{-# LANGUAGE CPP #-}
{-# LANGUAGE ViewPatterns #-}
#ifdef FILE_EMBED
{-# LANGUAGE TemplateHaskell #-}
#endif
module General.Template(runTemplate) where
import System.FilePath.Posix
import Control.Exception.Extra
import Data.Char
import Data.Time
import System.IO.Unsafe
import Development.Shake.Internal.Paths
import qualified Data.ByteString.Lazy.Char8 as LBS
import qualified Language.Javascript.DGTable as DGTable
import qualified Language.Javascript.Flot as Flot
import qualified Language.Javascript.JQuery as JQuery
#ifdef FILE_EMBED
import Data.FileEmbed
import Language.Haskell.TH.Syntax ( runIO )
#endif
{- HLINT ignore "Redundant bracket" -} -- a result of CPP expansion
-- Very hard to abstract over TH, so we do it with CPP
#ifdef FILE_EMBED
#define FILE(x) (return (LBS.fromStrict $(embedFile =<< runIO (x))))
#else
#define FILE(x) (LBS.readFile =<< (x))
#endif
libraries :: [(String, IO LBS.ByteString)]
libraries =
[("jquery.js", FILE(JQuery.file))
,("jquery.dgtable.js", FILE(DGTable.file))
,("jquery.flot.js", FILE(Flot.file Flot.Flot))
,("jquery.flot.stack.js", FILE(Flot.file Flot.FlotStack))
]
-- | Template Engine. Perform the following replacements on a line basis:
--
-- * ==>
--
-- * ==>
runTemplate :: (FilePath -> IO LBS.ByteString) -> LBS.ByteString -> IO LBS.ByteString
runTemplate ask = lbsMapLinesIO f
where
link = LBS.pack "\n" `LBS.append` res `LBS.append` LBS.pack "\n"
| Just file <- lbsStripPrefix link y = do res <- grab file; return $ LBS.pack ""
| otherwise = return x
where
y = LBS.dropWhile isSpace x
grab = asker . takeWhile (/= '\"') . LBS.unpack
asker o@(splitFileName -> ("lib/",x)) =
case lookup x libraries of
Nothing -> errorIO $ "Template library, unknown library: " ++ o
Just act -> act
asker "shake.js" = readDataFileHTML "shake.js"
asker "data/metadata.js" = do
time <- getCurrentTime
return $ LBS.pack $
"var version = " ++ show shakeVersionString ++
"\nvar generated = " ++ show (formatTime defaultTimeLocale (iso8601DateFormat (Just "%H:%M:%S")) time)
asker x = ask x
-- Perform a mapM on each line and put the result back together again
lbsMapLinesIO :: (LBS.ByteString -> IO LBS.ByteString) -> LBS.ByteString -> IO LBS.ByteString
-- If we do the obvious @fmap LBS.unlines . mapM f@ then all the monadic actions are run on all the lines
-- before it starts producing the lazy result, killing streaming and having more stack usage.
-- The real solution (albeit with too many dependencies for something small) is a streaming library,
-- but a little bit of unsafePerformIO does the trick too.
lbsMapLinesIO f = return . LBS.unlines . map (unsafePerformIO . f) . LBS.lines
---------------------------------------------------------------------
-- COMPATIBILITY
-- available in bytestring-0.10.8.0, GHC 8.0 and above
-- alternative implementation below
lbsStripPrefix :: LBS.ByteString -> LBS.ByteString -> Maybe LBS.ByteString
lbsStripPrefix prefix text = if a == prefix then Just b else Nothing
where (a,b) = LBS.splitAt (LBS.length prefix) text