Re: [boost] [regex] How robust are the <boost/regex/pending/unicode_iterator.hpp> adapters?

Subject: Re: [boost] [regex] How robust are the <boost/regex/pending/unicode_iterator.hpp> adapters?
From: Dave Abrahams (dave_at_[hidden])
Date: 2011-07-23 11:07:54

on Tue Jul 19 2011, John Maddock <boost.regex-AT-virgin.net> wrote:

> Actually, I'm thinking that the fix may be easier than I thought after
> all - 
> if I add a 2-arg "range-checked" constructor as an overload, then the
> iterator's constructor can validate the end-points of the underlying
> sequence during construction, 

Doesn't that make construction of an iterator over N bytes an O(N)
operation?

> and there's no need to otherwise change the implementation or add
> overhead by checking every increment/decrement for movement
> out-of-range because we'll know that it can't happen.

To be precise—I think—it can't happen unless the bytes in the underlying
buffer are changed after construction.  It's not *quite* the same
guarantee, but it's probably good enough, and maybe even preferable.

I would suggest that anyone needing the other kind of check adapt an
underlying iterator that contains the check.

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com