Parse Tree Implementation

[schuylermartin45]

This is the initial parse tree work. There is a lot here, so here are some highlights:

It has:

• A recipe parser that can track comments/selectors, Jinja variables, and values through look-up tables and a parse tree.
• Support for replace and test that closely (if not completely) follows the JSON Patch RPC requirements
• 18 Test cases. I believe there is at least 1 test case for every publicly available function that is completed. Tests pass locally with make tests
• Ability to:
  • Render recipes
  • Ability to traverse the tree structure with an underlying set of private traversal functions
  • Get/Set/Find variables and values in the data structure
  • Get selectors in the data structure
  • Validate incoming JSON Patch requests. Fields that are contingent on the op type are validated.

It does not have:

• Wiring into the existing percy framework. In other words, merging this will not break anything existing. This class is separate from the current recipe.py file.
• Code that is validated with mypy and pylint
• Support for the other 4 JSON Patch verbs
• Fixes for a handful of known bugs, tracked in the JIRA epic (see below)
• Ability to generically search for a regex statement across the parse tree and all variables/selectors (this is in a future ticket)

Known bugs and feature improvements are being tracked in our board as JIRA Epic PKG-2787

[schuylermartin45]

It appears linting is enforced to some degree by the package bots. I will see about getting pre-commit setup on my local machine. I was not aware that was enabled for this project.

Now some of this work uses 3.11/newer Python syntax. I don't think that should be an issue with the older versions as again, this isn't linked into any existing code and is a stand-alone file. We also talked about bumping our min version last week that would solve this issue.

[schuylermartin45]

Now some of this work uses 3.11/newer Python syntax. I don't think that should be an issue with the older versions as again, this isn't linked into any existing code and is a stand-alone file. We also talked about bumping our min version last week that would solve this issue.

Well, okay, if the tests are set to run in GitHub actions, I guess that'd execute code that may not be compatible.

[schuylermartin45]

I have been experimenting with incorporating the mypy and pylint learnings from perseverance-scripts into GitHub Actions today on this branch.

Once I finish the last few issues, I plan to merge those configuration changes into this PR. Or I'll make a second PR when this one gets merged.

[schuylermartin45]

I ran pytest locally against 3.9 to validate the type annotations in 7742a4f

[schuylermartin45]

Talked to Mark and Charles offline, we are good to merge!