From: "Reece Dunn" <msclrhd@hotmail.com>
Currently, this implementation is missing iterator support (and thus all basic_string functionality that relies on begin(), end(), etc). This is because I am wondering how to map them from the basic_string adaptor to the implementation (knowing that you cannot have const and non-const virtual functions).
Since when can you not have const and non-const virtual functions?
I have two possible solutions: [1] name the const versions cXXX (cbegin(), crend(), etc.) -- the problem with this is that you have 8 virtual functions!
You'd have those same eight variations with const and non-const virtual functions.
[2] direct to non-const versions and convert to const iterators: inline const_iterator begin() const { return( const_iterator( const_cast< basic_string_impl & >( *this ).begin())); } but I am debating whether this is standards compliant and if it is a good design decision.
If the object is really const, then this results in undefined behavior.
If there are alternate solutions, I'd like to hear them.
Use const and non-const virtual functions. ;-)
Another possibility would be to construct the iterators from offsets:
inline iterator begin() { return( get_impl().iter_offset( 0 )); } inline reverse_iterator rbegin() { return( reverse_iterator( get_impl().iter_offset( size() - 1 ))); }
That way you would only need two functions (iter_offset and const_iter_offset).
But how would the iterator know whether to give const or non-const access to the elements? -- Rob Stewart stewart@sig.com Software Engineer http://www.sig.com Susquehanna International Group, LLP using std::disclaimer;