From: Scott Meyers (usenet_at_[hidden])
Date: 2006-11-21 18:00:35
If I want to replace all the regex matches in a string, no problem,
regex_replace is just what I'm looking for. But suppose I want to
replace each match only if some predicate is satisfied, e.g., to
implement something like a string replacement in a text editor where the
user is allowed to approve or reject each proposed replacement. Is
there any direct support for something like this?
The only way I can think of to do this is to iterate over the string to
be searched, finding each match and then consulting the predicate to see
if the replacement should be performed for that match. If so, I can
call regex_replace on the found substring, but then I'll get back a new
string, and I'll have to manually handle the process of knitting
together the final revised string from the original string and the
results of each substitution. This is essentially what regex_replace
already does, except it unconditionally does a substitution for each
match.
What it seems I want is something like regex_replace_if. Is there such
a thing in Boost or TR1? If not, is it because there is little demand
for such functionality? That would surprise me, because pretty much
every text editor allows one to iteratively search for a match and query
the user to see if a replacement should be performed at that point.
Thanks,
Scott