View Source RDF.Statement (RDF.ex v2.0.1)
Helper functions for RDF statements.
An RDF statement is either a RDF.Triple
or a RDF.Quad
.
Summary
Functions
Returns a list of all RDF.BlankNode
s within the given statement
.
Creates a RDF.Statement
tuple with proper RDF values.
Coerces the given value
to a valid graph context of an RDF statement.
Coerces the given value
to a valid object of an RDF statement.
Coerces the given value
to a valid predicate of an RDF statement.
Coerces the given term
to a valid predicate of an RDF statement using a RDF.PropertyMap
.
Coerces the given value
to a valid subject of an RDF statement.
The graph name component of a statement.
Returns whether the given statement
contains a blank node.
Returns whether the given value
is a component of the given statement
.
Returns a tuple of native Elixir values from a RDF.Statement
of RDF terms.
Creates a RDF.Triple
or RDF.Quad
with proper RDF values.
The object component of a statement.
The predicate component of a statement.
The subject component of a statement.
Checks if the given tuple is a valid RDF statement, i.e. RDF triple or quad.
Returns a tuple of native Elixir values from a RDF.Statement
of RDF terms.
Types
@type coercible() :: RDF.Triple.coercible() | RDF.Quad.coercible()
@type coercible_graph_name() :: graph_name() | atom() | String.t()
@type coercible_predicate() :: RDF.Resource.coercible()
@type coercible_subject() :: RDF.Resource.coercible()
@type graph_name() :: RDF.Resource.t() | nil
@type object() :: RDF.Resource.t() | RDF.Literal.t()
@type position() :: :subject | :predicate | :object | :graph_name
@type predicate() :: RDF.Resource.t()
@type qualified_term() :: {position(), RDF.Term.t() | nil}
@type subject() :: RDF.Resource.t()
@type t() :: RDF.Triple.t() | RDF.Quad.t()
@type term_mapping() :: (qualified_term() -> any() | nil)
Functions
@spec bnodes(t()) :: [RDF.BlankNode.t()]
Returns a list of all RDF.BlankNode
s within the given statement
.
@spec coerce(coercible(), RDF.PropertyMap.t() | nil) :: RDF.Triple.t() | RDF.Quad.t()
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.coerce {"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.coerce {"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>}
@spec coerce_graph_name(coercible_graph_name()) :: graph_name()
Coerces the given value
to a valid graph context of an RDF statement.
Raises an RDF.Quad.InvalidGraphContextError
when the value can not be coerced.
@spec coerce_object(coercible_object()) :: object()
Coerces the given value
to a valid object of an RDF statement.
@spec coerce_predicate(coercible_predicate()) :: predicate()
Coerces the given value
to a valid predicate of an RDF statement.
Raises an RDF.Triple.InvalidPredicateError
when the value can not be coerced.
@spec coerce_predicate(coercible_predicate(), RDF.PropertyMap.t()) :: predicate()
Coerces the given term
to a valid predicate of an RDF statement using a RDF.PropertyMap
.
Raises an RDF.Triple.InvalidPredicateError
when the value can not be coerced.
@spec coerce_subject(coercible_subject()) :: subject()
Coerces the given value
to a valid subject of an RDF statement.
Raises an RDF.Triple.InvalidSubjectError
when the value can not be coerced.
@spec default_property_mapping(RDF.PropertyMap.t()) :: term_mapping()
The graph name component of a statement.
Examples
iex> RDF.Statement.graph_name {"http://example.com/S", "http://example.com/p", 42, "http://example.com/Graph"}
~I<http://example.com/Graph>
iex> RDF.Statement.graph_name {"http://example.com/S", "http://example.com/p", 42}
nil
Returns whether the given statement
contains a blank node.
Returns whether the given value
is a component of the given statement
.
@spec map(t(), term_mapping()) :: RDF.Triple.mapping_value() | RDF.Quad.mapping_value() | nil | nil
Returns a tuple of native Elixir values from a RDF.Statement
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
, :object
or
:graph_name
, 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> {~I<http://example.com/S>, ~I<http://example.com/p>, RDF.literal(42), ~I<http://example.com/Graph>}
...> |> RDF.Statement.map(fn
...> {:subject, subject} ->
...> subject |> to_string() |> String.last()
...> {:predicate, predicate} ->
...> predicate |> to_string() |> String.last() |> String.to_atom()
...> {:object, object} ->
...> RDF.Term.value(object)
...> {:graph_name, graph_name} ->
...> graph_name
...> end)
{"S", :p, 42, ~I<http://example.com/Graph>}
Creates a RDF.Triple
or RDF.Quad
with proper RDF values.
An error is raised when the given elements are not coercible to RDF values.
Note: The RDF.statement
function is a shortcut to this function.
Examples
iex> RDF.Statement.new({EX.S, EX.p, 42})
{RDF.iri("http://example.com/S"), RDF.iri("http://example.com/p"), RDF.literal(42)}
iex> RDF.Statement.new({EX.S, EX.p, 42, EX.Graph})
{RDF.iri("http://example.com/S"), RDF.iri("http://example.com/p"), RDF.literal(42), RDF.iri("http://example.com/Graph")}
iex> RDF.Statement.new({EX.S, :p, 42, EX.Graph}, RDF.PropertyMap.new(p: EX.p))
{RDF.iri("http://example.com/S"), RDF.iri("http://example.com/p"), RDF.literal(42), RDF.iri("http://example.com/Graph")}
See RDF.Triple.new/3
.
See RDF.Quad.new/4
.
The object component of a statement.
Examples
iex> RDF.Statement.object {"http://example.com/S", "http://example.com/p", 42}
RDF.literal(42)
The predicate component of a statement.
Examples
iex> RDF.Statement.predicate {"http://example.com/S", "http://example.com/p", 42}
~I<http://example.com/p>
The subject component of a statement.
Examples
iex> RDF.Statement.subject {"http://example.com/S", "http://example.com/p", 42}
~I<http://example.com/S>
@spec valid?(RDF.Triple.t() | RDF.Quad.t() | any()) :: boolean()
Checks if the given tuple is a valid RDF statement, i.e. RDF triple or quad.
The elements of a valid RDF statement must be RDF terms. On the subject position only IRIs and blank nodes allowed, while on the predicate and graph context position only IRIs allowed. The object position can be any RDF term.
@spec valid_graph_name?(graph_name() | any()) :: boolean()
@spec values( t(), keyword() ) :: RDF.Triple.mapping_value() | RDF.Quad.mapping_value() | nil
Returns a tuple of native Elixir values from a RDF.Statement
of RDF terms.
When a :context
option is given with a RDF.PropertyMap
, predicates will
be mapped to the terms defined in the RDF.PropertyMap
, if present.
Returns nil
if one of the components of the given tuple is not convertible via RDF.Term.value/1
.
Examples
iex> RDF.Statement.values {~I<http://example.com/S>, ~I<http://example.com/p>, RDF.literal(42)}
{"http://example.com/S", "http://example.com/p", 42}
iex> RDF.Statement.values {~I<http://example.com/S>, ~I<http://example.com/p>, RDF.literal(42), ~I<http://example.com/Graph>}
{"http://example.com/S", "http://example.com/p", 42, "http://example.com/Graph"}
iex> {~I<http://example.com/S>, ~I<http://example.com/p>, RDF.literal(42)}
...> |> RDF.Statement.values(context: %{p: ~I<http://example.com/p>})
{"http://example.com/S", :p, 42}