Created
January 25, 2017 20:06
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//: Playground - noun: a place where people can play | |
import UIKit | |
struct Person { | |
var name = Observable("Bob") | |
} | |
enum Event<T> { | |
case next(T) | |
case error(Error) | |
case completed | |
} | |
final class Observable<T> { | |
var value: T { | |
didSet { | |
subscribers.forEach { $0(.next(value)) } | |
} | |
} | |
private var subscribers: [(Event<T>) -> Void] = [] | |
init(_ value: T) { | |
self.value = value | |
} | |
deinit { | |
subscribers.forEach { $0(.completed) } | |
} | |
func subscribe(observer: @escaping (Event<T>) -> Void) { | |
subscribers.append(observer) | |
} | |
} | |
var person: Person? = Person() | |
person?.name.subscribe { event in | |
switch event { | |
case .next(let name): | |
print("new name is \(name)") | |
case .error(let error): | |
print("signal error: \(error)") | |
case .completed: | |
print("signal completed") | |
} | |
} | |
print(person!.name.value) | |
person?.name.value = "John" | |
person = nil | |
print("---") | |
final class AnyObservable<T> { | |
let handler: (@escaping (Event<T>) -> Void) -> Void | |
init(handler: @escaping (@escaping (Event<T>) -> Void) -> Void) { | |
self.handler = handler | |
} | |
func subscribe(observer: @escaping (Event<T>) -> Void) { | |
handler(observer) | |
} | |
func map<U>(_ transform: @escaping (T) -> U) -> AnyObservable<U> { | |
return AnyObservable<U> { observer in | |
self.subscribe { event in | |
switch event { | |
case .next(let value): | |
observer(.next(transform(value))) | |
case .error(let error): | |
observer(.error(error)) | |
case .completed: | |
observer(.completed) | |
} | |
} | |
} | |
} | |
} | |
let obs = AnyObservable<String> { observer in | |
observer(.next("Hello")) | |
observer(.next("World")) | |
observer(.completed) | |
} | |
obs.subscribe { event in | |
switch event { | |
case .next(let value): | |
print(".next: \(value)") | |
case .error(let error): | |
print(".error: \(error)") | |
case .completed: | |
print(".completed") | |
} | |
} | |
obs.map({ str in | |
return str.characters.count | |
}).subscribe { event in | |
switch event { | |
case .next(let value): | |
print(".next: \(value)") | |
case .error(let error): | |
print(".error: \(error)") | |
case .completed: | |
print(".completed") | |
} | |
} | |
//Bob | |
//new name is John | |
//signal completed | |
// --- | |
// .next: Hello | |
//.next: World | |
//.completed | |
//.next: 5 | |
//.next: 5 | |
//.completed | |
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