module Control.Monad.Apiary.Filter.Internal.Capture.TH where
import Language.Haskell.TH
import Language.Haskell.TH.Quote
import qualified Control.Monad.Apiary.Filter.Internal.Capture as Capture
import qualified Data.Text as T
import Data.Proxy
preCap :: String -> [String]
preCap "" = []
preCap "/" = []
preCap ('/':p) = splitPath p
preCap p = splitPath p
splitPath :: String -> [String]
splitPath = map T.unpack . T.splitOn "/" . T.pack
description :: Monad m => String -> m (String, Maybe String)
description s = case break (== '(') s of
(t, []) -> return (t, Nothing)
(t, st) -> case break (== ')') st of
(_:b, ")") -> return (t, Just b)
(_, _) -> fail "capture: syntax error."
mkCap :: [String] -> ExpQ
mkCap [] = [|Capture.endPath|]
mkCap ((':':tyStr):as) = do
(t, mbd) <- description tyStr
ty <- lookupTypeName t >>= maybe (fail $ t ++ " not found.") return
let d = case mbd of
Nothing -> [|Nothing|]
Just h -> [|Just $(stringE h)|]
[|Capture.fetch (Proxy :: Proxy $(conT ty)) $d . $(mkCap as)|]
mkCap (eq:as) = do
[|(Capture.path $(stringE eq)) . $(mkCap as) |]
capture :: QuasiQuoter
capture = QuasiQuoter
{ quoteExp = mkCap . preCap
, quotePat = \_ -> error "No quotePat."
, quoteType = \_ -> error "No quoteType."
, quoteDec = \_ -> error "No quoteDec."
}