# diff-match-patch-rs: Efficient port of Google's diff-match-patch implemented in Rust

A very **fast**, **accurate** and **wasm ready** port of [Diff Match Patch](https://github.com/dmsnell/diff-match-patch) in Rust. The
diff implementation is based on [Myers' diff algorithm](https://neil.fraser.name/writing/diff/myers.pdf).


## Highlights of this crate
- Exposes two modes of operating with `diff-match-patch`, a `Efficient` mode and `Compat` mode. While the `Efficient` mode squeezes out the max performance the `Compat` mode ensures compatibility across other libraries or implementations (rust or otherwise). According to [Benchmarks](#benchmarks), our slower `Compat` mode is still faster than other implementations in rust.
    - `**Efficient**` mode works on `&[u8]` and the generated diffs break compatibility with other implementation. Use the `**Efficient**` mode ONLY if you are using this `[crate]()` at the source of diff generation and the destination.
    - `**Compat**` mode on the other hand works on `&[char]` and the generated `diffs` and `patches` are compatible across other implementations of `diff-match-patch`. Checkout `tests/compat.rs` for some test cases around this.
-  `wasm` ready, you can check out a `[demo here](https://github.com/AnubhabB/wasm-diff.git)`
- **Accurate**, can't believe I have to write this but during the course of this implementation I've realised there are a bunch of implementations that have some implementation issues (wrong diffs, inaccurate flows, silent errors etc.).

## Benchmarks
Benchmarks are maintained [diff-match-patch-bench repository](https://github.com/AnubhabB/diff-match-patch-rs-bench)

| Lang.   | Library                                                                                  | Diff Avg. | Patch Avg. | Bencher    | Mode        | Correct |
|:-------:|:----------------------------------------------------------------------------------------:|:---------:|:----------:|:----------:|:-----------:|:-------:|
| `rust`  | [diff_match_patch v0.1.1<sup>**</sup>](https://crates.io/crates/diff_match_patch)        | 68.108 ms | 10.596 ms | Criterion   | -           |    ✅   |
| `rust`  | [diffmatchpatch v0.0.4<sup>***</sup>](https://crates.io/crates/diffmatchpatch)           | 66.454 ms | -         | Criterion   | -           |    ❌   |
| `rust`  | [dmp v0.2.0](https://crates.io/crates/dmp)                                               | 69.019 ms | 14.654 ms | Criterion   | -           |    ✅   |
| `rust`  | [diff-match-patch-rs](https://github.com/AnubhabB/diff-match-patch-rs.git)<sup>our</sup> | 65.487 ms | 631.13 µs | Criterion   | `Efficient` |    ✅   |
| `rust`  | [diff-match-patch-rs](https://github.com/AnubhabB/diff-match-patch-rs.git)<sup>our</sup> | 65.642 ms | 1.1703 ms | Criterion   | `Compat`    |    ✅   |
| `go`    | [go-diff<sup>*</sup>](https://github.com/sergi/go-diff)                                  | 50.31 ms  | 135.2 ms  | go test     | -           |    ❌   |
| `node`  | [diff-match-patch](https://www.npmjs.com/package/diff-match-patch)                       | 246.90 ms | 1.07 ms   | tinybench   | -           |    ✅   |
| `python`| [diff-match-patch](https://pypi.org/project/diff-match-patch/)                           | 1.01 s    | 0.25 ms   | timeit      | -           |    ✅   |

>
> Note:
> Omitting [dissimilar](https://crates.io/crates/dissimilar) from the results, I believe that crate has different goals and a headon benchmark is not fair
> Results: Avg[197.30] High[197.46] Low[197.19]

>
> `*` [go-diff](https://github.com/sergi/go-diff) seems to generate wrong diffs for emoticons. This benchmark is on the text with the emoticons removed. <br>
> `**` Adds an extra clone to the iterator because the `patch_apply` method takes mutable refc. to `diffs` <br>
> `***` The crate [diffmatchpatch v0.0.4](https://crates.io/crates/diffmatchpatch) is still a WIP, cound't find the `patch_apply` method <br>

## Related projects

Diff Match Patch was originally built in 2006 to power Google Docs.
- [Diff Match Patch](https://github.com/google/diff-match-patch) (and it's [fork](https://github.com/dmsnell/diff-match-patch))
- **Rust**: [Distil.io diff_match_patch](https://crates.io/crates/diff_match_patch)
- **Rust**: [dmp](https://crates.io/crates/dmp)
- **Rust**: [Dissimilar](https://crates.io/crates/dissimilar) by the awesome [David Tolnay](https://github.com/dtolnay)
- **Rust**: [diff_match_patch](https://crates.io/crates/diff_match_patch)