How is std.regex.replaceAllInto more efficient?

[Shriramana Sharma via Digitalmars-d]

Dmitry Olshansky wrote:

> I guess the idiomatic way is:
> 
> foreach (pos; iota(0, sink.data.length, 4).retro)

Mmm no that throws an assertion failure, since the guarantee of the regex is 
only to insert commas before every third digit *from the end*, but doing 
retro on an *ascending* iota fixes the end point at index zero, and start 
point at some multiple of four *from the beginning*, which isn't compatible 
with the regex's promise.

Thus the correct approach would be to do a *descending* iota:

        foreach (pos; iota(sink.data.length - 4, 0, -4))
            assert(sink.data[pos] == ',');

Pull: https://github.com/D-Programming-Language/phobos/pull/3731

I am not much experienced with GitHub pull requests, so I hope I did that 
correctly. IIUC after you pull, it will be back in my fork and its clone 
once I pull back from you, then I can delete my local branch, right?

BTW since I still didn't like that wraparound thing, (and it would fail in 
some extreme corner cases where sink.data.length is > size_t.max - 3 or 
such, I think) I thought of it much and arrived at the much more convoluted:

        for (size_t pos = sink.data.length; pos > 3; )
            { pos -= 4; assert(sink.data[pos] == ','); }

which is still not easy for one's mind to "wraparound"! So the descending 
iota solution we arrived above is the most elegant.

As I said, I'm still getting my "D-legs"...

-- 
Shriramana Sharma, Penguin #395953