Filter
Filters the elements of an observable sequence based on a predicate.
1
2
3
4
public func filter(_ predicate: @escaping (Element) throws -> Bool)
-> Observable<Element> {
return Filter(source: self.asObservable(), predicate: predicate)
}
final private class FilterSink<Observer: ObserverType>: Sink, ObserverType
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
typealias Predicate = (Element) throws -> Bool
private let _predicate: Predicate
func on(_ event: Event<Element>) {
switch event {
case .next(let value):
do {
let satisfies = try self._predicate(value)
// too easy to understand
if satisfies {
self.forwardOn(.next(value))
}
}
catch let e {
self.forwardOn(.error(e))
self.dispose()
}
case .completed, .error:
self.forwardOn(event)
self.dispose()
}
}
final private class Filter: Producer
1
2
3
4
5
6
7
8
9
10
typealias Predicate = (Element) throws -> Bool
private let _source: Observable<Element>
private let _predicate: Predicate
override func run<Observer: ObserverType>(_ observer: Observer, cancel: Cancelable) -> (sink: Disposable, subscription: Disposable) where Observer.Element == Element {
let sink = FilterSink(predicate: self._predicate, observer: observer, cancel: cancel)
let subscription = self._source.subscribe(sink)
return (sink: sink, subscription: subscription)
}