Remove macro-peeling to get the swagger-docs out

[ikitommi]

Biggest source of Evil in Compojure-api is the custom macro-peeler, to resolve the swagger-docs.

Why it's bad:

• swagger-docs are resolved at (Clojure) compile-time => extra latency in development as the whole handler sub-tree gets re-compiled.
• need to use defroutes* => can't create subroutes via functions (passing system via closure)
• but-ugly code to handle this

A better option:

• Compojure-api wrapped routes (GET* etc) return Records/Types, from where we extract the swagger-docs at runtime via a Ring-swagger protocol.
• We can still use compojure routing beneath, by making the Records invokable - or we could swicth the routing to totally something else, like bidi.

did a simple spike, looks promising.

[ikitommi]

WIP in https://github.com/metosin/compojure-api/tree/runtime-route-resolution

Bye-bye defroutes*:

(facts "nested routes"
  (let [middleware (fn [handler] (fn [request] (handler request)))
        more-routes (fn [version]
                      (routes*
                        (GET* "/more" []
                          (ok {:message version}))))
        routes (context* "/api/:version" []
                 :path-params [version :- String]
                 (GET* "/ping" []
                   (ok {:message (str "pong - " version)}))
                 (middlewares* [middleware]
                   (GET* "/hello" []
                     :return {:message String}
                     :summary "cool ping"
                     :query-params [name :- String]
                     (ok {:message (str "Hello, " name)}))
                   (more-routes version)))]

    (fact "routes can be extracted at runtime"
      (let [routes (r/get-routes routes)]
        routes => [["/api/:version/ping" :get {:parameters {:path {:version String, s/Keyword s/Any}}}]
                   ["/api/:version/hello" :get {:parameters {:query {:name String, s/Keyword s/Any}
                                                             :path {:version String, s/Keyword s/Any}}
                                                :responses {200 {:description "", :schema {:message String}}}
                                                :summary "cool ping"}]
                   ["/api/:version/more" :get {:parameters {:path {:version String, s/Keyword s/Any}}}]]))))

[ikitommi]

In one of the big c-api projects (with 100+ routes), the compile-time is no 750x faster with the new route collector.

[ikitommi]

merged to master.