Queries.swift

import Foundation

struct Person {
  var firstName: String
  var lastName: String
  var age: Int
}

extension Person {
  enum Query {
    case firstName(String)
    case lastName(String)
    case age(Int)
    
    func compare(person: Person) -> Bool
    {
      switch self {
      case .firstName(let firstName):
        return person.firstName == firstName
      case .lastName(let lastName):
        return person.lastName == lastName
      case .age(let age):
        return person.age == age
      }
    }
  }
}

class PhoneBook {
  let people = [Person(firstName: "Austin", lastName: "Feight")]
  
  func search(by options: [Person.Query]) -> Person?
  {
    let query = buildQuery(from: options)
    return people.filter(query).first
  }
  
  func buildQuery(from options: [Person.Query]) -> (Person) -> Bool
  {
    return { person in
      return options.map { $0.compare(person: person) }
                    .reduce(true, &&)
    }
  }
}

PhoneBook().search(by: [.firstName("Austin"), .lastName("Feight")])