class ActionView::PathResolver

def extract_handler_and_format(path, default_formats)

to the resolver.
from the path, or the handler, we should return the array of formats given
Extract handler and formats from path. If a format cannot be a found neither 
def extract_handler_and_format(path, default_formats)
  pieces = File.basename(path).split(".")
  pieces.shift
  handler  = Template.handler_class_for_extension(pieces.pop)
  if pieces.last == "html" && pieces[-2] == "text"
    correct_path = path.gsub(/\.text\.html/, ".html")
    ActiveSupport::Deprecation.warn "The file `#{path}` uses the deprecated format `text.html`. Please rename it to #{correct_path}", caller
  end
  if pieces.last == "plain" && pieces[-2] == "text"
    correct_path = path.gsub(/\.text\.plain/, ".text")
    pieces.pop
    ActiveSupport::Deprecation.warn "The file `#{path}` uses the deprecated format `text.plain`. Please rename it to #{correct_path}", caller
  end
  format   = pieces.last && Mime[pieces.last] && pieces.pop.to_sym
  format ||= handler.default_format if handler.respond_to?(:default_format)
  format ||= default_formats
  [handler, format]
end