Add support for Petri Nets

[ls1intum]

Add support for Petri Nets

[TobiasPr]

@Garfield96 my first implementation would look like this:

For the sake of consistency with the other diagrams, I kept the coloring to black and white. - I will think about a solution to the coloring of the different element types.

Please be aware, that we currently do not support any kind of formula symbols as text input. Would that be a requirement for you?

[Garfield96]

@TobiasPr This looks already great. I would recommend making the tokens a little bit smaller so that they will not touch each other.

I would consider symbols as nice-to-have but its not a requirement.

[TobiasPr]

@Garfield96 I included your feedback and deployed a new version to the standalone version to Apollon which includes a beta version of petri nets, so you can test out the new diagram type. Any feedback is welcome

[Garfield96]

@TobiasPr Thank you. I tested it and it worked fine. The last feature missing in order to use it is support for capacities and multiplicities.

[TobiasPr]

Edited
Updated once more, looks like this now

I did not constraint the amount of tokens in a place to the capacity. In my opinion, that's the responsibility of the student / modeler. I am unsure about whether I chose a good depiction of the capacity for places, since I couldn't find any examples online. Contrary to your initial request, I added a "C=" in front of the capacity for better readability. Capacities are displayed if its's different from the default, which is 1.
For adding multiplicity, you can double click an arc and enter the number (note - free text is also allowed, because it was easier in the current data model). Multiplicities are also only displayed if it is different from the default value, which is now inifinity

I was thinking about boolean petri nets - in my opinion it would also be okay to move the responsibility for modeling it correctly to the modeler/student and just provide the editor to fulfill the task (you can model boolean petri nets already in this diagram type).

[Garfield96]

Thanks for the update.

I did not constraint the amount of tokens in a place to the capacity.

This is fine.

I am unsure about whether I chose a good depiction of the capacity for places,

We normally don't use C=... but it's ok to use it here since it helps with readability.

Capacities are displayed if it's different from the default, which is 1.

The default is infinity and multiplicities have a default value of 1.

I tested it in Firefox and in Chrome and found a few bugs:

The token field is wider than the menu, which is inconvenient (only happens in Firefox).

Another bug which was reproducible in both browsers:

The infinity sign and a number are displayed on top of each other.

This effect can be triggered by:

1. Create a new place
2. Open context menu
3. Increase capacity by one using the increase button
4. Click on the infinity symbol
5. Click again on the increase button

Also reproducible in both browsers:

The context menu is not attached to the item it belongs to.

How to reproduce:

1. Open context menu
2. Use browser zoom

[TobiasPr]

both issues will be fixed in next release