Created
February 12, 2014 13:19
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Reads values of property from file
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import System.Environment | |
import Data.List | |
import Data.Maybe | |
data Arguments = Arguments String String | |
| UnexpectedArguments [String] | |
| NotEnoughArguments | |
deriving Show | |
parseArgs :: [String] -> Arguments | |
parseArgs ( path : k : [] ) = Arguments path k | |
parseArgs ( path : k : rest ) = UnexpectedArguments rest | |
parseArgs _ = NotEnoughArguments | |
data Property = Property String String | |
| MalformedProperty | |
deriving Show | |
match :: String -> Property -> Bool | |
match s ( Property k v ) = k == s | |
match s MalformedProperty = False | |
value :: Property -> String | |
value ( Property k v ) = v | |
parse :: String -> Property | |
parse s | |
| ( not $ null k ) && ( not $ null v ) = Property k v | |
| otherwise = MalformedProperty | |
where | |
v = drop 1 _v | |
( k , _v ) = break ( == '=' ) s | |
filter :: String -> [Property] -> [Property] | |
filter k pp = Data.List.filter ( match k ) pp | |
main = do | |
args <- getArgs | |
case parseArgs args of | |
Arguments path key -> do | |
contents <- readFile path | |
putStrLn $ foldl (++) "" $ foundValues key contents | |
where | |
foundValues k = map value . foundProperties k | |
foundProperties k = Main.filter k . properties | |
properties = map parse . lines | |
UnexpectedArguments aa -> do | |
putStrLn $ "Unexpected arguments: " ++ intercalate " " aa | |
NotEnoughArguments -> do | |
putStrLn "Not enough arguments" |
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