rdf-ex/lib/rdf.ex

defmodule RDF do
  @moduledoc """
  The top-level module of RDF.ex.

  RDF.ex consists of:

  - modules for the nodes of an RDF graph
    - `RDF.Term`
    - `RDF.IRI`
    - `RDF.BlankNode`
    - `RDF.Literal`
  - a facility for the mapping of URIs of a vocabulary to Elixir modules and
    functions: `RDF.Vocabulary.Namespace`
  - modules for the construction of statements
    - `RDF.Triple`
    - `RDF.Quad`
    - `RDF.Statement`
  - modules for collections of statements
    - `RDF.Description`
    - `RDF.Graph`
    - `RDF.Dataset`
    - `RDF.Data`
    - `RDF.List`
  - functions for working with RDF serializations: `RDF.Serialization`
  - behaviours for the definition of RDF serialization formats
    - `RDF.Serialization.Format`
    - `RDF.Serialization.Decoder`
    - `RDF.Serialization.Encoder`
  - and the implementation of various RDF serialization formats
    - `RDF.NTriples`
    - `RDF.NQuads`
    - `RDF.Turtle`

  This top-level module provides shortcut functions for the construction of the
  basic elements and structures of RDF and some general helper functions.

  For a general introduction you may refer to the guides on the [homepage](https://rdf-elixir.dev).
  """

  alias RDF.{IRI, Namespace, Literal, BlankNode, Triple, Quad,
             Description, Graph, Dataset, PrefixMap}


  @standard_prefixes PrefixMap.new(
                       xsd:  IRI.new("http://www.w3.org/2001/XMLSchema#"),
                       rdf:  IRI.new("http://www.w3.org/1999/02/22-rdf-syntax-ns#"),
                       rdfs: IRI.new("http://www.w3.org/2000/01/rdf-schema#")
                     )

  @doc """
  A fixed set prefixes that will always be part of the `default_prefixes/0`.

  ```elixir
  #{inspect(@standard_prefixes, pretty: true)}
  ```

  See `default_prefixes/0`, if you don't want these standard prefixes to be part
  of the default prefixes.
  """
  def standard_prefixes(), do: @standard_prefixes


  @doc """
  A user-defined `RDF.PrefixMap` of prefixes to IRI namespaces.

  This prefix map will be used implicitly wherever a prefix map is expected, but
  not provided. For example, when you don't pass a prefix map to the Turtle serializer,
  this prefix map will be used.

  By default the `standard_prefixes/0` are part of this prefix map, but you can
  define additional default prefixes via the `default_prefixes` compile-time
  configuration.

  For example:

      config :rdf,
        default_prefixes: %{
          ex: "http://example.com/"
        }

  If you don't want the `standard_prefixes/0` to be part of the default prefixes,
  or you want to map the standard prefixes to different namespaces (strongly discouraged!),
  you can set the `use_standard_prefixes` compile-time configuration flag to `false`.

      config :rdf,
        use_standard_prefixes: false

  """
  @default_prefixes Application.get_env(:rdf, :default_prefixes, %{}) |> PrefixMap.new()
  if Application.get_env(:rdf, :use_standard_prefixes, true) do
    def default_prefixes() do
      PrefixMap.merge!(@standard_prefixes, @default_prefixes)
    end
  else
    def default_prefixes() do
      @default_prefixes
    end
  end

  @doc """
  Returns the `default_prefixes/0` with additional prefix mappings.

  The `prefix_mappings` can be given in any format accepted by `RDF.PrefixMap.new/1`.
  """
  def default_prefixes(prefix_mappings) do
    default_prefixes() |> PrefixMap.merge!(prefix_mappings)
  end

  defdelegate read_string(content, opts),                 to: RDF.Serialization
  defdelegate read_string!(content, opts),                to: RDF.Serialization
  defdelegate read_file(filename, opts \\ []),            to: RDF.Serialization
  defdelegate read_file!(filename, opts \\ []),           to: RDF.Serialization
  defdelegate write_string(content, opts),                to: RDF.Serialization
  defdelegate write_string!(content, opts),               to: RDF.Serialization
  defdelegate write_file(content, filename, opts \\ []),  to: RDF.Serialization
  defdelegate write_file!(content, filename, opts \\ []), to: RDF.Serialization


  @doc """
  Checks if the given value is a RDF resource.

  ## Examples

  Supposed `EX` is a `RDF.Vocabulary.Namespace` and `Foo` is not.

      iex> RDF.resource?(RDF.iri("http://example.com/resource"))
      true
      iex> RDF.resource?(EX.resource)
      true
      iex> RDF.resource?(EX.Resource)
      true
      iex> RDF.resource?(Foo.Resource)
      false
      iex> RDF.resource?(RDF.bnode)
      true
      iex> RDF.resource?(RDF.integer(42))
      false
      iex> RDF.resource?(42)
      false
  """
  def resource?(value)
  def resource?(%IRI{}),                  do: true
  def resource?(%BlankNode{}),            do: true
  def resource?(atom) when is_atom(atom) and atom not in ~w[true false nil]a do
    resource?(Namespace.resolve_term(atom))
  rescue
    RDF.Namespace.UndefinedTermError -> false
  end

  def resource?(_),                       do: false

  @doc """
  Checks if the given value is a RDF term.

  ## Examples

  Supposed `EX` is a `RDF.Vocabulary.Namespace` and `Foo` is not.

      iex> RDF.term?(RDF.iri("http://example.com/resource"))
      true
      iex> RDF.term?(EX.resource)
      true
      iex> RDF.term?(EX.Resource)
      true
      iex> RDF.term?(Foo.Resource)
      false
      iex> RDF.term?(RDF.bnode)
      true
      iex> RDF.term?(RDF.integer(42))
      true
      iex> RDF.term?(42)
      false
  """
  def term?(value)
  def term?(%Literal{}), do: true
  def term?(value),      do: resource?(value)

  defdelegate uri?(value), to: IRI, as: :valid?
  defdelegate iri?(value), to: IRI, as: :valid?
  defdelegate uri(value),  to: IRI, as: :new
  defdelegate iri(value),  to: IRI, as: :new
  defdelegate uri!(value), to: IRI, as: :new!
  defdelegate iri!(value), to: IRI, as: :new!

  @doc """
  Checks if the given value is a blank node.

  ## Examples

      iex> RDF.bnode?(RDF.bnode)
      true
      iex> RDF.bnode?(RDF.iri("http://example.com/resource"))
      false
      iex> RDF.bnode?(42)
      false
  """
  def bnode?(%BlankNode{}), do: true
  def bnode?(_), do: false

  defdelegate bnode(),   to: BlankNode, as: :new
  defdelegate bnode(id), to: BlankNode, as: :new

  defdelegate literal(value),       to: Literal, as: :new
  defdelegate literal(value, opts), to: Literal, as: :new

  defdelegate triple(s, p, o),  to: Triple, as: :new
  defdelegate triple(tuple),    to: Triple, as: :new

  defdelegate quad(s, p, o, g), to: Quad, as: :new
  defdelegate quad(tuple),      to: Quad, as: :new

  defdelegate description(arg),               to: Description, as: :new
  defdelegate description(arg1, arg2),        to: Description, as: :new
  defdelegate description(arg1, arg2, arg3),  to: Description, as: :new

  defdelegate graph(),                        to: Graph, as: :new
  defdelegate graph(arg),                     to: Graph, as: :new
  defdelegate graph(arg1, arg2),              to: Graph, as: :new
  defdelegate graph(arg1, arg2, arg3),        to: Graph, as: :new
  defdelegate graph(arg1, arg2, arg3, arg4),  to: Graph, as: :new

  defdelegate dataset(),                      to: Dataset, as: :new
  defdelegate dataset(arg),                   to: Dataset, as: :new
  defdelegate dataset(arg1, arg2),            to: Dataset, as: :new

  defdelegate list?(resource, graph), to: RDF.List, as: :node?
  defdelegate list?(description),     to: RDF.List, as: :node?

  def list(native_list),            do: RDF.List.from(native_list)
  def list(head, %Graph{} = graph), do: RDF.List.new(head, graph)
  def list(native_list, opts),      do: RDF.List.from(native_list, opts)

  defdelegate string(value),            to: RDF.String,     as: :new
  defdelegate string(value, opts),      to: RDF.String,     as: :new
  defdelegate lang_string(value),       to: RDF.LangString, as: :new
  defdelegate lang_string(value, opts), to: RDF.LangString, as: :new
  defdelegate langString(value),        to: RDF.LangString, as: :new
  defdelegate langString(value, opts),  to: RDF.LangString, as: :new
  defdelegate boolean(value),           to: RDF.Boolean,    as: :new
  defdelegate boolean(value, opts),     to: RDF.Boolean,    as: :new
  defdelegate integer(value),           to: RDF.Integer,    as: :new
  defdelegate integer(value, opts),     to: RDF.Integer,    as: :new
  defdelegate double(value),            to: RDF.Double,     as: :new
  defdelegate double(value, opts),      to: RDF.Double,     as: :new
  defdelegate decimal(value),           to: RDF.Decimal,    as: :new
  defdelegate decimal(value, opts),     to: RDF.Decimal,    as: :new
  defdelegate date(value),              to: RDF.Date,       as: :new
  defdelegate date(value, opts),        to: RDF.Date,       as: :new
  defdelegate time(value),              to: RDF.Time,       as: :new
  defdelegate time(value, opts),        to: RDF.Time,       as: :new
  defdelegate date_time(value),         to: RDF.DateTime,   as: :new
  defdelegate date_time(value, opts),   to: RDF.DateTime,   as: :new
  defdelegate dateTime(value),          to: RDF.DateTime,   as: :new
  defdelegate dateTime(value, opts),    to: RDF.DateTime,   as: :new
  defdelegate datetime(value),          to: RDF.DateTime,   as: :new
  defdelegate datetime(value, opts),    to: RDF.DateTime,   as: :new

  defdelegate prefix_map(prefixes), to: RDF.PrefixMap, as: :new

  for term <- ~w[type subject predicate object first rest value]a do
    defdelegate unquote(term)(),                      to: RDF.NS.RDF
    defdelegate unquote(term)(s, o),                  to: RDF.NS.RDF
    defdelegate unquote(term)(s, o1, o2),             to: RDF.NS.RDF
    defdelegate unquote(term)(s, o1, o2, o3),         to: RDF.NS.RDF
    defdelegate unquote(term)(s, o1, o2, o3, o4),     to: RDF.NS.RDF
    defdelegate unquote(term)(s, o1, o2, o3, o4, o5), to: RDF.NS.RDF
  end

  defdelegate unquote(:true)(),  to: RDF.Boolean.Value
  defdelegate unquote(:false)(), to: RDF.Boolean.Value

  defdelegate langString(),   to: RDF.NS.RDF
  defdelegate unquote(nil)(), to: RDF.NS.RDF

  defdelegate __base_iri__(), to: RDF.NS.RDF
end