Swift extension of Array for getting difference from two arrays.

Array+diff.swift

extension Array where Element: Hashable {
	/// Result entity for `diff(with:)`
	typealias DiffResult = (old: [Element], changed: [Element], new: [Element])

	/**
	Return difference between two arrays.

	- Parameter newArray: New array.

	- Returns: DiffResult entity with:
		- old items from current array,
		- changed intersection items from new array
		- new items from new array.
	*/
	func diff(with newArray: [Element]) -> DiffResult {
		let itemsSet = Set(self)
		let newItemsSet = Set(newArray)
		return (
			Array(itemsSet.subtracting(newItemsSet)),
			Array(newItemsSet.intersection(itemsSet)),
			Array(newItemsSet.subtracting(itemsSet))
		)
	}
}