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January 25, 2017 19:57
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enum Event<T> { | |
case next(T) | |
case error(Error) | |
case completed | |
} | |
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") | |
} | |
} | |
// .next: Hello | |
// .next: World | |
// .completed | |
// .next: 5 | |
// .next: 5 | |
// .completed |
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