adobe-source-devel

[Adobe-source-devel] any_iterator equal

[Thomas W. <wi...@ac...>]

Hi,

any_iterator equal is currently implemented as follows

iterator.hpp:242

bool equal(const any_iterator& x) const
{
   return (type() == x.type()) && object_m->equal(*x.object_m);
}

IIUC the type equality check is unneeded and may hide bugs.

Type equality is given implicitly by the requirement that both iterators 
point into the same sequence. As a sidenote AFAICS any_iterators do not 
support interoperable iterators, eg. 
vector<int>::iterator/vector<int>::const_iterator but the equal 
implementations would yield false for these even if they point to the 
same position in a sequence.

What did I miss

Thomas

-- 
Thomas Witt
wi...@ac...

Re: [Adobe-source-devel] any_iterator equal

[Sean P. <sp...@ad...>]

On Dec 12, 2005, at 2:42 PM, Thomas Witt wrote:

>
> Hi,
>
> any_iterator equal is currently implemented as follows
>
> iterator.hpp:242
>
> bool equal(const any_iterator& x) const
> {
>   return (type() == x.type()) && object_m->equal(*x.object_m);
> }
>
> IIUC the type equality check is unneeded and may hide bugs.
>
> Type equality is given implicitly by the requirement that both  
> iterators point into the same sequence. As a sidenote AFAICS  
> any_iterators do not support interoperable iterators, eg.  
> vector<int>::iterator/vector<int>::const_iterator but the equal  
> implementations would yield false for these even if they point to  
> the same position in a sequence.
>
> What did I miss

Hi Thomas -
I don't think you missed anything. This is a good point about the type 
() equality being implicitly required - I will replace the check with  
an assert. "interoperable" iterators (iterators with different  
underlying types pointing to the same structure) was not a design goal.

Sean

>
> Thomas
>
> -- 
> Thomas Witt
> wi...@ac...
>
>
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