94fcd0cf59
This commit includes a paydown on technical debt incurred two years ago, when I didn't know that it was bad to make custom Read and Show instances for types. As the routes need Read and Show for Transfer, which includes a Key, and deriving my own Read instance of key was not practical, I had to finally clean that up. So the compact Key read and show functions are now file2key and key2file, and Read and Show are now derived instances. Changed all code that used the old instances, compiler checked. (There were a few places, particularly in Command.Unused, and the test suite where the Show instance continue to be used for legitimate comparisons; ie show key_x == show key_y (though really in a bloom filter))
78 lines
1.9 KiB
Haskell
78 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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key2file,
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file2key,
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prop_idempotent_key_encode
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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, Read, Show)
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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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{- Converts a key to a strings that are suitable for use as a filename.
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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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key2file :: Key -> FilePath
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key2file 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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file2key :: FilePath -> Maybe Key
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file2key 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_encode :: Key -> Bool
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prop_idempotent_key_encode k = Just k == (file2key . key2file) k
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