UNICODE_WORD_BREAK(3) Courier Unicode Library UNICODE_WORD_BREAK(3)NAME
unicode_wb_init, unicode_wb_next, unicode_wb_next_cnt, unicode_wb_end,
unicode_wbscan_init, unicode_wbscan_next, unicode_wbscan_end -
calculate word breaks
SYNOPSIS
#include <courier-unicode.h>
unicode_wb_info_t unicode_wb_init(int (*cb_func)(int, void *),
void *cb_arg);
int unicode_wb_next(unicode_wb_info_t wb, unicode_char c);
int unicode_wb_next_cnt(unicode_wb_info_t wb, const unicode_char *cptr,
size_t cnt);
int unicode_wb_end(unicode_wb_info_t wb);
unicode_wbscan_info_t unicode_wbscan_init(void);
int unicode_wbscan_next(unicode_wbscan_info_t wbs, unicode_char c);
size_t unicode_wbscan_end(unicode_wbscan_info_t wbs);
DESCRIPTION
These functions implement the unicode word breaking algorithm. Invoke
unicode_wb_init() to initialize the word breaking algorithm. The first
parameter is a callback function. The second parameter is an opaque
pointer. The callback function gets invoked with two parameters. The
second parameter is the opaque pointer that was given to
unicode_wb_init(); and the opaque pointer is not subject to any further
interpretation by these functions.
unicode_wb_init() returns an opaque handle. Repeated invocations of
unicode_wb_next(), passing the handle, and one unicode character
defines a sequence of unicode characters over which the word breaking
algorithm calculation takes place. unicode_wb_next_cnt() is a shortcut
for invoking unicode_wb_next() repeatedly over an array cptr containing
cnt unicode characters.
unicode_wb_end() denotes the end of the unicode character sequence.
After the call to unicode_wb_end() the word breaking unicode_wb_info_t
handle is no longer valid.
Between the call to unicode_wb_init() and unicode_wb_end(), the
callback function gets invoked exactly once for each unicode character
given to unicode_wb_next() or unicode_wb_next_cnt(). Usually each call
to unicode_wb_next() results in the callback function getting invoked
immediately, but it does not have to be. It's possible that a call to
unicode_wb_next() returns without invoking the callback function, and
some subsequent call to unicode_wb_next() (or unicode_wb_end()) invokes
the callback function more than once, to catch things up. The contract
is that before unicode_wb_end() returns, the callback function gets
invoked the exact number of times as the number of characters in the
unicode sequence defined by the intervening calls to unicode_wb_next()
and unicode_wb_next_cnt(), unless an error occurs.
Each call to the callback function reports the calculated wordbreaking
status of the corresponding character in the unicode character
sequence. If the parameter to the callback function is non zero, a word
break is permitted before the corresponding character. A zero value
indicates that a word break is prohibited before the corresponding
character.
The callback function should return 0. A non-zero value indicates to
the word breaking algorithm that an error has occured.
unicode_wb_next() and unicode_wb_next_cnt() return zero either if they
never invoked the callback function, or if each call to the callback
function returned zero. A non zero return from the callback function
results in unicode_wb_next() and unicode_wb_next_cnt() immediately
returning the same value.
unicode_wb_end() must be invoked to destroy the word breaking handle
even if unicode_wb_next() and unicode_wb_next_cnt() returned an error
indication. It's also possible that, under normal circumstances,
unicode_wb_end() invokes the callback function one or more times. The
return value from unicode_wb_end() has the same meaning as from
unicode_wb_next() and unicode_wb_next_cnt(); however in all cases after
unicode_wb_end() returns the line breaking handle is no longer valid.
Word scan
unicode_wbscan_init(), unicode_wbscan_next() and unicode_wbscan_end
scan for the next word boundary in a unicode character sequence.
unicode_wbscan_init() obtains a handle, then unicode_wbscan_next() gets
repeatedly invoked to define the unicode character sequence.
unicode_wbscan_end() deallocates the handle and returns the number of
leading characters in the unicode character sequence up to the first
word break.
A non-0 return value from unicode_wbscan_next() indicates that the word
boundary is already known, and any further calls to
unicode_wbscan_next() will be ignored. unicode_wbscan_end() must still
be called, to obtain the unicode character count.
SEE ALSO
TR-29[1], courier-unicode(7), unicode::wordbreak(3),
unicode_convert_tocase(3), unicode_line_break(3),
unicode_grapheme_break(3).
AUTHOR
Sam Varshavchik
Author
NOTES
1. TR-29
http://www.unicode.org/reports/tr29/tr29-27.html
Courier Unicode Library 07/29/2015 UNICODE_WORD_BREAK(3)
