diffsitter
Disclaimer
diffsitter is very much a work in progress and nowhere close to production ready (yet). Contributions are always welcome!
Summary
diffsitter creates semantically meaningful diffs that ignore formatting differences like spacing. It does so by computing a diff on the AST (abstract syntax tree) of a file rather than computing the diff on the text contents of the file.
diffsitter uses the parsers from the tree-sitter project to parse source code. As such, the languages supported by this tool are restricted to the languages supported by tree-sitter.
diffsitter supports the following languages:
- Bash
- C#
- C++
- CSS
- Go
- Java
- OCaml
- PHP
- Python
- Ruby
- Rust
- Typescript/TSX
- HCL
Examples
Take the following files:
fn main() {
let x = 1;
}
fn add_one {
}
fn
main
()
{
}
fn addition() {
}
fn add_two() {
}
The standard output from diff will get you:
1,2c1,12
< fn main() {
< let x = 1;
---
> fn
>
>
>
> main
>
> ()
>
> {
> }
>
> fn addition() {
5c15
< fn add_one {
---
> fn add_two() {
You can see that it picks up the formatting differences for the main function, even though they aren't semantically different.
Check out the output from diffsitter:
test_data/test_1_a.rs -> test_data/test_1_b.rs
==============================================
1:
--
- let x = 1;
4:
--
- fn add_one {
9:
--
+ }
11:
---
+ fn addition() {
14:
---
+ fn add_two() {
Note: the numbers correspond to line numbers from the original files.
Since it uses the AST to calculate the difference, it knows that the formatting differences in main between the two files isn't a meaningful difference, so it doesn't show up in the diff.
diffsitter has some nice (terminal aware) formatting too:
It also has extensive logging if you want to debug or see timing information:
Installation
Published binaries
This project uses Github actions to build and publish binaries for each tagged release. You can download binaries from there if your platform is listed. We publish nightly releases as well as tagged stable releases.
Cargo
You can install using cargo the standard way with cargo install diffsitter.
Homebrew
You can use my tap to install diffsitter:
brew tap afnanenayet/tap
brew install diffsitter
# brew install afnanenayet/tap/diffsitter
Arch Linux (AUR)
@samhh has packaged diffsitter for arch on the AUR. Use your favorite AUR helper to install diffsitter-bin.
Usage
For detailed help you can run diffsitter --help (diffsitter -h provides brief help messages).
You can configure file associations and formatting options for diffsitter using a config file. If a config is not supplied, the app will use the default config, which you can see with diffsitter --cmd dump_default_config. It will look for a config at ${XDG_HOME:-$HOME}/.config/diffsitter/config.json5 on macOS and Linux, and the standard directory for Windows. You can also refer to the sample config.
You can override the default config path by using the --config flag or set the DIFFSITTER_CONFIG environment variable.
Note: the tests for this crate check to make sure the provided sample config is a valid config.
Dependencies
diffsitter is usually compiled as a static binary, so the tree-sitter grammars/libraries are baked into the binary as static libraries. There is an option to build with support for dynamic libraries which will look for shared library files in the user's default library path. This will search for library files of the form libtree-sitter-{lang}.{ext}, where lang is the language that the user is trying to diff and ext is the platform-specific extension for shared library files (.so, .dylib, etc). The user can override the dynamic library file for each language in the config as such:
{
"grammar": {
// You can specify the dynamic library names for each language
"dylib-overrides": {
// with a filename
"rust": "libtree-sitter-rust.so",
// with an absolute path
"c": "/usr/lib/libtree-sitter-c.so",
// with a relative path
"cpp": "../libtree-sitter-c.so",
},
}
}
The above excerpt was taken from the sample config.
Questions, Bugs, and Support
If you notice any bugs, have any issues, want to see a new feature, or just have a question, feel free to open an issue or create a discussion post.
If you file an issue, it would be preferable that you include a minimal example and/or post the log output of diffsitter (which you can do by adding the -d/--debug flag).
Contributing
See CONTRIBUTING.md.
![[BUG] Subdirectory for grammar rust was not found](https://avatars.githubusercontent.com/u/90570748?v=4)
![[BUG] Out of Bounds error while diffing two Terraform files](https://avatars.githubusercontent.com/u/583359?v=4)
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