RDF.ex

v0.7.1

RDF.ex v0.7.1 RDF.Triple View Source

Helper functions for RDF triples.

A RDF Triple is represented as a plain Elixir tuple consisting of three valid RDF values for subject, predicate and object.

Link to this section Summary

Types

coercible_t()
t()
t_values()

Functions

new(arg)

Creates a RDF.Triple with proper RDF values.

new(subject, predicate, object)

Creates a RDF.Triple with proper RDF values.

valid?(tuple)

Checks if the given tuple is a valid RDF triple.

values(triple, mapping \\ &Statement.default_term_mapping/1)

Returns a tuple of native Elixir values from a RDF.Triple of RDF terms.

Link to this section Types

Link to this type

coercible_t()

View Source 
coercible_t() ::
  {RDF.Statement.coercible_subject(), RDF.Statement.coercible_predicate(),
   RDF.Statement.coercible_object()}
Link to this type

t()

View Source 
t() ::
  {RDF.Statement.subject(), RDF.Statement.predicate(), RDF.Statement.object()}
Link to this type

t_values()

View Source 
t_values() :: {String.t(), String.t(), RDF.Literal.literal_value()}

Link to this section Functions

Link to this function

new(arg)

View Source 
new(coercible_t()) :: t()

Creates a RDF.Triple with proper RDF values.

An error is raised when the given elements are not coercible to RDF values.

Note: The RDF.triple function is a shortcut to this function.

Examples 

iex> RDF.Triple.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.Triple.new {EX.S, EX.p, 42}
{RDF.iri("http://example.com/S"), RDF.iri("http://example.com/p"), RDF.literal(42)}
Link to this function

new(subject, predicate, object)

View Source 
new(
  RDF.Statement.coercible_subject(),
  RDF.Statement.coercible_predicate(),
  RDF.Statement.coercible_object()
) :: t()

Creates a RDF.Triple with proper RDF values.

An error is raised when the given elements are not coercible to RDF values.

Note: The RDF.triple function is a shortcut to this function.

Examples 

iex> RDF.Triple.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.Triple.new(EX.S, EX.p, 42)
{RDF.iri("http://example.com/S"), RDF.iri("http://example.com/p"), RDF.literal(42)}
Link to this function

valid?(tuple)

View Source 
valid?(t() | any()) :: boolean()

Checks if the given tuple is a valid RDF triple.

The elements of a valid RDF triple must be RDF terms. On the subject position only IRIs and blank nodes allowed, while on the predicate position only IRIs allowed. The object position can be any RDF term.

Link to this function

values(triple, mapping \\ &Statement.default_term_mapping/1)

View Source 
values(t() | any(), RDF.Statement.term_mapping()) :: t_values() | nil

Returns a tuple of native Elixir values from a RDF.Triple of RDF terms.

Returns nil if one of the components of the given tuple is not convertible via RDF.Term.value/1.

The optional second argument allows to specify a custom mapping with a function which will receive a tuple {statement_position, rdf_term} where statement_position is one of the atoms :subject, :predicate or :object, while rdf_term is the RDF term to be mapped. When the given function returns nil this will be interpreted as an error and will become the overhaul result of the values/2 call.

Examples 

iex> RDF.Triple.values {~I<http://example.com/S>, ~I<http://example.com/p>, RDF.literal(42)}
{"http://example.com/S", "http://example.com/p", 42}

iex> {~I<http://example.com/S>, ~I<http://example.com/p>, RDF.literal(42)}
...> |> RDF.Triple.values(fn
...>      {:object, object} -> RDF.Term.value(object)
...>      {_, term}         -> term |> to_string() |> String.last()
...>    end)
{"S", "p", 42}