Added show_diagram method for Push Down Automata

[Vipul-Cariappa]

Implemented the show_diagram method for Push Down Automata.
I have just adapted the FA.show_diagram (Finite Automata) code for PDA.show_diagram.

I have not yet implemented show_diagram with input_str. I will require some suggestions here. Should I also show the operations performed on the stack, or only the state transitions are sufficient?

I have not tested the code, except for DPDA and NPDA in the docs. I have attached the images below.

DPDA:

NPDA:

Reminder for myself and the maintainer: I should also update the docs to reflect the new feature, before merging this PR.

Hope this is helpful. Please let me know if any changes are required.

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Edited:

I have implemented the construction of the diagram with an input_str.

DPDA from docs with input_str = "aabb":

NPDA from docs with input_str = "abba":

I have updated the docs. I should now write down some test cases.

[coveralls]

coverage: 99.639% (-0.2%) from 99.847% when pulling 510e471 on Vipul-Cariappa:pda-visualizer into 35b68fd on caleb531:develop.

[caleb531]

@Vipul-Cariappa To answer your question, I would personally prefer that the stack operation show for each transition because in principle, you want the diagram to be a visual representation of the machine. And changes to the stack can drastically affect the machine's behavior for a PDA.

@eliotwrobson Do you have any thoughts on any of this?

[Vipul-Cariappa]

@caleb531 I have updated the code to also display the stack operations. Results:

DPDA from docs with input_str = "aabb":

NPDA from docs with input_str = "abba":

[eliotwrobson]

Left some early comments. Overall looks good, but needs some test cases and I think some things can be simplified significantly. Thanks for the contribution @Vipul-Cariappa !

[eliotwrobson]

@Vipul-Cariappa To answer your question, I would personally prefer that the stack operation show for each transition because in principle, you want the diagram to be a visual representation of the machine. And changes to the stack can drastically affect the machine's behavior for a PDA.

I'm in agreement @caleb531 , it's nice to be able to generate the states of the stack along with the visual representation of the machine. @Vipul-Cariappa, it would be awesome to have a flag enabling displaying only the machine or only the stack (both by default).

[Vipul-Cariappa]

it would be awesome to have a flag enabling displaying only the machine or only the stack (both by default).

@eliotwrobson, I have implemented the feature you asked for.

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I have refactored the code to remove duplications, to the best of my abilities, according to what I felt makes sense.

Please have a look at it, and let me know if any other changes are required.

Two things left to do:

• Write test cases
• Update the md doc file for with_machine and with_stack parameters

[Vipul-Cariappa]

I have added test cases. Again, I adapted test cases from dfa and nfa. Please review it and let me know if any more changes are required.

[eliotwrobson]

New changes are looking good, in particular the tests seem fairly comprehensive! Left comments in a few places, I think some logic can be simplified significantly and there were a few things I had questions about.

[Vipul-Cariappa]

I have made some of the changes @eliotwrobson suggested. Also, left some clarifications and questions.
Please have a look at it.

[Vipul-Cariappa]

I guess all change requests are implemented. Please have a look. Let me know if I missed any.

[eliotwrobson]

Don't want to approve quite yet (as I'd like a little more time to review everything, and requested a few changes), but this is getting very close to being ready to merge!

[eliotwrobson]

I want to double check whatever is going on with the closing bracket in the unresolved discussion, but the code looks good!

EDIT: Resolved the above. @caleb531 I would say go ahead and merge if you think everything looks good. Would prefer to have another set of eyes before merging just because of the volume of changes.

[caleb531]

@eliotwrobson I won't have time to review it today, but I can probably look tomorrow or Monday. In the meantime, could you please add some tests for the NotImplemented / NotImplementedError cases? That will bring the coverage back up, and there should be some existing tests you can use as reference.

[caleb531]

@eliotwrobson @Vipul-Cariappa This PR looks very good! I only have one requested change (well, technically two, I suppose) related to the new DiagramException class. But if one of you could please make those couple changes quick, I'll be ready to give this the final sign-off!

Thanks also to both of you for all your hard work on this PR so far.

[caleb531]

@eliotwrobson Thanks for that! Everything looks good to me now. Approving and merging...