std.algorithm.splitter on a string not always bidirectional

[H. S. Teoh]

On Friday, 22 January 2021 at 17:29:08 UTC, Steven Schveighoffer 
wrote:
> On 1/22/21 11:57 AM, Jon Degenhardt wrote:
[...]
>> Another way to look at it: If split (eager) took a predicate, 
>> that 'xyz.splitter(args).back' and 'xyz.split(args).back' 
>> should produce the same result. But they will not with the 
>> example given.
>
> With what example given? The example you gave is incomplete 
> (what are args?)
[...]

Here is a case for which iterating forwards yields a different 
sequence
from iterating backwards (if we were to allow the latter):

     "bbcbcba".splitter("bcb")

Iterating forwards gives us the subranges: "b", "cba".

Iterating backwards gives us: "a", "bbc".

So it cannot be a bidirectional range, at least not in the 
expected sense
that iterating from the back ought to give us the same subranges 
as
iterating from the front, only in a reverse order.  Here iterating
backwards yields a completely different decomposition.


--T