Re: [boost] [String algorithm] is_any_of has inefficient implementation

From: Pavol Droba (droba_at_[hidden])
Date: 2008-02-14 08:10:02

Hi,

Joe Gottman wrote:
> I just discovered that the string algorithm predicate is_any_of has an 
> inefficient implementation. Internally it uses a std::set.  There are 
> two problems with this.  First, since the order of the characters does 
> not matter, std::unordered_set is probably faster.  

TR1 was not available at the time this class was implemented. So 
couldn't have used it. Thanks for suggestion.

> Second, the 
> contained set has to be copied each time the object is used in, for 
> instance, a split() statement.  Since split can reuse a predicate 
> literally thousands of times when splitting a large string, this is a 
> lot of unnecessary copying.
> 

I'm aware of this. I'm working on am optimization for passing functors 
around the string_algo algorithms, but I'm not finished with it yet.
Once finished, the copying will be mostly eliminated.

Regards,
Pavol.