DOKK / manpages / debian 12 / libcourier-unicode-dev / unicode::linebreakc_callback_base.3.en
UNICODE::LINEBREAK(3) Courier Unicode Library UNICODE::LINEBREAK(3)

unicode::linebreak_callback_base, unicode::linebreak_callback_save_buf, unicode::linebreakc_callback_base, unicode::linebreak_iter, unicode::linebreakc_iter - unicode line-breaking rules

#include <courier-unicode.h>
class linebreak : public unicode::linebreak_callback_base {
public:

using unicode::linebreak_callback_base::operator<<;
using unicode::linebreak_callback_base::operator();
int callback(int linebreak_code)
{
// ...
} }; char32_t c; std::u32string buf; linebreak compute_linebreak; compute_linebreak.set_opts(UNICODE_LB_OPT_SYBREAK); compute_linebreak << c; compute_linebreak(buf); compute_linebreak(buf.begin(), buf.end()); compute_linebreak.finish(); // ... unicode::linebreak_callback_save_buf linebreaks; std::list<int> lb=linebreaks.lb_buf; class linebreakc : public unicode::linebreakc_callback_base { public:
using unicode::linebreak_callback_base::operator<<;
using unicode::linebreak_callback_base::operator();
int callback(int linebreak_code, char32_t ch)
{
// ...
} }; // ... std::u32string buf; typedef unicode::linebreak_iter<std::u32string::const_iterator> iter_t; iter_t beg_iter(buf.begin(), buf.end()), end_iter; beg_iter.set_opts(UNICODE_LB_OPT_SYBREAK); std::vector<int> linebreaks; std::copy(beg_iter, end_iter, std::back_insert_iterator<std::vector<int>>(linebreaks)); // ... typedef unicode::linebreakc_iter<std::u32string::const_iterator> iter_t; iter_t beg_iter(buf.begin(), buf.end()), end_iter; beg_iter.set_opts(UNICODE_LB_OPT_SYBREAK); std::vector<std::pair<int, char32_t>> linebreaks; std::copy(beg_iter, end_iter, std::back_insert_iterator<std::vector<int>>(linebreaks));

unicode::linebreak_callback_base is a C++ binding for the unicode line-breaking rule implementation described in unicode_line_break(3).

Subclass unicode::linebreak_callback_base and implement callback() that's virtually inherited from unicode::linebreak_callback_base. The callback() callback function receives the output values from the line-breaking algorithm, the UNICODE_LB_MANDATORY, UNICODE_LB_NONE, or the UNICODE_LB_ALLOWED value, for each unicode character.

callback() should return 0. A non-zero return reports an error, that stops the line-breaking algorithm. See unicode_line_break(3) for more information.

The alternate unicode::linebreakc_callback_base interface uses a virtually inherited callback() that receives two parameters, the line-break code value, and the corresponding unicode character.

The input unicode characters for the line-breaking algorithm are provided by the << operator, one unicode character at a time; or by the () operator, passing either a container, or a beginning and an ending iterator value for an input sequence of unicode characters. finish() indicates the end of the unicode character sequence.

set_opts sets line-breaking options (see unicode_lb_set_opts() for more information).

unicode::linebreak_callback_save_buf is a subclass that implements callback() by saving the linebreaks codes into a std::list.

The linebreak_iter template implements an input iterator over ints. The template parameter is an input iterator over unicode chars. The constructor's parameters are a beginning and an ending iterator value for a sequence of char32_t. This constructs the beginning iterator value for a sequence of ints consisting of line-break values (UNICODE_LB_MANDATORY, UNICODE_LB_NONE, or UNICODE_LB_ALLOWED) corresponding to each char32_t in the underlying sequence. The default constructor creates the ending iterator value for the sequence.

The iterator implements a set_opts() methods that sets the options for the line-breaking algorithm.

The linebreakc_iter template implements a similar input iterator, with the difference that it ends up iterating over a std::pair of line-breaking values and the corresponding char32_t from the underlying input sequence.

courier-unicode(7), unicode_line_break(3).

Sam Varshavchik

Author
11/25/2020 Courier Unicode Library