[swift-users] Reducing Array<OptionSet> to OptionSet

[Jon Shier]

Thanks Erica. I’ve been able to transform arrays of strings into arrays of my OptionSets using an enum approach like you describe. I was looking more for a generic approach that I could apply to all of the various OptionSets I have to decode from JSON. I suppose whether it’s from an array of strings or array of the OptionSet is less important, but getting to the array of the OptionSet itself is something I can already do. 


Thanks,

Jon

> On Nov 3, 2016, at 9:37 PM, Erica Sadun <erica at ericasadun.com> wrote:
> 
> Maybe something like this? Or you could just bitwise || individual sets. Or you could use a dictionary to lookup [string: rawValue]. etc.
> 
> public struct MyOptionSet: OptionSet {
>     public static let one = MyOptionSet(rawValue: 1 << 0)
>     public static let two = MyOptionSet(rawValue: 1 << 1)
>     public static let three = MyOptionSet(rawValue: 1 << 2)
>     
>     public var rawValue: Int { return _rawValue }
>     public init(rawValue: Int) { self._rawValue = rawValue }
>     private let _rawValue: Int
>     
>     private enum StringEnum: String { case one, two, three }
>     public init(strings: [String]) {
>         var set = MyOptionSet()
>         strings.flatMap({ StringEnum(rawValue: $0) })
>             .flatMap({ MyOptionSet(rawValue: 1 << $0.hashValue) })
>             .forEach { set.insert($0) }
>         _rawValue = set.rawValue
>     }
> }
> 
> let stringArray: [String] = ["one", "three"]
> let stringOptions = MyOptionSet(strings: stringArray)
> stringOptions.rawValue
> 
>> On Nov 3, 2016, at 7:09 PM, Jon Shier via swift-users <swift-users at swift.org <mailto:swift-users at swift.org>> wrote:
>> 
>> Swifters:
>> 	I’m dealing with a JSON API where sets of options are returned as arrays of strings. Representing these as OptionSets seems ideal. I can decode the arrays of strings into an array of individual OptionSet values, but I’ve run into a dead end when trying generically reduce the array of OptionSets to a single OptionSet value. I’ve tried variety of ways of definition a Collection extension, even tried defining a global function, but I can’t seem to use the OptionSet sequence initializer or reduce itself (cannot invoke insert with argument of type (OptionSet) (or T)). Any guidance here? 
>> 	Here’s what I’ve tried:
>> 
>> extension Collection where Iterator.Element == OptionSet {
>> 
>>    func reduced() -> Iterator.Element {
>>        return reduce(Iterator.Element()) {
>>            var newResult = $0
>>            newResult.insert($1)
>>            return newResult
>>        }
>>    }
>> 
>> }
>> 
>> extension Collection where Iterator.Element == OptionSet {
>> 
>>    func reduced<T: OptionSet>() -> T {
>>        return reduce(T()) {
>>            var newResult = $0
>>            newResult.insert($1)
>>            return newResult
>>        }
>>    }
>> 
>> }
>> 
>> 
>> extension Collection where Iterator.Element == OptionSet {
>>    func reduced() -> Iterator.Element {
>>        return Iterator.Element(self)
>>    }
>> }
>> 
>> func reduced<T: OptionSet>(_ options: [T]) -> T {
>>    return options.reduce(T()) {
>>        var newResult = $0
>>        newResult.insert($1)
>> 
>>        return newResult
>>    }
>> }
>> 
>> Jon Shier
>> _______________________________________________
>> swift-users mailing list
>> swift-users at swift.org <mailto:swift-users at swift.org>
>> https://lists.swift.org/mailman/listinfo/swift-users
> 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.swift.org/pipermail/swift-users/attachments/20161103/e51a8d4e/attachment.html>