diffsitter

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.

diffstter 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

Examples

Take the following files:

a.rs

fn main() {
    let x = 1;
}

fn add_one {
}

b.rs

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.

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/.config on macOS and Linux, and the standard directory for Windows. You can also refer to the sample config.

Note: the tests for this crate check to make sure the provided sample config is a valid config.

Development

You need a Rust toolchain, which you can install from here: https://rustup.rs. You will also need a C and C++ compiler, any standard-compliant one should be fine (GCC, Clang, or Visual Studio).

If you're on Mac and have Homebrew installed:

brew install llvm

# or

brew install gcc

The built-in Apple clang that comes with XCode is also fine.

If you're on Ubuntu:

sudo apt install gcc

If you're on Arch Linux:

sudo pacman -S gcc

Once you have the requisite toolchains installed, you'll want to clone the project and initialize submodules:

git clone
git submodule --init --recursive

This project targets the latest stable version of rustc, it may work on older versions, but support is only guaranteed for the latest stable version.