A convenience function to tune the ICU BreakIterator's behavior
in some text boundary analysis functions, see
stringi-search-boundaries.
stri_opts_brkiter(
  type,
  locale,
  skip_word_none,
  skip_word_number,
  skip_word_letter,
  skip_word_kana,
  skip_word_ideo,
  skip_line_soft,
  skip_line_hard,
  skip_sentence_term,
  skip_sentence_sep,
  ...
)single string; either the break iterator type, one of character,
line_break, sentence, word;
or a custom set of ICU break iteration rules.
see stringi-search-boundaries
single string, NULL or '' for default locale
logical; perform no action for 'words' that do not fit into any other categories
logical; perform no action for words that appear to be numbers
logical; perform no action for words that contain letters, excluding hiragana, katakana, or ideographic characters
logical; perform no action for words containing kana characters
logical; perform no action for words containing ideographic characters
logical; perform no action for soft line breaks, i.e., positions where a line break is acceptable but not required
logical; perform no action for hard, or mandatory line breaks
logical; perform no action for sentences
ending with a sentence terminator ('.', ',', '?',
'!'), possibly followed by a hard separator
(CR, LF, PS, etc.)
logical; perform no action for sentences that do not contain an ending sentence terminator, but are ended by a hard separator or end of input
[DEPRECATED] any other arguments passed to this function generate a warning; this argument will be removed in the future
Returns a named list object.
Omitted skip_* values act as they have been set to FALSE.
The skip_* family of settings may be used to prevent performing
any special actions on particular types of text boundaries, e.g.,
in case of the stri_locate_all_boundaries and
stri_split_boundaries functions.
Note that custom break iterator rules (advanced users only) should be specified as a single string. For a detailed description of the syntax of RBBI rules, please refer to the ICU User Guide on Boundary Analysis.
ubrk.h File Reference -- ICU4C API Documentation,
https://unicode-org.github.io/icu-docs/apidoc/dev/icu4c/ubrk_8h.html
Boundary Analysis -- ICU User Guide, http://userguide.icu-project.org/boundaryanalysis
Other text_boundaries: 
about_search_boundaries,
about_search,
stri_count_boundaries(),
stri_extract_all_boundaries(),
stri_locate_all_boundaries(),
stri_split_boundaries(),
stri_split_lines(),
stri_trans_tolower(),
stri_wrap()