Mathias Gaunard wrote:
An error policy isn't really enough though, because to do full checks you need each iterator to know about the begin and the end of the range it's working on which could be avoided altogether when trusting the input.
The idea of an "iterator that knows where its end is" is something that comes up fairly often; do the Range experts have any comments about it? I think that in this case an iterator that can be incremented and dereferenced in some limited way beyond its end would be sufficient. For example, a std::string normally has a 0 byte beyond its end so that c_str() can work, so it is safe (for some value of safe!) to keep advancing a std::string::iterator until a 0 is seen, without looking for end(). A UTF-8 decoding algorithm that processes multi-byte characters by continuing until the top bit is not set would safely terminate in this case. For iterators that don't offer this sort of behaviour you can provide a wrapper that knows where end is and returns a sentinel 0 in that case. Just a thought.... Phil.