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sourcecode:
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module Names where
import Data.Char ( isAlphaNum )
import Data.List ( intercalate )
import Data.Maybe ( fromJust, isJust )
genCorrectIdentifier :: String -> String
genCorrectIdentifier [] = error "genCorrectIdentifier: empty identifier"
genCorrectIdentifier (c:cs)
| all opChar (c:cs) = c:cs
| otherwise = replaceNonIdChars "" "" (c:cs)
where
opChar = (`elem` "!#$%&*+./<=>?@\\^|-~")
showOpChar :: Char -> String
showOpChar c = case c of
'_' -> "_" --"underscore" TODO: Can this lead to a name clash?
'~' -> "tilde"
'!' -> "bang"
'@' -> "at"
'#' -> "hash"
'$' -> "dollar"
'%' -> "percent"
'^' -> "caret"
'&' -> "ampersand"
'*' -> "star"
'+' -> "plus"
'-' -> "minus"
'=' -> "eq"
'<' -> "lt"
'>' -> "gt"
'?' -> "qmark"
'.' -> "dot"
'/' -> "slash"
'|' -> "bar"
'\\' ->"backslash"
':' -> "colon"
'(' -> "oparen"
')' -> "cparen"
'[' -> "obracket"
']' -> "cbracket"
',' -> "comma"
'\'' -> "tick"
_ -> error $ "unexpected symbol: " ++ show c
-- | replaces characters that are not valid haskell identifiers,
-- | if there were no characters replaced, the first prefix,
-- | otherwise the snd prefix ist prepended
replaceNonIdChars :: String -> String -> String -> String
replaceNonIdChars pfxNonOp pfxOp str = case strings of
[] -> error "replaceNonIdChars: empty identifier"
[s] -> if isAlphaNum (head str)
then pfxNonOp ++ s
else pfxOp ++ s
_ -> pfxOp ++ intercalate "_" strings
where strings = separateAndReplace isIdentChar showOpChar str
isIdentChar c = isAlphaNum c || c == '_' || c == '\''
separateAndReplace :: (a -> Bool) -> (a -> [a]) -> [a] -> [[a]]
separateAndReplace pred f list = case rest of
[] -> case sep of
[] -> []
_ -> [sep]
(x:xs) -> case sep of
[] -> f x : separateAndReplace pred f xs
_ -> sep : f x : separateAndReplace pred f xs
where (sep,rest) = break (not . pred) list
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