std.data.json formal review

[Martin Nowak via Digitalmars-d]

On Saturday, 22 August 2015 at 13:41:49 UTC, Sönke Ludwig wrote:
> There is more than the actual call to validate(), such as 
> writing tests and making sure the surroundings work, adjusting 
> the interface and writing documentation. It's not *that* much 
> work, but nonetheless wasted work.
>
> I also still think that this hasn't been a bad idea at all. 
> Because it speeds up the most important use case, parsing JSON 
> from a non-memory source that has not yet been validated. I 
> also very much like the idea of making it a programming error 
> to have invalid UTF stored in a string, i.e. forcing the 
> validation to happen before the cast from bytes to chars.

Also see "utf/unicode should only be validated once"
https://issues.dlang.org/show_bug.cgi?id=14919

If combining lexing and validation is faster (why?) then a ubyte 
consuming interface should be available, though why couldn't it 
be done by adding a lazy ubyte->char validator range to std.utf.
In any case during lexing we should avoid autodecoding of narrow 
strings for redundant validation.