Ctags parse header

[Muream]

So, I went down a rabbit hole...

parse_header.py was failing on some header files required for #25.
I tried upgrading it but didn't feel like handling a billion edge cases like manually parsing C++ seems to be like

I ended up relying on Universal Ctags which outputs a list of all the classes, methods, etc. that are in a given file.

It's not perfect but it works on all the files I've tested so far

Some things that are not supported yet:

1. Functions declared out of the scope of a class
2. Properties
3. Nested classes
4. Enums

I'll probably leave it at that for this PR though and we can improve on that as we need.

I've made a separate parse_header_ctags.py script in case parse_header.py still produces better results on some files

And of course, ctags needs to be installed and available in your path

[mottosso]

ctags? Interesting. :) I might use this for other things too, didn't know this existed.

Can you give some examples of what it failed on before, and what it looks like now?

[Muream]

the current parse_header script fails to generate the inl file for MPxNode with this stack trace:

Traceback (most recent call last):
  File "scripts\parse_header.py", line 534, in <module>
    main()
  File "scripts\parse_header.py", line 524, in main
    parse_header(opts.header)
  File "scripts\parse_header.py", line 181, in parse_header
    arguments)
  File "scripts\parse_header.py", line 325, in parse_method
    raise RuntimeError("Cannot parse signature: {}".format(signature))
RuntimeError: Cannot parse signature: MDataBlock                                _forceCache             ()                 { return forceCache(); } void                                    _setDoNotWrite  ( bool flag )   { setDoNotWrite(flag); } bool                                       _doNotWrite             ()                              { return doNotWrite

I won't paste the generated file of parse_header_ctags here because it's 650 lines long but it works.
The file won't compile out of the box though as some types like PostEvaluationType should be MPxNode::PostEvaluationType and possibly a few more things to clean up.

Running it against classes like MDagPath produces files that compile directly, however.

One thing to note: I'm only including methods that exist in maya.OpenMaya because ctags would list a lot more things including private methods. This felt like a sensible way to filter all that out but I'm not 100% sure if maya.OpenMaya has 100% parity with the C++ API.

[mottosso]

I'm not 100% sure if maya.OpenMaya has 100% parity with the C++ API.

It's lacking a ton of stuff, so it won't get us all the way there. But if it helps.. But, why do we need to involve maya.OpenMaya here at all? :O Sorry I haven't looked more closely at the contents of this PR yet. But I would have thought all we need are the C++ headers? If we can use maya.OpenMaya, could we not fetch members and argument signatures directly from there via Python?

[Muream]

haha That was my quick way of filtering out some garbage that ctags was picking up on, I thought maya.OpenMaya was feature complete.
I can definitely remove that filter and see where that takes us 👍
I know ctags was confused on things like the OPENMAYA_DEPRECATED statements and a few other things that are in the header files