Swarm framework HTTPRouter using patterns

swarm-http-router.shn

class HTTPRouter
   self()
      self.routes = { }
   end
   add(verb is String, path is String, func is Function)
      self.routes[#self.routes + 1] = Route(verb, path, func)
   end
   match(verb, path)
      for i=1, #self.routes do
         m, q = self.routes[i].match(verb, path)
         if m then
            return self.routes[i], m, q
         end
      end
   end

   class Route
      local frag_patt = / '/' %1 { [^/?]+ } /

      self(verb, path, func)
         self.handler = func
         self.verb = verb
         self.path = path
         self.patt = / /
         for frag in path.gmatch("(:?[^/]*)") do
            if frag == '' then
               continue
            end
            if frag[1] == ':' then
               -- named path parameter
               name = frag[2..-1]
               self.patt *= frag_patt % (a, v) =>
                  a[name] = v
               end
            else 
               -- literal match
               self.patt *= / '/' <{frag}> /
            end
         end

         -- collect the remaining path fragments
         self.patt *= / <{frag_patt}> -> (a, v) =>
            a[#a + 1] = v
         end / ** 0

         -- collect the remaining query part
         self.patt *= / %1 ('/'? {.+})? /
      end

      match(verb, path)
         if self.verb != verb then
            return nil
         end
         return self.patt.match(path, 1, { })
      end
   end
end