UnwrapOptional.swift

UnwrapOptional.swift

import Foundation

extension Optional {
    struct NilError: Error {
        let file: String
        let line: Int
        let column: Int
        let function: String
    }

    /// Unwrap an optional, throwing a NilError if nil.
    func unwrap(
        file: String = #file,
        line: Int = #line,
        column: Int = #column,
        function: String = #function
    ) throws -> Wrapped {
        return try unwrap(
            or: NilError(
                file: file,
                line: line,
                column: column,
                function: function
            )
        )
    }

    /// Unwrap an optional, throwing an error if nil.
    func unwrap(or error: @autoclosure () -> Error) throws -> Wrapped {
        switch self {
        case .some(let value):
            return value
        case .none:
            throw error()
        }
    }
}

extension Optional.NilError: LocalizedError {
    public var errorDescription: String? {
        """
        Failed to unwrap nil value (Optional.NilError)
        File: \(self.file)
        Line: \(self.line)
        Column: \(self.column)
        Function: \(self.function)
        """
    }
}