[swift-dev] Very slow Set<String>(arrayOfStrings) for some arrayOfStrings

[Jens Persson]

Interesting, thanks!
I tried using this extension
extension String {
    func componentsSeparatedByNewLineCharacter() -> [String] {
        var lines = [String]()
        var currStr = String.UnicodeScalarView()
        let newLineUCS = UnicodeScalar("\n")
        for ucs in self.unicodeScalars {
            switch ucs {
            case newLineUCS: lines.append(String(currStr));
currStr.removeAll()
            default: currStr.append(ucs)
            }
        }
        return lines
    }
}
instead of componentsSeparatedByString("\n")

This made the slow non-caseSwapped test(strings) run in 2.3 seconds instead
of the previous 9.5 seconds, but that is still relatively slow compared to
the 0.066 seconds of the test(caseSwappedStrings).

Is there a way to make sure a String in Swift has the isASCII bit set
(provided the original string contains only ASCII of course)?

/Jens


On Wed, Mar 2, 2016 at 7:24 PM, Daniel Duan via swift-dev <
swift-dev at swift.org> wrote:

> Arnold Schwaighofer via swift-dev <swift-dev <at> swift.org> writes:
>
> >
> > That is the difference between a “String” type instance that can use the
> > ascii fast path and NSString backed “String” type instances.
> >
>
> This makes total sense now :) I was very mystified by this issue and
> thought
> it's a weird bias in the hashing function at some point.
>
> Thanks for the insight Arnold.
> _______________________________________________
> swift-dev mailing list
> swift-dev at swift.org
> https://lists.swift.org/mailman/listinfo/swift-dev
>



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