Proposal for Optimized Character Type Function

[Florian Weimer]

* The Cuthour:

> I am writing to propose an enhancement to the character type functions 
> such as isalpha(), isupper(), and islower() through the use of optimized 
> lookup tables. By using a single lookup table with bitwise operations, 
> we can achieve efficient and concise implementations for these 
> functions. Below is a brief overview of the proposed implementation:

Isn't this basically what the current implementation does, via
__ctype_b_loc?  Per-thread state is required to support uselocale.