Module: Ethereum::FastRLP

Extended by:
FastRLP
Includes:
RLP::Encode
Included in:
FastRLP
Defined in:
lib/ethereum/fast_rlp.rb

Instance Method Summary collapse

Instance Method Details

#consume_length_prefix(rlp, start) ⇒ Object

Read a length prefix from an RLP string.

  • ‘rlp` - the rlp string to read from

  • ‘start` - the position at which to start reading

Returns an array ‘[type, length, end]`, where `type` is either `:str` or `:list` depending on the type of the following payload, `length` is the length of the payload in bytes, and `end` is the position of the first payload byte in the rlp string (thus the end of length prefix).



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# File 'lib/ethereum/fast_rlp.rb', line 57

def consume_length_prefix(rlp, start)
  b0 = rlp[start].ord

  if b0 < PRIMITIVE_PREFIX_OFFSET # single byte
    [:str, 1, start]
  elsif b0 < PRIMITIVE_PREFIX_OFFSET + SHORT_LENGTH_LIMIT # short string
    [:str, b0 - PRIMITIVE_PREFIX_OFFSET, start + 1]
  elsif b0 < LIST_PREFIX_OFFSET # long string
    ll = b0 - PRIMITIVE_PREFIX_OFFSET - SHORT_LENGTH_LIMIT + 1
    l = big_endian_to_int rlp[(start+1)...(start+1+ll)]
    [:str, l, start+1+ll]
  elsif b0 < LIST_PREFIX_OFFSET + SHORT_LENGTH_LIMIT # short list
    [:list, b0 - LIST_PREFIX_OFFSET, start + 1]
  else # long list
    ll = b0 - LIST_PREFIX_OFFSET - SHORT_LENGTH_LIMIT + 1
    l = big_endian_to_int rlp[(start+1)...(start+1+ll)]
    [:list, l, start+1+ll]
  end
end

#decode(rlp) ⇒ Object 



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# File 'lib/ethereum/fast_rlp.rb', line 29

def decode(rlp)
  o = []
  pos = 0

  type, len, pos = consume_length_prefix rlp, pos
  return rlp[pos, len] if type != :list

  while pos < rlp.size
    _, _len, _pos = consume_length_prefix rlp, pos
    to = _len + _pos
    o.push decode(rlp[pos...to])
    pos = to
  end

  o
end

#encode(item) ⇒ Object

Alias to encode_nested_bytes, override default encode.



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# File 'lib/ethereum/fast_rlp.rb', line 25

def encode(item)
  encode_nested_bytes item
end

#encode_nested_bytes(item) ⇒ Object

RLP encode (a nested list of ) bytes.



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# File 'lib/ethereum/fast_rlp.rb', line 10

def encode_nested_bytes(item)
  if item.instance_of?(String)
    return item if item.size == 1 && item.ord < PRIMITIVE_PREFIX_OFFSET
    prefix = length_prefix item.size, PRIMITIVE_PREFIX_OFFSET
  else # list
    item = item.map {|x| encode_nested_bytes(x) }.join
    prefix = length_prefix item.size, LIST_PREFIX_OFFSET
  end

  "#{prefix}#{item}"
end