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

[Erica Sadun]

Like this?

let sets: [MyOptionSet] = [MyOptionSet(strings: ["one"]), MyOptionSet(strings: ["two"]), MyOptionSet(strings: ["one", "two"])]
let unioned = sets.reduce(MyOptionSet(rawValue: 0)) {
    (result, set) in return result.union(set)
}
unioned.rawValue


> On Nov 3, 2016, at 7:44 PM, Jon Shier <jon at jonshier.com> wrote:
> 
> 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 <mailto: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 <https://lists.swift.org/mailman/listinfo/swift-users>
>> 
> 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.swift.org/pipermail/swift-users/attachments/20161103/5531773f/attachment.html>