Method: Eth::Abi#decode

Defined in:
lib/eth/abi.rb

#decode(types, data) ⇒ Array

Decodes Application Binary Interface (ABI) data. It accepts multiple arguments and decodes using the head/tail mechanism.

Raises:



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# File 'lib/eth/abi.rb', line 98

def decode(types, data)

  # accept hex abi but decode it first
  data = Util.hex_to_bin data if Util.hex? data

  # parse all types
  parsed_types = types.map { |t| Type.parse(t) }

  # prepare output data
  outputs = [nil] * types.size
  start_positions = [nil] * types.size + [data.size]
  pos = 0
  parsed_types.each_with_index do |t, i|
    if t.dynamic?

      # record start position for dynamic type
      start_positions[i] = Util.deserialize_big_endian_to_int(data[pos, 32])
      j = i - 1
      while j >= 0 and start_positions[j].nil?
        start_positions[j] = start_positions[i]
        j -= 1
      end
      pos += 32
    else

      # get data directly for static types
      outputs[i] = data[pos, t.size]
      pos += t.size
    end
  end

  # add start position equal the length of the entire data
  j = types.size - 1
  while j >= 0 and start_positions[j].nil?
    start_positions[j] = start_positions[types.size]
    j -= 1
  end
  raise DecodingError, "Not enough data for head" unless pos <= data.size

  # add dynamic types
  parsed_types.each_with_index do |t, i|
    if t.dynamic?
      offset, next_offset = start_positions[i, 2]
      outputs[i] = data[offset...next_offset]
    end
  end

  # return the decoded ABI types and data
  parsed_types.zip(outputs).map { |(type, out)| Abi::Decoder.type(type, out) }
end