hello, does this work?
pLine = many (noneOf "\n") pLines = pLine `sepEndBy` char '\n'
bye iavor On Sun, Apr 07, 2002 at 07:44:42PM +0200, Till Doerges wrote:
Hi folks,
when trying to write a parser for unix-style textfiles, I stumbled across the problem having to distinguish between lines w/ a newline character at the end and lines w/o a newline at the end (i.e. the last line in a file doesn't have to have it).
Eventually I want to be able to use my parser 'linep' with 'many' on no matter which text-files.
The first version I tried, was
--- snip --- skip1 :: Parser() skip1 = do anyChar return()
linep :: Parser(String) linep = do { cs <- many (noneOf "\n") ; skip1 ; return cs } --- snap ---
Well, this only works, if the last line in the file is also terminated by '\n'. So, I tried to be smarter using:
--- snip --- lineWith :: Parser(String) lineWith = try (do { cs <- many (noneOf "\n") ; skip1 ; return cs })
lineWithOut :: Parser(String) lineWithOut = many anyChar
linep :: Parser(String) linep = lineWith <|> lineWithOut "line" --- snap ---
But this doesn't do the trick either, instead it'll overflow my stack if used in conjunction w/ 'many':
--- snip --- parse (do {many linep}) "stdin" (unlines ["hallo","ballo"]) ^CInterrupted. ReadOrig> parse (do {many linep}) "stdin" ("hallo\nballo") ^CInterrupted. --- snap ---
Avoiding many OTOH works fine: --- snip --- parse (do {linep;linep}) "stdin" (unlines ["hallo","ballo"]) Right "ballo" ReadOrig> parse (do {linep;linep}) "stdin" ("hallo\nballo") Right "ballo" --- snap ---
Besides these two attempts explicitly spelled out I've made quite a few others, but none of them did the trick.
The documentation for 'try' says that it'll only consume input upon success, but why doesn't it work w/ 'many'?
I know about the Prelude-functions unlines, lines etc., but they don't really help, since linep should be used within another parser of mine.
I am using Parsec as of Jan 25, 2001 (the version included w/ ghc 5.02).
Any hints/solutions/... would be greatly appreciated!
Bye -- Till _______________________________________________ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
-- ---------------------------------------+---------------------------------------- Iavor S. Diatchki | email: diatchki@cse.ogi.edu Dept. of Computer Science | web: http://www.cse.ogi.edu/~diatchki OGI School of Science and Engineering | work phone: 5037481631 OHSU | home phone: 5036434085 ---------------------------------------+----------------------------------------