Generating a unique name by adding or incrementing suffix number of base name.

String+makeuniquename.swift

//	String.makeUniqueName
//
//	The MIT License (MIT)
//
//	Copyright (c) 2021 Electricwoods LLC, Kaz Yoshikawa.
//
//	Permission is hereby granted, free of charge, to any person obtaining a copy
//	of this software and associated documentation files (the "Software"), to deal
//	in the Software without restriction, including without limitation the rights
//	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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//
//	The above copyright notice and this permission notice shall be included in
//	all copies or substantial portions of the Software.
//
//	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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//	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//	THE SOFTWARE.
//

import Foundation

//	function: makeUniqueName()
//	In some case, you may want to find a name to duplicate a file by adding or by increminting suffix number.  This function adds or incremnet its
//	suffix number, you may have to provide a closure to check if given name is uniqe to the context.

extension String {

	public static func makeUniqueName(name: String, validating: ((String)->Bool)) -> String {
		var candidate = name
		let numberRange: Range<String.Index>? = name.range(of: "[0-9]+$", options: [.regularExpression])
		var number: Int = numberRange.flatMap { Int(name[$0]) } ?? 2
		while !validating(candidate) {
			defer { number += 1 }
			candidate = numberRange.map { name.replacingCharacters(in: $0, with: String(number + 1)) } ?? (name + " " + String(number))
		}
		return candidate
	}

}


let names = ["Hello", "Hello 2", "Hello 3", "Hello 12", "World", "World2", "World3", "World-21"]
print(String.makeUniqueName(name: "Hello") { (name) -> Bool in !names.contains(name) })		// "Hello 4"
print(String.makeUniqueName(name: "Hello2") { (name) -> Bool in !names.contains(name) })	// "Hello2"
print(String.makeUniqueName(name: "Hello 12") { (name) -> Bool in !names.contains(name) })	// "Hello 13"
print(String.makeUniqueName(name: "World") { (name) -> Bool in !names.contains(name) })		// "World 2"
print(String.makeUniqueName(name: "World2") { (name) -> Bool in !names.contains(name) })	// "World4"
print(String.makeUniqueName(name: "World-21") { (name) -> Bool in !names.contains(name) })	// "World-22"