FA-80500 / Bidirectional text layout / Member archive

Line-end whitespace level reset: isolate controls in reset runs · case 05

Isolate controls at the line end keep embedded levels.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

Input [original classes, resolved levels, paragraph level]. Reset to the paragraph level: every S and B; any run of WS and isolate formatting characters (FSI LRI RLI PDI) immediately before an S or B; and such a run at the end of the line. Return levels.

Why this case matters

Mixed right-to-left and left-to-right text must resolve levels and visual order exactly, or words, numbers and carets land in the wrong place.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression: isolate controls in reset runs	`[0, 0, 0, 1, 1, 1, 1]`	`[0, 0, 0, 0, 0, 0, 0]`	Failed

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