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 and later standardized by the W3C RDF working group.

This module acts as a plugin to rdf_load/2, for processing files with one of the extensions .ttl or .n3.

See also

- http://www.w3.org/TR/turtle/ (used W3C Recommendation 25 February 2014)

 rdf_read_turtle(+Input, -Triples, +Options)

Read a stream or file into a set of triples or quadruples (if faced with TriG input) of the format

rdf(Subject, Predicate, Object [, Graph])

The representation is consistent with the SWI-Prolog RDF/XML and ntriples parsers. Provided options are:

base_uri(+BaseURI)

Initial base URI. Defaults to file://<file> for loading files.

anon_prefix(+Prefix)

Blank nodes are generated as <Prefix>1, <Prefix>2, etc. If Prefix is not an atom blank nodes are generated as node(1), node(2), ...

format(+Format)

One of auto (default), turtle or trig. The auto mode switches to TriG format of there is a { before the first triple. Finally, of the format is explicitly stated as turtle and the file appears to be a TriG file, a warning is printed and the data is loaded while ignoring the graphs.

resources(URIorIRI)

Officially, Turtle resources are IRIs. Quite a few applications however send URIs. By default we do URI->IRI mapping because this rarely causes errors. To force strictly conforming mode, pass iri.

prefixes(-Pairs)

Return encountered prefix declarations as a list of Alias-URI

namespaces(-Pairs)

Same as prefixes(Pairs). Compatibility to rdf_load/2.

base_used(-Base)

Base URI used for processing the data. Unified to [] if there is no base-uri.

on_error(+ErrorMode)

In warning (default), print the error and continue parsing the remainder of the file. If error, abort with an exception on the first error encountered.

error_count(-Count)

If on_error(warning) is active, this option cane be used to retrieve the number of generated errors.

Arguments:

Input

- is one of stream(Stream), atom(Atom), a http, https or file url or a filename specification as accepted by absolute_file_name/3.

 rdf_load_turtle(+Input, -Triples, +Options)

deprecated

- Use rdf_read_turtle/3

 rdf_process_turtle(+Input, :OnObject, +Options) is det

Streaming Turtle parser. The predicate rdf_process_turtle/3 processes Turtle data from Input, calling OnObject with a list of triples for every Turtle statement found in Input. OnObject is called as below, where ListOfTriples is a list of rdf(S,P,O) terms for a normal Turtle file or rdf(S,P,O,G) terms if the GRAPH keyword is used to associate a set of triples in the document with a particular graph. The Graph argument provides the default graph for storing the triples and Line is the line number where the statement started.

call(OnObject, ListOfTriples, Graph:Line)

This predicate supports the same Options as rdf_load_turtle/3.

Errors encountered are sent to print_message/2, after which the parser tries to recover and parse the remainder of the data.

See also

- This predicate is normally used by load_rdf/2 for processing RDF data.

 turtle_pn_local(+Atom:atom) is semidet

True if Atom is a valid Turtle PN_LOCAL name. The PN_LOCAL name is what can follow the : in a resource. In the new Turtle, this can be anything and this function becomes meaningless. In the old turtle, PN_LOCAL is defined similar (but not equal) to an XML name. This predicate is used by rdf_save_turtle/2 to write files such that can be read by old parsers.

See also

- xml_name/2.

 turtle_write_quoted_string(+Out, +Value) is det

Same as turtle_write_quoted_string(Out, Value, false), writing a string with only a single ". Embedded newlines are escapes as \n.

 turtle_write_uri(+Out, +Value) is det

Write a URI as <...>

 rdf_db:rdf_load_stream(+Format, +Stream, :Options)[multifile]

(Turtle clauses)

Undocumented predicates

The following predicates are exported, but not or incorrectly documented.

 rdf_save_turtle(Arg1, Arg2)

 rdf_save_canonical_turtle(Arg1, Arg2)

 rdf_save_trig(Arg1, Arg2)

 rdf_save_canonical_trig(Arg1, Arg2)

 rdf_save_ntriples(Arg1, Arg2)