This module defines the expansion of
Prefix:Local terms to full IRIs.
This library is typically not intended for the end-user. It may be
included into other RDF and XML libraries and relevant parts may be
- rdf_empty_prefix_cache(+Alias, +URI)[multifile]
- Multifile hook called if the binding Alias -> URI is modified. May be used to update derived caches.
- 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_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_db:ns(?Alias, ?URI) is nondet[multifile]
- Dynamic and multifile predicate that maintains the registered namespace aliases.
- rdf_register_prefix(+Prefix, +URI) is det
- rdf_register_prefix(+Prefix, +URI, +Options) is det
- Register Prefix as an abbreviation for URI. Options:
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.
trueand 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:
- rdf_unregister_prefix(+Alias) is det
- Delete a prefix global registration.
- rdf_current_ns(:Prefix, ?URI) is nondet
- rdf_register_ns(:Prefix, ?URI) is det
- rdf_register_ns(:Prefix, ?URI, +Options) is det
- Register an RDF prefix.
- register_file_prefixes(+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.
- rdf_global_id(?IRISpec, :IRI) is semidet
- Convert between Prefix:Local and full IRI (an atom). If IRISpec is
an atom, it is simply unified with IRI. This predicate fails
silently if IRI is an RDF literal.
Note that this predicate is a meta-predicate on its output argument. This is necessary to get the module context while the first argument may be of the form (:)/2. The above mode description is correct, but should be interpreted as (?,?).
- 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.
- rdf_global_term(+TermIn, :GlobalTerm) is det
- Performs rdf_global_id/2 on predixed IRIs and rdf_global_object/2 on RDF literals, 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.
- 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.
- The argument must be a resource. If it is a term prefix:local it is translated.
- The argument is an object or resource. See rdf_global_object/2.
- 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_metais 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:Localterms. 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.
The following predicates are exported, but not or incorrectly documented.