defprotocol Reactor.Dsl.Build do
  @moduledoc """
  A protocol which DSL entities must implement.
  """

  @doc """
  Build an entity into a Reactor.

  This function is called during conversion of a DSL module into a Reactor
  struct.  This allows extensions to specify the behaviour of how they want
  to alter the structure of the Reactor.
  """
  @spec build(t, Reactor.t()) :: {:ok, Reactor.t()} | {:error, any}
  def build(entity, reactor)

  @doc """
  Perform any transformation that is needed to make the entity work in the
  system before building.

  See `Spark.Dsl.Transformer` for more information.
  """
  @spec transform(t, Spark.Dsl.t()) :: {:ok, Spark.Dsl.t()} | {:error, any}
  def transform(entity, dsl_state)

  @doc """
  Perform any after-compilation verification that is needed to make the entity
  work.

  See `Spark.Dsl.Verifier` for more information.
  """
  @spec verify(t, Spark.Dsl.t()) :: :ok | {:error, any}
  def verify(entity, dsl_state)
end