class RuboCop::Cop::Lint::ParenthesesAsGroupedExpression

def on_send(node)
  return unless node.arguments.one?
  return if node.operator_method? || node.setter_method?
  return unless node.first_argument.source.start_with?('(')
  space_length = spaces_before_left_parenthesis(node)
  return unless space_length > 0
  add_offense(nil, space_range(node.first_argument.source_range,
                               space_length))
end

def space_range(expr, space_length)
  range_between(expr.begin_pos - space_length, expr.begin_pos)
end

def spaces_before_left_parenthesis(node)
  receiver = node.receiver
  receiver_length = if receiver
                      receiver.source.length
                    else
                      0
                    end
  without_receiver = node.source[receiver_length..-1]
  # Escape question mark if any.
  method_regexp = Regexp.escape(node.method_name)
  match = without_receiver.match(/^\s*\.?\s*#{method_regexp}(\s+)\(/)
  match ? match.captures[0].length : 0
end