gistfile1.ex

defmodule Xbp do
  @moduledoc ~S"""
  Dumps binaries in a similar way to xxd
  """

  import Enum, only: [chunk: 4, join: 2, map: 2, with_index: 1, zip: 2]

  @chunk_len 16
  @offset_len 8

  def dump(bx) when is_binary bx do
    map(fragments(bx),
      fn {{l,idx},{r,idx}} ->
        (String.ljust Integer.to_string(idx), @offset_len)
        <> (String.ljust join(l, " "), 2+@chunk_len*3)
        <> r
      end)
    :ok
  end

  def chunk(l, n \\ @chunk_len), do: with_index chunk(l, n, n, [])

  def fragments(bx) when is_binary bx do
    zip chunk(bin_to_hexstr bx), chunk(bin_to_printable bx)
  end

  defp byte_to_hex(b) when b in 0..255, do: Integer.to_string(b, 16)

  defp byte_to_printable(b) when b in 32..?~, do: b
  defp byte_to_printable(_), do: "."
  defp bin_to_printable(bx) when is_binary bx do
    for <<b <- bx>>, do: byte_to_printable b
  end

  defp bin_to_hexstr(bx) when is_binary bx do
    for <<b <- bx>>, do: maybe_add_leading_0 (byte_to_hex b)
  end

  defp maybe_add_leading_0(<<_::size(8)>>=b), do: "0" <> b
  defp maybe_add_leading_0(<<_::size(16)>>=b), do: b

  defimpl Inspect, for: BitString do
    def inspect(bs, _) do
      Xbp.dump(bs)
    end
  end

end