textual-astview

View the code in action on YouTube

Introduction

This is a combination of a Textual widget library and also a command line tool. The aim is to provide tools for displaying and exploring the Python AST.

It's early days

This is a very early release of this code, it's still very much a work in progress. This means things may change and break; it's also sitting atop Textual which is, of course, still undergoing rapid development. As much as possible I'll try and ensure that it's always working with the latest stable release of Textual.

Also, because it's early days... while I love the collaborative aspect of FOSS, I'm highly unlikely to be accepting any non-trivial PRs at the moment. Developing this is a learning exercise for me, it's a hobby project, and it's also something to help me further test Textual (disclaimer for those who may not have gathered, I am employed by Textualize).

On the other hand: I'm very open to feedback and suggestions so don't hesitate to engage with me in Discussions, or if it's a bug,in Issues. I can't and won't promise that I'll take everything on board (see above about hobby project, etc), but helpful input should help make this as useful as possible in the longer term.

Installing

The package can be installed with pip or related tools, for example:

$ pip install textual_astview

As well as the library (which I'll give some minimal documentation for below -- hopefully more comprehensive documentation will follow eventually), a command is also installed called astare. This can be used to load up and explore a Python source file.

The library

In the library you'll find the following Textual widgets:

ASTView

This is the main AST tree view. Create it by passing a Python Path object for the file you want it to display.

Source

This is a widget that shows the source code for a Python file. Create this by also passing it a Python Path object for the file you want it to display. It, of course, only really makes sense to have it show the same file as the ASTView it'll work in concert with.

NodeInfo

This is a widget that is intended to be used as a footer bar, of sorts, giving a summary of where an ASTView is focused.

Putting the widgets together

The way they all work is far from final, so the best way to get an idea of how to use them, right now, is to take a look at the code for astare. There's not a whole lot to it (right now anyway) so hopefully it'll be easy enough to follow.

Known issues

• The Source widget doesn't self-handle switches from dark/light mode within a Textual app; this is down to a problem with Textual's watch system not quite fully working yet. For now Source needs to be told to switch by your own application code.

TODO

If you're seeing this that means I decided to release so folk can have a play. There's a bunch of stuff I still want to do but it can be out there and available and then have this sorted.

• Add some actual error checking around loading the file.
• Test on Windows.
• Test on GNU/Linux.
• Dial in the colour and style until I'm really happy with it.
  • Add some styling options for NodeInfo.
  • Think about which styles should end stay in DEFAULT_CSS and which should go into an app-level CSS -- this might be a bit all over the place right now.
• More navigation features.
  • Lots of keyboard navigation coverage.
  • Searching.
• Extend and test all the styling options.
• Allow loading another file without leaving the app.
• A more "rainbow" approach to highlighting the source and tree position.
• Add support for setting the source style.
• Add a dark/light mode toggle to astare.
• Better handle really long "paths" in NodeInfo.
• In astare allow resizing of the panes.
• Look at making the rainbow highlight in the source more of an "onion" style (try and use indentation columns to show the layers too).
• Add more muted labels to the tree, but perhaps place them behind a verbosity switch so the tree doesn't get too cluttered.
• Keep on having fun hacking on it.
• Other stuff. I'm sure there's other stuff.