OverloadedStrings
, UnicodeSyntax
#-}
-{-# OPTIONS_HADDOCK prune #-}
-
--- |Manipulation of entity tags.
+-- |Entity tags
module Network.HTTP.Lucu.ETag
( ETag(..)
-
+ , parseETag
, printETag
, strongETag
, eTagListP
)
where
+import Control.Applicative
import Control.Monad
-import Control.Monad.Unicode
-import Data.Ascii (Ascii)
+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
--- |An entity tag is made of a weakness flag and a opaque string.
+-- |An entity tag consists of a weakness flag and an opaque string.
data ETag = ETag {
-- |The weakness flag. Weak tags looks like W\/\"blahblah\" and
- -- strong tags are like \"blahblah\".
+ -- strong tags are like \"blahblah\". See:
+ -- <http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html#sec13.3.3>
etagIsWeak ∷ !Bool
-- |An opaque string. Only characters from 0x20 (sp) to 0x7e (~)
-- are allowed.
, etagToken ∷ !Ascii
} deriving (Eq, Show)
--- |Convert an 'ETag' to 'Ascii'.
-printETag ∷ ETag → Ascii
+-- |Convert an 'ETag' to an 'AsciiBuilder'.
+printETag ∷ ETag → AsciiBuilder
+{-# INLINEABLE printETag #-}
printETag et
- = A.fromAsciiBuilder $
- ( ( if etagIsWeak et then
- A.toAsciiBuilder "W/"
- else
- (∅)
- )
- ⊕
- quoteStr (etagToken et) )
+ = ( if etagIsWeak et then
+ A.toAsciiBuilder "W/"
+ else
+ (∅)
+ )
+ ⊕
+ quoteStr (etagToken et)
+
+-- |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
+-- |This is equivalent to @'ETag' '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
--- |This is equivalent to @'ETag' 'Prelude.True'@.
+-- |This is equivalent to @'ETag' 'True'@.
weakETag ∷ Ascii → ETag
+{-# INLINE weakETag #-}
weakETag = ETag True
+-- |'Parser' for an 'ETag'.
eTagP ∷ Parser ETag
-eTagP = do isWeak ← option False (string "W/" ≫ return True)
+{-# INLINEABLE eTagP #-}
+eTagP = do isWeak ← option False (string "W/" *> return True)
str ← quotedStr
return $ ETag isWeak str
+-- |'Parser' for a list of 'ETag's.
eTagListP ∷ Parser [ETag]
+{-# INLINEABLE eTagListP #-}
eTagListP = do xs ← listOf eTagP
when (null xs) $
fail "empty list of ETags"