module ActionDispatch::Http::FilterParameters

def env_filter
  parameter_filter_for(Array.wrap(@env["action_dispatch.parameter_filter"]) << /RAW_POST_DATA/)
end

def filtered_env
  @filtered_env ||= env_filter.filter(@env)
end

def filtered_parameters
  @filtered_parameters ||= parameter_filter.filter(parameters)
end

def filtered_path
  @filtered_path ||= query_string.empty? ? path : "#{path}?#{filtered_query_string}"
end

def filtered_query_string
  query_string.gsub(PAIR_RE) do |_|
    parameter_filter.filter([[$1, $2]]).first.join("=")
  end
end

def parameter_filter
  parameter_filter_for(@env["action_dispatch.parameter_filter"])
end

def parameter_filter_for(filters)
  @@parameter_filter_for[filters] ||= ParameterFilter.new(filters)
end