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fix(ios): classify RN writing direction beyond the BMP - #975
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Follow-up to #907 for the React Native package. ENRMFirstStrongDirection scanned UTF-16 units against letterCharacterSet and three BMP ranges, so a letter beyond the BMP (Adlam, Old Hungarian) never counted, a leading U+200F, U+200E or U+061C was ignored, and a combining mark counted as a letter. The scan now decodes surrogate pairs to a scalar, returns LTR for U+200E and RTL for U+200F and U+061C, skips marks, and classifies letters with the two Plane 1 right-to-left ranges added to the table. The predefined character sets are looked up once in the file's constructor. Unlike the Swift resolver, an astral combining mark is skipped rather than classified. Adds the first XCTest suite under __tests__/ios, mirroring the Swift WritingDirectionTests cases. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
eszlamczyk
approved these changes
Oct 22, 2026
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Follow-up to #907 for the React Native package. ENRMFirstStrongDirection scanned UTF-16 units against letterCharacterSet and three BMP ranges, so a letter beyond the BMP (Adlam, Old Hungarian) never counted, a leading U+200F, U+200E or U+061C was ignored, and a combining mark counted as a letter.
The scan now decodes surrogate pairs to a scalar, returns LTR for U+200E and RTL for U+200F and U+061C, skips marks, and classifies letters with the two Plane 1 right-to-left ranges added to the table. The predefined character sets are looked up once in the file's constructor. Unlike the Swift resolver, an astral combining mark is skipped rather than classified.
Adds the first XCTest suite under tests/ios, mirroring the Swift WritingDirectionTests cases.
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