current_page? (ActionView::Helpers::UrlHelper)

    # File lib/action_view/helpers/url_helper.rb, line 518
          def current_page?(options)
            url_string = CGI.escapeHTML(url_for(options))
            request = @controller.request
            # We ignore any extra parameters in the request_uri if the
            # submitted url doesn't have any either.  This lets the function
            # work with things like ?order=asc
            if url_string.index("?")
              request_uri = request.request_uri
            else
              request_uri = request.request_uri.split('?').first
            end
            if url_string =~ /^\w+:\/\//
              url_string == "#{request.protocol}#{request.host_with_port}#{request_uri}"
            else
              url_string == request_uri
            end
          end