Module: Eth::Abi

Extended by:
Abi
Included in:
Abi
Defined in:
lib/eth/abi.rb,
lib/eth/abi/type.rb,
lib/eth/abi/event.rb,
lib/eth/abi/decoder.rb,
lib/eth/abi/encoder.rb,
lib/eth/abi/packed/encoder.rb

Overview

Provides a Ruby implementation of the Ethereum Application Binary Interface (ABI).

Defined Under Namespace

Modules: Decoder, Encoder, Event, Packed Classes: DecodingError, EncodingError, Type, ValueOutOfBounds

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.decode(types, data) ⇒ Array

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

Parameters:

  • types (Array) —

    the ABI to be decoded.

  • data (String) —

    ABI data to be decoded.

Returns:

  • (Array) —

    the decoded ABI data.

Raises:



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# File 'lib/eth/abi.rb', line 97

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

.encode(types, args, packed = false) ⇒ String

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

Parameters:

  • types (Array) —

    types to be ABI-encoded.

  • args (Array) —

    values to be ABI-encoded.

  • packed (Bool) (defaults to: false) —

    set true to return packed encoding (default: false).

Returns:

  • (String) —

    the encoded ABI data.



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# File 'lib/eth/abi.rb', line 43

def encode(types, args, packed = false)
  return solidity_packed(types, args) if packed
  types = [types] unless types.instance_of? Array
  args = [args] unless args.instance_of? Array

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

  # prepare the "head"
  head_size = (0...args.size)
    .map { |i| parsed_types[i].size or 32 }
    .reduce(0, &:+)
  head, tail = "", ""

  # encode types and arguments
  args.each_with_index do |arg, i|
    if parsed_types[i].dynamic?
      head += Abi::Encoder.type(Type.size_type, head_size + tail.size)
      tail += Abi::Encoder.type(parsed_types[i], arg)
    else
      head += Abi::Encoder.type(parsed_types[i], arg)
    end
  end

  # return the encoded ABI blob
  "#{head}#{tail}"
end

.solidity_packed(types, args) ⇒ String

Encodes Application Binary Interface (ABI) data in non-standard packed mode. It accepts multiple arguments and encodes using the head/tail mechanism.

Parameters:

  • types (Array) —

    types to be ABI-encoded.

  • args (Array) —

    values to be ABI-encoded.

Returns:

  • (String) —

    the encoded packed ABI data.

Raises:

  • (ArgumentError) —

    if types and args are of different size.



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# File 'lib/eth/abi.rb', line 78

def solidity_packed(types, args)
  raise ArgumentError, "Types and values must be the same length" if types.length != args.length

  # We do not use the type system for packed encoding but want to call the parser once
  # to enforce the type validation.
  _ = types.map { |t| Type === t ? t : Type.parse(t) }

  packed = types.zip(args).map do |type, arg|
    Abi::Packed::Encoder.type(type, arg)
  end.join
  packed.force_encoding(Encoding::ASCII_8BIT)
end

Instance Method Details

#decode(types, data) ⇒ Array

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

Parameters:

  • types (Array) —

    the ABI to be decoded.

  • data (String) —

    ABI data to be decoded.

Returns:

  • (Array) —

    the decoded ABI data.

Raises:



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# File 'lib/eth/abi.rb', line 97

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

#encode(types, args, packed = false) ⇒ String

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

Parameters:

  • types (Array) —

    types to be ABI-encoded.

  • args (Array) —

    values to be ABI-encoded.

  • packed (Bool) (defaults to: false) —

    set true to return packed encoding (default: false).

Returns:

  • (String) —

    the encoded ABI data.



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# File 'lib/eth/abi.rb', line 43

def encode(types, args, packed = false)
  return solidity_packed(types, args) if packed
  types = [types] unless types.instance_of? Array
  args = [args] unless args.instance_of? Array

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

  # prepare the "head"
  head_size = (0...args.size)
    .map { |i| parsed_types[i].size or 32 }
    .reduce(0, &:+)
  head, tail = "", ""

  # encode types and arguments
  args.each_with_index do |arg, i|
    if parsed_types[i].dynamic?
      head += Abi::Encoder.type(Type.size_type, head_size + tail.size)
      tail += Abi::Encoder.type(parsed_types[i], arg)
    else
      head += Abi::Encoder.type(parsed_types[i], arg)
    end
  end

  # return the encoded ABI blob
  "#{head}#{tail}"
end

#solidity_packed(types, args) ⇒ String

Encodes Application Binary Interface (ABI) data in non-standard packed mode. It accepts multiple arguments and encodes using the head/tail mechanism.

Parameters:

  • types (Array) —

    types to be ABI-encoded.

  • args (Array) —

    values to be ABI-encoded.

Returns:

  • (String) —

    the encoded packed ABI data.

Raises:

  • (ArgumentError) —

    if types and args are of different size.



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# File 'lib/eth/abi.rb', line 78

def solidity_packed(types, args)
  raise ArgumentError, "Types and values must be the same length" if types.length != args.length

  # We do not use the type system for packed encoding but want to call the parser once
  # to enforce the type validation.
  _ = types.map { |t| Type === t ? t : Type.parse(t) }

  packed = types.zip(args).map do |type, arg|
    Abi::Packed::Encoder.type(type, arg)
  end.join
  packed.force_encoding(Encoding::ASCII_8BIT)
end