class ActiveSupport::JSON::Encoding::Encoder

def as_json(value, use_options = true)
  check_for_circular_references(value) do
    use_options ? value.as_json(options_for(value)) : value.as_json
  end
end

def check_for_circular_references(value)
  unless @seen.add?(value.__id__)
    raise CircularReferenceError, 'object references itself'
  end
  yield
ensure
  @seen.delete(value.__id__)
end

def encode(value, use_options = true)
  check_for_circular_references(value) do
    jsonified = use_options ? value.as_json(options_for(value)) : value.as_json
    jsonified.encode_json(self)
  end
end

def escape(string)
  Encoding.escape(string)
end

def initialize(options = nil)
  @options = options || {}
  @seen = Set.new
end

def options_for(value)
  if value.is_a?(Array) || value.is_a?(Hash)
    # hashes and arrays need to get encoder in the options, so that
    # they can detect circular references.
    options.merge(:encoder => self)
  else
    options.dup
  end
end