String Handling

Session Owners

Marc Mutz

Notes

Issues:

• QByteArray doubles as QUtf8String
• UTF-8 is not a good in-memory format:
  • Comparison cannot early-exit based on size (when comparing to L1 or U16)
  • Indexing (too many muti-code-unit encodings; UTF-16 has fewer)
  • Searching (no Boyer-Moore for general UTF-8)
• Suggestion of where to go:
  • complete mixed string operations (comparison, searching, tokenisation)
  • add UTF-8 searching and tokenisation
  • add UTF-32 (for Python compat)
  • add owning versions of all

• Can QString get more constexpr support?
  • Unlikely, it requires more C++ support
  • QString has implicit sharing and a lot of out-of-line API

• QAnyStringView is missing a lot of API
  • because QUtf8StringView are also lacking such

• Thiago requests that we make proof-of-concept of the final state of this API
  • Avoid breaking user code (e.g., implicit conversions to QString)
  • Create a Library API Design document what to create
    • Needs a plan for getting there from where we are
    • Return types
    • Where to keep simple QStrings (for other develoeprs not working on QtCore)

• QString considers equal only strings that have the exact same code units.
  • Equivalence based on Unicode transforms (NFD, NFC) is not taken into account
    • but there's API to do the conversions if needed.