[swift-evolution] NSRange and Range

Wed May 11 12:19:12 CDT 2016

I’m not sure we’re going to stick to that in the future. It’s possible we’ll want String to support UTF-8 buffers as well.

Jordan

> On May 11, 2016, at 10:15, Zach Waldowski <zach at waldowski.me> wrote:
> 
> Conceptually, yes, but is that not exactly how it is implemented? https://github.com/apple/swift/blob/master/stdlib/public/core/StringUTF16.swift#L24 <https://github.com/apple/swift/blob/master/stdlib/public/core/StringUTF16.swift#L24>
>  
> Sincerely,
>   Zachary Waldowski
>   zach at waldowski.me <mailto:zach at waldowski.me>
>  
>  
> On Wed, May 11, 2016, at 01:13 PM, Jordan Rose wrote:
>> That’s correct, but how would you make the String.UTF16Index values without the reference String? They’re not (guaranteed to be) integers.
>>  
>> Jordan
>>  
>>  
>>> On May 10, 2016, at 16:04, Zach Waldowski <zach at waldowski.me <mailto:zach at waldowski.me>> wrote:
>>>  
>>> Right, I 100% get it. :) This is a difficult problem space, and I'm sure you folks are aware that that difficulty is also reflected in how brutal it is to use all of these derivative string-range-based things in Swift right now. In this case, having no answer to this problem is worse than not having the API at all — check Stack Overflow or GitHub for how often a "just paste this in" String.Index.init(_: Int) comes up.
>>>  
>>> As far as NSTextCheckingResult goes, its ranges are always in the "indices" always in the space of the original string… do I have that right? So it would be programmer error to use those ranges in the wrong string just like it is with any Range<String.UTF16Index> today.
>>>  
>>> Zach Waldowski
>>>  
>>>  
>>> On Tue, May 10, 2016, at 06:51 PM, Jordan Rose wrote:
>>>> By the way, this doesn’t mean it can’t be done, or that we can’t decide on some kind of partial solution! It just means that it needs to be carefully considered and explicitly addressed.
>>>>  
>>>> Jordan
>>>>  
>>>>  
>>>>> On May 10, 2016, at 15:49, Jordan Rose <jordan_rose at apple.com <mailto:jordan_rose at apple.com>> wrote:
>>>>>  
>>>>> We thought about that too. The problem is that it’s not always obvious what NSString or NSAttributedString the indexes refer to. For example, most of the NSRegularExpression APIs produce matches in the form of NSTextCheckingResult, which then doesn’t have a reference to the original string.
>>>>>  
>>>>> Jordan
>>>>>  
>>>>>  
>>>>>> On May 10, 2016, at 13:43, Zach Waldowski via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>>>>>  
>>>>>> Would it be feasible to annotate those and have them appropriately converted to Range<String.UTF16Index> upon crossing the bridge? Thinking in particular of TextKit and friends — it'd away with quite a lot of the pain of, e.g., not having a native struct-y AttributedString.
>>>>>>  
>>>>>> Cheers!
>>>>>>   Zachary Waldowski
>>>>>>   zach at waldowski.me <mailto:zach at waldowski.me>
>>>>>>  
>>>>>>  
>>>>>> On Tue, May 10, 2016, at 12:37 PM, Jordan Rose via swift-evolution wrote:
>>>>>>> One particular concern we've had is that many NSRanges aren’t Range<Int>; they’re Range<String.UTF16Index>. I suppose things wouldn’t get any worse there, though.
>>>>>>>  
>>>>>>> Jordan
>>>>>>>  
>>>>>>>  
>>>>>>>> On May 10, 2016, at 00:14, David Hart via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>>>>>>>  
>>>>>>>> But it’s reasonably implementable? I guess the answer is yes if you have already faced the same bridging concerns with NSArray/Array. I’de really like this going forward, but I don’t know how confident I am in writing a proposal.
>>>>>>>>  
>>>>>>>>> On 10 May 2016, at 08:29, Douglas Gregor <dgregor at apple.com <mailto:dgregor at apple.com>> wrote:
>>>>>>>>>  
>>>>>>>>>  
>>>>>>>>>> On May 9, 2016, at 11:23 PM, David Hart <david at hartbit.com <mailto:david at hartbit.com>> wrote:
>>>>>>>>>>  
>>>>>>>>>> Why wouldn't it completely eliminate NSRange?
>>>>>>>>>  
>>>>>>>>> Because NSRange has a different representation than Range<Int> (start+length vs. start/end), a pointer-to-NSRange has to come in as Unsafe(Mutable)Pointer<NSRange> rather than Unsafe(Mutable)Pointer<Range<Int>>. It’s the same reason that (e.g.), an NSArray** parameter comes in as UnsafeMutablePointer<NSArray> rather than UnsafeMutablePointer<[AnyObject]>.
>>>>>>>>>  
>>>>>>>>>> Are you thinking of NSNotFound? Could we migrate those APIs to return an Optional Range<Int>?
>>>>>>>>>  
>>>>>>>>> If you had annotations on the APIs to say that they use NSNotFound as a sentinel, yes.
>>>>>>>>>  
>>>>>>>>> - Doug
>>>>>>>>>  
>>>>>>>>>>  
>>>>>>>>>>> On 10 May 2016, at 05:49, Douglas Gregor <dgregor at apple.com <mailto:dgregor at apple.com>> wrote:
>>>>>>>>>>>  
>>>>>>>>>>>  
>>>>>>>>>>>> On May 8, 2016, at 2:10 PM, David Hart via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>>>>>>>>>>>  
>>>>>>>>>>>> Hello Swift-Evolution,
>>>>>>>>>>>>  
>>>>>>>>>>>> I spent some time coding on Linux with Swift 3 (latest developement snapshot) and corelibs-foundation and I’ve hit one major hurdle: passing and converting NSRange and Range around between the different stdlib and Foundation APIs - specifically in regards to String.
>>>>>>>>>>>>  
>>>>>>>>>>>> Is there a plan to simplify those pain points by converting all corelibs-foundation APIs to accept/return Range on String instead of NSRange? In that case, can’t we get rid of NSRange completely?
>>>>>>>>>>>  
>>>>>>>>>>>  
>>>>>>>>>>> One idea that had come up before was to bridge NSRange to Range<Int>, although it wouldn’t completely eliminate NSRange because the two types are not representationally identical.
>>>>>>>>>>>  
>>>>>>>>>>> - Doug
>>>>>>>>>>>  
>>>>>>>>>>  
>>>>>>>>>  
>>>>>>>>  
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>>>>>>> 
>>>>>>>  
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