15 pnfrag add whitespace support and petri net export is buggy

[AdamBanham]

This patch adds white space to the label of transitions for pnfrag and a bug fixes for the exporting pnml that can be read by prom.
Additional prom bits can be exported using a flag but is off by default.

The additionals allow for the example @ https://adamburkeware.net/2021/05/20/petri-net-fragments.html to be reproduced with the following code:

from pmkoalas.models.pnfrag import parse_net_fragments
from pmkoalas.models.petrinet import export_net_to_pnml

from os.path import join

def gen():
    net = parse_net_fragments(
        "burke test model",
        "I -> {register request 1.0} -> p1 -> {examine throughly 1.0} -> p2",
        "I -> {register request 1.0} -> p1 -> {examine casually 10.0} -> p2",
        "I -> {register request 1.0} -> p3 -> {check ticket 1.0} -> p4",
        "p2 -> {decide 1.0} -> p5",
        "p4 -> {decide 1.0} -> p5",
        "p5 -> {pay compensation 1.0} -> F",
        "p5 -> {reject request 2.0} -> F",
        "p5 -> {reinitiate request 1.0} -> p3"
    )
    print(net)
    export_net_to_pnml(
        net,
        join(".", net.name.replace(" ","_").lower()+".pnml"),
        True
    )

if __name__ == "__main__":
    gen()

When visualised the net shows the same layout as before (but I am not sure of the export extension for weights Petri nets).
Visualised layout from ProM of the underlying Petri net:

Note that this net eventually deadlocks if the transition 'reinitiate request' is fired. Unsure if the model was intended to have this behaviour, but matches the blog post.

[adamburkegh]

Thanks for the patch. Better Petri net interoperability will be nice. I suspect it worked at the Java program level but not through the ProM GUI, which is how it went undetected. I can see the whitespace labels being handy too.

I had a question about why UUID ids were desirable or needed.

[adamburkegh]

There is no special extension for PNML files with weights or other stochastic distribution info.

[adamburkegh]

I can't remember why that Petri net had a deadlock. I should probably fix it in the blog post as it will irritate PN heads.

[AdamBanham]

I can't remember why that Petri net had a deadlock. I should probably fix it in the blog post as it will irritate PN heads.

Na let them boil over with rage, then feed off their energy!