Fix lua-objc mapping to handle high/low surrogate pairs in hs.styledtext #3356
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stickler-ci
reviewed
Jan 13, 2023
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@asmagill I'm not going to pretend to understand all the unicode stuff - are you happy for this to merge? |
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I left in a debugging function that I originally had commented out... it's undocumented, but might be helpful if someone does find a specific case where this fails, so I'm inclined to leave it as is. If you don't mind the undocumented function being left in, then yes, I think this is ready to be merged -- it hasn't broken anything on my setup and passed every test I've thought to come up with at it... Though to be fair, I don't think a set of comprehensive unicode tests that covers absolutely all use cases exists... sometimes I feel like they make it up as they go! 😁 |
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Addresses issues in #3219
Completely rewrites lua-objc index mapping to properly handle UTF16 High/Low surrogate pairs
UTF8 (which Lua uses) can have Unicode characters of 1-4 bytes
UTF16 (which Objective-C/Swift use) are always 2 bytes, but for Unicode characters above U+10000 inclusive, 2 UTF16 characters (i.e. 4 bytes) are used.
This code assumes that no 1-byte UTF8 character can be a surrogate member... as far as I can tell this is a safe assumption, but I haven't found an explicit statement to that effect, so if anyone knows otherwise, please chime in.