/* Part of SWI-Prolog Author: Jan Wielemaker E-mail: J.Wielemaker@vu.nl WWW: http://www.swi-prolog.org Copyright (c) 2009-2022, University of Amsterdam VU University Amsterdam CWI, 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_turtle_write, [ rdf_save_turtle/2, % +File, +Options rdf_save_canonical_turtle/2, % +File, +Options rdf_save_trig/2, % +File, +Options rdf_save_canonical_trig/2, % +File, +Options rdf_save_ntriples/2 % +File, +Options ]). :- use_module(library(record),[(record)/1, op(_,_,record)]). :- use_module(library(semweb/turtle), []). % we make calls to public preds here :- use_module(library(semweb/rdf_prefixes), [ rdf_current_prefix/2, rdf_global_id/2 ]). :- if(exists_source(library(semweb/rdf_db))). :- use_module(library(semweb/rdf_db), [ rdf_graph/1, rdf_graph_prefixes/3, rdf_is_bnode/1, rdf_equal/2, rdf_graph_property/2, rdf_statistics/1, rdf/4, rdf_resource/1, rdf_subject/1, rdf/3 ]). have_rdf_db. :- else. have_rdf_db :- fail. :- endif. :- autoload(library(apply),[maplist/3,include/3,partition/4]). :- autoload(library(debug),[assertion/1]). :- autoload(library(error),[must_be/2,existence_error/2,type_error/2]). :- autoload(library(lists), [append/2,reverse/2,delete/3,append/3,select/3,member/2]). :- autoload(library(option),[meta_options/3]). :- autoload(library(pairs), [ transpose_pairs/2, map_list_to_pairs/3, pairs_values/2, group_pairs_by_key/2 ]). :- autoload(library(rbtrees), [ ord_list_to_rbtree/2, rb_lookup/3, rb_insert/4, rb_empty/1, rb_update/5 ]). :- autoload(library(sgml), [xml_name/1,xml_is_dom/1,xsd_number_string/2]). :- autoload(library(sgml_write),[xml_write/2]). :- autoload(library(url),[file_name_to_url/2,parse_url/2]). :- predicate_options(rdf_save_turtle/2, 2, [ graph(atom), base(atom), encoding(oneof([utf8])), indent(nonneg), tab_distance(nonneg), silent(boolean), subject_white_lines(nonneg), align_prefixes(boolean), user_prefixes(boolean), prefixes(list), only_known_prefixes(boolean), comment(boolean), group(boolean), inline_bnodes(boolean), single_line_bnodes(boolean), abbreviate_literals(boolean), canonize_numbers(boolean), canonical(boolean), a(boolean), expand(any) ]). :- predicate_options(rdf_save_canonical_turtle/2, 2, [ pass_to(rdf_save_turtle/2, 2) ]). /** Turtle - Terse RDF Triple Language writer This module implements the Turtle language for representing the RDF triple model as defined by Dave Beckett from the Institute for Learning and Research Technology University of Bristol in the document: * http://www.w3.org/TeamSubmission/turtle/ * http://www.w3.org/TeamSubmission/2008/SUBM-turtle-20080114/#sec-conformance The Turtle format is designed as an RDF serialization that is easy to read and write by both machines and humans. Due to the latter property, this library goes a long way in trying to produce human-readable output. In addition to the human-readable format, this library can write a _canonical_ representation of RDF graphs. The canonical representation has the following properties: * Equivalent graphs result in the same document. Graphs are considered equivalent iff they contain the same _set_ of triples, regardless of the labeling of blank nodes in the graph. * Changes to the graph are diff-friendly. This means - Prefixes are combined in the header and thus changes to the namespaces only result in changes in the header. - Blank nodes that are used only once (including collections) are written in-line with the object they belong to. - For other blank nodes we to realise stable labeling that is based on property-values. @tbd Low-level string output takes 28% of the time. Move to C? */ :- record tw_state(graph, % graph being saved graphs:list(atom), % TriG graphs being saved base, % The base-URI encoding=utf8, % Desired encoding indent:nonneg=8, % Indent for ; and ,-lists tab_distance:nonneg=8, % Tab distance silent:boolean=false, % If true, do not print a message subject_white_lines:nonneg=1,%Extra lines between subjects a:boolean=true, % Use 'a' for rdf:type align_prefixes:boolean=true,%Align prefix declarations prefixes:list, % Provide prefixes user_prefixes:boolean=true,% Use rdf_current_ns/2? only_known_prefixes:boolean=false,% Only use known prefixes comment:boolean=true, % write some comments into the file group:boolean=true, % Group using ; and , inline_bnodes:boolean=true, % Inline single-used bnodes single_line_bnodes:boolean=false, % No newline after ; abbreviate_literals:boolean=true, % Abbreviate known types canonize_numbers:boolean=false, % How to write numbers canonical:boolean=false, expand:any=lookup, % Access to the triples % Private fields bnode_id=0, % Incrementing bnode-id nodeid_map, % RBTree mapping NodeIDs to Refs bnode_hash, % RBTree holding reuse-count of hashes subject_count=0, % # subjects saved triple_count=0, % # triples saved base_root, % Root URL of base base_dir, % Directory base_path, % Path of base prefix_map). % List of Prefix-Map :- meta_predicate rdf_save_turtle(+, :), rdf_save_canonical_turtle(+, :), rdf_save_canonical_trig(+, :), rdf_save_trig(+, :). %! rdf_save_turtle(+Out, :Options) is det. % % Save an RDF graph as Turtle. Options processed are: % % * a(+Boolean) % If =true= (default), use =a= for the predicate =rdf:type=. % Otherwise use the full resource. % * align_prefixes(+Boolean) % Nicely align the @prefix declarations % * base(+Base) % Save relative to the given Base % * canonize_numbers(+Boolean) % If =true= (default =false=), emit numeric datatypes using % Prolog's write to achieve canonical output. % * comment(+Boolean) % It =true= (default), write some informative comments % between the output segments % * encoding(+Encoding) % Encoding used for the output stream. Default is UTF-8. % * expand(:Goal) % Query an alternative graph-representation. See below. % * indent(+Column) % Indentation for ; -lists. `0' does not indent, but % writes on the same line. Default is 8. % * graph(+Graph) % Save only the named graph % * group(+Boolean) % If =true= (default), using P-O and O-grouping. % * inline_bnodes(+Boolean) % if =true= (default), inline bnodes that are used once. % * abbreviate_literals(+Boolean) % if =true= (default), omit the type if allowed by turtle. % * only_known_prefixes(+Boolean) % Only use prefix notation for known prefixes. Without, some % documents produce _huge_ amounts of prefixes. % * prefixes(+List) % If provided, uses exactly these prefixes. List is a list % of prefix specifications, where each specification is either % a term _Prefix_-_URI_ or a prefix that is known to % rdf_current_prefix/2. % * silent(+Boolean) % If =true= (default =false=), do not print the final % informational message. % * single_line_bnodes(+Bool) % If =true= (default =false=), write [...] and (...) on a % single line. % * subject_white_lines(+Count) % Extra white lines to insert between statements about a % different subject. Default is 1. % * tab_distance(+Tab) % Distance between tab-stops. `0' forces the library to % use only spaces for layout. Default is 8. % * user_prefixes(+Boolean) % If =true= (default), use prefixes from rdf_current_prefix/2. % % The option =expand= allows for serializing alternative graph % representations. It is called through call/5, where the first % argument is the expand-option, followed by S,P,O,G. G is the % graph-option (which is by default a variable). This notably % allows for writing RDF graphs represented as rdf(S,P,O) using % the following code fragment: % % == % triple_in(RDF, S,P,O,_G) :- % member(rdf(S,P,O), RDF). % % ..., % rdf_save_turtle(Out, [ expand(triple_in(RDF)) ]), % == % % @param Out is one of stream(Stream), a stream handle, a file-URL % or an atom that denotes a filename. rdf_save_turtle(Spec, QOptions) :- meta_options(is_meta, QOptions, Options), statistics(cputime, T0), must_be(list, Options), make_tw_state(Options, State0, _Rest), init_base(State0, State1), init_prefix_map(State1, State), tw_state_encoding(State, Enc), setup_call_cleanup( open_output(Spec, Enc, Stream, Cleanup), ( tw_prefix_map(State, Stream), tw_graph(State, Stream) ), Cleanup), statistics(cputime, T1), Time is T1-T0, tw_state_triple_count(State, SavedTriples), tw_state_subject_count(State, SavedSubjects), ( tw_state_silent(State, true) -> true ; print_message(informational, rdf(saved(Spec, Time, SavedSubjects, SavedTriples))) ). is_meta(expand). %! rdf_save_canonical_turtle(+Spec, :Options) is det. % % Save triples in a canonical format. This is the same as % rdf_save_turtle/2, but using different defaults. In particular: % % * encoding(utf8), % * indent(0), % * tab_distance(0), % * subject_white_lines(1), % * align_prefixes(false), % * user_prefixes(false) % * comment(false), % * group(false), % * single_line_bnodes(true) % % @tbd Work in progress. Notably blank-node handling is % incomplete. rdf_save_canonical_turtle(Spec, M:Options) :- canonical_options(CannonicalOptions, Options), rdf_save_turtle(Spec, M:CannonicalOptions). canonical_options([ encoding(utf8), indent(0), tab_distance(0), subject_white_lines(1), align_prefixes(false), user_prefixes(false), comment(false), group(false), single_line_bnodes(true), canonical(true) | Options ], Options). %! rdf_save_ntriples(+Spec, :Options) is det. % % Save RDF using ntriples format. The ntriples format is a subset % of Turtle, writing each triple fully qualified on its own line. rdf_save_ntriples(File, Options):- rdf_save_turtle(File, [ comment(false), encoding(utf8), group(false), prefixes([]), subject_white_lines(0), a(false), inline_bnodes(false), abbreviate_literals(false) | Options ]). %! rdf_save_trig(+Spec, :Options) is det. % % Save multiple RDF graphs into a TriG file. Options are the same % as for rdf_save_turtle/2. rdf_save_trig/2 ignores the % graph(+Graph) option and instead processes one additional % option: % % - graphs(+ListOfGraphs) % List of graphs to save. When omitted, all graphs in the RDF % store are stored in the TriG file. rdf_save_trig(Spec, QOptions) :- meta_options(is_meta, QOptions, Options), thread_self(Me), thread_statistics(Me, cputime, T0), must_be(list, Options), make_tw_state(Options, State0, _Rest), init_base(State0, State1), trig_graphs(State1, Graphs), init_prefix_map(State1, Graphs, State2), tw_state_encoding(State2, Enc), setup_call_cleanup( open_output(Spec, Enc, Stream, Cleanup), ( tw_prefix_map(State2, Stream), tw_trig_graphs(Graphs, Stream, State2, State) ), Cleanup), thread_statistics(Me, cputime, T1), Time is T1-T0, tw_state_triple_count(State, SavedTriples), tw_state_subject_count(State, SavedSubjects), length(Graphs, SavedGraphs), ( tw_state_silent(State, true) -> true ; print_message(informational, rdf(saved(Spec, Time, SavedSubjects, SavedTriples, SavedGraphs))) ). %! rdf_save_canonical_trig(+Spec, :Options) is det. % % Save triples in a canonical format. See % rdf_save_canonical_turtle/2 foir details. rdf_save_canonical_trig(Spec, M:Options) :- canonical_options(CannonicalOptions, Options), rdf_save_trig(Spec, M:CannonicalOptions). tw_trig_graphs([], _, State, State). tw_trig_graphs([H|T], Stream, State0, State) :- set_graph_of_tw_state(H, State0, State1), nl(Stream), tw_resource(H, State1, Stream), format(Stream, ' {~n', []), tw_graph(State1, Stream), format(Stream, '~N}~n', []), set_bnode_id_of_tw_state(0, State1, State2), set_nodeid_map_of_tw_state(_, State2, State3), set_bnode_hash_of_tw_state(_, State3, State4), tw_trig_graphs(T, Stream, State4, State). %! trig_graphs(+State, -Graphs) is det. % % True when Graphs is the (sorted) list of graphs we must save. If % the _expand_ argument is used and no graphs are specified, it % enumerates all triples and extracts the graphs. trig_graphs(State, Graphs) :- tw_state_graphs(State, Graphs), ( nonvar(Graphs) -> true ; tw_state_expand(State, Expand), graphs(Expand, Graphs0), sort(Graphs0, Graphs) ). :- if(have_rdf_db). graphs(lookup, Graphs) :- findall(G, rdf_graph(G), Graphs). :- endif. graphs(Expand, Graphs) :- findall(G, distinct(G, call(Expand,_S,_P,_O,G)), Graphs). %! open_output(+Spec, +Encoding, -Stream, -Cleanup) is det. % % Open output Spec, returning a stream using Encoding. % % @param Cleanup is a goal that must be used to revert the side % effects of open_output/4. open_output(stream(Out), Encoding, Out, Cleanup) :- !, stream_property(Out, encoding(Old)), ( ( Old == Encoding ; Old == wchar_t % Internal encoding ) -> Cleanup = true ; set_stream(Out, encoding(Encoding)), Cleanup = set_stream(Out, encoding(Old)) ). open_output(Stream, Encoding, Out, Cleanup) :- \+ atom(Stream), is_stream(Stream), !, open_output(stream(Stream), Encoding, Out, Cleanup). open_output(Spec, Encoding, Out, close(Out)) :- out_to_file(Spec, File), open(File, write, Out, [encoding(Encoding)]). out_to_file(URL, File) :- atom(URL), file_name_to_url(File, URL), !. out_to_file(File, File). /******************************* * PREFIXES * *******************************/ %! init_prefix_map(+State, -State) is det. % % Set the prefix_map of State. The prefix map is list of % Prefix-URI of prefixes to use for emitting the graph requested % in State. If multiple prefixes are present where the one is a % prefix of the other, the longer one appears first in the list. init_prefix_map(State0, State) :- tw_state_prefixes(State0, Prefixes), nonvar(Prefixes), !, user_prefix_map(Prefixes, PrefixMap), set_prefix_map_of_tw_state(PrefixMap, State0, State). init_prefix_map(State0, State) :- tw_state_graph(State0, Graph), graph_prefix_map(State0, Graph, PrefixMap), set_prefix_map_of_tw_state(PrefixMap, State0, State). init_prefix_map(State0, _Graphs, State) :- % TriG version tw_state_prefixes(State0, Prefixes), nonvar(Prefixes), !, user_prefix_map(Prefixes, PrefixMap), set_prefix_map_of_tw_state(PrefixMap, State0, State). init_prefix_map(State0, Graphs, State) :- % TriG version maplist(graph_prefixes(State0), Graphs, NestedPrefixes), append(NestedPrefixes, Prefixes0), sort(Prefixes0, Prefixes), prefix_map(State0, Prefixes, PrefixMap), set_prefix_map_of_tw_state(PrefixMap, State0, State). graph_prefix_map(State, Graph, PrefixMap) :- graph_prefixes(State, Graph, Prefixes), prefix_map(State, Prefixes, PrefixMap). graph_prefixes(State0, Graph, Prefixes) :- tw_state_expand(State0, Expand), tw_state_only_known_prefixes(State0, OnlyKnown), rdf_graph_prefixes(Graph, Prefixes, [ filter(turtle_prefix(OnlyKnown)), expand(Expand), min_count(2), get_prefix(turtle:iri_turtle_prefix) ]). prefix_map(State, Prefixes, PrefixMap) :- remove_base(State, Prefixes, Prefixes2), prefix_names(Prefixes2, State, Pairs), transpose_pairs(Pairs, URI_Abrevs), reverse(URI_Abrevs, RURI_Abrevs), flip_pairs(RURI_Abrevs, PrefixMap). %! user_prefix_map(+Prefixes, -PrefixMap) is det. % % Convert a list of prefix specifications to a list Prefix-URI, % longest URI first. user_prefix_map(Prefixes, PrefixMap) :- must_be(list, Prefixes), maplist(prefix_pair, Prefixes, Pairs), map_list_to_pairs(prefix_length, Pairs, LenPairs), sort(LenPairs, LenPairs1), pairs_values(LenPairs1, RevPrefixMap), reverse(RevPrefixMap, PrefixMap). prefix_pair(Prefix-URI, Prefix-URI) :- !, must_be(atom, Prefix), must_be(atom, URI). prefix_pair(Prefix, Prefix-URI) :- must_be(atom, Prefix), ( rdf_current_prefix(Prefix, URI) -> true ; existence_error(prefix, Prefix) ). prefix_length(_-URI, Len) :- atom_length(URI, Len). %! turtle_prefix(+OnlyKnown, +Where, +Prefix, +URI) is semidet. % % Test whether we want to include the proposed prefix in the % @prefix declaration. :- public turtle_prefix/4. % called through rdf_graph_prefixes/3. turtle_prefix(true, _, Prefix, _) :- !, rdf_current_prefix(_, Prefix), !. turtle_prefix(_, _, Prefix, URI) :- sub_atom(Prefix, _, 1, 0, Last), turtle_prefix_char(Last), atom_concat(Prefix, Local, URI), \+ sub_atom(Local, _, _, _, '.'). turtle_prefix_char('#'). turtle_prefix_char('/'). remove_base(State, Prefixes, PrefixesNoBase) :- tw_state_base_dir(State, BaseDir), atom(BaseDir), !, delete(Prefixes, BaseDir, PrefixesNoBase). remove_base(_State, Prefixes, Prefixes). flip_pairs([], []). flip_pairs([Key-Val|Pairs], [Val-Key|Flipped]) :- flip_pairs(Pairs, Flipped). prefix_names(URIs, State, Prefixes) :- prefix_names(URIs, State, 1, Prefixes, []). prefix_names([], _, _, List, List) :- !. prefix_names(URIs, State, Len, Prefixes, Tail) :- prefix_names(URIs, State, Len, Prefixes, PTail, Rest), Len1 is Len + 1, prefix_names(Rest, State, Len1, PTail, Tail). prefix_names(URIs, State, Len, Prefixes, PTail, Rest) :- map_list_to_pairs(propose_abbrev(State, Len), URIs, Pairs), !, keysort(Pairs, Sorted), unique(Sorted, Prefixes, PTail, Rest). prefix_names(URIs, _, _, Prefixes, PTail, []) :- number_prefixes(URIs, 1, Prefixes, PTail). number_prefixes([], _, PL, PL). number_prefixes([H|T0], N, [P-H|PL], T) :- atomic_concat(ns, N, P), succ(N, N1), number_prefixes(T0, N1, PL, T). unique([], L, L, []). unique([A-U|T0], [A-U|T], L, Rest) :- T0 \= [A-_|_], !, unique(T0, T, L, Rest). unique([A-U|T0], Prefixes, L, [U|Rest0]) :- strip_keys(T0, A, T1, Rest0, Rest), unique(T1, Prefixes, L, Rest). strip_keys([A-U|T0], A, T, [U|R0], R) :- !, strip_keys(T0, A, T, R0, R). strip_keys(L, _, L, R, R). %! propose_abbrev(+State, +Len, +URI, -Abbrev) is multi. % % Propose an abbreviation for URI. Backtracking yields longer % ones. propose_abbrev(_, _, URI, Abbrev) :- well_known_ns(Abbrev, URI), !. propose_abbrev(State, _, URI, Abbrev) :- tw_state_user_prefixes(State, true), rdf_current_prefix(Abbrev, URI), !. propose_abbrev(_, Len, URI, Abbrev) :- namespace_parts(URI, Parts), include(abbrev_part, Parts, Names), reverse(Names, RevNames), length(Use, Len), append(Use, _, RevNames), atomic_list_concat(Use, -, Abbrev). abbrev_part(X) :- xml_name(X), \+ well_known_ns(X, _), \+ well_known_extension(X). well_known_ns(rdf, 'http://www.w3.org/1999/02/22-rdf-syntax-ns#'). well_known_ns(rdfs, 'http://www.w3.org/2000/01/rdf-schema#'). well_known_ns(owl, 'http://www.w3.org/2002/07/owl#'). well_known_ns(xsd, 'http://www.w3.org/2001/XMLSchema#'). well_known_ns(dc, 'http://purl.org/dc/elements/1.1/'). well_known_extension(ttl). well_known_extension(nt). well_known_extension(n3). well_known_extension(xml). well_known_extension(rdf). well_known_extension(owl). %! namespace_parts(+URL, -Parts) namespace_parts(URL, Parts) :- atom_codes(URL, Codes), phrase(parts(Parts), Codes), !. namespace_parts(URL, _) :- format(user_error, 'Couldn\'t split ~q~n', [URL]), fail. parts(List) --> sep2, parts2(List). parts2([H|T]) --> string(Codes), {Codes \== []}, sep, !, {atom_codes(H, Codes)}, parts2(T). parts2([]) --> []. string([]) --> []. string([H|T]) --> [H], string(T). sep --> sep_char, sep2. sep([], []). sep2 --> sep_char, !, sep2. sep2 --> []. sep_char --> "/". sep_char --> ":". sep_char --> ".". sep_char --> "?". sep_char --> "#". %! init_base(+State0, -State) is det. % % Initialise dealing with the base URI. It sets two attributes of % the state: base_root and base_path. init_base(State0, State) :- tw_state_base(State0, BaseURI), atom(BaseURI), !, parse_url(BaseURI, Attributes), include(root_part, Attributes, RootAttrs), parse_url(BaseRoot, RootAttrs), memberchk(path(BasePath), Attributes), file_directory_name(BasePath, BaseDir), atomic_list_concat([BaseRoot, BaseDir, /], BaseDirURI), set_base_root_of_tw_state(BaseRoot, State0, State1), set_base_path_of_tw_state(BasePath, State1, State2), set_base_dir_of_tw_state(BaseDirURI, State2, State). init_base(State, State). root_part(protocol(_)). root_part(host(_)). root_part(port(_)). /******************************* * SAVE * *******************************/ %! tw_graph(+State, +Out) is det. % % Write an RDF graph as Turtle data. % % @tbd Write unconnected and multi-connected blank-nodes. tw_graph(State, Out) :- subjects(State, Subjects), length(Subjects, SubjectCount), inc_subject_count(State, SubjectCount), partition(rdf_is_bnode, Subjects, BNodes, ProperSubjects), maplist(pair_var, BNodes, Pairs), ord_list_to_rbtree(Pairs, BNTree), tw_state_nodeid_map(State, BNTree), ( ProperSubjects == [] -> true ; length(ProperSubjects, PSCount), comment(State, 'Named toplevel resources (~D)', [PSCount], Out), tw_proper_subjects(ProperSubjects, State, Out) ), tw_bnodes(Pairs, State, Out). pair_var(BNode, BNode-_). tw_prefix_map(State, Out) :- tw_state_prefix_map(State, PrefixMap), tw_prefix_map(PrefixMap, State, Out). %! tw_prefix_map(+PrefixMap, +State, +Out) is det. % % Write the @base and @prefix declarations tw_prefix_map(PrefixMap, State, Out) :- tw_state_align_prefixes(State, true), !, longest_prefix(PrefixMap, 0, Length), PrefixCol is Length+10, tw_base(PrefixCol, State, Out), tw_prefix_map(PrefixMap, PrefixCol, State, Out). tw_prefix_map(PrefixMap, State, Out) :- tw_base(0, State, Out), tw_prefix_map(PrefixMap, 0, State, Out). longest_prefix([], L, L). longest_prefix([Prefix-_|T], L0, L) :- atom_length(Prefix, L1), L2 is max(L0, L1), longest_prefix(T, L2, L). tw_base(Col, State, Out) :- tw_state_base(State, Base), atom(Base), !, format(Out, '@base ~t~*|', [Col]), turtle:turtle_write_uri(Out, Base), format(Out, ' .~n', []). tw_base(_, _, _). tw_prefix_map([], _, _, _). tw_prefix_map([Prefix-URI|T], Col, State, Out) :- format(Out, '@prefix ~t~w: ~*|', [Prefix, Col]), tw_relative_uri(URI, State, Out), format(Out, ' .~n', []), ( T == [] -> true ; tw_prefix_map(T, Col, State, Out) ). %! tw_proper_subjects(+Subjects, +State, +Out) is det. % % Write the subjects that are not Bnodes. tw_proper_subjects([], _, _). tw_proper_subjects([H|T], State, Out) :- separate_subjects(State, Out), tw_subject(H, H, State, Out), tw_proper_subjects(T, State, Out). separate_subjects(State, Out) :- tw_state_subject_white_lines(State, ExtraLines), put_n(ExtraLines, '\n', Out). %! tw_subject(+URI, +State, +Out) is det. % % Write a toplevel non-bnode subject. tw_subject(URI, Ref, State, Out) :- subject_triples(URI, State, Pairs), length(Pairs, Count), inc_triple_count(State, Count), group_po(Pairs, Grouped), tw_subject_triples(Grouped, Ref, State, Out). group_po(Pairs, Grouped) :- group_pairs_by_key(Pairs, Grouped0), rdf_equal(rdf:type, RDFType), ( select(RDFType-Types, Grouped0, Grouped1) -> Grouped = [RDFType-Types|Grouped1] ; Grouped = Grouped0 ). %! tw_bnodes(+Pairs, +State, +Out) is det. % % Write the Bnodes. Pairs is a list URI-Ref, where Ref is one of % =written= if the Bnode is already written; an integer if it is % used multiple times or a variable if it has not been written. % The order in which we deal with bnodes is defined as follows: % % * First, write the bnodes that are not referenced at all % as toplevel bnodes using [ ... ] notation. % % * Next, write the bnodes that need written as toplevel % nodes using the _:XX notation because they are referenced % multiple times in the graph. Continue this process until it % is exhausted. tw_bnodes(Pairs, State, Out) :- tw_top_bnodes(Pairs, State, Out, Rest1), tw_numbered_bnodes(Rest1, State, Out, 1, Rest2), tw_cyclic_bnodes(Rest2, State, Out, 0). tw_numbered_bnodes([], _, _, _, []) :- !. tw_numbered_bnodes(Pairs, State, Out, Level, Rest) :- multi_referenced(Pairs, RefPairs, Rest0), ( RefPairs == [] -> Rest = Rest0 ; length(RefPairs, Count), comment(State, 'Level ~D multi-referenced blank-nodes (~D)', [ Level, Count ], Out), tw_ref_bnodes(RefPairs, State, Out), Level1 is Level + 1, tw_numbered_bnodes(Rest0, State, Out, Level1, Rest) ). multi_referenced([], [], []). multi_referenced([H|T], RefPairs, Rest) :- H = _-Ref, ( Ref == written -> multi_referenced(T, RefPairs, Rest) ; var(Ref) -> Rest = [H|TR], multi_referenced(T, RefPairs, TR) ; assertion(Ref = bnode(_)), RefPairs = [H|TRP], % assigned reference multi_referenced(T, TRP, Rest) ). tw_ref_bnodes([], _, _). tw_ref_bnodes([BNode-Ref|T], State, Out) :- separate_subjects(State, Out), tw_subject(BNode, Ref, State, Out), tw_ref_bnodes(T, State, Out). %! tw_top_bnodes(+Pairs, +State, +Out, -Rest) % % Write the top bnodes: those that do not appear as an object % anywhere. tw_top_bnodes(Pairs, State, Out, Rest) :- unreferenced(Pairs, State, TopBNodes, Rest), ( TopBNodes == [] -> true ; length(TopBNodes, Count), comment(State, 'Toplevel blank-nodes (~D)', [Count], Out), sort_bnodes(TopBNodes, SortedTopBNodes, State), tw_top_bnodes(SortedTopBNodes, State, Out) ). unreferenced([], _, [], []). unreferenced([H|T], State, UnrefPairs, Rest) :- H = BNode-Ref, ( Ref == written -> unreferenced(T, State, UnrefPairs, Rest) ; var(Ref), object_link_count(BNode, State, 0) -> UnrefPairs = [H|URT], unreferenced(T, State, URT, Rest) ; Rest = [H|TR], unreferenced(T, State, UnrefPairs, TR) ). tw_top_bnodes([], _, _). tw_top_bnodes([BNode-_|T], State, Out) :- tw_bnode(BNode, State, Out), tw_top_bnodes(T, State, Out). tw_bnode(BNode, State, Out) :- subject_triples(BNode, State, Pairs), length(Pairs, Count), inc_triple_count(State, Count), ( tw_state_inline_bnodes(State, true) -> tw_bnode_triples(Pairs, State, Out), format(Out, ' .~n', []) ; next_bnode_id(State, BNode, Ref), tw_bnode_ntriples(Pairs, Ref, State, Out) ). tw_bnode_triples(Pairs, State, Out) :- group_po(Pairs, Grouped), ( tw_state_single_line_bnodes(State, true) -> format(Out, '[ ', []), tw_triples(Grouped, -1, State, Out), format(Out, ' ]', []) ; line_position(Out, Indent), format(Out, '[ ', []), line_position(Out, AIndent), tw_triples(Grouped, AIndent, State, Out), nl_indent(Out, State, Indent), format(Out, ']', []) ). tw_bnode_ntriples([], _, _, _). tw_bnode_ntriples([P-O|T], Ref, State, Out) :- tw_bnode_ref(Ref, Out), format(Out, ' ', []), tw_predicate(P, State, Out), format(Out, ' ', []), tw_object(O, State, Out), format(Out, ' .~n', []), tw_bnode_ntriples(T, Ref, State, Out). %! tw_cyclic_bnodes(+Pairs, +BNode, +State, +Out, +Cycle) % % The rest. These are groups of bnodes that are reachable, but we % cannot find a starting point, neither from a named resource, nor % from an unlinked bnode. As long as we are not considering stable % canonical output, we can break the cycle at any point. tw_cyclic_bnodes([], _State, _Out, _) :- !. tw_cyclic_bnodes(Pairs, State, Out, Cycle0) :- ( tw_state_canonical(State, true) -> sort_bnode_pairs(Pairs, BNodes, State) ; BNodes = Pairs ), succ(Cycle0, Cycle), BNodes = [BNode-Ref|_], next_bnode_id(State, BNode, Ref), comment(State, 'Breaking cycle ~D', [Cycle], Out), tw_numbered_bnodes(Pairs, State, Out, 1, Rest), tw_cyclic_bnodes(Rest, State, Out, Cycle). %! tw_subject_triples(+Grouped, +Subject, +State, +Out) % % Save triples on Subject. Combine groups of triples with the % same subject (;) and same subject+predicate (,). % % @param Subject is either a URI or an integer. The latter is % used for writing a named bnode. tw_subject_triples([], _, _, _) :- !. tw_subject_triples(Grouped, URI, State, Out) :- tw_state_group(State, false), !, tw_ungrouped_triples(Grouped, URI, State, Out). tw_subject_triples(Grouped, URI, State, Out) :- tw_resource(URI, State, Out), ( tw_state_indent(State, Indent), Indent > 0 -> nl_indent(Out, State, Indent) ; put_char(Out, ' '), line_position(Out, Indent) ), tw_triples(Grouped, Indent, State, Out), format(Out, ' .~n', []). %! tw_ungrouped_triples(+Grouped, +URI, +State, +Out) % % Write triples for subject URI as one line per triple. Used % for canonical output. tw_ungrouped_triples([], _, _, _). tw_ungrouped_triples([P-Vs|Groups], URI, State, Out) :- partition(rdf_is_bnode, Vs, BNVs, ProperVs), tw_ungrouped_values(ProperVs, P, URI, State, Out), sort_bnodes(BNVs, SortedBNVs, State), tw_ungrouped_values(SortedBNVs, P, URI, State, Out), tw_ungrouped_triples(Groups, URI, State, Out). tw_ungrouped_values([], _, _, _, _). tw_ungrouped_values([V|T], P, URI, State, Out) :- tw_resource(URI, State, Out), put_char(Out, ' '), tw_predicate(P, State, Out), put_char(Out, ' '), tw_object(V, State, Out), format(Out, ' .~n', []), tw_ungrouped_values(T, P, URI, State, Out). %! tw_triples(+Groups, +Indent, +State, +Out) is det. % % Triple writer that uses ; and ,- grouping tw_triples([P-Vs|MoreGroups], Indent, State, Out) :- tw_write_pvs(Vs, P, State, Out), ( MoreGroups == [] -> true ; format(Out, ' ;', []), nl_indent(Out, State, Indent), tw_triples(MoreGroups, Indent, State, Out) ). tw_write_pvs(Values, P, State, Out) :- tw_predicate(P, State, Out), put_char(Out, ' '), line_position(Out, Indent), tw_write_vs(Values, Indent, State, Out). tw_predicate(P, State, Out) :- ( rdf_equal(P, rdf:type), tw_state_a(State, true) -> format(Out, 'a', []) ; tw_resource(P, State, Out) ). tw_write_vs([H|T], Indent, State, Out) :- tw_object(H, State, Out), ( T == [] -> true ; format(Out, ' ,', []), nl_indent(Out, State, Indent), tw_write_vs(T, Indent, State, Out) ). %! tw_object(+Value, +State, +Out) is det. % % Write the object of a triple. tw_object(Value, State, Out) :- rdf_is_bnode(Value), !, tw_bnode_object(Value, State, Out). tw_object(Value, State, Out) :- atom(Value), !, tw_resource(Value, State, Out). tw_object(Literal, State, Out) :- tw_literal(Literal, State, Out). %! tw_bnode_object(+Value, +State, +Out) is det. % % Write a Bnode value. There are a number of cases: % % * The BNode was already written. Write the same ref. % * The BNode is not shared. Inline and set =written= % * The BNode is shared. Generate a NodeID and store it % * The BNode is once as object: Generate a NodeID % * The BNode is more than once object: Generate a NodeID % and put in table. tw_bnode_object(BNode, State, Out) :- tw_state_nodeid_map(State, BNTree), rb_lookup(BNode, Ref, BNTree), !, ( var(Ref) -> ( tw_state_inline_bnodes(State, true), tw_unshared_bnode(BNode, State, Out) -> Ref = written ; next_bnode_id(State, BNode, Ref), tw_bnode_ref(Ref, Out) ) ; tw_bnode_ref(Ref, Out) ). tw_bnode_object(BNode, State, Out) :- object_link_count(BNode, State, N), N > 1, !, tw_state_nodeid_map(State, BNTree0), rb_insert(BNTree0, BNode, Ref, BNTree), set_nodeid_map_of_tw_state(BNTree, State), next_bnode_id(State, BNode, Ref), tw_bnode_ref(Ref, Out). tw_bnode_object(BNode, State, Out) :- next_bnode_id(State, BNode, Ref), tw_bnode_ref(Ref, Out). tw_bnode_ref(bnode(Ref), Out) :- ( integer(Ref) -> format(Out, '_:bn~w', [Ref]) ; format(Out, '_:~w', [Ref]) ). %! tw_unshared_bnode(+BNode, +State, +Out) is semidet. % % Write a bnode if this is the only place it is used. tw_unshared_bnode(BNode, State, Out) :- object_link_count(BNode, State, 1), subject_triples(BNode, State, Pairs), ( Pairs == [] -> format(Out, '[]', []) ; pairs_unshared_collection(Pairs, State, Collection) -> ( Collection == [] -> format(Out, '()', []) ; tw_state_nodeid_map(State, BNTree), rb_lookup(BNode, written, BNTree), length(Collection, NMembers), Triples is 2*NMembers, inc_triple_count(State, Triples), ( tw_state_single_line_bnodes(State, true) -> format(Out, '( ', []), tw_collection(Collection, -1, State, Out), format(Out, ' )', []) ; line_position(Out, Indent), format(Out, '( ', []), line_position(Out, AIndent), tw_collection(Collection, AIndent, State, Out), nl_indent(Out, State, Indent), format(Out, ')', []) ) ) ; tw_bnode_triples(Pairs, State, Out) ). tw_collection([H|T], Indent, State, Out) :- tw_object(H, State, Out), ( T \== [] -> nl_indent(Out, State, Indent), tw_collection(T, Indent, State, Out) ; true ). %! unshared_collection(+URI, +State, -Members) is semidet. % % True if URI denodes an RDF list that is made up from bnodes, is % linked exactly once to its context and contains no extra % triples. unshared_collection(C, _, []) :- rdf_equal(C, rdf:nil), !. unshared_collection(C, State, List) :- rdf_is_bnode(C), object_link_count(C, State, 1), tw_state_nodeid_map(State, BNTree), rb_lookup(C, written, BNTree), subject_triples(C, State, Pairs), pairs_unshared_collection(Pairs, State, List). pairs_unshared_collection(Pairs, State, [H|T]) :- rdf_equal(rdf:first, RDFFirst), rdf_equal(rdf:rest, RDFRest), Pairs = [ RDFFirst-H, RDFRest-Rest | More ], ( More == [] ; rdf_equal(rdf:type, RDFType), rdf_equal(rdf:'List', RDFList), More == [RDFType-RDFList] ), unshared_collection(Rest, State, T). %! object_link_count(+BNode, +STate, -Count) is det. % % Number of times BNode is used as an object in the graph object_link_count(BNode, State, Count) :- tw_state_graph(State, Graph), tw_state_expand(State, Expand), findall(S-P, call(Expand,S,P,BNode,Graph), Pairs0), sort(Pairs0, Pairs), % remove duplicates length(Pairs, Count). %! nl_indent(+Out, +State, +Indent) is det. % % Write a newline and indent to column Indent. nl_indent(Out, _, -1) :- !, put_char(Out, ' '). nl_indent(Out, State, Indent) :- nl(Out), tw_state_tab_distance(State, TD), ( TD == 0 -> tab(Out, Indent) ; Tabs is Indent//TD, Spaces is Indent mod TD, put_n(Tabs, '\t', Out), put_n(Spaces, ' ', Out) ). put_n(N, Char, Out) :- N > 0, !, put_char(Out, Char), N2 is N - 1, put_n(N2, Char, Out). put_n(_, _, _). %! subject_triples(+URI, +State, -Pairs) is det. % % Pairs is a sorted list of P-O pairs representing all triples on % the subject URI. subject_triples(URI, State, Pairs) :- tw_state_graph(State, Graph), tw_state_expand(State, Expand), findall(P-O, call(Expand, URI, P, O, Graph), Pairs0), sort(Pairs0, Pairs). /******************************* * GRAPH-LOGIC * *******************************/ %! subjects(+State, -Subjects:ord_set) is det. % % Subjects is a list of all subjects in the graph requested in % State. subjects(State, Subjects) :- tw_state_expand(State, Expand), tw_state_graph(State, Graph), ( Expand == lookup, atom(Graph), ( rdf_graph_property(Graph, triples(Count)) -> true ; Count = 0 % non-existing graph ), rdf_statistics(triples(Total)), Count * 10 < Total -> findall(S, rdf(S,_,_,Graph), List), sort(List, Subjects) ; Expand \== lookup -> findall(S, call(Expand, S,_,_,Graph), List), sort(List, Subjects) ; findall(Subject, subject(State, Subject), AllSubjects), sort(AllSubjects, Subjects) ). subject(State, Subject) :- tw_state_graph(State, Graph), ( atom(Graph) -> rdf_resource(Subject), ( rdf(Subject, _, _, Graph) -> true ) ; rdf_subject(Subject) ). :- if(have_rdf_db). :- public lookup/4. % called from expand hook. lookup(S,P,O,G) :- ( var(G) -> rdf(S,P,O) ; rdf(S,P,O,G) ). :- else. lookup(_S,_P,_O,_G) :- print_message(error, turtle_write(no_rdf_db)), fail. :- endif. /******************************* * CANONICAL ORDERING * *******************************/ /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - This section deals with the two problems of canonical graphs: * Keep blank nodes in the same order * Assign stable names to blank nodes that we need to give a name. There are two cases: (1) a blank nodes is used in more than one place and (2) a blank node series is cyclic. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */ %! sort_bnodes(+BNodes, -Sorted, +State) is det. % % Sort a list of blank nodes. sort_bnodes(BNodes, Sorted, _State) :- sort(BNodes, Sorted). %! sort_bnode_pairs(+Pairs, -Sorted, +State) is det. % % Sort a list of Pairs BNode-Ref sort_bnode_pairs(Pairs, Sorted, _State) :- sort(Pairs, Sorted). %! bnode_to_term(+BNode, -Term, +State) % % Term is a canonical representation of the graph formed by BNode. % The transformation of a bnode is % % bnode(p-[o1,o2,..], ..) % % The arguments are alphabetically sorted on predicate (can't we % leave the preds out them?) and the objects are alphabetically % sorted. Sorting multiple bnode values? %! next_bnode_id(+State, +BNode, -Ref) is det. % % Generate a node-id for BNode. When writing non-canonically, we % simply number the bnodes. Otherwise we want a more stable % numbering. Our numbering is a hash of the content of the bnode. % It is not unlikely that we find muliple copies, and therefore we % number the full id is bn__, counting 0... next_bnode_id(State, _BNode, bnode(Ref)) :- tw_state_canonical(State, false), !, tw_state_bnode_id(State, Ref0), Ref is Ref0+1, nb_set_bnode_id_of_tw_state(Ref, State). next_bnode_id(State, BNode, bnode(Ref)) :- bnode_hash(BNode, Hash), tw_state_bnode_hash(State, BNHash), ( var(BNHash) -> rb_empty(BNHash) ; true ), ( rb_update(BNHash, Hash, C0, C, BNHash1) -> C is C0+1 ; C = 0, rb_insert(BNHash, Hash, C, BNHash1) ), set_bnode_hash_of_tw_state(BNHash1, State), format(atom(Ref), 'bn_~w_~d', [Hash, C]). %! bnode_hash(+BNode, -Hash) is det. % % Hash is the hash-value for a bnode. % % @tbd: Hash on content. bnode_hash(BNode, Hash) :- term_hash(BNode, Hash). /******************************* * PRIMITIVES * *******************************/ %! tw_resource(+Resource, +State, +Out) is det. % % Write a resource tw_resource(BNodeID, _, Out) :- BNodeID = bnode(_), !, tw_bnode_ref(BNodeID, Out). tw_resource(Resource, State, Out) :- tw_state_prefix_map(State, PrefixMap), member(Prefix-Full, PrefixMap), atom_concat(Full, Name, Resource), ( turtle:turtle_pn_local(Name) -> true ; Name == '' ), !, format(Out, '~w:', [Prefix]), turtle:turtle_write_pn_local(Out, Name). tw_resource(Resource, State, Out) :- tw_relative_uri(Resource, State, Out). tw_relative_uri(Resource, State, Out) :- tw_state_base_root(State, Root), atom(Root), atom_concat(Root, ResPath, Resource), sub_atom(ResPath, 0, _, _, /), tw_state_base_path(State, BasePath), relative_path(ResPath, BasePath, RelPath), !, turtle:turtle_write_uri(Out, RelPath). tw_relative_uri(Resource, _, Out) :- turtle:turtle_write_uri(Out, Resource). relative_path(Path, RelTo, RelPath) :- atomic_list_concat(PL, /, Path), atomic_list_concat(RL, /, RelTo), delete_common_prefix(PL, RL, PL1, PL2), to_dot_dot(PL2, DotDot, PL1), atomic_list_concat(DotDot, /, RelPath). delete_common_prefix([H|T01], [H|T02], T1, T2) :- !, delete_common_prefix(T01, T02, T1, T2). delete_common_prefix(T1, T2, T1, T2). to_dot_dot([], Tail, Tail). to_dot_dot([_], Tail, Tail) :- !. to_dot_dot([_|T0], ['..'|T], Tail) :- to_dot_dot(T0, T, Tail). %! tw_literal(+Literal, +State, +Out) is det. % % Write a literal value to the stream Out. tw_literal(^^(Value, Type), State, Out) :- !, tw_typed_literal(Type, Value, State, Out). tw_literal(literal(type(Type, Value)), State, Out) :- !, tw_typed_literal(Type, Value, State, Out). tw_literal(@(Value, Lang), State, Out) :- !, tw_quoted_string(Value, State, Out), downcase_atom(Lang, TurtleLang), % Turtle lang = [a-z]+('-'[a-z0-9]+)* format(Out, '@~w', [TurtleLang]). tw_literal(literal(lang(Lang, Value)), State, Out) :- !, tw_quoted_string(Value, State, Out), downcase_atom(Lang, TurtleLang), % Turtle lang = [a-z]+('-'[a-z0-9]+)* format(Out, '@~w', [TurtleLang]). tw_literal(literal(Value), State, Out) :- atom(Value), !, rdf_equal(xsd:string, TypeString), tw_typed_literal(TypeString, Value, State, Out). % Add types automatically tw_literal(literal(Value), State, Out) :- integer(Value), !, rdf_equal(Type, xsd:integer), tw_typed_literal(Type, Value, State, Out). tw_literal(literal(Value), State, Out) :- float(Value), !, rdf_equal(Type, xsd:double), tw_typed_literal(Type, Value, State, Out). tw_literal(literal(Value), State, Out) :- xml_is_dom(Value), !, rdf_equal(Type, rdf:'XMLLiteral'), tw_typed_literal(Type, Value, State, Out). tw_literal(Literal, _State, _Out) :- type_error(rdf_literal, Literal). tw_typed_literal(Type, Value, State, Out) :- tw_state_abbreviate_literals(State, true), tw_abbreviated_literal(Type, Value, State, Out), !. tw_typed_literal(Type, Value, State, Out) :- (atom(Value) ; string(Value)), !, tw_quoted_string(Value, State, Out), write(Out, '^^'), tw_resource(Type, State, Out). tw_typed_literal(Type, Value, State, Out) :- rdf_equal(Type, rdf:'XMLLiteral'), !, with_output_to(string(Tmp), xml_write(Value, [header(false)])), tw_quoted_string(Tmp, State, Out), write(Out, '^^'), tw_resource(Type, State, Out). tw_typed_literal(Type, Value, State, Out) :- format(string(Tmp), '~q', [Value]), tw_quoted_string(Tmp, State, Out), write(Out, '^^'), tw_resource(Type, State, Out). %! tw_abbreviated_literal(+Type, +Value, +State, +Out) is semidet. % % Turtle abbreviated typed literals. % % @tbd: Deal with canonical forms (or is this a task of the % RDF parser? % @tbd: What if the value is not in the lexical space of the type? term_expansion((tw_abbreviated_literal(NS:Local, Value, State, Out) :- Body), (tw_abbreviated_literal(Type, Value, State, Out) :- Body)) :- atom(NS), rdf_global_id(NS:Local, Type). tw_abbreviated_literal(xsd:integer, Value, State, Out) :- ( tw_state_canonize_numbers(State, false) -> write(Out, Value) ; atom_number(Value, Int), format(Out, '~d', [Int]) ). tw_abbreviated_literal(xsd:double, Value, State, Out) :- ( tw_state_canonize_numbers(State, false) -> write(Out, Value) ; ValueF is float(Value), xsd_number_string(ValueF, FloatS), format(Out, '~s', [FloatS]) ). tw_abbreviated_literal(xsd:string, Value, State, Out) :- tw_quoted_string(Value, State, Out). tw_abbreviated_literal(xsd:decimal, Value, _, Out) :- format(Out, '~w', [Value]). tw_abbreviated_literal(xsd:boolean, Value, _, Out) :- format(Out, '~w', [Value]). %! tw_quoted_string(+Atom, +State, +Out) is det. % % Write Atom to Out as a quoted string. We only use the % single-"..." representation. tw_quoted_string(Atom, _, Out) :- turtle:turtle_write_quoted_string(Out, Atom). /******************************* * COMMENT * *******************************/ comment(State, Format, Args, Out) :- tw_state_comment(State, true), !, format(Out, '~n# ', []), format(Out, Format, Args), format(Out, '~n', []). comment(_, _, _, _). /******************************* * STATISTICS * *******************************/ inc_triple_count(State, Count) :- tw_state_triple_count(State, C0), C1 is C0+Count, nb_set_triple_count_of_tw_state(C1, State). inc_subject_count(State, Count) :- tw_state_subject_count(State, C0), C1 is C0+Count, nb_set_subject_count_of_tw_state(C1, State). :- multifile prolog:message//1. prolog:message(rdf(saved(File, Time, SavedSubjects, SavedTriples))) --> [ 'Saved ~D triples about ~D subjects into '-[SavedTriples, SavedSubjects] ], rdf_output(File), [ ' (~3f sec)'-[Time] ]. prolog:message(rdf(saved(File, Time, SavedSubjects, SavedTriples, SavedGraphs))) --> [ 'Saved ~D graphs, ~D triples about ~D subjects into '- [SavedGraphs, SavedTriples, SavedSubjects] ], rdf_output(File), [ ' (~3f sec)'-[Time] ]. rdf_output(StreamSpec) --> { ( StreamSpec = stream(Stream) -> true ; Stream = StreamSpec ), is_stream(Stream), stream_property(Stream, file_name(File)) }, !, [ '~p'-[File] ]. rdf_output(File) --> [ '~p'-[File] ].