A few weeks ago an e-mail from Didier Garcin popped up on the Stratego mailing list. He explained that he had written a python script that could visualize an abstract syntax signature. The script was also send to the list and I finally had some time to check it out.
It turned out that I had almost anything installed to use the script, only the pydot dependency needed some work. This was mostly because the script only seems to work with the 0.9.10 version of this library. After getting the script started it was really simple to generate the signature from the PHP-Front grammar.
So, here is the one for PHP4:
And the one for PHP5:
The first thing I notices where the big rectangles in both versions. These rectangles are the statements (smaller one) and expressions grouped together. What I also notices was that in both versions we see that the bottom of the graph (which corresponds with the smallest units in the language) looks the most complicated. This corresponds very well with the amount of effort put into the modeling of this part of the language.
Comparing both grammars to each other we can see that the latest versions is the most complicated one. Furthermore, if we compare both graphs to the graphs shown in this post we can see that the Java-graph appears to be the most similar one.
Actually, I do not think these images show anything, but please explain it to me when you think I just don't see it. Anyway, at least we have some nice pictures now :)
P.S. for those who are interested, more detailed images (in svg-format) are available here.