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rdf_db.pl
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rdf_db.pl
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/* Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@vu.nl
WWW: http://www.swi-prolog.org
Copyright (c) 2003-2016, University of Amsterdam
VU University 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(rdf_db,
[ rdf_version/1, % -Version
rdf/3, % ?Subject, ?Predicate, ?Object
rdf/4, % ?Subject, ?Predicate, ?Object, ?DB
rdf_has/3, % ?Subject, +Pred, ?Obj
rdf_has/4, % ?Subject, +Pred, ?Obj, -RealPred
rdf_reachable/3, % ?Subject, +Pred, ?Object
rdf_reachable/5, % ?Subject, +Pred, ?Object, +MaxD, ?D
rdf_resource/1, % ?Resource
rdf_subject/1, % ?Subject
rdf_member_property/2, % ?Property, ?Index
rdf_assert/3, % +Subject, +Predicate, +Object
rdf_assert/4, % +Subject, +Predicate, +Object, +DB
rdf_retractall/3, % ?Subject, ?Predicate, ?Object
rdf_retractall/4, % ?Subject, ?Predicate, ?Object, +DB
rdf_update/4, % +Subject, +Predicate, +Object, +Act
rdf_update/5, % +Subject, +Predicate, +Object, +Src, +Act
rdf_set_predicate/2, % +Predicate, +Property
rdf_predicate_property/2, % +Predicate, ?Property
rdf_current_predicate/1, % -Predicate
rdf_current_literal/1, % -Literal
rdf_transaction/1, % :Goal
rdf_transaction/2, % :Goal, +Id
rdf_transaction/3, % :Goal, +Id, +Options
rdf_active_transaction/1, % ?Id
rdf_monitor/2, % :Goal, +Options
rdf_save_db/1, % +File
rdf_save_db/2, % +File, +DB
rdf_load_db/1, % +File
rdf_reset_db/0,
rdf_node/1, % -Id
rdf_bnode/1, % -Id
rdf_is_bnode/1, % +Id
rdf_is_resource/1, % +Term
rdf_is_literal/1, % +Term
rdf_literal_value/2, % +Term, -Value
rdf_load/1, % +File
rdf_load/2, % +File, +Options
rdf_save/1, % +File
rdf_save/2, % +File, +Options
rdf_unload/1, % +File
rdf_unload_graph/1, % +Graph
rdf_md5/2, % +DB, -MD5
rdf_atom_md5/3, % +Text, +Times, -MD5
rdf_create_graph/1, % ?Graph
rdf_graph_property/2, % ?Graph, ?Property
rdf_set_graph/2, % +Graph, +Property
rdf_graph/1, % ?Graph
rdf_source/1, % ?File
rdf_source/2, % ?DB, ?SourceURL
rdf_make/0, % Reload modified databases
rdf_gc/0, % Garbage collection
rdf_source_location/2, % +Subject, -Source
rdf_statistics/1, % -Key
rdf_set/1, % +Term
rdf_generation/1, % -Generation
rdf_snapshot/1, % -Snapshot
rdf_delete_snapshot/1, % +Snapshot
rdf_current_snapshot/1, % +Snapshot
rdf_estimate_complexity/4, % +S,+P,+O,-Count
rdf_save_subject/3, % +Stream, +Subject, +DB
rdf_save_header/2, % +Out, +Options
rdf_save_footer/1, % +Out
rdf_equal/2, % ?Resource, ?Resource
lang_equal/2, % +Lang1, +Lang2
lang_matches/2, % +Lang, +Pattern
rdf_prefix/2, % :Alias, +URI
rdf_current_prefix/2, % :Alias, ?URI
rdf_register_prefix/2, % +Alias, +URI
rdf_register_prefix/3, % +Alias, +URI, +Options
rdf_current_ns/2, % :Alias, ?URI
rdf_register_ns/2, % +Alias, +URI
rdf_register_ns/3, % +Alias, +URI, +Options
rdf_global_id/2, % ?NS:Name, :Global
rdf_global_object/2, % ?Object, :NSExpandedObject
rdf_global_term/2, % Term, :WithExpandedNS
rdf_compare/3, % -Dif, +Object1, +Object2
rdf_match_label/3, % +How, +String, +Label
rdf_split_url/3, % ?Base, ?Local, ?URL
rdf_url_namespace/2, % +URL, ?Base
rdf_warm_indexes/0,
rdf_warm_indexes/1, % +Indexed
rdf_update_duplicates/0,
rdf_debug/1, % Set verbosity
rdf_new_literal_map/1, % -Handle
rdf_destroy_literal_map/1, % +Handle
rdf_reset_literal_map/1, % +Handle
rdf_insert_literal_map/3, % +Handle, +Key, +Literal
rdf_insert_literal_map/4, % +Handle, +Key, +Literal, -NewKeys
rdf_delete_literal_map/3, % +Handle, +Key, +Literal
rdf_delete_literal_map/2, % +Handle, +Key
rdf_find_literal_map/3, % +Handle, +KeyList, -Literals
rdf_keys_in_literal_map/3, % +Handle, +Spec, -Keys
rdf_statistics_literal_map/2, % +Handle, +Name(-Arg...)
rdf_graph_prefixes/2, % ?Graph, -Prefixes
rdf_graph_prefixes/3, % ?Graph, -Prefixes, :Filter
(rdf_meta)/1, % +Heads
op(1150, fx, (rdf_meta))
]).
:- use_module(library(rdf)).
:- use_module(library(lists)).
:- use_module(library(pairs)).
:- use_module(library(shlib)).
:- use_module(library(gensym)).
:- use_module(library(sgml)).
:- use_module(library(sgml_write)).
:- use_module(library(option)).
:- use_module(library(error)).
:- use_module(library(uri)).
:- use_module(library(debug)).
:- use_module(library(apply)).
:- use_module(library(xsdp_types)).
:- if(exists_source(library(thread))).
:- use_module(library(thread)).
:- endif.
:- use_module(library(semweb/rdf_cache)).
:- use_foreign_library(foreign(rdf_db)).
:- public rdf_print_predicate_cloud/2. % print matrix of reachable predicates
:- meta_predicate
rdf_current_prefix(:, -),
rdf_current_ns(:, -),
rdf_global_id(+, :),
rdf_global_term(+, :),
rdf_global_object(+, :),
rdf_transaction(0),
rdf_transaction(0, +),
rdf_transaction(0, +, +),
rdf_monitor(1, +),
rdf_save(+, :),
rdf_load(+, :).
:- predicate_options(rdf_graph_prefixes/3, 3,
[expand(callable), filter(callable), min_count(nonneg)]).
:- predicate_options(rdf_load/2, 2,
[ base_uri(atom),
cache(boolean),
concurrent(positive_integer),
db(atom),
format(oneof([xml,triples,turtle,trig,nquads,ntriples])),
graph(atom),
if(oneof([true,changed,not_loaded])),
modified(-float),
silent(boolean),
register_namespaces(boolean)
]).
:- predicate_options(rdf_register_ns/3, 3, [force(boolean), keep(boolean)]).
:- predicate_options(rdf_save/2, 2,
[ graph(atom),
db(atom),
anon(boolean),
base_uri(atom),
write_xml_base(boolean),
convert_typed_literal(callable),
encoding(encoding),
document_language(atom),
namespaces(list(atom)),
xml_attributes(boolean),
inline(boolean)
]).
:- predicate_options(rdf_save_header/2, 2,
[ graph(atom),
db(atom),
namespaces(list(atom))
]).
:- predicate_options(rdf_save_subject/3, 3,
[ graph(atom),
base_uri(atom),
convert_typed_literal(callable),
document_language(atom)
]).
:- predicate_options(rdf_transaction/3, 3,
[ snapshot(any)
]).
:- multifile ns/2.
:- dynamic ns/2. % ID, URL
:- discontiguous
term_expansion/2.
/** <module> Core RDF database
The file library(semweb/rdf_db) provides the core of the SWI-Prolog RDF
store.
@deprecated New applications should use library(semweb/rdf11), which
provides a much more intuitive API to the RDF store, notably
for handling literals. The library(semweb/rdf11) runs
currently on top of this library and both can run side-by-side
in the same application. Terms retrieved from the database
however have a different shape and can not be exchanged without
precautions.
*/
/*******************************
* PREFIXES *
*******************************/
%% rdf_current_prefix(:Alias, ?URI) is nondet.
%
% Query predefined prefixes and prefixes defined with
% rdf_register_prefix/2 and local prefixes defined with
% rdf_prefix/2. If Alias is unbound and one URI is the prefix of
% another, the longest is returned first. This allows turning a
% resource into a prefix/local couple using the simple enumeration
% below. See rdf_global_id/2.
%
% ==
% rdf_current_prefix(Prefix, Expansion),
% atom_concat(Expansion, Local, URI),
% ==
rdf_current_prefix(Module:Alias, URI) :-
nonvar(Alias), !,
rdf_current_prefix(Module, Alias, URI), !.
rdf_current_prefix(Module:Alias, URI) :-
rdf_current_prefix(Module, Alias, URI).
rdf_current_prefix(system, Alias, URI) :- !,
ns(Alias, URI).
rdf_current_prefix(Module, Alias, URI) :-
default_module(Module, M),
( M == system
-> ns(Alias, URI)
; '$flushed_predicate'(M:'rdf prefix'(_,_)),
call(M:'rdf prefix'(Alias,URI))
).
%% rdf_prefix(:Alias, +URI) is det.
%
% Register a _local_ prefix. This declaration takes precedence
% over globally defined prefixes using rdf_register_prefix/2,3.
% Module local prefixes are notably required to deal with SWISH,
% where users need to be able to have independent namespace
% declarations.
rdf_prefix(Alias, URI) :-
throw(error(context_error(nodirective, rdf_prefix(Alias, URI)), _)).
system:term_expansion((:- rdf_prefix(AliasSpec, URI)), Clauses) :-
prolog_load_context(module, Module),
strip_module(Module:AliasSpec, TM, Alias),
must_be(atom, Alias),
must_be(atom, URI),
( rdf_current_prefix(TM:Alias, URI)
-> Clauses = []
; TM == Module
-> Clauses = 'rdf prefix'(Alias, URI)
; Clauses = TM:'rdf prefix'(Alias, URI)
).
%% ns(?Alias, ?URI) is nondet.
%
% Dynamic and multifile predicate that maintains the registered
% namespace aliases.
%
% @deprecated New code must modify the namespace table using
% rdf_register_ns/3 and query using rdf_current_ns/2.
ns(dc, 'http://purl.org/dc/elements/1.1/').
ns(dcterms, 'http://purl.org/dc/terms/').
ns(eor, 'http://dublincore.org/2000/03/13/eor#').
ns(foaf, 'http://xmlns.com/foaf/0.1/').
ns(owl, 'http://www.w3.org/2002/07/owl#').
ns(rdf, 'http://www.w3.org/1999/02/22-rdf-syntax-ns#').
ns(rdfs, 'http://www.w3.org/2000/01/rdf-schema#').
ns(serql, 'http://www.openrdf.org/schema/serql#').
ns(skos, 'http://www.w3.org/2004/02/skos/core#').
ns(void, 'http://rdfs.org/ns/void#').
ns(xsd, 'http://www.w3.org/2001/XMLSchema#').
%% rdf_register_prefix(+Prefix, +URI) is det.
%% rdf_register_prefix(+Prefix, +URI, +Options) is det.
%
% Register Prefix as an abbreviation for URI. Options:
%
% * force(Boolean)
% If =true=, Replace existing namespace alias. Please note
% that replacing a namespace is dangerous as namespaces
% affect preprocessing. Make sure all code that depends on
% a namespace is compiled after changing the registration.
%
% * keep(Boolean)
% If =true= and Alias is already defined, keep the
% original binding for Prefix and succeed silently.
%
% Without options, an attempt to redefine an alias raises a
% permission error.
%
% Predefined prefixes are:
%
% | **Alias** | **IRI prefix** |
% | dc | http://purl.org/dc/elements/1.1/ |
% | dcterms | http://purl.org/dc/terms/ |
% | eor | http://dublincore.org/2000/03/13/eor# |
% | foaf | http://xmlns.com/foaf/0.1/ |
% | owl | http://www.w3.org/2002/07/owl# |
% | rdf | http://www.w3.org/1999/02/22-rdf-syntax-ns# |
% | rdfs | http://www.w3.org/2000/01/rdf-schema# |
% | serql | http://www.openrdf.org/schema/serql# |
% | skos | http://www.w3.org/2004/02/skos/core# |
% | void | http://rdfs.org/ns/void# |
% | xsd | http://www.w3.org/2001/XMLSchema# |
rdf_register_prefix(Alias, URI) :-
rdf_register_prefix(Alias, URI, []).
rdf_register_prefix(Alias, URI, Options) :-
must_be(atom, Alias),
must_be(atom, URI),
( rdf_current_prefix(system:Alias, URI)
-> true
; register_global_prefix(Alias, URI, Options)
).
%% register_global_prefix(+Alias, +URI, +Options)
%
% Register a global prefix.
register_global_prefix(Alias, URI, Options) :-
ns(Alias, _), !,
( option(force(true), Options, false)
-> retractall(ns(Alias, _)),
rdf_register_prefix(Alias, URI, Options),
rdf_empty_prefix_cache
; option(keep(true), Options, false)
-> true
; throw(error(permission_error(register, namespace, Alias),
context(_, 'Already defined')))
).
register_global_prefix(Alias, URI, _) :-
findall(P-U, prefix_conflict(URI, P, U), Pairs),
order_prefixes([Alias-URI|Pairs], Ordered),
forall(member(P-U, Pairs), retract(ns(P,U))),
forall(member(P-U, Ordered), assert(ns(P,U))).
prefix_conflict(URI, P, U) :-
ns(P,U),
( sub_atom(URI, 0, _, _, U)
-> true
; sub_atom(U, 0, _, _, URI)
).
order_prefixes(Pairs, Sorted) :-
map_list_to_pairs(prefix_uri_length, Pairs, ByLen),
sort(1, >=, ByLen, SortedByLen),
pairs_values(SortedByLen, Sorted).
prefix_uri_length(_-URI, Len) :-
atom_length(URI, Len).
%% rdf_current_ns(:Prefix, ?URI) is nondet.
%
% @deprecated. Use rdf_current_prefix/2.
rdf_current_ns(Prefix, URI) :-
rdf_current_prefix(Prefix, URI).
%% rdf_register_ns(:Prefix, ?URI) is det.
%% rdf_register_ns(:Prefix, ?URI, +Options) is det.
%
% Register an RDF prefix.
%
% @deprecated. Use rdf_register_prefix/2 or rdf_register_prefix/3.
rdf_register_ns(Prefix, URI) :-
rdf_register_prefix(Prefix, URI).
rdf_register_ns(Prefix, URI, Options) :-
rdf_register_prefix(Prefix, URI, Options).
%% register_file_ns(+Map:list(pair)) is det.
%
% Register a namespace as encounted in the namespace list of an
% RDF document. We only register if both the abbreviation and URL
% are not already known. Is there a better way? This code could
% also do checks on the consistency of RDF and other well-known
% namespaces.
%
% @tbd Better error handling
register_file_ns([]) :- !.
register_file_ns([Decl|T]) :- !,
register_file_ns(Decl),
register_file_ns(T).
register_file_ns([]=_) :- !. % xmlns= (overall default)
register_file_ns(NS=URL) :- !, % compatibility
register_file_ns(NS-URL).
register_file_ns(NS-URL) :-
( ns(NS, URL)
-> true
; ns(NS, _)
-> true % redefined abbreviation
; ns(_, URL)
-> true % redefined URL
; rdf_register_ns(NS, URL)
).
%% rdf_global_id(?Id, :GlobalId) is det.
%
% Convert between NS:Local and global atomic identifier. To be
% completed. Note that the predicate is a meta-predicate on the
% output argument. This is necessary to get the module context
% while the first argument may be of the form (:)/2.
rdf_global_id(Id, Module:Global) :-
rdf_global_id(Id, Global, Module).
rdf_global_id(NS:Local, Global, Module) :-
global(NS, Local, Global, Module), !.
rdf_global_id(Global, Global, _).
%% rdf_global_object(+Object, :GlobalObject) is semidet.
%% rdf_global_object(-Object, :GlobalObject) is semidet.
%
% Same as rdf_global_id/2, but intended for dealing with the
% object part of a triple, in particular the type for typed
% literals. Note that the predicate is a meta-predicate on the
% output argument. This is necessary to get the module context
% while the first argument may be of the form (:)/2.
%
% @error existence_error(rdf_prefix, Prefix)
rdf_global_object(Object, Module:GlobalObject) :-
rdf_global_object(Object, GlobalObject, Module).
rdf_global_object(Var, Global, _M) :-
var(Var), !,
Global = Var.
rdf_global_object(Prefix:Local, Global, M) :-
global(Prefix, Local, Global, M), !.
rdf_global_object(literal(type(Prefix:Local, Value)),
literal(type(Global, Value)), M) :-
global(Prefix, Local, Global, M), !.
rdf_global_object(^^(Value,Prefix:Local),
^^(Value,Global), M) :-
global(Prefix, Local, Global, M), !.
rdf_global_object(literal(Query0, type(Prefix:Local, Value)),
literal(Query1, type(Global, Value)), M) :-
global(Prefix, Local, Global, M), !,
rdf_global_term(Query0, Query1, M).
rdf_global_object(literal(Query0, Value),
literal(Query1, Value), M) :- !,
rdf_global_term(Query0, Query1, M).
rdf_global_object(Global, Global, _).
global(Prefix, Local, Global, Module) :-
( atom(Global)
-> rdf_current_prefix(Module:Prefix, Full),
atom_concat(Full, Local, Global)
; atom(Prefix), atom(Local)
-> ( rdf_current_prefix(Module:Prefix, Full)
*-> atom_concat(Full, Local, Global)
; current_prolog_flag(xref, true)
-> Global = Prefix:Local
; existence_error(rdf_prefix, Prefix)
)
).
%% rdf_global_term(+TermIn, :GlobalTerm) is det.
%
% Does rdf_global_id/2 on all terms NS:Local by recursively
% analysing the term. Note that the predicate is a meta-predicate
% on the output argument. This is necessary to get the module
% context while the first argument may be of the form (:)/2.
%
% Terms of the form Prefix:Local that appear in TermIn for which
% Prefix is not defined are not replaced. Unlike rdf_global_id/2
% and rdf_global_object/2, no error is raised.
rdf_global_term(TermIn, Module:TermOut) :-
rdf_global_term(TermIn, TermOut, Module).
rdf_global_term(Var, Var, _M) :-
var(Var), !.
rdf_global_term(Prefix:Local, Global, Module) :-
atom(Prefix), atom(Local),
rdf_current_prefix(Module:Prefix, Full), !,
atom_concat(Full, Local, Global).
rdf_global_term([H0|T0], [H|T], M) :- !,
rdf_global_term(H0, H, M),
rdf_global_term(T0, T, M).
rdf_global_term(Term0, Term, M) :-
compound(Term0), !,
Term0 =.. [H|L0],
rdf_global_term(L0, L, M),
Term =.. [H|L].
rdf_global_term(Term, Term, _).
%% rdf_global_graph(+TermIn, -GlobalTerm, +Module) is det.
%
% Preforms rdf_global_id/2 on rdf/4, etc graph arguments
rdf_global_graph(Prefix:Local, Global, Module) :-
atom(Prefix), atom(Local), !,
global(Prefix, Local, Global, Module).
rdf_global_graph(G, G, _).
/*******************************
* EXPANSION *
*******************************/
:- multifile
system:term_expansion/2,
system:goal_expansion/2.
system:term_expansion((:- rdf_meta(Heads)), Clauses) :-
prolog_load_context(module, M),
phrase(mk_clauses(Heads, M), Clauses).
mk_clauses((A,B), M) -->
mk_clause(A, M),
mk_clauses(B, M).
mk_clauses(A, M) -->
mk_clause(A, M).
mk_clause(Head0, M0) -->
{ strip_module(M0:Head0, Module, Head),
valid_rdf_meta_head(Head),
functor(Head, Name, Arity),
functor(Unbound, Name, Arity),
qualify(Module, 'rdf meta specification'/2, Decl)
},
[ (:- multifile(Decl)),
Module:'rdf meta specification'(Unbound, Head)
].
qualify(Module, Decl, Decl) :-
prolog_load_context(module, Module), !.
qualify(Module, Decl, Module:Decl).
valid_rdf_meta_head(Head) :-
callable(Head), !,
Head =.. [_|Args],
valid_args(Args).
valid_rdf_meta_head(Head) :-
throw(error(type_error(callable, Head), _)).
valid_args([]).
valid_args([H|T]) :-
valid_arg(H), !,
valid_args(T).
valid_arg(:). % meta argument
valid_arg(+). % non-var
valid_arg(-). % var
valid_arg(?). % either var or non-var
valid_arg(@). % not modified
valid_arg(r). % RDF resource
valid_arg(o). % RDF object
valid_arg(t). % term with RDF resources
valid_arg(g). % graph argument
valid_arg(A) :-
throw(error(type_error(rdf_meta_argument, A), _)).
%% rdf_meta(+Heads)
%
% This directive defines the argument types of the named
% predicates, which will force compile time namespace expansion
% for these predicates. Heads is a coma-separated list of callable
% terms. Defined argument properties are:
%
% $ : :
% Argument is a goal. The goal is processed using expand_goal/2,
% recursively applying goal transformation on the argument.
%
% $ + :
% The argument is instantiated at entry. Nothing is changed.
%
% $ - :
% The argument is not instantiated at entry. Nothing is changed.
%
% $ ? :
% The argument is unbound or instantiated at entry. Nothing is
% changed.
%
% $ @ :
% The argument is not changed.
%
% $ r :
% The argument must be a resource. If it is a term
% _prefix_:_local_ it is translated.
%
% $ o :
% The argument is an object or resource. See
% rdf_global_object/2.
%
% $ t :
% The argument is a term that must be translated. Expansion will
% translate all occurences of _prefix_:_local_ appearing
% anywhere in the term. See rdf_global_term/2.
%
% As it is subject to term_expansion/2, the rdf_meta/1 declaration
% can only be used as a directive. The directive must be processed
% before the definition of the predicates as well as before
% compiling code that uses the rdf meta-predicates. The atom
% =rdf_meta= is declared as an operator exported from
% library(semweb/rdf_db). Files using rdf_meta/1 must explicitely
% load this library.
%
% Beginning with SWI-Prolog 7.3.17, the low-level RDF interface
% (rdf/3, rdf_assert/3, etc.) perform runtime expansion of
% `Prefix:Local` terms. This eliminates the need for rdf_meta/1
% for simple cases. However, runtime expansion comes at a
% significant overhead and having two representations for IRIs (a
% plain atom and a term `Prefix:Local`) implies that simple
% operations such as comparison of IRIs no longer map to native
% Prolog operations such as `IRI1 == IRI2`.
rdf_meta(Heads) :-
throw(error(context_error(nodirective, rdf_meta(Heads)), _)).
%% rdf_meta_specification(+General, +Module, -Spec) is semidet.
%
% True when Spec is the RDF meta specification for Module:General.
%
% @arg General is the term Spec with all arguments replaced with
% variables.
rdf_meta_specification(Unbounded, Module, Spec) :-
'$flushed_predicate'(Module:'rdf meta specification'(_,_)),
call(Module:'rdf meta specification'(Unbounded, Spec)).
system:goal_expansion(G, Expanded) :-
\+ predicate_property(G, iso),
prolog_load_context(module, LM),
predicate_property(LM:G, implementation_module(IM)),
rdf_meta_specification(G, IM, Spec),
rdf_expand(G, Spec, Expanded, LM).
system:term_expansion(Fact, Expanded) :-
prolog_load_context(module, Module),
rdf_meta_specification(Fact, Module, Spec),
rdf_expand(Fact, Spec, Expanded, Module),
Fact \== Expanded.
system:term_expansion((Head :- Body), (Expanded :- Body)) :-
prolog_load_context(module, Module),
rdf_meta_specification(Head, Module, Spec),
rdf_expand(Head, Spec, Expanded, Module),
Head \== Expanded.
rdf_expand(G, Spec, Expanded, M) :-
functor(G, Name, Arity),
functor(Expanded, Name, Arity),
rdf_expand_args(0, Arity, G, Spec, Expanded, M).
rdf_expand_args(Arity, Arity, _, _, _, _) :- !.
rdf_expand_args(I0, Arity, Goal, Spec, Expanded, M) :-
I is I0 + 1,
arg(I, Goal, GA),
arg(I, Spec, SA),
arg(I, Expanded, EA),
rdf_expand_arg(SA, GA, EA, M),
rdf_expand_args(I, Arity, Goal, Spec, Expanded, M).
rdf_expand_arg(r, A, E, M) :-
mk_global(A, E, M), !.
rdf_expand_arg(o, A, E, M) :-
rdf_global_object(A, E, M), !.
rdf_expand_arg(t, A, E, M) :-
rdf_global_term(A, E, M), !.
rdf_expand_arg(g, A, E, M) :-
rdf_global_graph(A, E, M), !.
rdf_expand_arg(:, A, E, _M) :- !,
expand_goal(A, E).
rdf_expand_arg(_, A, A, _M).
%% mk_global(+Src, -Resource, +Module)
%
% Realised rdf_global_id(+, -), but adds compiletime checking,
% notably to see whether a namespace is not yet defined.
mk_global(X, X, _) :-
var(X), !.
mk_global(X, X, _) :-
atom(X), !.
mk_global(Prefix:Local, Global, Module) :-
must_be(atom, Prefix),
must_be(atom, Local),
( rdf_current_prefix(Module:Prefix, Full)
-> atom_concat(Full, Local, Global)
; current_prolog_flag(xref, true)
-> Global = Prefix:Local
; existence_error(rdf_prefix, Prefix)
).
:- rdf_meta
rdf(r,r,o),
rdf_has(r,r,o,r),
rdf_has(r,r,o),
rdf_assert(r,r,o),
rdf_retractall(r,r,o),
rdf(r,r,o,?),
rdf_assert(r,r,o,+),
rdf_retractall(r,r,o,?),
rdf_reachable(r,r,o),
rdf_reachable(r,r,o,+,?),
rdf_update(r,r,o,t),
rdf_update(r,r,o,+,t),
rdf_equal(o,o),
rdf_source_location(r,-),
rdf_resource(r),
rdf_subject(r),
rdf_create_graph(r),
rdf_graph(r),
rdf_graph_property(r,?),
rdf_set_graph(r,+),
rdf_unload_graph(r),
rdf_set_predicate(r, t),
rdf_predicate_property(r, -),
rdf_estimate_complexity(r,r,r,-),
rdf_print_predicate_cloud(r,+).
%% rdf_equal(?Resource1, ?Resource2)
%
% Simple equality test to exploit goal-expansion
rdf_equal(Resource, Resource).
%% lang_equal(+Lang1, +Lang2) is semidet.
%
% True if two RFC language specifiers denote the same language
%
% @see lang_matches/2.
lang_equal(Lang, Lang) :- !.
lang_equal(Lang1, Lang2) :-
downcase_atom(Lang1, LangCannon),
downcase_atom(Lang2, LangCannon).
%% lang_matches(+Lang, +Pattern) is semidet.
%
% True if Lang matches Pattern. This implements XML language
% matching conform RFC 4647. Both Lang and Pattern are
% dash-separated strings of identifiers or (for Pattern) the
% wildcart *. Identifiers are matched case-insensitive and a *
% matches any number of identifiers. A short pattern is the same
% as *.
/*******************************
* BASIC TRIPLE QUERIES *
*******************************/
%% rdf(?Subject, ?Predicate, ?Object) is nondet.
%
% Elementary query for triples. Subject and Predicate are atoms
% representing the fully qualified URL of the resource. Object is
% either an atom representing a resource or literal(Value) if the
% object is a literal value. If a value of the form
% NameSpaceID:LocalName is provided it is expanded to a ground
% atom using expand_goal/2. This implies you can use this
% construct in compiled code without paying a performance penalty.
% Literal values take one of the following forms:
%
% * Atom
% If the value is a simple atom it is the textual representation
% of a string literal without explicit type or language
% qualifier.
%
% * lang(LangID, Atom)
% Atom represents the text of a string literal qualified with
% the given language.
%
% * type(TypeID, Value)
% Used for attributes qualified using the =|rdf:datatype|=
% TypeID. The Value is either the textual representation or a
% natural Prolog representation. See the option
% convert_typed_literal(:Convertor) of the parser. The storage
% layer provides efficient handling of atoms, integers (64-bit)
% and floats (native C-doubles). All other data is represented
% as a Prolog record.
%
% For literal querying purposes, Object can be of the form
% literal(+Query, -Value), where Query is one of the terms below.
% If the Query takes a literal argument and the value has a
% numeric type numerical comparison is performed.
%
% * plain(+Text)
% Perform exact match and demand the language or type qualifiers
% to match. This query is fully indexed.
%
% * icase(+Text)
% Perform a full but case-insensitive match. This query is
% fully indexed.
%
% * exact(+Text)
% Same as icase(Text). Backward compatibility.
%
% * substring(+Text)
% Match any literal that contains Text as a case-insensitive
% substring. The query is not indexed on Object.
%
% * word(+Text)
% Match any literal that contains Text delimited by a non
% alpha-numeric character, the start or end of the string. The
% query is not indexed on Object.
%
% * prefix(+Text)
% Match any literal that starts with Text. This call is intended
% for completion. The query is indexed using the skip list of
% literals.
%
% * ge(+Literal)
% Match any literal that is equal or larger then Literal in the
% ordered set of literals.
%
% * gt(+Literal)
% Match any literal that is larger then Literal in the ordered set
% of literals.
%
% * eq(+Literal)
% Match any literal that is equal to Literal in the ordered set
% of literals.
%
% * le(+Literal)
% Match any literal that is equal or smaller then Literal in the
% ordered set of literals.
%
% * lt(+Literal)
% Match any literal that is smaller then Literal in the ordered set
% of literals.
%
% * between(+Literal1, +Literal2)
% Match any literal that is between Literal1 and Literal2 in the
% ordered set of literals. This may include both Literal1 and
% Literal2.
%
% * like(+Pattern)
% Match any literal that matches Pattern case insensitively,
% where the `*' character in Pattern matches zero or more
% characters.
%
% Backtracking never returns duplicate triples. Duplicates can be
% retrieved using rdf/4. The predicate rdf/3 raises a type-error
% if called with improper arguments. If rdf/3 is called with a
% term literal(_) as Subject or Predicate object it fails
% silently. This allows for graph matching goals like
% rdf(S,P,O),rdf(O,P2,O2) to proceed without errors.
%% rdf(?Subject, ?Predicate, ?Object, ?Source) is nondet.
%
% As rdf/3 but in addition query the graph to which the triple
% belongs. Unlike rdf/3, this predicate does not remove duplicates
% from the result set.
%
% @param Source is a term Graph:Line. If Source is instatiated,
% passing an atom is the same as passing Atom:_.
%% rdf_has(?Subject, +Predicate, ?Object) is nondet.
%
% Succeeds if the triple rdf(Subject, Predicate, Object) is true
% exploiting the rdfs:subPropertyOf predicate as well as inverse
% predicates declared using rdf_set_predicate/2 with the
% =inverse_of= property.
%% rdf_has(?Subject, +Predicate, ?Object, -RealPredicate) is nondet.
%
% Same as rdf_has/3, but RealPredicate is unified to the actual
% predicate that makes this relation true. RealPredicate must be
% Predicate or an rdfs:subPropertyOf Predicate. If an inverse
% match is found, RealPredicate is the term inverse_of(Pred).
%% rdf_reachable(?Subject, +Predicate, ?Object) is nondet.
%
% Is true if Object can be reached from Subject following the
% transitive predicate Predicate or a sub-property thereof, while
% repecting the symetric(true) or inverse_of(P2) properties.
%
% If used with either Subject or Object unbound, it first returns
% the origin, followed by the reachable nodes in breath-first
% search-order. The implementation internally looks one solution
% ahead and succeeds deterministically on the last solution. This
% predicate never generates the same node twice and is robust
% against cycles in the transitive relation.
%
% With all arguments instantiated, it succeeds deterministically
% if a path can be found from Subject to Object. Searching starts
% at Subject, assuming the branching factor is normally lower. A
% call with both Subject and Object unbound raises an
% instantiation error. The following example generates all
% subclasses of rdfs:Resource:
%
% ==
% ?- rdf_reachable(X, rdfs:subClassOf, rdfs:'Resource').
% X = 'http://www.w3.org/2000/01/rdf-schema#Resource' ;
% X = 'http://www.w3.org/2000/01/rdf-schema#Class' ;
% X = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#Property' ;
% ...
% ==
%% rdf_reachable(?Subject, +Predicate, ?Object, +MaxD, -D) is nondet.
%
% Same as rdf_reachable/3, but in addition, MaxD limits the number
% of edges expanded and D is unified with the `distance' between
% Subject and Object. Distance 0 means Subject and Object are the
% same resource. MaxD can be the constant =infinite= to impose no
% distance-limit.
%% rdf_subject(?Resource) is nondet.
%
% True if Resource appears as a subject. This query respects the
% visibility rules implied by the logical update view.
%
% @see rdf_resource/1.
rdf_subject(Resource) :-
rdf_resource(Resource),
( rdf(Resource, _, _) -> true ).
%% rdf_resource(?Resource) is nondet.
%
% True when Resource is a resource used as a subject or object in
% a triple.
%
% This predicate is primarily intended as a way to process all
% resources without processing resources twice. The user must be
% aware that some of the returned resources may not appear in any
% _visible_ triple.
/*******************************
* TRIPLE MODIFICATIONS *
*******************************/
%% rdf_assert(+Subject, +Predicate, +Object) is det.
%
% Assert a new triple into the database. This is equivalent to
% rdf_assert/4 using Graph =user=. Subject and Predicate are
% resources. Object is either a resource or a term literal(Value).
% See rdf/3 for an explanation of Value for typed and language
% qualified literals. All arguments are subject to name-space
% expansion. Complete duplicates (including the same graph and
% `line' and with a compatible `lifespan') are not added to the
% database.