Module: Eth::Abi::Event

Extended by:
Event
Included in:
Event
Defined in:
lib/eth/abi/event.rb

Overview

Provides a module to decode transaction log events.

Defined Under Namespace

Classes: LogDescription

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.compute_topic(interface) ⇒ String

Compute topic for ABI event interface.

Parameters:

  • interface (Hash) —

    ABI event interface.

Returns:

  • (String) —

    a hex-string topic.



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# File 'lib/eth/abi/event.rb', line 31

def compute_topic(interface)
  sig = signature(interface)
  Util.prefix_hex(Util.bin_to_hex(Util.keccak256(sig)))
end

.decode_log(inputs, data, topics, anonymous = false) ⇒ [Array, Hash]

Decodes event log argument values.

Parameters:

  • inputs (Array) —

    event ABI types.

  • data (String) —

    ABI event data to be decoded.

  • topics (Array) —

    ABI event topics to be decoded.

  • anonymous (Boolean) (defaults to: false) —

    If event signature is excluded from topics.

Returns:

  • ([Array, Hash]) —

    decoded positional arguments and decoded keyword arguments.

Raises:



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# File 'lib/eth/abi/event.rb', line 130

def decode_log(inputs, data, topics, anonymous = false)
  topic_inputs, data_inputs = inputs.partition { |i| i["indexed"] }

  topic_types = topic_inputs.map do |i|
    if i["type"] == "tuple"
      Type.parse(i["type"], i["components"], i["name"])
    else
      i["type"]
    end
  end
  data_types = data_inputs.map do |i|
    if i["type"] == "tuple"
      Type.parse(i["type"], i["components"], i["name"])
    else
      i["type"]
    end
  end
  # If event is anonymous, all topics are arguments. Otherwise, the first
  # topic will be the event signature.
  if anonymous == false
    topics = topics[1..-1]
  end

  decoded_topics = topics.map.with_index { |t, i| Abi.decode([topic_types[i]], t)[0] }
  decoded_data = Abi.decode(data_types, data)

  args = []
  kwargs = {}

  inputs.each_with_index do |input, index|
    if input["indexed"]
      value = decoded_topics[topic_inputs.index(input)]
    else
      value = decoded_data[data_inputs.index(input)]
    end
    args[index] = value
    kwargs[input["name"].to_sym] = value
  end

  return args, kwargs
end

.decode_logs(interfaces, logs) ⇒ Hash

Decodes a stream of receipt logs with a set of ABI interfaces.

Parameters:

  • interfaces (Array) —

    event ABI types.

  • logs (Array) —

    transaction receipt logs

Returns:

  • (Hash) —

    an enumerator of LogDescription objects.



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# File 'lib/eth/abi/event.rb', line 107

def decode_logs(interfaces, logs)
  Enumerator.new do |y|
    topic_to_interfaces = Hash[interfaces.map { |i| [compute_topic(i), i] }]

    logs.each do |log|
      topic = log.fetch("topics", [])[0]
      if topic && interface = topic_to_interfaces[topic]
        y << [log, LogDescription.new(interface, log)]
      else
        y << [log, nil]
      end
    end
  end
end

.signature(interface) ⇒ String

Build event signature string from ABI interface.

Parameters:

  • interface (Hash) —

    ABI event interface.

Returns:

  • (String) —

    interface signature string.



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# File 'lib/eth/abi/event.rb', line 40

def signature(interface)
  name = interface.fetch("name")
  inputs = interface.fetch("inputs", [])
  types = inputs.map { |i| type(i) }
  "#{name}(#{types.join(",")})"
end

.type(input) ⇒ String

Gets the input type for events.

Parameters:

  • input (Hash) —

    events input.

Returns:

  • (String) —

    input type.



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# File 'lib/eth/abi/event.rb', line 51

def type(input)
  if input["type"] == "tuple"
    "(#{input["components"].map { |c| type(c) }.join(",")})"
  elsif input["type"] == "enum"
    "uint8"
  else
    input["type"]
  end
end

Instance Method Details

#compute_topic(interface) ⇒ String

Compute topic for ABI event interface.

Parameters:

  • interface (Hash) —

    ABI event interface.

Returns:

  • (String) —

    a hex-string topic.



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# File 'lib/eth/abi/event.rb', line 31

def compute_topic(interface)
  sig = signature(interface)
  Util.prefix_hex(Util.bin_to_hex(Util.keccak256(sig)))
end

#decode_log(inputs, data, topics, anonymous = false) ⇒ [Array, Hash]

Decodes event log argument values.

Parameters:

  • inputs (Array) —

    event ABI types.

  • data (String) —

    ABI event data to be decoded.

  • topics (Array) —

    ABI event topics to be decoded.

  • anonymous (Boolean) (defaults to: false) —

    If event signature is excluded from topics.

Returns:

  • ([Array, Hash]) —

    decoded positional arguments and decoded keyword arguments.

Raises:



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# File 'lib/eth/abi/event.rb', line 130

def decode_log(inputs, data, topics, anonymous = false)
  topic_inputs, data_inputs = inputs.partition { |i| i["indexed"] }

  topic_types = topic_inputs.map do |i|
    if i["type"] == "tuple"
      Type.parse(i["type"], i["components"], i["name"])
    else
      i["type"]
    end
  end
  data_types = data_inputs.map do |i|
    if i["type"] == "tuple"
      Type.parse(i["type"], i["components"], i["name"])
    else
      i["type"]
    end
  end
  # If event is anonymous, all topics are arguments. Otherwise, the first
  # topic will be the event signature.
  if anonymous == false
    topics = topics[1..-1]
  end

  decoded_topics = topics.map.with_index { |t, i| Abi.decode([topic_types[i]], t)[0] }
  decoded_data = Abi.decode(data_types, data)

  args = []
  kwargs = {}

  inputs.each_with_index do |input, index|
    if input["indexed"]
      value = decoded_topics[topic_inputs.index(input)]
    else
      value = decoded_data[data_inputs.index(input)]
    end
    args[index] = value
    kwargs[input["name"].to_sym] = value
  end

  return args, kwargs
end

#decode_logs(interfaces, logs) ⇒ Hash

Decodes a stream of receipt logs with a set of ABI interfaces.

Parameters:

  • interfaces (Array) —

    event ABI types.

  • logs (Array) —

    transaction receipt logs

Returns:

  • (Hash) —

    an enumerator of LogDescription objects.



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# File 'lib/eth/abi/event.rb', line 107

def decode_logs(interfaces, logs)
  Enumerator.new do |y|
    topic_to_interfaces = Hash[interfaces.map { |i| [compute_topic(i), i] }]

    logs.each do |log|
      topic = log.fetch("topics", [])[0]
      if topic && interface = topic_to_interfaces[topic]
        y << [log, LogDescription.new(interface, log)]
      else
        y << [log, nil]
      end
    end
  end
end

#signature(interface) ⇒ String

Build event signature string from ABI interface.

Parameters:

  • interface (Hash) —

    ABI event interface.

Returns:

  • (String) —

    interface signature string.



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# File 'lib/eth/abi/event.rb', line 40

def signature(interface)
  name = interface.fetch("name")
  inputs = interface.fetch("inputs", [])
  types = inputs.map { |i| type(i) }
  "#{name}(#{types.join(",")})"
end

#type(input) ⇒ String

Gets the input type for events.

Parameters:

  • input (Hash) —

    events input.

Returns:

  • (String) —

    input type.



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# File 'lib/eth/abi/event.rb', line 51

def type(input)
  if input["type"] == "tuple"
    "(#{input["components"].map { |c| type(c) }.join(",")})"
  elsif input["type"] == "enum"
    "uint8"
  else
    input["type"]
  end
end