SideStore/Sources/Shared/Extensions/Result+Conveniences.swift

//
//  Result+Conveniences.swift
//  AltStore
//
//  Created by Riley Testut on 5/22/19.
//  Copyright © 2019 Riley Testut. All rights reserved.
//

import Foundation

public extension Result {
    var value: Success? {
        switch self {
        case let .success(value): return value
        case .failure: return nil
        }
    }

    var error: Failure? {
        switch self {
        case .success: return nil
        case let .failure(error): return error
        }
    }

    init(_ value: Success?, _ error: Failure?) {
        switch (value, error) {
        case let (value?, _): self = .success(value)
        case let (_, error?): self = .failure(error)
        case (nil, nil): preconditionFailure("Either value or error must be non-nil")
        }
    }
}

public extension Result where Success == Void {
    init(_ success: Bool, _ error: Failure?) {
        if success {
            self = .success(())
        } else if let error = error {
            self = .failure(error)
        } else {
            preconditionFailure("Error must be non-nil if success is false")
        }
    }
}

public extension Result {
    init<T, U>(_ values: (T?, U?), _ error: Failure?) where Success == (T, U) {
        if let value1 = values.0, let value2 = values.1 {
            self = .success((value1, value2))
        } else if let error = error {
            self = .failure(error)
        } else {
            preconditionFailure("Error must be non-nil if either provided values are nil")
        }
    }
}