Fast switching..

[janderson]

Jarrett Billingsley wrote:
> "janderson" <askme at me.com> wrote in message 
> news:g2q2bp$13ef$3 at digitalmars.com...
>>
>> I thought in a discussion earlier with Walter (a few years back) that DMD 
>> would generate a string hash and then jump to that hash when you use a 
>> string as the input.  In many cases the branching will be the expensive 
>> part so I guess a hash is pretty close to optimal performance for the 
>> general case.  Although with optimisation you can always make things run 
>> faster.
>>
>> -Joel
> 
> Guessing won't be necessary :)  The implementation of string switches is in 
> dmd/src/phobos/internal/switch.d.  The compiler puts the case names into a 
> sorted array of strings, and the string switch just does a binary search on 
> it.  It's somewhat optimized though -- it won't actually do a string 
> comparison unless the strings are of the same length and their first 
> character is the same. 
> 
> 

ic.  I guess I should have just looked.  I guess if anyone wanted to 
write a faster one they could send an updated version to Walter (after 
they had run many benchmark tests).

-Joel