Servant.Server.Internal.Router

Documentation

type Router env = Router' env RoutingApplication

data Router' env a

Internal representation of a router.

The first argument describes an environment type that is expected as extra input by the routers at the leaves. The environment is filled while running the router, with path components that can be used to process captures.

Constructors

StaticRouter (Map Text (Router' env a)) [env -> a]

the map contains routers for subpaths (first path component used for lookup and removed afterwards), the list contains handlers for the empty path, to be tried in order

CaptureRouter (Router' (Text, env) a)

first path component is passed to the child router in its environment and removed afterwards

CaptureAllRouter (Router' ([Text], env) a)

all path components are passed to the child router in its environment and are removed afterwards

RawRouter (env -> a)

to be used for routes we do not know anything about

Choice (Router' env a) (Router' env a)

left-biased choice between two routers

Instances

Functor (Router' env)

Methods

fmap :: (a -> b) -> Router' env a -> Router' env b

(<$) :: a -> Router' env b -> Router' env a

pathRouter :: Text -> Router' env a -> Router' env a

Smart constructor for a single static path component.

leafRouter :: (env -> a) -> Router' env a

Smart constructor for a leaf, i.e., a router that expects the empty path.

choice :: Router' env a -> Router' env a -> Router' env a

Smart constructor for the choice between routers. We currently optimize the following cases:

• Two static routers can be joined by joining their maps and concatenating their leaf-lists.
• Two dynamic routers can be joined by joining their codomains.
• Choice nodes can be reordered.

data RouterStructure

Datatype used for representing and debugging the structure of a router. Abstracts from the handlers at the leaves.

Two Routers can be structurally compared by computing their RouterStructure using routerStructure and then testing for equality, see sameStructure.

Constructors

StaticRouterStructure (Map Text RouterStructure) Int

CaptureRouterStructure RouterStructure

RawRouterStructure

ChoiceStructure RouterStructure RouterStructure

Instances

Eq RouterStructure

Methods

(==) :: RouterStructure -> RouterStructure -> Bool

(/=) :: RouterStructure -> RouterStructure -> Bool

Show RouterStructure

Methods

showsPrec :: Int -> RouterStructure -> ShowS

show :: RouterStructure -> String

showList :: [RouterStructure] -> ShowS

routerStructure :: Router' env a -> RouterStructure

Compute the structure of a router.

Assumes that the request or text being passed in WithRequest or CaptureRouter does not affect the structure of the underlying tree.

sameStructure :: Router' env a -> Router' env b -> Bool

Compare the structure of two routers.

routerLayout :: Router' env a -> Text

Provide a textual representation of the structure of a router.

tweakResponse :: (RouteResult Response -> RouteResult Response) -> Router env -> Router env

Apply a transformation to the response of a Router.

runRouter :: Router () -> RoutingApplication

Interpret a router as an application.

runRouterEnv :: Router env -> env -> RoutingApplication

runChoice :: [env -> RoutingApplication] -> env -> RoutingApplication

Try a list of routing applications in order. We stop as soon as one fails fatally or succeeds. If all fail normally, we pick the "best" error.

worseHTTPCode :: Int -> Int -> Bool