[swift-dev] Make offset index available for String

[Wallacy]

95% ASCII? Even if you forgot the rest of the World and consider only US
this doesn’t seems right.

But of course people (in the general) don’t care about Unicode Clusters.
Because that, we should focus on keep Unicode string manipulation easy,
instead just forget the Unicode rules.


Em qui, 14 de dez de 2017 às 17:28, Kelvin Ma via swift-dev <
swift-dev at swift.org> escreveu:

> I think there’s a middle ground here as the current API is overly complex
> and general. 95% of the time people are dealing with ASCII strings and
> don’t care about things like unicode cluster boundaries and whatnot
>
> On Thu, Dec 14, 2017 at 12:13 PM, Jordan Rose via swift-dev <
> swift-dev at swift.org> wrote:
>
>> We really don't want to make subscripting a non-O(1) operation. That just
>> provides false convenience and encourages people to do the wrong thing with
>> Strings anyway.
>>
>> I'm always interested in why people want this kind of ability. Yes, it's
>> nice for teaching programming to be able to split strings on character
>> boundaries indexed by integers, but where does it come up in real life? The
>> most common cases I see are trying to strip off the first or last
>> character, or a known prefix or suffix, and I feel like we should have
>> better answers for those than "use integer indexes" anyway.
>>
>> Jordan
>>
>>
>> On Dec 13, 2017, at 22:30, Cao, Jiannan via swift-dev <
>> swift-dev at swift.org> wrote:
>>
>> Hi,
>>
>> I would like to discuss the String.Index problem within Swift. I know the
>> current situation of String.Index is based on the nature of the underlaying
>> data structure of the string.
>>
>> But could we just make String.Index contain offset information? Or make
>> offset index subscript available for accessing character in String?
>>
>> for example:
>>
>> let a = "01234"
>> print(a[0]) // 0
>> print(a[0...4]) // 01234
>> print(a[...]) // 01234
>> print(a[..<2]) // 01
>> print(a[...2]) // 012
>> print(a[2...]) // 234
>> print(a[2...3]) // 23
>> print(a[2...2]) // 2
>> if let number = a.index(of: "1") {
>>     print(number) // 1
>>     print(a[number...]) // 1234
>> }
>>
>>
>>
>> 0 equals to Collection.Index of collection.index(startIndex, offsetBy: 0)
>> 1 equals to Collection.Index of collection.index(startIndex, offsetBy: 1)
>> ...
>> we keep the String.Index, but allow another kind of index, which is
>> called "offsetIndex" to access the String.Index and the character in the
>> string.
>> Any Collection could use the offset index to access their element,
>> regarding the real index of it.
>>
>> I have make the Collection OffsetIndexable protocol available here, and
>> make it more accessible for StringProtocol considering all API related to
>> the index.
>>
>> https://github.com/frogcjn/OffsetIndexableCollection-String-Int-Indexable-
>>
>> If someone want to make the offset index/range available for any
>> collection, you just need to extend the collection:
>>
>> extension String : OffsetIndexableCollection {
>> }
>> extension Substring : OffsetIndexableCollection {
>> }
>>
>>
>>
>> I hope the Swift core team could consider bring the offset index to
>> string, or make it available to other collection, thus let developer to
>> decide whether their collection could use offset indices as an assistant
>> for the real index of the collection.
>>
>>
>> Thanks!
>> Jiannan
>>
>>
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