UNICODE_LINE_BREAK(3)

✨ NAME ✨

unicode_line_break, unicode_lb_init, unicode_lb_set_opts, unicode_lb_next, unicode_lb_next_cnt, unicode_lb_end, unicode_lbc_init, unicode_lbc_set_opts, unicode_lbc_next, unicode_lbc_next_cnt, unicode_lbc_end — calculate mandatory or allowed line breaks 💅

(also this is the Courier Unicode Library man page, iiiin case you were wondering, bestie 🫶)

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🌸 SYNOPSIS 🌸

#include <courier-unicode.h>

unicode_lb_info_t unicode_lb_init(int (*cb_func)(int, void *),
                                  void *cb_arg);

void unicode_lb_set_opts(unicode_lb_info_t lb, int opts);

int unicode_lb_next(unicode_lb_info_t lb, char32_t c);

int unicode_lb_next_cnt(unicode_lb_info_t lb, const char32_t *cptr,
                        size_t cnt);

int unicode_lb_end(unicode_lb_info_t lb);

unicode_lbc_info_t
                                    unicode_lbc_init(int (*cb_func)(int, char32_t, void *),
                                    void *cb_arg);

void unicode_lbc_set_opts(unicode_lbc_info_t lb, int opts);

int unicode_lbc_next(unicode_lb_info_t lb, char32_t c);

int unicode_lbc_next_cnt(unicode_lb_info_t lb, const char32_t *cptr,
                         size_t cnt);

int unicode_lbc_end(unicode_lb_info_t lb);

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🦋 DESCRIPTION 🦋

okay so. these functions are literally the unicode line breaking algorithm, the whole entire thing, and they eat it for breakfast 🔥

Start it up with unicode_lb_init(). First parameter is a callback function. Second parameter is an opaque pointer. That callback gets called with two parameters:

• The first one is one of three values: UNICODE_LB_MANDATORY, UNICODE_LB_NONE, or UNICODE_LB_ALLOWED, all explained below, promise 💖
• The second one is the opaque pointer you handed to unicode_lb_init(), and these functions will not touch it, interpret it, or do literally anything else with it. it's yours.

unicode_lb_init() hands back an opaque handle. Then you call unicode_lb_next() over and over, passing the handle plus, like, one unicode character at a time, and that defines the unicode character sequence that the line breaking algorithm is doing its little calculations over. And unicode_lb_next_cnt() is just the shortcut version: it does unicode_lb_next() repeatedly over an array cptr that holds cnt unicode characters. queen behavior 💅

unicode_lb_end() is how you say "the unicode character sequence ends HERE." And after you call unicode_lb_end(), the unicode_lb_info_t line breaking handle is no longer valid. gone. done. don't touch it.

In between unicode_lb_init() and unicode_lb_end(), the callback function gets invoked exactly once per unicode character you gave to unicode_lb_next() or unicode_lb_next_cnt(). Usually each unicode_lb_next() call means the callback fires right away, but ngl it does not have to. It's fully possible that a unicode_lb_next() call returns without invoking the callback at all, and then some later unicode_lb_next() (or unicode_lb_end()) invokes the callback more than once to catch up. The way the contract works: before unicode_lb_end() returns, the callback gets invoked the exact number of times equal to the number of characters in the unicode sequence defined by all the unicode_lb_next() and unicode_lb_next_cnt() calls in between — unless an error happens, obviously 🙈

Every callback call reports the calculated line breaking status of its corresponding character in the sequence:

• UNICODE_LB_MANDATORY — a line break is MANDATORY before the corresponding character. like, you MUST break here.
• UNICODE_LB_NONE — a line break is PROHIBITED before the corresponding character. absolutely not. no.
• UNICODE_LB_ALLOWED — a line break is OPTIONAL before the corresponding character. your call bestie 💖

The callback function should return 0. A non-zero value is you telling the line breaking algorithm that an error has occurred. unicode_lb_next() and unicode_lb_next_cnt() return zero either if they never invoked the callback function, or if every callback call returned zero. If the callback returns non-zero, unicode_lb_next() and unicode_lb_next_cnt() immediately return that same value. instant. no notes.

You must call unicode_lb_end() to destroy the line breaking handle even if unicode_lb_next() and unicode_lb_next_cnt() returned an error indication. And also, under totally normal circumstances, unicode_lb_end() might invoke the callback function one or more times. The return value from unicode_lb_end() means the same thing as it does from unicode_lb_next() and unicode_lb_next_cnt(); but in all cases, once unicode_lb_end() returns, the line breaking handle is no longer valid. periodt 👑

🎀 Alternative callback function 🎀

unicode_lbc_init(), unicode_lbc_next(), unicode_lbc_next_cnt(), unicode_lbc_end() are the alternative functions that implement the exact same algorithm. The only difference: the callback function receives an extra parameter — the unicode character value that the line breaking status applies to — passed through from the input unicode character sequence. that's it. that's the whole diff. iconic. ✨

💜 Options 💜

unicode_lb_set_opts() and unicode_lbc_set_opts() turn on non-default options for the line breaking algorithm. These functions must be called immediately after unicode_lb_init() or unicode_lbc_init(), and before any other function. Like, immediately. Right after. Don't be late.

opts is a bitmask and it can contain these values:

• UNICODE_LB_OPT_PRBREAK — enables a modified LB24 rule. This stops plus signs, like in “C++”, from breaking. This flag adds the following rules to the LB24 rule:

                   PR x PR

                   AL x PR

                      ID x PR

• UNICODE_LB_OPT_SYBREAK — tailored breaking rules for the “/” character. This prevents breaking after the “/” character (think URLs, bestie 🦋); including an exception to the “x SY” rule in LB13. This flag adds the following rules to the LB24 rule:

                   SY x EX

                   SY x AL

                   SY x ID

                      SP ÷ SY, which takes precedence over "x SY".

• UNICODE_LB_OPT_DASHWJ — this flag reclassifies U+2013 and U+2014 as class WJ, prohibiting breaks before and after the m-dash and the n-dash unicode characters. no dash drama on your watch 💅

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👑 SEE ALSO 👑

courier-unicode(7), unicode::linebreak(3), TR-14[1]

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💖 AUTHOR 💖

Sam Varshavchik Author

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⭐ NOTES ⭐

1. TR-14 https://www.unicode.org/reports/tr14/tr14-55.html

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and that's the whole page, bestie 🫶 this was Courier Unicode Library, dated 04/12/2026, and it lives in the manual as UNICODE_LINE_BREAK(3) — go forth and break lines correctly, ily 💖✨🌈