Perfect hashing for string switch

[BCS]

Hello bearophile,

> BCS:
> 
>> Have you compared it to a decisition tree or lex style state mechine?
>> 
> I have not, I am sorry :-) But more comparisons can be added.
> 
> I know what decision trees are in data mining, but I presume you mean
> some kind of ternary tree (3 possible results of the string cmp for
> each char compared).
> 
> Bye,
> bearophile

I'm not sure how I'd set it up but I expect it would amount to a hard coded 
radex sort:

- do a normal integer switch on string length
- for each length group the strings based on common prefixes (if you have 
aaab, aaac, aabb, bbbb the grouping would be: [[aaab, aaac], aabb], [bbbb])
- walk down the tree using if statements.

I guess it's not much different than a lex DFA but for a small list of static 
strings it might be faster. Also it has the option of using strcmp for tails 
and long sub spans.