> On Feb 6, 2017, at 10:26 AM, Ted F.A. van Gaalen via swift-evolution > <swift-evolution@swift.org> wrote: > > Hi Dave, > Oops! yes, you’re right! > I did read again more thoroughly about Unicode > and how Unicode is handled within Swift... > -should have done that before I write something- sorry. > > Nevertheless: > > How about this solution: (if I am not making other omissions in my thinking > again) > -Store the string as a collection of fixed-width 32 bit UTF-32 characters > anyway. > -however, if the Unicode character is a grapheme cluster (2..n Unicode > characters),then > store a pointer to a hidden child string containing the actual grapheme > cluster, like so: > > 1: [UTF32, UTF32, UTF32, 1pointer, UTF32, UTF32, 1pointer, UTF32, UTF32] > | > | > 2: [UTF32, UTF32] [UTF32, > UTF32, UTF32, ...] > > whereby (1) is aString as seen by the programmer. > and (2) are hidden child strings, each containing a grapheme cluster.
The random access would require a uniform layout, so a pointer and scalar would need to be the same size. The above would work with a 32 bit platform with a tagged pointer, but would require a 64-bit slot for pointers on 64-bit systems like macOS and iOS. Today when I need to do random access into a string, I convert it to an Array<Character>. Hardly efficient memory-wise, but efficient enough for random access. -DW _______________________________________________ swift-evolution mailing list swift-evolution@swift.org https://lists.swift.org/mailman/listinfo/swift-evolution
