On Wed, Jan 28, 2015 at 10:59:48AM -0500, Ehsan Akhgari wrote:
> On 2015-01-27 9:24 PM, Xidorn Quan wrote:
> >I asked a question in #developers that what is the best way to reversely
> >iterating nsTArray, and there are some suggestions:
> >
> ><tbsaunde> uint32_t count = array.Length(); for (uint32_t i = length - 1; i
> >< length; i--)
> ><smaug> iterate from length() to 1 and index using i - 1
> ><jcranmer> for (uint32_t i = array.Length(); i-- > 0; ) { }
> >
> >tbsaunde's method should work fine, but not intuitive. smaug's looks fine
> >to me, but could cause some problem if I use i instead of i-1 by mistake.
> >jcranmer's... I don't think it is a good idea, anyway. None of them looks
> >prefect to me.
> >
> >
> >As we have supported range-based for loop in our code, I purpose that we
> >have something like ReverseIntegerRange, and use this with range-based loop
> >to iterate the index. So we can use, for example: for (auto i :
> >ReverseIntegerRange(array.Length()))
> >
> >Maybe we can also add IntegerRange to benefit from the integer type
> >dedution.
> >
> >How does it sound?
>
> No, please don't do this. We need to make our container classes more
> similar to the STL containers, not less, and since this is about adding new
> functionality, here is what we need to do:
where the stl didn't make poor choices sure, and I'll agree while stl
iterators are a bit weird they aren't terrible.
> * Add a begin() and end() function to nsTArray that return iterators with
> STL semantics.
> * Add a rbegin() and rend() function to nsTArray with similar semantics
> which return a reverse iterator.
> * Add something similar to boost::adaptors::reverse, probably to MFBT.
>
> That way you can write:
>
> for (auto& elem : array)
>
> or:
>
> for (auto& elem : mozilla::Reverse(array))
imho auto in range based for should be strongly discouraged since you
need to go look up the type of the array and then play games to figure
out what the type of elem is.
Trev
>
> And that would work no matter whether array is an nsTArray or a std::vector.
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