BreakPolicy.mode

BreakPolicy supplies every classification choice explicitly. rules selects the character boundary policy. mode selects word protection. The two choices are independent and neither consults the host locale.

forbidBefore and forbidAfter contain Unicode scalar values. Each integer must be between zero and 1114111 and outside 55296 through 57343. Invalid values return TypesetError.InvalidPolicy. Ordering and duplicate entries do not change membership.

At an ordinary interior boundary, forbidAfter checks the final scalar on the left and forbidBefore checks the first scalar on the right. These custom bans filter admitted candidates and do not create candidates. They do not replace non-tailorable Unicode decisions.

The shaping boundary mask can remove an ordinary candidate. A mask conflict with a mandatory or non-tailorable required Unicode opportunity returns TypesetError.InvalidInput. A generated hyphen or character mode never bypasses a false mask entry.

generatedHyphenEnds contains exclusive interior cluster indices. Both neighboring clusters must consist of Unicode Alphabetic scalars or the apostrophes U+0027 and U+2019. An out of range index or nonword neighbor returns TypesetError.InvalidInput. Duplicate indices have no additional effect.

A generated index changes a missing or HardFallback candidate to LatinSoftHyphen when Unicode permits tailoring there. It does not replace another category or a non-tailorable prohibition. The selected locale, custom bans, shaping mask, and short-word policy still apply. The function does not insert text or measure a hyphen glyph.

narrowestWordTarget and bodyWordTarget are independent nonnegative point lengths. A negative target returns TypesetError.InvalidPolicy. Zero is accepted and equality with a target counts as fitting.

For a HardFallback inside a contiguous run of Alphabetic or apostrophe clusters, protectFittingLatin suppresses the break when the measured run width is at most narrowestWordTarget. Word mode also suppresses that break when the run width is at most bodyWordTarget. Character mode removes this second word-fit test while retaining all other constraints.

Word mode can add emergency boundaries inside an oversized word whose width exceeds bodyWordTarget. Unicode modes retain non-tailorable prohibitions and locale bans. Unicode16Ko also preserves a fitting whitespace-delimited Hangul run at bodyWordTarget.

With preserveShortWords, an interior boundary between nonwhitespace clusters is suppressed when their whitespace-delimited run has at most three Alphabetic or Number scalars. It is also suppressed when that run fits bodyWordTarget. These tests include generated hyphens. Mandatory and non-tailorable required Unicode opportunities retain their priority.