Combine+ResultHelpers.swift

Combine+ResultHelpers.swift

//
//  Combine+Helpers.swift
//

import Foundation
import Combine


public extension Publisher {
    func asResult<S, E: Error>() -> AnyPublisher<Result<S, E>, Never> where Self.Output == S, Self.Failure == E {
        
        self
            .map(Result.success)
            .catch { error in Just(.failure(error)) }
            .eraseToAnyPublisher()
    }
}

public extension Publisher where Failure == Never {
    
    func sinkResult<U, E>(
        receiveSuccess: @escaping ((U) -> Void),
        receiveFailure: @escaping ((E) -> Void)
    ) -> AnyCancellable where Output == Result<U, E> {
        let subscriber = Subscribers.Sink<Output, Failure>(
            receiveCompletion: { _ in },
            receiveValue: { result in
                switch result {
                case .success(let value):
                    receiveSuccess(value)
                case .failure(let failure):
                    receiveFailure(failure)
                }
            }
        )
        subscribe(subscriber)
        return AnyCancellable(subscriber)
    }
    
    func ignoreFailure<U, E>()-> AnyPublisher<U, Never> where Self.Output == Result<U, E> {
        self.tryMap {
            try $0.get()
        }
        .catch { _ in Empty<U, Never>() }
        .eraseToAnyPublisher()
    }
    
    func handleAsCompletion<U, E: Error>(completion: @escaping (Result<U, E>) -> Void) where Output == Result<U, E>  {
        
        let subscriber = Subscribers.Sink<Output, Failure>(
            receiveCompletion: { _ in },
            receiveValue: { result in
                completion(result)
            }
        )
        self.subscribe(subscriber)
    }
}