module Text.Hakyll.Internal.Template
( Template
, fromString
, readTemplate
, substitute
, regularSubstitute
, finalSubstitute
) where
import qualified Data.Map as M
import Data.List (isPrefixOf)
import Data.Char (isAlphaNum)
import Data.Binary
import Control.Monad (liftM, liftM2, replicateM)
import Control.Applicative ((<$>))
import Data.Maybe (fromMaybe)
import System.FilePath ((</>))
import Control.Monad.Reader (liftIO)
import Test.QuickCheck
import Text.Hakyll.Hakyll (Hakyll)
import Text.Hakyll.Context (Context)
import Text.Hakyll.Internal.Cache
data Template = Chunk String Template
| Identifier String Template
| EscapeCharacter Template
| End
deriving (Show, Read, Eq)
fromString :: String -> Template
fromString [] = End
fromString string
| "$$" `isPrefixOf` string = EscapeCharacter (fromString $ tail tail')
| "$" `isPrefixOf` string = let (key, rest) = span isAlphaNum tail'
in Identifier key (fromString rest)
| otherwise = let (chunk, rest) = break (== '$') string
in Chunk chunk (fromString rest)
where
tail' = tail string
readTemplate :: FilePath -> Hakyll Template
readTemplate path = do
isCacheMoreRecent' <- isCacheMoreRecent fileName [path]
if isCacheMoreRecent' then getFromCache fileName
else do content <- liftIO $ readFile path
let template = fromString content
storeInCache template fileName
return template
where
fileName = "templates" </> path
substitute :: String -> Template -> Context -> String
substitute escaper (Chunk chunk template) context =
chunk ++ substitute escaper template context
substitute escaper (Identifier key template) context =
replacement ++ substitute escaper template context
where
replacement = fromMaybe ('$' : key) $ M.lookup key context
substitute escaper (EscapeCharacter template) context =
escaper ++ substitute escaper template context
substitute _ End _ = []
regularSubstitute :: Template -> Context -> String
regularSubstitute = substitute "$$"
finalSubstitute :: Template -> Context -> String
finalSubstitute = substitute "$"
instance Binary Template where
put (Chunk string template) = put (0 :: Word8) >> put string >> put template
put (Identifier key template) = put (1 :: Word8) >> put key >> put template
put (EscapeCharacter template) = put (2 :: Word8) >> put template
put (End) = put (3 :: Word8)
get = do tag <- getWord8
case tag of 0 -> liftM2 Chunk get get
1 -> liftM2 Identifier get get
2 -> liftM EscapeCharacter get
3 -> return End
_ -> error "Error reading template"
arbitraryTemplate :: Int -> Gen Template
arbitraryTemplate 0 = return End
arbitraryTemplate length' = oneof [ do chunk <- chunk'
Chunk chunk <$> template'
, do key <- key'
Identifier key <$> template'
, EscapeCharacter <$> template'
]
where
template' = arbitraryTemplate (length' 1)
key' = do l <- choose (5, 10)
replicateM l $ choose ('a', 'z')
chunk' = do string <- arbitrary
let sanitized = filter (/= '$') string
return $ if null sanitized then "foo"
else sanitized
instance Arbitrary Template where
arbitrary = choose (0, 20) >>= arbitraryTemplate
shrink (Chunk chunk template) = [template, Chunk chunk End]
shrink (Identifier key template) = [template, Identifier key End]
shrink (EscapeCharacter template) = [template, EscapeCharacter End]
shrink End = []