forked from GitHub/gf-core
134 lines
4.8 KiB
Haskell
134 lines
4.8 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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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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json <- case path of
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"/parse" -> return (doParse pgf) `ap` getText `ap` getCat `ap` getFrom
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"/linearize" -> return (doLinearize pgf) `ap` getTree `ap` getTo
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"/translate" -> return (doTranslate pgf) `ap` getText `ap` getCat `ap` getFrom `ap` getTo
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"/categories" -> return $ doCategories pgf
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"/languages" -> return $ doLanguages pgf
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_ -> throwCGIError 404 "Not Found" ["Resource not found: " ++ path]
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outputJSON json
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where
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getText :: CGI String
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getText = liftM (fromMaybe "") $ getInput "input"
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getTree :: CGI PGF.Tree
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getTree = do mt <- getInput "tree"
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t <- maybe (throwCGIError 400 "No tree given" ["No tree given"]) return mt
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maybe (throwCGIError 400 "Bad tree" ["Bad tree: " ++ t]) return (PGF.readTree t)
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getCat :: CGI (Maybe PGF.Category)
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getCat =
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do mcat <- getInput "cat"
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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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getFrom :: CGI (Maybe PGF.Language)
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getFrom = getLang "from"
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getTo :: CGI (Maybe PGF.Language)
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getTo = getLang "to"
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getLang :: String -> CGI (Maybe PGF.Language)
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getLang 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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doTranslate :: PGF -> String -> Maybe PGF.Category -> Maybe PGF.Language -> Maybe PGF.Language -> JSValue
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doTranslate pgf input mcat mfrom mto = showJSON $ toJSObject $
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[(from, [toJSObject (linearize' pgf mto tree) | tree <- trees])
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| (from,trees) <- parse' pgf input mcat mfrom]
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doParse :: PGF -> String -> Maybe PGF.Category -> Maybe PGF.Language -> JSValue
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doParse pgf input mcat mfrom = showJSON $ toJSObject $
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[(from, map PGF.showTree trees) | (from,trees) <- parse' pgf input mcat mfrom]
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doLinearize :: PGF -> PGF.Tree -> Maybe PGF.Language -> JSValue
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doLinearize pgf tree mto = showJSON $ toJSObject $ linearize' pgf mto tree
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doLanguages :: PGF -> JSValue
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doLanguages pgf = showJSON $ toJSObject [(l,toJSObject (info l)) | l <- PGF.languages pgf]
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where info l = [("languageCode", showJSON (fromMaybe "" (PGF.languageCode pgf l))),
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("canParse", showJSON (PGF.canParse pgf l))]
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doCategories :: PGF -> JSValue
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doCategories pgf = showJSON (PGF.categories pgf)
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-- * PGF utilities
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parse' :: PGF -> String -> Maybe PGF.Category -> Maybe PGF.Language -> [(PGF.Language,[PGF.Tree])]
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parse' pgf input mcat mfrom =
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case mfrom of
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Nothing -> PGF.parseAllLang pgf cat input
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Just from -> [(from, PGF.parse pgf from cat input)]
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where cat = fromMaybe (PGF.startCat pgf) mcat
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linearize' :: PGF -> Maybe PGF.Language -> PGF.Tree -> [(PGF.Language,String)]
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linearize' pgf mto tree =
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case mto of
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Nothing -> PGF.linearizeAllLang pgf tree
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Just to -> [(to,PGF.linearize pgf to tree)]
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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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-- * General CGI and JSON stuff
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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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