9 module Network.HTTP.Lucu.ETag
20 import Control.Applicative
22 import Data.Ascii (Ascii, AsciiBuilder)
23 import qualified Data.Ascii as A
24 import Data.Attoparsec.Char8
26 import Data.Monoid.Unicode
27 import Language.Haskell.TH.Syntax
28 import Network.HTTP.Lucu.Parser
29 import Network.HTTP.Lucu.Parser.Http hiding (token)
30 import Network.HTTP.Lucu.Utils
31 import Prelude.Unicode
33 -- |An entity tag consists of a weakness flag and an opaque string.
35 -- |The weakness flag. Weak tags looks like W\/\"blahblah\" and
36 -- strong tags are like \"blahblah\". See:
37 -- <http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html#sec13.3.3>
39 -- |An opaque string. Only characters from 0x20 (sp) to 0x7e (~)
42 } deriving (Eq, Show, Data, Typeable)
44 instance Lift ETag where
47 etagIsWeak = $(lift etagIsWeak)
48 , etagToken = $(liftAscii etagToken)
52 -- |Convert an 'ETag' to an 'AsciiBuilder'.
53 printETag ∷ ETag → AsciiBuilder
54 {-# INLINEABLE printETag #-}
56 = ( if etagIsWeak et then
62 quoteStr (etagToken et)
64 -- |Parse 'Etag' from an 'Ascii'. This functions throws an exception
66 parseETag ∷ Ascii → ETag
67 {-# INLINEABLE parseETag #-}
69 = case parseOnly (finishOff eTag) $ A.toByteString str of
71 Left err → error ("unparsable ETag: " ⧺ A.toString str ⧺ ": " ⧺ err)
73 -- |This is equivalent to @'ETag' 'False'@. If you want to generate an
74 -- ETag from a file, try using
75 -- 'Network.HTTP.Lucu.StaticFile.generateETagFromFile'.
76 strongETag ∷ Ascii → ETag
77 {-# INLINE strongETag #-}
78 strongETag = ETag False
80 -- |This is equivalent to @'ETag' 'True'@.
81 weakETag ∷ Ascii → ETag
82 {-# INLINE weakETag #-}
85 -- |'Parser' for an 'ETag'.
87 {-# INLINEABLE eTag #-}
88 eTag = do isWeak ← option False (string "W/" *> return True)
90 return $ ETag isWeak str
92 -- |'Parser' for a list of 'ETag's.
93 eTagList ∷ Parser [ETag]
94 {-# INLINEABLE eTagList #-}
95 eTagList = do xs ← listOf eTag
97 fail "empty list of ETags"