requirements

# File actionpack/lib/action_dispatch/routing/mapper.rb, line 140
          def requirements
            @requirements ||= (@options[:constraints].is_a?(Hash) ? @options[:constraints] : {}).tap do |requirements|
              requirements.reverse_merge!(@scope[:constraints]) if @scope[:constraints]
              @options.each { |k, v| requirements[k] = v if v.is_a?(Regexp) }
            end
          end