rdf-ex/lib/rdf/serializations/ntriples_encoder.ex
2020-06-29 10:37:42 +02:00

47 lines
1.3 KiB
Elixir

defmodule RDF.NTriples.Encoder do
@moduledoc false
use RDF.Serialization.Encoder
alias RDF.{BlankNode, Dataset, Graph, IRI, XSD, Literal, Statement, Triple, LangString}
@impl RDF.Serialization.Encoder
@callback encode(Graph.t() | Dataset.t(), keyword | map) :: {:ok, String.t()} | {:error, any}
def encode(data, _opts \\ []) do
result =
data
|> Enum.reduce([], fn statement, result ->
[statement(statement) | result]
end)
|> Enum.reverse()
|> Enum.join("\n")
{:ok, if(result == "", do: result, else: result <> "\n")}
end
@spec statement(Triple.t()) :: String.t()
def statement({subject, predicate, object}) do
"#{term(subject)} #{term(predicate)} #{term(object)} ."
end
@spec term(Statement.subject() | Statement.predicate() | Statement.object()) :: String.t()
def term(%IRI{} = iri) do
"<#{to_string(iri)}>"
end
def term(%Literal{literal: %LangString{} = lang_string}) do
~s["#{lang_string.value}"@#{lang_string.language}]
end
def term(%Literal{literal: %XSD.String{} = xsd_string}) do
~s["#{xsd_string.value}"]
end
def term(%Literal{} = literal) do
~s["#{Literal.lexical(literal)}"^^<#{to_string(Literal.datatype_id(literal))}>]
end
def term(%BlankNode{} = bnode) do
to_string(bnode)
end
end