Re: [boost] [gsoc] Request Feedback for Boost.Ustr Unicode String Adapter

Subject: Re: [boost] [gsoc] Request Feedback for Boost.Ustr Unicode String Adapter
From: Soares Chen Ruo Fei (crf_at_[hidden])
Date: 2011-08-15 10:22:08

On Mon, Aug 15, 2011 at 4:37 AM, Gordon Woodhull <gordon_at_[hidden]> wrote:
> +1
>
> Please use standard iterator concepts and provide the expected behavior. Emulating bidirectional or random access iterators on top of a forward iterator is never good. People can use std::advance if they really need to.
>
> It's not just an issue for really long strings. Consider someone trying to read a moderate sized string backward. If only forward access is possible efficiently, there should be no operator--().

On Mon, Aug 15, 2011, Phil Endecott wrote:
> Err...
>
> No, I disagree.  I should be able to have a string as large as my virtual
> memory will allow, and it should continue to perform according to its
> documented complexity guarantees however large it gets.  For example, I have
> an IMAP mail server that uses std::string internally.  This is not code that
> needs to be especially fast, but it does require that O(1) operations don't
> become O(N) operations, or that O(N) operations become O(N^2) operations.

Ok I got what you mean. I think it'll be easier to just remove the
decrement function completely. During implementation I also wondered
if there is any real use for reverse code point iterator, but since I
still got time I just implemented it anyway to leave it for just in
case. (Actually it's also because I don't know if there is any way to
conditionally let the code point iterator inherit from either
std::forward_iterator or std::bidirectional_iterator)