Using `&&` for `attachments` and `content` you can save a few lines:
```ruby
def parse_preview_data
  page = @wiki.find_page(params[:id])
  attachments = page && page.attachments
  previewed = page && page.content

  # page is nil when previewing a new page
  return render_403 unless page.nil? || editable?(page)

  text = params[:content][:text]

  return [text], attachments, previewed
end
```