Semantic diff for Neovim using Tree-sitter. Understands code structure to detect moved functions, updated blocks, and real changes, not just line differences.

Features

• Move detection — Knows when code blocks are moved, not deleted and re-added
• Update detection — Highlights modified code in place
• Insert/Delete detection — Shows new and removed code
• Rename detection — Shows renamed variables and functions
• Language agnostic — Works with languages that have Tree-sitter parsers and diffmantic query support

Installation

Using lazy.nvim:

{
    "HarshK97/diffmantic.nvim",
    config = function()
        require("diffmantic").setup()
    end,
}

Usage

Compare two files:

:Diffmantic path/to/file1 path/to/file2

Compare current buffer with another file:

:Diffmantic path/to/other_file

How It Works

The current core follows a multi-phase AST matching pipeline:

1. Pre-match — Seeds stable mappings from unchanged lines
2. Top-down matching — Finds identical/high-confidence subtree pairs
3. Bottom-up matching — Expands matches using mapped descendants
4. Recovery matching — Iteratively recovers remaining valid mappings
5. Action generation + analysis — Produces move/update/insert/delete actions and refined hunks

Requirements

• Neovim 0.9+
• Tree-sitter parser for the language you're diffing

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgements

• GumTree repository: https://github.com/GumTreeDiff/gumtree
• GumTree paper: https://hal.science/hal-04855170v1/file/GumTree_simple__fine_grained__accurate_and_scalable_source_differencing.pdf
• Beyond GumTree paper: https://www.researchgate.net/publication/335498580_Beyond_GumTree_A_Hybrid_Approach_to_Generate_Edit_Scripts