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µDiff - a micro Go diffing library

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aymanbagabas/go-udiff

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µDiff

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Micro diff (µDiff) is a Go library that implements the Myers' diffing algorithm. It aims to provide a minimal API to compute and apply diffs with zero dependencies. It also supports generating diffs in the Unified Format. If you are looking for a way to parse unified diffs, check out sourcegraph/go-diff.

This is merely a copy of the Golang tools internal diff package with a few modifications to export package symbols. All credit goes to the Go authors.

Usage

You can import the package using the following command:

go get github.com/aymanbagabas/go-udiff

Examples

Generate a unified diff for strings a and b with the default number of context lines (3). Use udiff.ToUnified to specify the number of context lines.

package main

import (
    "fmt"

    "github.com/aymanbagabas/go-udiff"
)

func main() {
    a := "Hello, world!\n"
    b := "Hello, Go!\nSay hi to µDiff"
    unified := udiff.Unified("a.txt", "b.txt", a, b)
    fmt.Println(unified)
}
--- a.txt
+++ b.txt
@@ -1 +1,2 @@
-Hello, world!
+Hello, Go!
+Say hi to µDiff
\ No newline at end of file

Apply changes to a string.

package main

import (
    "fmt"

    "github.com/aymanbagabas/go-udiff"
)

func main() {
    a := "Hello, world!\n"
    b := "Hello, Go!\nSay hi to µDiff"

    edits := udiff.Strings(a, b)
    final, err := udiff.Apply(a, edits)
    if err != nil {
        panic(err)
    }

    fmt.Println(final)
}
Hello, Go!
Say hi to µDiff

To get a line-by-line diff and edits:

package main

import (
    "fmt"

    "github.com/aymanbagabas/go-udiff"
)

func main() {
    a := "Hello, world!\n"
    b := "Hello, Go!\nSay hi to µDiff"

    edits := udiff.Strings(a, b)
    d, err := udiff.ToUnifiedDiff("a.txt", "b.txt", a, edits, udiff.DefaultContextLines)
    if err != nil {
        panic(err)
    }

    for _, h := range d.Hunks {
        fmt.Printf("hunk: -%d, +%d\n", h.FromLine, h.ToLine)
        for _, l := range h.Lines {
            fmt.Printf("%s %q\n", l.Kind, l.Content)
        }
    }
}
hunk: -1, +1
delete "Hello, world!\n"
insert "Hello, Go!\n"
insert "Say hi to µDiff"

Alternatives

Contributing

Please send any contributions upstream. Pull requests made against the upstream diff package are welcome.

License

BSD 3-Clause and MIT.