gistfile1.hs

dropLast n bstr = BS.take (BS.length bstr - n) bstr
takeLast n bstr = BS.drop (BS.length bstr - n) bstr

reComp pat = makeRegexOpts compBlank execBlank pat

breakNextRegex re bstr =
    if pos >= 0
    then BS.splitAt pos bstr
    else (bstr, BS.empty)
    where (pos, len) = bstr =~ re :: (MatchOffset,MatchLength)

afterLast :: ByteStr -> ByteStr -> ByteStr
afterLast pat bstr = revSearch 0 bstr
  where
  revSearch n s
        | BS.null s             = bstr -- not found                            
        | pat `BS.isSuffixOf` s = BS.drop (BS.length bstr - n) bstr            
        | otherwise             = revSearch (n+1) (BSUS.unsafeInit s)          
        
afterLastRegex :: String -> ByteStr -> ByteStr                                 
afterLastRegex re bstr = revSearchRE 0 bstr                                    
    where          
    revSearchRE n s
        | BS.null s   = bstr 
        | offset >= 0 = takeLast (consumed - offset) bstr                      
        | otherwise   = revSearchRE consumed remaining
        where        
        lastline = afterLast (pack "\n") s
        (offset, l) = lastline =~ re :: (MatchOffset,MatchLength)              
        consumed  = n + BS.length lastline                                     
        remaining = dropLast consumed bstr