Implement support for character classes.

This patch uses standard C++ headers, contrary to the rest of groff.
Ideally, everything in groff should be updated to do the same.

* src/include/font.h (glyph_to_unicode): New function.

* src/libs/libgroff/font.cpp (glyph_to_unicode): Implement it.
(font::contains, font::get_code): Use it.

* src/roff/troff/charinfo.h: Include <vector> and <utility>.
(charinfo): New members `ranges' and `nested_classes'.
New member functions `get_unicode_code' and `get_flags'.
New member functions `add_to_class', `is_class', and `contains'.
(charinfo::overlaps_horizontally, charinfo::overlaps_vertically,
charinfo::can_break_before, charinfo::can_break_after,
charinfo::can_break_after, charinfo::ends_sentence,
charinfo::transparent,, charinfo:ignore_hcodes): Use `get_flags',
which handles character classes also.

* src/roff/troff/input.cpp (char_class_dictionary): New global
variable.
(define_class): New function.
(init_input_requests): Register `class'.

(charinfo::get_unicode_code, charinfo::get_flags,
charinfo::contains): Implement it.

* NEWS, doc/groff.texinfo (Character Classes), man/groff_diff.man,
man/groff.man: Document it.

1 files changed, 4 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index c5028c4b..00a41b47 100644
--- a/NEWS
+++ b/NEWS
@@ -24,6 +24,10 @@ o There is a new warning category `file', enabled by default.  The `mso'
   request emits warnings in this category when the requested macro file does
   not exist.
 
+o The new `class' request assigns a short name to a set of characters
+  which can be referred to in the `cflags' request.  This is especially
+  useful to control line-breaking and hyphenation rules in CJK languages.
+
 Tbl
 ---