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module PropertyFile(readPropertyFile,updatePropertyFile) where
import Directory
import IOExts
import Char
readPropertyFile :: String -> IO [(String,String)]
readPropertyFile file = do
pfexists <- doesFileExist file
if pfexists
then do rcs <- readCompleteFile file
return $ splitEqs . filter (\l->not (null l) && isAlpha (head l))
. lines $ rcs
else return []
where
splitEqs [] = []
splitEqs (eq:eqs) = case break (=='=') eq of
(prop,_:val) -> (prop,val) : splitEqs eqs
_ -> splitEqs eqs
updatePropertyFile :: String -> String -> String -> IO ()
updatePropertyFile file pname pval = do
props <- readPropertyFile file
if lookup pname props == Nothing
then appendFile file (pname++"="++pval++"\n")
else changePropertyInFile file pname pval
changePropertyInFile :: String -> String -> String -> IO ()
changePropertyInFile file pname pval = do
updateFile (\rcs -> unlines . map changeProp . lines $ rcs) file
where
changeProp l = let (s1,s2) = break (=='=') l
in if null l || not (isAlpha (head l)) || null s2
then l
else if s1==pname then s1++"="++pval else l
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