59 lines
2 KiB
Elixir
59 lines
2 KiB
Elixir
defmodule RDF.NQuads.Decoder do
|
|
@moduledoc """
|
|
A decoder for N-Quads serializations to `RDF.Dataset`s.
|
|
|
|
As for all decoders of `RDF.Serialization.Format`s, you normally won't use these
|
|
functions directly, but via one of the `read_` functions on the `RDF.NQuads` format
|
|
module or the generic `RDF.Serialization` module.
|
|
"""
|
|
|
|
use RDF.Serialization.Decoder
|
|
|
|
import RDF.Serialization.ParseHelper, only: [error_description: 1]
|
|
|
|
alias RDF.Dataset
|
|
|
|
@impl RDF.Serialization.Decoder
|
|
@spec decode(String.t(), keyword) :: {:ok, Dataset.t()} | {:error, any}
|
|
def decode(string, _opts \\ []) do
|
|
with {:ok, ast} <- do_decode(string, true) do
|
|
{:ok, build_dataset(ast)}
|
|
end
|
|
end
|
|
|
|
@impl RDF.Serialization.Decoder
|
|
@spec decode_from_stream(Enumerable.t(), keyword) :: {:ok, Dataset.t()} | {:error, any}
|
|
def decode_from_stream(stream, _opts \\ []) do
|
|
Enum.reduce_while(stream, {:ok, Dataset.new()}, fn line, {:ok, dataset} ->
|
|
case do_decode(line, false) do
|
|
{:ok, []} -> {:cont, {:ok, dataset}}
|
|
{:ok, [[quad]]} -> {:cont, {:ok, Dataset.add(dataset, quad)}}
|
|
{:error, _} = error -> {:halt, error}
|
|
end
|
|
end)
|
|
end
|
|
|
|
defp do_decode(content, error_with_line_number) do
|
|
with {:ok, tokens, _} <- tokenize(content) do
|
|
parse(tokens)
|
|
else
|
|
{:error, {error_line, :ntriples_lexer, error_descriptor}, _error_line_again} ->
|
|
{:error,
|
|
"N-Quad scanner error#{if error_with_line_number, do: " on line #{error_line}"}: #{error_description(error_descriptor)}"}
|
|
|
|
{:error, {error_line, :nquads_parser, error_descriptor}} ->
|
|
{:error,
|
|
"N-Quad parser error#{if error_with_line_number, do: " on line #{error_line}"}: #{error_description(error_descriptor)}"}
|
|
end
|
|
end
|
|
|
|
defp tokenize(content), do: content |> to_charlist() |> :ntriples_lexer.string()
|
|
|
|
defp parse(tokens), do: tokens |> :nquads_parser.parse()
|
|
|
|
defp build_dataset([]), do: Dataset.new()
|
|
|
|
defp build_dataset([quads]) do
|
|
Enum.reduce(quads, Dataset.new(), &Dataset.add(&2, &1))
|
|
end
|
|
end
|