RDF.Literal.Datatype behaviour (RDF.ex v0.9.2) View Source
A behaviour for datatypes for RDF.Literal
s.
An implementation of this behaviour defines a struct for a datatype IRI and the semantics of its values via the functions defined by this behaviour.
There are three important groups of RDF.Literal.Datatype
implementations:
RDF.XSD.Datatype
: This is another, more specific behaviour for XSD datatypes. RDF.ex comes with builtin implementations of this behaviour for the most important XSD datatypes, but you define your own custom datatypes by deriving from these builtin datatypes and constraining them viaRDF.XSD.Facet
s.- Non-XSD datatypes which implement the
RDF.Literal.Datatype
directly: There's currently only one builtin datatype of this category -RDF.LangString
for language tagged RDF literals. RDF.Literal.Generic
: This is a generic implementation which is used forRDF.Literal
s with a datatype that has no ownRDF.Literal.Datatype
implementation defining its semantics.
Link to this section Summary
Functions
Returns the RDF.Literal.Datatype
for a datatype IRI.
Callbacks
Produces the canonical representation of a RDF.Literal
.
Determines if the lexical form of a RDF.Literal
is the canonical form.
Returns the canonical lexical form of a RDF.Literal
.
Checks if the given RDF.Literal
has the datatype for which the RDF.Literal.Datatype
is implemented or is derived from it.
The datatype IRI of the given RDF.Literal
.
Callback for datatype specific castings.
Callback for datatype specific compare/2
comparisons between two RDF.Literal
s.
Callback for datatype specific equal_value?/2
comparisons when the given literals have different datatypes.
Callback for datatype specific equal_value?/2
comparisons when the given literals have the same or derived datatypes.
The IRI of the datatype.
The language of the given RDF.Literal
if present.
Returns the lexical form of a RDF.Literal
.
The name of the datatype.
Updates the value of a RDF.Literal
without changing everything else.
Updates the value of a RDF.Literal
without changing anything else.
Determines if a RDF.Literal
has a proper value of the value space of its datatype.
Returns the value of a RDF.Literal
.
Link to this section Types
Link to this section Functions
Returns the RDF.Literal.Datatype
for a datatype IRI.
Link to this section Callbacks
Specs
canonical(RDF.Literal.t() | literal()) :: RDF.Literal.t()
Produces the canonical representation of a RDF.Literal
.
Specs
canonical?(RDF.Literal.t() | literal() | any()) :: boolean()
Determines if the lexical form of a RDF.Literal
is the canonical form.
Note: For RDF.Literal.Generic
literals with the canonical form not defined,
this always returns true
.
Specs
canonical_lexical(RDF.Literal.t() | literal()) :: String.t() | nil
Returns the canonical lexical form of a RDF.Literal
.
If the given literal is invalid, nil
is returned.
Specs
datatype?(RDF.Literal.t() | t() | literal()) :: boolean()
Checks if the given RDF.Literal
has the datatype for which the RDF.Literal.Datatype
is implemented or is derived from it.
Example
iex> RDF.XSD.byte(42) |> RDF.XSD.Integer.datatype?()
true
Specs
datatype_id(RDF.Literal.t() | literal()) :: RDF.IRI.t()
The datatype IRI of the given RDF.Literal
.
Specs
do_cast(literal() | RDF.IRI.t() | RDF.BlankNode.t()) :: RDF.Literal.t() | nil
Callback for datatype specific castings.
This callback is called by the auto-generated cast/1
function on the implementations, which already deals with the basic cases.
So, implementations can assume the passed argument is a valid RDF.Literal.Datatype
struct,
a RDF.IRI
or a RDF.BlankNode
.
If the given literal can not be converted into this datatype an implementation should return nil
.
A final catch-all clause should delegate to super
. For example RDF.XSD.Datatype
s will handle casting from derived
datatypes in the default implementation.
Specs
do_compare(literal() | any(), literal() | any()) :: comparison_result() | :indeterminate | nil
Callback for datatype specific compare/2
comparisons between two RDF.Literal
s.
This callback is called by auto-generated compare/2
function on the implementations, which already deals with the basic cases.
So, implementations can assume the passed arguments are valid RDF.Literal.Datatype
structs and
have the same datatypes or are derived from each other.
Should return :gt
if value of the first literal is greater than the value of the second in
terms of their datatype and :lt
for vice versa. If the two literals can be considered equal :eq
should be returned.
For datatypes with only partial ordering :indeterminate
should be returned when the
order of the given literals is not defined.
nil
should be returned when the given arguments are not comparable datatypes or if one them is invalid.
The default implementation of the _using__
macro of RDF.Literal.Datatype
s
just compares the values of the given literals.
Specs
Callback for datatype specific equal_value?/2
comparisons when the given literals have different datatypes.
This callback is called by auto-generated equal_value?/2
function when the given literals have
different datatypes and are not derived from each other.
Should return nil
when the given arguments are not comparable as literals of this
datatype. This behaviour is particularly important for SPARQL.ex where this
function is used for the =
operator, where comparisons between incomparable
terms are treated as errors and immediately leads to a rejection of a possible
match.
Specs
Callback for datatype specific equal_value?/2
comparisons when the given literals have the same or derived datatypes.
This callback is called by auto-generated equal_value?/2
function when the given literals have
the same datatype or one is derived from the other.
Should return nil
when the given arguments are not comparable as literals of this
datatype. This behaviour is particularly important for SPARQL.ex where this
function is used for the =
operator, where comparisons between incomparable
terms are treated as errors and immediately leads to a rejection of a possible
match.
See also do_equal_value_different_datatypes?/2
.
Specs
id() :: RDF.IRI.t() | nil
The IRI of the datatype.
Specs
language(RDF.Literal.t() | literal()) :: String.t() | nil
The language of the given RDF.Literal
if present.
Specs
lexical(RDF.Literal.t() | literal()) :: String.t()
Returns the lexical form of a RDF.Literal
.
Specs
name() :: String.t()
The name of the datatype.
Specs
new(any()) :: RDF.Literal.t()
Specs
new(any(), Keyword.t()) :: RDF.Literal.t()
Specs
new!(any()) :: RDF.Literal.t()
Specs
new!(any(), Keyword.t()) :: RDF.Literal.t()
Specs
update(RDF.Literal.t() | literal(), (... -> any())) :: RDF.Literal.t()
Updates the value of a RDF.Literal
without changing everything else.
Example
iex> RDF.XSD.integer(42) |> RDF.XSD.Integer.update(fn value -> value + 1 end)
RDF.XSD.integer(43)
iex> ~L"foo"de |> RDF.LangString.update(fn _ -> "bar" end)
~L"bar"de
iex> RDF.literal("foo", datatype: "http://example.com/dt") |> RDF.Literal.Generic.update(fn _ -> "bar" end)
RDF.literal("bar", datatype: "http://example.com/dt")
Specs
update(RDF.Literal.t() | literal(), (... -> any()), keyword()) :: RDF.Literal.t()
Updates the value of a RDF.Literal
without changing anything else.
This variant of update/2
allows with the :as
option to specify what will
be passed to fun
, eg. with as: :lexical
the lexical is passed to the function.
Example
iex> RDF.XSD.integer(42) |> RDF.XSD.Integer.update(
...> fn value -> value <> "1" end, as: :lexical)
RDF.XSD.integer(421)
Specs
valid?(RDF.Literal.t() | literal() | any()) :: boolean()
Determines if a RDF.Literal
has a proper value of the value space of its datatype.
This function also accepts literals of derived datatypes.
Specs
value(RDF.Literal.t() | literal()) :: any()
Returns the value of a RDF.Literal
.
This function also accepts literals of derived datatypes.