[henshin-dev] Optimizations

[Christian Krause <henshin.ck@xxxxxxxxx>]

Hi,

I implemented a number of optimizations for the state space tools. Most 
importantly, the hash code function for EMF models is now a 'real' graph
 hash function. This was the main bottleneck up to now; the performance 
gain from this change alone is tremendous for graph-based equality 
checking. Additionally, the actual graph isomorphy checking is done 
using the matching engine now, and for the state space generation a 
static analysis is used to determine a partial match in advance before 
doing the isomorphy checking.

There are still a couple of bugs that need to be fixed and I think that 
the performance can be further improved. My guess is that it is still 
slower than GROOVE but we are getting better. Once the bugs are all 
fixed, I will set up some tests which we can also use for benchmarks 
then. At some point we can think about writing a technical report about 
the matching algorithms that we use in Henshin, because I think we 
already gathered a number of interesting optimizations which are worth 
to publish.

Cheers,
Christian