locust VS difftastic

Nice!

Have been working on something similar, although my use case is more about learning how code has changed across git commits: https://github.com/bugout-dev/locust

For Javascript/Typescript/React support, like you, I hooked into the Babel toolchain. Can't recommend it highly enough.

There's also a newish project called quick-lint-js which seems to have written their own from-scratch AST parser for JS, but I haven't tried it yet: https://github.com/quick-lint/quick-lint-js

Finally, another project that I know in this space is comby (I believe it is owned/maintained by the folks at Sourcegraph): https://comby.dev/

Don't know why I dumped all those links there. Just figured there may be something useful in them for you. Am also just super passionate about building knowledge about code bases by analyzing their ASTs. Nice to meet a fellow enthusiast. :)

I maintain a free/open source project that does exactly what the author asks for: https://github.com/bugout-dev/locust.

Our tool uses git as the foundation of its functionality. It superimposes git diffs on top of ASTs.

It is insanely powerful.

For example, we use it to power semantic code search and current support Python, Javascript, and Java. We generate a JSON object defining the AST differences between initial and terminal commits on GitHub PRs and doing text search on the JSON objects performs surprisingly well when we want to answer questions like, "When did we add dateutils as a dependency?" or "When did we last change the /journals handler on the API?"

The Python integration currently sees the most use but if you are interested in other languages, we would be happy to support it.

Do drop me a DM if you want help getting started with Locust.

My team has a similar project (Locust: https://github.com/bugout-dev/locust) where the goal is to learn the semantic meanings of code changes in git commits, GitHub PRs, etc.

Since we took git diffs as a target for semantic analysis, we have a different approach to our diffs. We start with line-by-line diffs (specifically using "git diff") and then take a semantic diff by superimposing the git diff information on top of the initial and terminal ASTs.

This makes the diff calculation cheaper because we don't have to do full diff between trees.

Haven't updated the code in a few months, but my team is actively using Locust on public GitHub repos to learn the semantics of those code bases. We do plan to do some work on it soon to make it easier to make Locust easier to use (especially as a library).

Really need to sit down and take a proper look at tree-sitter. We currently support Locust diffs for Python, Javascript, and Java, but each one is custom written and implements the same basic algorithm. It looks like tree sitter might just crush this problem for us.

i want a diff tool that shows me exactly which tokens have changed, and which haven't, regardless of how they are laid out.

These already exist: https://github.com/Wilfred/difftastic

when we get that, then we should get even less merge conflicts.

Counterintuitively, that is not the case. AST-merge is a much, much, much, much, much harder problem than AST-diff.

https://github.com/Wilfred/difftastic?tab=readme-ov-file#can...

The fact that diffs can be used to drive a 3-way merge is in fact an accidental property that arises due to the sheer crudeness of the diff format. As soon as you start using more-sophisticated diff formats, solutions to "the diff problem" no longer lead directly to solutions to "the merge problem".

Yes there is an `—-override` option you can use to specify the language in which a file should be parsed.

https://github.com/Wilfred/difftastic/blob/master/CHANGELOG....

Use the fantastic difftastic instead of git's diff. https://difftastic.wilfred.me.uk/

  [alias]

difftastic provides similar capabilities in a free tool based on treesitter

difftastic? https://github.com/Wilfred/difftastic

If you're looking for a VS Code extension or a GitHub app, check out https://semanticdiff.com/. I'm a co-founder of this project.

If you prefer a CLI tool, check out https://github.com/Wilfred/difftastic. It supports more languages, but doesn't recognize when code has been replaced by an equivalent version ("invariances"). So it will show some changes (e.g. replacing a character in a string with an escape sequence) even though they are technically equivalent.

Shameless plug: I've written difftastic[1], a tool that builds ASTs and then does a structural diff of them. You can use it with git too.

It's an incredibly hard problem though, both from a computational complexity point of view, and trying to build a comprehensible UI once you've done the structural AST diff.

[1]: https://github.com/wilfred/difftastic

There is a diff tool called difftastic: https://github.com/Wilfred/difftastic

The idea is that it does not show diff based on text change, but on syntastic meaning. For that, it uses tree-sitter.

I think it still shows the trailing comma in the situation as shown in the article, but it's quite different experience than the standard text based diff.