Simple diffing library in pure Swift.

You can use Carthage or Swift Package Manager to install Diff.

Start by importing the package:

import Diff

If there is no difference, the diff will be nil.

diff("Hello", "Hello") // nil

For the sake of brevity, we'll ! the rest of the examples since we know they're different.

let (range, string) = diff("Hello world", "Hello there world")!
// range: 6..<6
// string: "there "

let (range, string) = diff("Hello there world", "Hello world")!
// range: 6..<12
// string: ""

Diff can diff any array. Here's an array of things that conform to Equatable:

let (range, replacement) = diff([1, 2, 3], [1, 2, 3, 4])!
// range: 3..<3
// replacement: [4]

You can even use arrays of anything as long as you can compare them:

let before: [Foo] = [a, b]
let after: [Foo] = [b]
let (range, replacement) = diff(before, after, compare: Foo.compare)!
// range: 0..<1
// replacement: []

If you want to contribute to Diff, please write a test.

Building and running the tests locally with SPM is easy:

$ git clone https://github.com/soffes/Diff
$ cd Diff
$ swift build
$ swift test

Thanks to Jonathan Clem for the original algorithm and Caleb Davenport for inspiration for the generics implementation and help debugging a few edge cases!