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/*
This source file is part of the Swift.org open source project
Copyright (c) 2021 Apple Inc. and the Swift project authors
Licensed under Apache License v2.0 with Runtime Library Exception
See https://swift.org/LICENSE.txt for license information
See https://swift.org/CONTRIBUTORS.txt for Swift project authors
*/
import Foundation
/// A conjunction in a grammatical list.
enum Conjunction: String {
/// "or"
case or
/// "and"
case and
}
extension BidirectionalCollection where Element: CustomStringConvertible {
/**
Returns this collection of elements separated by commas, terminating with `finalConjunction`.
For example, for the array `[1,2,3]`, will return "1, 2, or 3" or "1, 2, and 3".
*/
func list(finalConjunction: Conjunction) -> String {
switch count {
case 0:
return ""
case 1:
return "\(self.first!)"
case 2:
let firstIndex = startIndex
let secondIndex = index(after: firstIndex)
return "\(self[firstIndex]) \(finalConjunction) \(self[secondIndex])"
default:
let prefix = self.prefix(self.count - 1).map { $0.description }.joined(separator: ", ")
return "\(prefix), \(finalConjunction.rawValue) \(self.last!.description)"
}
}
}
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