rdf-ex/lib/rdf/serialization/decoder.ex
2020-11-16 13:22:07 +01:00

86 lines
2.7 KiB
Elixir

defmodule RDF.Serialization.Decoder do
@moduledoc """
A behaviour for decoders of strings encoded in a specific `RDF.Serialization` format.
"""
alias RDF.{Dataset, Graph}
@doc """
Decodes a serialized `RDF.Graph` or `RDF.Dataset` from a string.
It returns an `{:ok, data}` tuple, with `data` being the deserialized graph or
dataset, or `{:error, reason}` if an error occurs.
"""
@callback decode(String.t(), keyword) :: {:ok, Graph.t() | Dataset.t()} | {:error, any}
@doc """
Decodes a serialized `RDF.Graph` or `RDF.Dataset` from a string.
As opposed to `decode/2`, it raises an exception if an error occurs.
Note: The `__using__` macro automatically provides an overridable default
implementation based on the non-bang `decode` function.
"""
@callback decode!(String.t(), keyword) :: Graph.t() | Dataset.t()
@doc """
Decodes a serialized `RDF.Graph` or `RDF.Dataset` from a stream.
It returns an `{:ok, data}` tuple, with `data` being the deserialized graph or
dataset, or `{:error, reason}` if an error occurs.
"""
@callback decode_from_stream(Enumerable.t(), keyword) ::
{:ok, Graph.t() | Dataset.t()} | {:error, any}
@doc """
Decodes a serialized `RDF.Graph` or `RDF.Dataset` from a stream.
As opposed to `decode_from_stream/2`, it raises an exception if an error occurs.
Note: The `__using__` macro automatically provides an overridable default
implementation based on the non-bang `decode` function.
"""
@callback decode_from_stream!(Enumerable.t(), keyword) :: Graph.t() | Dataset.t()
@optional_callbacks decode_from_stream: 2, decode_from_stream!: 2
defmacro __using__(_) do
quote bind_quoted: [], unquote: true do
@behaviour unquote(__MODULE__)
@impl unquote(__MODULE__)
@spec decode!(String.t(), keyword) :: Graph.t() | Dataset.t()
def decode!(content, opts \\ []) do
case decode(content, opts) do
{:ok, data} -> data
{:error, reason} -> raise reason
end
end
defoverridable unquote(__MODULE__)
@before_compile unquote(__MODULE__)
end
end
defmacro __before_compile__(_env) do
quote do
@stream_support __MODULE__
|> Module.definitions_in()
|> Keyword.has_key?(:decode_from_stream)
@doc false
def stream_support?, do: @stream_support
if @stream_support and
not (__MODULE__ |> Module.definitions_in() |> Keyword.has_key?(:decode_from_stream!)) do
@impl unquote(__MODULE__)
def decode_from_stream!(stream, opts \\ []) do
case decode_from_stream(stream, opts) do
{:ok, data} -> data
{:error, reason} -> raise reason
end
end
end
end
end
end