[boost] Re: [regex] Escaping a search string?

From: Ross Smith (rosss_at_[hidden])
Date: 2003-08-07 17:04:58

George A. Heintzelman wrote:
>>Given that I have a string 's' from somewhere, I'd like to create a 
>>regular expression where some part must match that string. The problem 
>>is, the 's' could contain characters that have a special meaning in 
>>regular expressions. Is there some support function that can provide an 
>>escaped version of 's'? Something that transforms "my.*string" into 
>>"my\.\*string"? If there isn't, would it be possible/easy to provide one?
> 
> Second that request. I just had a need for this, though I wound up 
> ignoring the problem rather than fixing it...

There must be something in the air; I just had a need for this too. My 
quick-and-dirty solution was to simply replace every non-alphanumeric 
character with a hex escape sequence (\xNN).

Having it just add escapes to a list of special characters wouldn't work 
as a general solution, because the list of characters depends on the 
flags passed to the regex functions. Of course there are settings where 
my hex-escape solution won't work either. I don't think a general 
solution is possible without making it part of the library; it needs 
access to the innards of the regex objects in order to know the exact 
syntax they recognise.

-- 
Ross Smith ...................... Pharos Systems, Auckland, New Zealand
            "Remember when we told you there was no future?
                    Well, this is it." -- Blank Reg