4 ms·

Navigate ASTs with x-path-like queries

28 points by bdg 4y ago

anitil 4y ago
This is great! I think I've seen a similar thing used for picking up issues like deprecated usages and things like that. I've found myself manually writing code for finding things in python's AST but a tool like this would be much more succinct Edit: the author's website is a delight - http://engelschall.com/ http://engelschall.com/
- dimator 4y ago
  for work, i wrote a tool that takes an astroid AST tree and translates it into XML (in memory), which are very close in spirit since they're both tree-like structures. this lets one write linter tools using familiar XPath queries and assert on the results. it's good for some kinds of pattern/anti-pattern enforcement. https://pylint.pycqa.org/projects/astroid/en/latest/index.html https://pylint.pycqa.org/projects/astroid/en/latest/index.ht...
  - anitil 4y ago
    That's a clever way of leveraging existing tooling! I hadn't heard of astroid before, I've always used the built in ast module
  - bdg 4y ago
    Just curious, what do you use the resultant XML for? Analysis? Rewriting code?
    - dimator 4y ago
      no rewrites (the AST->XML bridging is one way), we use it for checking for forbidden patterns that we don't want developers using.
- bdg 4y ago
  >I've found myself manually writing code for finding things in python's AST but a tool like this would be much more succinct Wow, I also am writing a tool for finding things in the Python AST: https://github.com/Incognito/python-architecture-linter https://github.com/Incognito/python-architecture-linter It does other things too, but one of the key features is reading the AST. It's a bit of a prototype but if you want to jam together on a project I'd be open to it.
  - anitil 4y ago
    Your tool is _much_ more powerful than what I've been doing. I've been looking at things like 'what proportion of functions have docstrings, and what format are they in?' or 'how much of our codebase is using typing?' Yours is much more ambitious, if I understand it correctly?
mdaniel 4y ago
... "for JavaScript" would have helped I hope in addition to the cute operators they also support actual XPath, since it'd be less reinventing the wheel for those who already know XPath Also, prior art for static analysis using XPath: https://pmd.github.io/pmd-6.47.0/ https://pmd.github.io/pmd-6.47.0/
- bdg 4y ago
  What would it have helped with?
  - mdaniel 4y ago
    It would have helped potential readers to know that this project is both in, and for, JavaScript, unlike the PMD project that I mentioned which offers that same XPath querying but for a bunch of target languages

28 points by bdg 4y ago

This is great! I think I've seen a similar thing used for picking up issues like deprecated usages and things like that. I've found myself manually writing code for finding things in python's AST but a tool like this would be much more succinct Edit: the author's website is a delight - http://engelschall.com/ http://engelschall.com/

dimator 4y ago
for work, i wrote a tool that takes an astroid AST tree and translates it into XML (in memory), which are very close in spirit since they're both tree-like structures. this lets one write linter tools using familiar XPath queries and assert on the results. it's good for some kinds of pattern/anti-pattern enforcement. https://pylint.pycqa.org/projects/astroid/en/latest/index.html https://pylint.pycqa.org/projects/astroid/en/latest/index.ht...
- anitil 4y ago
  That's a clever way of leveraging existing tooling! I hadn't heard of astroid before, I've always used the built in ast module
- bdg 4y ago
  Just curious, what do you use the resultant XML for? Analysis? Rewriting code?
  - dimator 4y ago
    no rewrites (the AST->XML bridging is one way), we use it for checking for forbidden patterns that we don't want developers using.
bdg 4y ago
>I've found myself manually writing code for finding things in python's AST but a tool like this would be much more succinct Wow, I also am writing a tool for finding things in the Python AST: https://github.com/Incognito/python-architecture-linter https://github.com/Incognito/python-architecture-linter It does other things too, but one of the key features is reading the AST. It's a bit of a prototype but if you want to jam together on a project I'd be open to it.
- anitil 4y ago
  Your tool is _much_ more powerful than what I've been doing. I've been looking at things like 'what proportion of functions have docstrings, and what format are they in?' or 'how much of our codebase is using typing?' Yours is much more ambitious, if I understand it correctly?

mdaniel 4y ago

... "for JavaScript" would have helped I hope in addition to the cute operators they also support actual XPath, since it'd be less reinventing the wheel for those who already know XPath Also, prior art for static analysis using XPath: https://pmd.github.io/pmd-6.47.0/ https://pmd.github.io/pmd-6.47.0/

bdg 4y ago
What would it have helped with?
- mdaniel 4y ago
  It would have helped potential readers to know that this project is both in, and for, JavaScript, unlike the PMD project that I mentioned which offers that same XPath querying but for a bunch of target languages