@@ -11,6 +11,7 @@ import GHC.Generics
1111import qualified Data.ByteString as BS
1212import qualified Data.ByteString.Char8 as BS8
1313import Data.Binary
14+ import Data.List
1415
1516-- utility
1617
@@ -68,11 +69,26 @@ data Unique
6869 = Unique ! Char ! Int
6970 deriving (Eq , Ord , Generic )
7071
72+ instance Read Unique where
73+ readsPrec _d r =
74+ [ (Unique c (base62ToInt numStr), s)
75+ | (c : numStr, s) <- lex r
76+ ]
77+ 7178instance Show Unique where
72- show (Unique c n) = c : iToBase62 n
79+ show (Unique c n) = c : intToBase62 n
80+ 81+ base62ToInt :: String -> Int
82+ base62ToInt numStr = sum
83+ [ 62 ^ e * i
84+ | (e, n) <- zip ([0 .. ] :: [Int $ reverse numStr
85+ , Just i <- [elemIndex n chars62]
86+ ]
87+ where
88+ chars62 = " 0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
7389
74- iToBase62 :: Int -> String
75- iToBase62 n_ = go n_ " " where
90+ intToBase62 :: Int -> String
91+ intToBase62 n_ = go n_ " " where
7692 go n cs | n < 62
7793 = let c = chooseChar62 n in c : cs
7894 | otherwise
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