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ex_rlp

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Ethereum's Recursive Length Prefix (RLP) encoding

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lib/ex_rlp.ex 

defmodule ExRLP do

  alias ExRLP.{Encoder, Decoder}



  @moduledoc File.read!("#{__DIR__}/../README.md")



  @type t :: nil | [t] | binary()



  @doc """

  Given an RLP structure, returns the encoding as a string.



  ## Examples



    iex> ExRLP.encode("dog")

    <<0x83, ?d, ?o, ?g>>



    iex> ExRLP.encode("dog", encoding: :hex)

    "83646f67"



    iex> ExRLP.encode(Enum.join(for _ <- 1..60, do: "A"))

    <<184, 60, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65>>



    iex> ExRLP.encode(["cat", "dog"])

    <<0xc8, 0x83, ?c, ?a, ?t, 0x83, ?d, ?o, ?g>>



    iex> ExRLP.encode("")

    <<0x80>>



    iex> ExRLP.encode([])

    <<0xc0>>



    iex> ExRLP.encode("\x0f")

    <<0x0f>>



    iex> ExRLP.encode(15)

    <<0x0f>>



    iex> ExRLP.encode(15_000_000_000_000_000_000_000_000_000_000_000)

    <<143, 2, 227, 142, 158, 4, 75, 160, 83, 84, 85, 150, 0, 0, 0, 0>>



    iex> ExRLP.encode(1024)

    <<0x82, 0x04, 0x00>>



    iex> ExRLP.encode("\x04\x00")

    <<0x82, 0x04, 0x00>>



    iex> ExRLP.encode([[],[[]],[[],[[]]]])

    <<0xc7, 0xc0, 0xc1, 0xc0, 0xc3, 0xc0, 0xc1, 0xc0>>



    iex> ExRLP.encode(for _ <- 1..60, do: [])

    <<248, 60, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192>>

  """

  @spec encode(t, keyword()) :: binary()

  def encode(item, options \\ []) do

    item |> Encoder.encode(options)

  end



  @doc """

  Given an RLP-encoded string, returns a decoded RPL structure (which is an array of RLP structures or binaries).



  ## Examples



    iex> ExRLP.decode(<<>>)

    nil



    iex> ExRLP.decode(<<0x83, ?d, ?o, ?g>>)

    "dog"



    iex> ExRLP.decode("83646f67", :binary, encoding: :hex)

    "dog"



    iex> ExRLP.decode(<<184, 60, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65, 65>>)

    Enum.join(for _ <- 1..60, do: "A")



    iex> ExRLP.decode(<<0xc8, 0x83, ?c, ?a, ?t, 0x83, ?d, ?o, ?g>>)

    ["cat", "dog"]



    iex> ExRLP.decode(<<198, 51, 132, 99, 111, 111, 108>>)

    ["3", "cool"]



    iex> ExRLP.decode(<<0x80>>)

    ""



    iex> ExRLP.decode(<<0xc0>>)

    []



    iex> ExRLP.decode(<<0x0f>>)

    <<0x0f>>



    iex> ExRLP.decode(<<0x82, 0x04, 0x00>>)

    "\x04\x00"



    iex> ExRLP.decode(<<0xc7, 0xc0, 0xc1, 0xc0, 0xc3, 0xc0, 0xc1, 0xc0>>)

    [[],[[]],[[],[[]]]]



    iex> ExRLP.decode(<<248, 60, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192>>)

    for _ <- 1..60, do: []



    iex> ExRLP.decode(<<143, 2, 227, 142, 158, 4, 75, 160, 83, 84, 85, 150, 0, 0, 0, 0>>) |> :binary.decode_unsigned

    15_000_000_000_000_000_000_000_000_000_000_000

  """

  @spec decode(binary(), atom(), keyword()) :: t

  def decode(item, type \\ :binary, options \\ []) do

    item |> Decoder.decode(type, options)

  end



end