77 lines
1.9 KiB
Haskell
77 lines
1.9 KiB
Haskell
{- git-annex Key data type
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-
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- Most things should not need this, using Types instead
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-
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- Copyright 2011 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Types.Key (
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Key(..),
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stubKey,
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readKey,
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prop_idempotent_key_read_show
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) where
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import System.Posix.Types
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import Common
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{- A Key has a unique name, is associated with a key/value backend,
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- and may contain other optional metadata. -}
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data Key = Key {
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keyName :: String,
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keyBackendName :: String,
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keySize :: Maybe Integer,
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keyMtime :: Maybe EpochTime
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} deriving (Eq, Ord)
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stubKey :: Key
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stubKey = Key {
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keyName = "",
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keyBackendName = "",
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keySize = Nothing,
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keyMtime = Nothing
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}
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fieldSep :: Char
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fieldSep = '-'
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{- Keys show as strings that are suitable for use as filenames.
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- The name field is always shown last, separated by doubled fieldSeps,
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- and is the only field allowed to contain the fieldSep. -}
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instance Show Key where
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show Key { keyBackendName = b, keySize = s, keyMtime = m, keyName = n } =
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b +++ ('s' ?: s) +++ ('m' ?: m) +++ (fieldSep : n)
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where
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"" +++ y = y
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x +++ "" = x
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x +++ y = x ++ fieldSep:y
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c ?: (Just v) = c : show v
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_ ?: _ = ""
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readKey :: String -> Maybe Key
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readKey s = if key == Just stubKey then Nothing else key
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where
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key = startbackend stubKey s
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startbackend k v = sepfield k v addbackend
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sepfield k v a = case span (/= fieldSep) v of
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(v', _:r) -> findfields r $ a k v'
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_ -> Nothing
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findfields (c:v) (Just k)
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| c == fieldSep = Just $ k { keyName = v }
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| otherwise = sepfield k v $ addfield c
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findfields _ v = v
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addbackend k v = Just k { keyBackendName = v }
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addfield 's' k v = Just k { keySize = readish v }
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addfield 'm' k v = Just k { keyMtime = readish v }
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addfield _ _ _ = Nothing
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prop_idempotent_key_read_show :: Key -> Bool
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prop_idempotent_key_read_show k = Just k == (readKey . show) k
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