FA-80194 / Typography line breaking / Member archive

Ties and discretionary hyphens: hyphen at taken discretionary · case 04

Words broken at a discretionary lose their hyphen.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

Input [source, width]. Runs of spaces are one breakable space; "~" is an unbreakable space rendered " "; "\-" is a discretionary hyphen: invisible unless the line breaks there, then rendered "-"; "|" is an invisible break opportunity. Greedy: append the next chunk if the line (without a potential hyphen) fits, else break at that opportunity. Return rendered lines.

Why this case matters

Line breaking decides where paragraphs wrap on screen and in print; a wrong decision point shifts every following line.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression: hyphen at taken discretionary	`["x 10 pt a", " Dr. Knuth bc", "Dr. Knuth hy", "phen set composi", "tion"]`	`["x 10 pt a", " Dr. Knuth bc", "Dr. Knuth hy-", "phen set composi-", "tion"]`	Failed

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