class ActiveSupport::SafeBuffer

def %(args)
  case args
  when Hash
    escaped_args = Hash[args.map { |k,arg| [k, html_escape_interpolated_argument(arg)] }]
  else
    escaped_args = Array(args).map { |arg| html_escape_interpolated_argument(arg) }
  end
  self.class.new(super(escaped_args))
end

def +(other)
  dup.concat(other)
end

def [](*args)
  if args.size < 2
    super
  else
    if html_safe?
      new_safe_buffer = super
      new_safe_buffer.instance_eval { @html_safe = true }
      new_safe_buffer
    else
      to_str[*args]
    end
  end
end

def clone_empty
  self[0, 0]
end

def concat(value)
  if !html_safe? || value.html_safe?
    super(value)
  else
    super(ERB::Util.h(value))
  end
end

def encode_with(coder)
  coder.represent_scalar nil, to_str
end

def html_escape_interpolated_argument(arg)
  (!html_safe? || arg.html_safe?) ? arg : ERB::Util.h(arg)
end

def html_safe?
  defined?(@html_safe) && @html_safe
end

def initialize(*)
  @html_safe = true
  super
end

def initialize_copy(other)
  super
  @html_safe = other.html_safe?
end

def safe_concat(value)
  raise SafeConcatError unless html_safe?
  original_concat(value)
end

def to_param
  to_str
end

def to_s
  self
end