74 lines
3 KiB
Elixir
74 lines
3 KiB
Elixir
defmodule RDF.Statement do
|
|
@moduledoc """
|
|
Helper functions for RDF statements.
|
|
|
|
A RDF statement is either a `RDF.Triple` or a `RDF.Quad`.
|
|
"""
|
|
|
|
alias RDF.{Triple, Quad, IRI, BlankNode, Literal}
|
|
|
|
@type subject :: IRI.t | BlankNode.t
|
|
@type predicate :: IRI.t
|
|
@type object :: IRI.t | BlankNode.t | Literal.t
|
|
@type graph_name :: IRI.t | BlankNode.t
|
|
|
|
@type coercible_subject :: subject | atom | String.t
|
|
@type coercible_predicate :: predicate | atom | String.t
|
|
@type coercible_object :: object | atom | String.t # TODO: all basic Elixir types coercible to Literals
|
|
@type coercible_graph_name :: graph_name | atom | String.t
|
|
|
|
|
|
@doc """
|
|
Creates a `RDF.Statement` tuple with proper RDF values.
|
|
|
|
An error is raised when the given elements are not coercible to RDF values.
|
|
|
|
## Examples
|
|
|
|
iex> RDF.Statement.new {"http://example.com/S", "http://example.com/p", 42}
|
|
{~I<http://example.com/S>, ~I<http://example.com/p>, RDF.literal(42)}
|
|
iex> RDF.Statement.new {"http://example.com/S", "http://example.com/p", 42, "http://example.com/Graph"}
|
|
{~I<http://example.com/S>, ~I<http://example.com/p>, RDF.literal(42), ~I<http://example.com/Graph>}
|
|
"""
|
|
def coerce(statement)
|
|
def coerce({_, _, _} = triple), do: Triple.new(triple)
|
|
def coerce({_, _, _, _} = quad), do: Quad.new(quad)
|
|
|
|
@doc false
|
|
def coerce_subject(iri)
|
|
def coerce_subject(iri = %IRI{}), do: iri
|
|
def coerce_subject(bnode = %BlankNode{}), do: bnode
|
|
def coerce_subject("_:" <> identifier), do: RDF.bnode(identifier)
|
|
def coerce_subject(iri) when is_atom(iri) or is_binary(iri), do: RDF.iri!(iri)
|
|
def coerce_subject(arg), do: raise RDF.Triple.InvalidSubjectError, subject: arg
|
|
|
|
@doc false
|
|
def coerce_predicate(iri)
|
|
def coerce_predicate(iri = %IRI{}), do: iri
|
|
# Note: Although, RDF does not allow blank nodes for properties, JSON-LD allows
|
|
# them, by introducing the notion of "generalized RDF".
|
|
# TODO: Support an option `:strict_rdf` to explicitly disallow them or produce warnings or ...
|
|
def coerce_predicate(bnode = %BlankNode{}), do: bnode
|
|
def coerce_predicate(iri) when is_atom(iri) or is_binary(iri), do: RDF.iri!(iri)
|
|
def coerce_predicate(arg), do: raise RDF.Triple.InvalidPredicateError, predicate: arg
|
|
|
|
@doc false
|
|
def coerce_object(iri)
|
|
def coerce_object(iri = %IRI{}), do: iri
|
|
def coerce_object(literal = %Literal{}), do: literal
|
|
def coerce_object(bnode = %BlankNode{}), do: bnode
|
|
def coerce_object(bool) when is_boolean(bool), do: Literal.new(bool)
|
|
def coerce_object(atom) when is_atom(atom), do: RDF.iri(atom)
|
|
def coerce_object(arg), do: Literal.new(arg)
|
|
|
|
@doc false
|
|
def coerce_graph_name(iri)
|
|
def coerce_graph_name(nil), do: nil
|
|
def coerce_graph_name(iri = %IRI{}), do: iri
|
|
def coerce_graph_name(bnode = %BlankNode{}), do: bnode
|
|
def coerce_graph_name("_:" <> identifier), do: RDF.bnode(identifier)
|
|
def coerce_graph_name(iri) when is_atom(iri) or is_binary(iri), do: RDF.iri!(iri)
|
|
def coerce_graph_name(arg),
|
|
do: raise RDF.Quad.InvalidGraphContextError, graph_context: arg
|
|
|
|
end
|