More fun with autodecoding

[Steven Schveighoffer]

On 9/8/18 8:36 AM, Steven Schveighoffer wrote:
> On 8/9/18 2:44 AM, Walter Bright wrote:
>> On 8/8/2018 2:01 PM, Steven Schveighoffer wrote:
>>> Here's where I'm struggling -- because a string provides indexing, 
>>> slicing, length, etc. but Phobos ignores that. I can't make a new 
>>> type that does the same thing. Not only that, but I'm finding the 
>>> specializations of algorithms only work on the type "string", and 
>>> nothing else.
>>
>> One of the worst things about autodecoding is it is special, it *only* 
>> steps in for strings. Fortunately, however, that specialness enabled 
>> us to save things with byCodePoint and byCodeUnit.
> 
> So it turns out that technically the problem here, even though it seemed 
> like an autodecoding problem, is a problem with splitter.
> 
> splitter doesn't deal with encodings of character ranges at all.
> 
> For instance, when you have this:
> 
> "abc 123".byCodeUnit.splitter;
> 
> What happens is splitter only has one overload that takes one parameter, 
> and that requires a character *array*, not a range.
> 
> So the byCodeUnit result is aliased-this to its original, and surprise! 
> the elements from that splitter are string.
> 
> Next, I tried to use a parameter:
> 
> "abc 123".byCodeUnit.splitter(" ");
> 
> Nope, still devolves to string. It turns out it can't figure out how to 
> split character ranges using a character array as input.

Hm... I made some erroneous assumptions in determining these problems.

1. There is no alias this for the source in ByCodeUnitImpl. I'm not sure 
how it was working when I tested before, but byCodeUnit definitely 
doesn't have it, and doesn't compile with the no-arg splitter call.
2. The .splitter(" ") does actually work and return a range of 
ByCodeUnitImpl elements.

So some of my analysis must have been based on bad testing.

However, the issue with the no-arg splitter is still there, and I still 
think it should be fixed.

I'll have to figure out why my specialized range doesn't allow splitting 
based on " ".

-Steve