forked from GitHub/gf-core
99 lines
3.5 KiB
Haskell
99 lines
3.5 KiB
Haskell
{-# LANGUAGE DeriveDataTypeable #-}
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import PGF (PGF)
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import qualified PGF
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import FastCGIUtils
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import Network.CGI
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import Text.JSON
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import qualified Codec.Binary.UTF8.String as UTF8 (encodeString)
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import Control.Exception
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import Control.Monad
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import Data.Dynamic
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import Data.Maybe
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grammarFile :: FilePath
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grammarFile = "grammar.pgf"
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newtype Record a = Record { unRecord :: [(String,a)] }
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type Translation = Record [Record String]
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instance JSON a => JSON (Record a) where
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readJSON = fmap (Record . fromJSObject) . readJSON
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showJSON = showJSON . toJSObject . unRecord
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main :: IO ()
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main = do initFastCGI
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r <- newDataRef
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loopFastCGI (handleErrors (handleCGIErrors (fcgiMain r)))
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fcgiMain :: DataRef PGF -> CGI CGIResult
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fcgiMain ref = getData PGF.readPGF ref grammarFile >>= cgiMain
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cgiMain :: PGF -> CGI CGIResult
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cgiMain pgf =
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do path <- pathInfo
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case path of
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"/translate" -> do input <- liftM (fromMaybe "") $ getInput "input"
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mcat <- getCat pgf "cat"
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mfrom <- getLang pgf "from"
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mto <- getLang pgf "to"
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outputJSON $ translate pgf input mcat mfrom mto
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"/categories" -> outputJSON $ PGF.categories pgf
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"/languages" -> outputJSON $ PGF.languages pgf
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_ -> outputNotFound path
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getCat :: PGF -> String -> CGI (Maybe PGF.Category)
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getCat pgf i =
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do mcat <- getInput i
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case mcat of
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Just "" -> return Nothing
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Just cat | cat `notElem` PGF.categories pgf ->
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throwCGIError 400 "Unknown category" ["Unknown category: " ++ cat]
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_ -> return mcat
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getLang :: PGF -> String -> CGI (Maybe PGF.Language)
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getLang pgf i =
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do mlang <- getInput i
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case mlang of
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Just "" -> return Nothing
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Just lang | lang `notElem` PGF.languages pgf ->
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throwCGIError 400 "Unknown language" ["Unknown language: " ++ lang]
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_ -> return mlang
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outputJSON :: JSON a => a -> CGI CGIResult
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outputJSON x = do setHeader "Content-Type" "text/json; charset=utf-8"
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outputStrict $ UTF8.encodeString $ encode x
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outputStrict :: String -> CGI CGIResult
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outputStrict x | x == x = output x
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| otherwise = fail "I am the pope."
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translate :: PGF -> String -> Maybe PGF.Category -> Maybe PGF.Language -> Maybe PGF.Language -> Translation
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translate pgf input mcat mfrom mto =
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Record [(from, [Record [(to, PGF.linearize pgf to tree) | to <- toLangs] | tree <- trees])
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| from <- fromLangs, let trees = PGF.parse pgf from cat input, not (null trees)]
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where cat = fromMaybe (PGF.startCat pgf) mcat
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fromLangs = maybe (PGF.languages pgf) (:[]) mfrom
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toLangs = maybe (PGF.languages pgf) (:[]) mto
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-- * General CGI Error exception mechanism
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data CGIError = CGIError { cgiErrorCode :: Int, cgiErrorMessage :: String, cgiErrorText :: [String] }
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deriving Typeable
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throwCGIError :: Int -> String -> [String] -> CGI a
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throwCGIError c m t = throwCGI $ DynException $ toDyn $ CGIError c m t
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handleCGIErrors :: CGI CGIResult -> CGI CGIResult
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handleCGIErrors x = x `catchCGI` \e -> case e of
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DynException d -> case fromDynamic d of
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Nothing -> throw e
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Just (CGIError c m t) -> outputError c m t
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_ -> throw e
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