defmodule Timex.Parse.DateTime.Tokenizer do
  @moduledoc """
  Defines the API for a custom tokenizer which can extend Timex's datetime parsing facilities.
  """
  alias Timex.Parse.DateTime.Tokenizers.Directive

  @callback tokenize(format_string :: String.t) :: {:ok, [Directive.t]} | {:error, term}
  @callback apply(DateTime.t, token :: atom, value :: term) :: DateTime.t | {:error, term} | :unrecognized

  defmacro __using__(_) do
    quote do
      @behaviour Timex.Parse.DateTime.Tokenizer

      import Timex.Parse.DateTime.Tokenizer
      alias Timex.Parse.DateTime.Tokenizers.Directive
    end
  end
end