module Network.Wai.Middleware.Routes.TH.RouteAttrs
( mkRouteAttrsInstance
) where
import Network.Wai.Middleware.Routes.TH.Types
import Network.Wai.Middleware.Routes.Class
import Language.Haskell.TH.Syntax
import Data.Set (fromList)
import Data.Text (pack)
mkRouteAttrsInstance :: Type -> [ResourceTree a] -> Q Dec
mkRouteAttrsInstance typ ress = do
clauses <- mapM (goTree id) ress
return $ InstanceD [] (ConT ''RouteAttrs `AppT` typ)
[ FunD 'routeAttrs $ concat clauses
]
goTree :: (Pat -> Pat) -> ResourceTree a -> Q [Clause]
goTree front (ResourceLeaf res) = fmap return $ goRes front res
goTree front (ResourceParent name _check pieces trees) =
fmap concat $ mapM (goTree front') trees
where
ignored = ((replicate toIgnore WildP ++) . return)
toIgnore = length $ filter isDynamic pieces
isDynamic Dynamic{} = True
isDynamic Static{} = False
front' = front . ConP (mkName name) . ignored
goRes :: (Pat -> Pat) -> Resource a -> Q Clause
goRes front Resource {..} =
return $ Clause
[front $ RecP (mkName resourceName) []]
(NormalB $ VarE 'fromList `AppE` ListE (map toText resourceAttrs))
[]
where
toText s = VarE 'pack `AppE` LitE (StringL s)