[Haskell-cafe] Re: Parsec question (new user): unexpected end of input

[Christian Maeder]

Am 29.09.2010 09:54, schrieb Christian Maeder:
> Am 29.09.2010 05:35, schrieb Peter Schmitz:
> [...]
>> Error parsing file: "...\sampleTaggedContent.txt" (line 4, column 1):
>> unexpected end of input
>> expecting "<"
>>
>> The input was:
> [...]
>>
>>> -- Parsers:
>>> taggedContent = do
>>>    optionalWhiteSpace
>>>    aTag
>>>    many tagOrContent
>>>    aTag
> 
> "many tagOrContent" will consume all tags, so that no tag for the
> following "aTag" will be left.

if you want to match a final tag, you could try:

  manyTill tagOrContent (try (aTag >> eof))

> 
> Cheers Christian
> 
>>>    eof
>>>    return "Parse complete."
>>>
>>> tagOrContent = aTag <|> someContent <?> "tagOrContent"
>>>
>>> aTag = do
>>>    tagBegin
>>>    xs <- many (noneOf [tagEndChar])

this also looks like "manyTill anyChar tagEnd"

C.

>>>    tagEnd
>>>    optionalWhiteSpace
>>>    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 = '>'
>>
>> --------