Swift utils

CanBeEmpty.swift

public protocol CanBeEmpty {
    var isEmpty: Bool { get }
    var isNotEmpty: Bool { get }
    var nilIfEmpty: Self? { get }
}


public extension CanBeEmpty {

    /// Returns nil if empty, otherwise returns self
    var nilIfEmpty: Self? { return self.isEmpty ? nil : self }

    /// A Boolean value that indicates whether the collection is not empty.
    var isNotEmpty: Bool { return !self.isEmpty }

}


extension String: CanBeEmpty {}
extension Array: CanBeEmpty {}
extension Set: CanBeEmpty {}
extension Dictionary: CanBeEmpty {}


public extension Optional where Wrapped: CanBeEmpty {

    /// Returns whether self is nil or the unwrapped collection is empty
    var isNilOrEmpty: Bool { return self.flatMap({ $0.isEmpty }) ?? true }

    /// Returns whether the unwrapped collection is not empty
    var isNotEmpty: Bool { return !self.isNilOrEmpty }

}