Edward Diener wrote: > Ross Smith wrote: >> 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. > > That is a good point. However you always know what flags are passed > to the regex function since they are available. That's not arguing > against such a function as being part of the library itself but it is > still doable by you. Furthermore you can set the flag mode you like > to simplify your escaping, > but of course this is not a general solution as the rest of the > regular expression may require particular flags set. > >> 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. > > That is not true. One just needs to read and understand the > documentation on the particular flags and what they mean. There are > no "secret innards" which retain information about escaping > characters which you can't find for yourself by testing the flags.
Let me add to my remark by saying that it is true that you can change the characters of a regular expression using localization with a dll or message catalog, but again you know what changes have been made and should be able to escape the appropriate characters. _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
