mkliteral(Text, literal(Val), Options) :-
atom(Text),
( rdf_state_lang(Options, Lang),
Lang \== ''
-> Val = lang(Lang, Text)
; Val = Text
).
%% typed_literal(+Type, +Content, -Literal, +Options)
%
% Handle a literal attribute with rdf:datatype=Type qualifier. NB:
% possibly it is faster to use a global variable for the
% conversion hook.
typed_literal(Type, Content, literal(Object), Options) :-
rdf_state_convert_typed_literal(Options, Convert),
nonvar(Convert), !,
( catch(call(Convert, Type, Content, Object), E, true)
-> ( var(E)
-> true
; Object = E
)
; Object = error(cannot_convert(Type, Content), _)
).
typed_literal(Type, [], literal(type(Type, '')), _Options) :- !.
typed_literal(Type, [Text], literal(type(Type, Text)), _Options) :- !.
typed_literal(Type, Content, literal(type(Type, Content)), _Options).
idAboutAttr(id(Id), Options) ::=
\idAttr(Id, Options), !.
idAboutAttr(about(About), Options) ::=
\aboutAttr(About, Options), !.
idAboutAttr(node(About), _Options) ::=
\nodeIDAttr(About), !.
%% an_rdf_object(-Object, +OptionsURI)
%
% Deals with an object, but there may be spaces around. I'm still
% not sure where to deal with these. Best is to ask the XML parser
% to get rid of them, So most likely this code will change if this
% happens.
an_rdf_object(Object, Options) ::=
[ \nodeElement(Object, Options)
], !.
an_rdf_object(Object, Options) ::=
[ (\ws, !)
| \an_rdf_object(Object, Options)
].
an_rdf_object(Object, Options) ::=
[ \nodeElement(Object, Options),
\ws
], !.
ws ::=
A,
{ atom(A),
atom_chars(A, Chars),
all_blank(Chars), !
}.
ws ::=
pi(_).
all_ws ::=
[], !.
all_ws ::=
[\ws | \all_ws].
all_blank([]).
all_blank([H|T]) :-
char_type(H, space), % SWI-Prolog specific
all_blank(T).
/*******************************
* RDF ATTRIBUTES *
*******************************/
idAttr(Id, Options) ::=
\rdf_or_unqualified('ID') = \uniqueid(Id, Options).
aboutAttr(About, Options) ::=
\rdf_or_unqualified(about) = \value_uri(About, Options).
nodeIDAttr(About) ::=
\rdf_or_unqualified(nodeID) = About.
resourceAttr(URI, Options) ::=
\rdf_or_unqualified(resource) = \value_uri(URI, Options).
typeAttr(Type, Options) ::=
\rdf_or_unqualified(datatype) = \value_uri(Type, Options).
name_uri(URI, Options) ::=
NS:Local,
{ !, atom_concat(NS, Local, A),
rewrite(\value_uri(URI, Options), A)
}.
name_uri(URI, Options) ::=
\value_uri(URI, Options).
value_uri(URI, Options) ::=
A,
{ rdf_state_base_uri(Options, Base),
uri_normalized_iri(A, Base, URI)
}.
globalid(Id, Options) ::=
A,
{ make_globalid(A, Options, Id)
}.
uniqueid(Id, Options) ::=
A,
{ unique_xml_name(A, HashID),
make_globalid(HashID, Options, Id)
}.
unique_xml_name(Name, HashID) :-
atom_concat(#, Name, HashID),
( xml_name(Name)
-> true
; print_message(warning, rdf(not_a_name(Name)))
).
make_globalid(In, Options, Id) :-
rdf_state_base_uri(Options, Base),
uri_normalized_iri(In, Base, Id).
parseLiteral ::= \rdf_or_unqualified(parseType) = 'Literal'.
parseResource ::= \rdf_or_unqualified(parseType) = 'Resource'.
parseCollection ::= \rdf_or_unqualified(parseType) = 'Collection'.
/*******************************
* PRIMITIVES *
*******************************/
rdf(Tag) ::=
NS:Tag,
{ rdf_name_space(NS), !
}.
rdf_or_unqualified(Tag) ::=
Tag.
rdf_or_unqualified(Tag) ::=
NS:Tag,
{ rdf_name_space(NS), !
}.
/*******************************
* BASICS *
*******************************/
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
This code is translated by the goal_expansion/2 rule at the start of
this file. We leave the original code for reference.
attrs(Bag) ::=
L0,
{ do_attrs(Bag, L0)
}.
do_attrs([], _) :- !.
do_attrs([\?H|T], L0) :- !, % optional
( select(X, L0, L),
rewrite(\H, X)
-> true
; L = L0
),
do_attrs(T, L).
do_attrs([H|T], L0) :-
select(X, L0, L),
rewrite(H, X), !,
do_attrs(T, L).
do_attrs(C, L) :-
rewrite(C, L).
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
% \noMoreAttrs
%
% Check attribute-list is empty. Reserved xml: attributes are
% excluded from this test.
noMoreAttrs ::=
[], !.
noMoreAttrs ::=
[ xml:_=_
| \noMoreAttrs
].
%% modify_state(+Element0, +Options0, -Element, -Options) is semidet.
%
% If Element0 contains xml:base = Base, strip it from the
% attributes list and update base_uri(_) in the Options
%
% It Element0 contains xml:lang = Lang, strip it from the
% attributes list and update lang(_) in the Options
%
% Remove all xmlns=_, xmlns:_=_ and xml:_=_. Only succeed
% if something changed.
modify_state(element(Name, Attrs0, Content), Options0,
element(Name, Attrs, Content), Options) :-
modify_a_state(Attrs0, Options0, Attrs, Options),
Attrs0 \== Attrs.
rdf_modify_state(Attributes, State0, State) :-
modify_a_state(Attributes, State0, _, State).
modify_a_state([], Options, [], Options).
modify_a_state([Name=Value|T0], Options0, T, Options) :-
modify_a(Name, Value, Options0, Options1), !,
modify_a_state(T0, Options1, T, Options).
modify_a_state([H|T0], Options0, [H|T], Options) :-
modify_a_state(T0, Options0, T, Options).
modify_a(xml:base, Base1, Options0, Options) :- !,
rdf_state_base_uri(Options0, Base0),
remove_fragment(Base1, Base2),
uri_normalized_iri(Base2, Base0, Base),
set_base_uri_of_rdf_state(Base, Options0, Options).
modify_a(xml:lang, Lang, Options0, Options) :- !,
rdf_state_ignore_lang(Options0, false), !,
set_lang_of_rdf_state(Lang, Options0, Options).
modify_a(xmlns, _, Options, Options).
modify_a(xmlns:_, _, Options, Options).
modify_a(xml:_, _, Options, Options).
%% remove_fragment(+URI, -WithoutFragment)
%
% When handling xml:base, we must delete the possible fragment.
remove_fragment(URI, Plain) :-
sub_atom(URI, B, _, _, #), !,
sub_atom(URI, 0, B, _, Plain).
remove_fragment(URI, URI).
/*******************************
* HELP PCE-EMACS A BIT *
*******************************/
:- multifile
emacs_prolog_colours:term_colours/2,
emacs_prolog_colours:goal_classification/2.
expand(c(X), _, X) :- !.
expand(In, Pattern, Colours) :-
compound(In), !,
In =.. [F|Args],
expand_list(Args, PatternArgs, ColourArgs),
Pattern =.. [F|PatternArgs],
Colours = functor(F) - ColourArgs.
expand(X, X, classify).
expand_list([], [], []).
expand_list([H|T], [PH|PT], [CH|CT]) :-
expand(H, PH, CH),
expand_list(T, PT, CT).
:- discontiguous
term_expansion/2.
term_expansion(term_colours(C),
emacs_prolog_colours:term_colours(Pattern, Colours)) :-
expand(C, Pattern, Colours).
term_colours((c(head(+(1))) ::= c(match), {c(body)})).
term_colours((c(head(+(1))) ::= c(match))).
emacs_prolog_colours:goal_classification(\_, expanded).
:- dynamic
prolog:meta_goal/2.
:- multifile
prolog:meta_goal/2,
prolog:called_by/2.
prolog:meta_goal(rewrite(A, _), [A]).
prolog:meta_goal(\A, [A+1]).
prolog:called_by(attrs(Attrs, _Term), Called) :-
findall(G+1, sub_term(\?G, Attrs), Called, Tail),
findall(G+1, sub_term(\G, Attrs), Tail).