defmodule Methods do
  @moduledoc """
  Documentation for `Methods`.

  This adds method calls for Elixir structs.

  Call methods with "..". 

  This breaks ranges if the second argument is a function call.

  defmodule Rect do
    defstruct [width: 0, height: 0]

    def area(self) do
      self.width * self.height
    end
  end 

  defmodule Main do
    use Methods

    def main do
      r1 = %Rect{width: 10, height: 10}
      area = r1..area()
    end
  end
  """

  import Kernel, except: [..: 2]

  defmacro __using__(_opts) do
    quote do
      import Kernel, except: [..: 2]
      import Methods
    end
  end

  @doc """
  Method call.

  myDog..bark()

  If myDog is a %Dog{}, this calls Dog.bark(myDog).

  If the thing after the ".." doesn't look like a method call,
  this falls back to constructing a range.
  """

  defmacro aa..bb do
    case bb do
      {method, _, args} ->
        args = [aa | args]

        quote do
          apply(unquote(aa).__struct__, unquote(method), unquote(args))
        end

      _ ->
        quote do
          Range.new(unquote(aa), unquote(bb), 1)
        end
    end
  end
end