Re: does anoybody use ul?

[Ted Unangst]

Christian Weisgerber wrote:
> Ted Unangst:
> 
> > --- ul.c    10 Oct 2015 16:15:03 -0000      1.19
> > +++ ul.c    23 Oct 2015 10:29:43 -0000
> > @@ -241,6 +241,8 @@ mfilter(FILE *f)
> >                     obuf[col].c_mode |= BOLD|mode;
> >             else
> >                     obuf[col].c_mode = mode;
> > +           if ((c & (0x80 | 0x40)) == 0x80 && col > 0)
> > +                   obuf[col].c_mode = obuf[col - 1].c_mode;
> >             col++;
> >             if (col > maxcol)
> >                     maxcol = col;
> 
> That doesn't quite work.  Check out this:
> 
> mandoc /usr/share/man/man1/ksh.1 | sed -n 1185,1190p | ul

so that works with the diff below. i'm not sure how far down this road we need
to travel, but i figure it's worth a little exploration.

note that i don't think this handles the case of one character, backspace, a
different character correctly, though it can asymptotically approach
correct with some care.

Index: ul.c
===================================================================
RCS file: /cvs/src/usr.bin/ul/ul.c,v
retrieving revision 1.19
diff -u -p -r1.19 ul.c
--- ul.c        10 Oct 2015 16:15:03 -0000      1.19
+++ ul.c        23 Oct 2015 13:31:45 -0000
@@ -151,6 +151,12 @@ main(int argc, char *argv[])
        exit(0);
 }
 
+int
+isu8cont(unsigned char c)
+{
+       return (c & (0x80 | 0x40)) == 0x80;
+}
+
 void
 mfilter(FILE *f)
 {
@@ -158,8 +164,11 @@ mfilter(FILE *f)
 
        while ((c = getc(f)) != EOF && col < MAXBUF) switch(c) {
        case '\b':
-               if (col > 0)
+               while (col > 0) {
                        col--;
+                       if (!isu8cont(obuf[col].c_char))
+                               break;
+               }
                continue;
        case '\t':
                col = (col+8) & ~07;
@@ -241,6 +250,8 @@ mfilter(FILE *f)
                        obuf[col].c_mode |= BOLD|mode;
                else
                        obuf[col].c_mode = mode;
+               if ((c & (0x80 | 0x40)) == 0x80 && col > 0)
+                       obuf[col].c_mode = obuf[col - 1].c_mode;
                col++;
                if (col > maxcol)
                        maxcol = col;