Improve CJK support with new values for `.cflags'.

This patch introduces three new values to `.cflags':

  don't break before character: 128
  don't break after character:  256
  allow inter-character break:  512

They are handled differently if compared to other cflags values:

  (1) hcode values are completely ignored
  (2) similar to kern values, and contrary to the other cflags
      values, troff looks at pairs of characters to decide whether a
      break gets inserted

A yet-to-be-written patch should add inter-character spacing if
those flags are active; currently, only zero-width breakpoints are
inserted.

* src/roff/troff/charinfo.h (charinfo): Change type of `flags' to
`int'.  Update callers accordingly.
New enum values `DONT_BREAK_BEFORE', `DONT_BREAK_AFTER', and
`INTER_CHAR_SPACE'.
New member functions `prohibit_break_before',
`prohibit_break_after', and `inter_char_space'.
* src/roff/troff/input.cpp: Updated.

* src/roff/troff/node.cpp (inter_char_space_node): New class similar
to kern_pair_node, collecting charinfo entities with the
abovementioned cflags values.
(break_char_type): Add new enum values.
(glyph_node::merge_glyph_node): Handle abovementioned cflags values
and emit an `inter_char_space_node' if necessary.

* tmac/ja.tmac: Use new cflags values.

* doc/groff.texinfo, NEWS, man/groff_diff.man: Document new values.

1 files changed, 3 insertions, 3 deletions

diff --git a/tmac/ja.tmac b/tmac/ja.tmac
index d6883f8f..f0ecd75b 100644
--- a/tmac/ja.tmac
+++ b/tmac/ja.tmac
@@ -44,6 +44,6 @@
 .class [CJKnormal] \
   \[u3041]-\[u3096] \[u30A0]-\[u30FF] \[u4E00]-\[u9FFF]
 .
-.cflags 2 \C'[CJKprepunct]'
-.cflags 4 \C'[CJKpostpunct]'
-.cflags 66 \C'[CJKnormal]'
+.cflags 128 \C'[CJKprepunct]'
+.cflags 266 \C'[CJKpostpunct]'
+.cflags 512 \C'[CJKnormal]'