[Haskell-cafe] Parsec question (new user): unexpected end of input
ps.haskell at gmail.com
Tue Sep 28 23:35:23 EDT 2010
I am a new Parsec user, and having some trouble with a relatively
The grammar I want to parse contains tags (not html) marked by
angle brackets (e.g., "<some tag>"), with arbitrary text (no angle
brackets allowed) optionally in between tags.
Tags may not nest, but the input must begin and end with a tag.
Whitespace may occur anywhere (beginning/end of input,
inside/between tags, etc.), and is optional.
I think my problem may be a lack of using "try", but I'm not sure
At runtime I get:
Error parsing file: "...\sampleTaggedContent.txt" (line 4, column 1):
unexpected end of input
The input was:
more stuff < tag 3 > even more
The code is below. (I'm using Parsec-188.8.131.52.) I don't really want
to return anything meaningful yet; just parse okay.
Any advice about the error (or how to simplify or improve the code)
would be appreciated.
> -- Parsers:
> taggedContent = do
> many tagOrContent
> return "Parse complete."
> tagOrContent = aTag <|> someContent <?> "tagOrContent"
> aTag = do
> xs <- many (noneOf [tagEndChar])
> return ()
> someContent = do
> manyTill anyChar tagBegin
> return ()
> optionalWhiteSpace = spaces -- i.e., any of " \v\f\t\r\n"
> tagBegin = char tagBeginChar
> tagEnd = char tagEndChar
> -- Etc:
> tagBeginChar = '<'
> tagEndChar = '>'
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