Fix GraphemeCursor for GB11 case on a chunk boundary#172
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Pull request overview
Fixes an incorrect grapheme boundary result in GraphemeCursor for GB11 when the ZWJ occurs at a chunk boundary by preserving intermediate emoji-state across PreContext requests.
Changes:
- Extends
GraphemeState::Emojito carry aseen_zwjsub-state so GB11 handling can resume correctly across chunks. - Updates the GB11 backtracking logic (
handle_emoji) to use/persist theseen_zwjflag when requesting additional pre-context. - Adds regression and coverage tests for chunked emoji/ZWJ boundary scenarios.
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| /// Whether the ZWJ char has been seen already an only a "\p{Extended_Pictographic} Extend*" | ||
| /// part of GB11 has to be checked |
Manishearth
approved these changes
May 24, 2026
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Fixes #118
For a case with two chunks
👩and\u{200d}🔬, when the "pre-context" is processed, the knowledge of the fact that the ZWJ byte has been seen is lost. That's why it's expected again.This commit fixes this by keeping this "substate" in a
GraphemeState::Emojivariant