gotextdiff - unified text diffing in Go

This is a copy of the Go text diffing packages that the official Go language server gopls uses internally to generate unified diffs.

If you've previously tried to generate unified text diffs in Go (like the ones you see in Git and on GitHub), you may have found github.com/sergi/go-diff which is a Go port of Neil Fraser's google-diff-match-patch code - however it does not support unified diffs.

This is arguably one of the best (and most maintained) unified text diffing packages in Go as of at least 2020.

(All credit goes to the Go authors, I am merely re-publishing their work so others can use it.)

Example usage

Import the packages:

import (
    "github.com/hexops/gotextdiff"
    "github.com/hexops/gotextdiff/myers"
)

Assuming you want to diff a.txt and b.txt, whose contents are stored in aString and bString then:

edits := myers.ComputeEdits(span.URIFromPath("a.txt"), aString, bString)
diff := fmt.Sprint(gotextdiff.ToUnified("a.txt", "b.txt", aString, edits))

diff will be a string like:

--- a.txt
+++ b.txt
@@ -1,13 +1,28 @@
-foo
+bar

API compatibility

We will publish a new major version anytime the API changes in a backwards-incompatible way. Because the upstream is not being developed with this being a public package in mind, API breakages may occur more often than in other Go packages (but you can always continue using the old version thanks to Go modules.)

Alternatives

• github.com/andreyvit/diff: Quick'n'easy string diffing functions for Golang based on github.com/sergi/go-diff.
• github.com/kylelemons/godebug/diff: implements a linewise diff algorithm (inactive).

Contributing

We will only accept changes made upstream, please send any contributions to the upstream instead! Compared to the upstream, only import paths will be modified (to be non-internal so they are importable.) The only thing we add here is this README.

License

See https://github.com/golang/tools/blob/master/LICENSE