+{-# LANGUAGE
+ OverloadedStrings
+ , UnicodeSyntax
+ #-}
+-- |Manipulation of entity tags.
module Network.HTTP.Lucu.ETag
- ( ETag
- , mkETag -- Bool -> String -> ETag
- , eTagP -- Parser ETag
- , eTagListP -- Parser [ETag]
+ ( ETag(..)
+ , parseETag
+ , printETag
+
+ , strongETag
+ , weakETag
+ , eTagP
+ , eTagListP
)
where
+import Control.Applicative
+import Control.Monad
+import Data.Ascii (Ascii, AsciiBuilder)
+import qualified Data.Ascii as A
+import Data.Attoparsec.Char8
+import Data.Monoid.Unicode
+import Network.HTTP.Lucu.Parser.Http hiding (token)
+import Network.HTTP.Lucu.Utils
+import Prelude.Unicode
-import Network.HTTP.Lucu.Parser
-import Network.HTTP.Lucu.Parser.Http
-
-
+-- |An entity tag is made of a weakness flag and a opaque string.
data ETag = ETag {
- etagIsWeak :: Bool
- , etagToken :: String
- } deriving (Eq)
+ -- |The weakness flag. Weak tags looks like W\/\"blahblah\" and
+ -- strong tags are like \"blahblah\".
+ etagIsWeak ∷ !Bool
+ -- |An opaque string. Only characters from 0x20 (sp) to 0x7e (~)
+ -- are allowed.
+ , etagToken ∷ !Ascii
+ } deriving (Eq, Show)
+-- |Convert an 'ETag' to 'AsciiBuilder'.
+printETag ∷ ETag → AsciiBuilder
+{-# INLINEABLE printETag #-}
+printETag et
+ = ( if etagIsWeak et then
+ A.toAsciiBuilder "W/"
+ else
+ (∅)
+ )
+ ⊕
+ quoteStr (etagToken et)
-instance Show ETag where
- show (ETag isWeak token) = (if isWeak then
- "W/"
- else
- "")
- ++
- foldr (++) "" (["\""] ++ map quote token ++ ["\""])
- where
- quote :: Char -> String
- quote '"' = "\\\""
- quote c = [c]
-
-
-mkETag :: Bool -> String -> ETag
-mkETag = ETag
+-- |Parse 'Etag' from an 'Ascii'. This functions throws an exception
+-- for parse error.
+parseETag ∷ Ascii → ETag
+{-# INLINEABLE parseETag #-}
+parseETag str
+ = case parseOnly p $ A.toByteString str of
+ Right et → et
+ Left err → error ("unparsable ETag: " ⧺ A.toString str ⧺ ": " ⧺ err)
+ where
+ p ∷ Parser ETag
+ {-# INLINE p #-}
+ p = do et ← eTagP
+ endOfInput
+ return et
+-- |This is equivalent to @'ETag' 'Prelude.False'@. If you want to
+-- generate an ETag from a file, try using
+-- 'Network.HTTP.Lucu.StaticFile.generateETagFromFile'.
+strongETag ∷ Ascii → ETag
+{-# INLINE strongETag #-}
+strongETag = ETag False
-eTagP :: Parser ETag
-eTagP = do isWeak <- option False (string "W/" >> return True)
- str <- quotedStr
- return $ mkETag isWeak str
+-- |This is equivalent to @'ETag' 'Prelude.True'@.
+weakETag ∷ Ascii → ETag
+{-# INLINE weakETag #-}
+weakETag = ETag True
+eTagP ∷ Parser ETag
+{-# INLINEABLE eTagP #-}
+eTagP = do isWeak ← option False (string "W/" *> return True)
+ str ← quotedStr
+ return $ ETag isWeak str
-eTagListP :: Parser [ETag]
-eTagListP = allowEOF
- $ sepBy1 eTagP (do many sp
- char ','
- many sp)
+eTagListP ∷ Parser [ETag]
+{-# INLINEABLE eTagListP #-}
+eTagListP = do xs ← listOf eTagP
+ when (null xs) $
+ fail "empty list of ETags"
+ return xs