gistfile1.ex

def(at(<<var!(head) :: binary - size(2), rest :: binary>>, ptr, meta) when ptr >= 8 and ptr <= 9) do
  new_posn = ptr + 2
  case({:meta, {:header_length, head}}) do
    {:halt, _} = halt ->
      halt
    {:meta, {key, val}} ->
      {rest, new_posn, Dict.put(meta, key, val), []}
    result ->
      {rest, new_posn, meta, [result]}
  end
end
def(at(<<var!(head) :: binary - size(2), rest :: binary>>, ptr, meta) when ptr >= 10 and ptr <= 11) do
  new_posn = ptr + 2
  case({:meta, {:record_length, head}}) do
    {:halt, _} = halt ->
      halt
    {:meta, {key, val}} ->
      {rest, new_posn, Dict.put(meta, key, val), []}
    result ->
      {rest, new_posn, meta, [result]}
  end
end

  defp build_byte_reader(from_byte, to_byte, type, endianness, body) do
    byte_size = (to_byte - from_byte) + 1
    units_to_match = to_match_unit(byte_size, type)

    matcher = build_byte_matcher(type, units_to_match, endianness)

    # Macro.to_string(matcher) |> IO.puts

    wat = quote do
      def at(unquote(matcher), ptr, meta) when ptr >= unquote(from_byte) and ptr <= unquote(to_byte) do
        new_posn = ptr + unquote(byte_size)
        case unquote(body[:do]) do
          {:halt, _} = halt -> halt
          {:meta, {key, val}} -> {rest, new_posn, Dict.put(meta, key, val), []}
          result -> {rest, new_posn, meta, [result]}
        end
      end
    end

    Macro.to_string(wat) |> IO.puts

    wat
  end