🚀 go-pugleaf

In article <8909121817.AA11159@gem> lang@PRC.UNISYS.COM writes:
...
>% grep -i '\Wx\W' foo
>
>But the effect here is that the -i flag makes the '\W'
>meta-character non-case-sensitive as well

I would call this a bug (and patched it).
I traced the problem to the following piece of code in dfa.c:

/* Parse and analyze a single string of the given length. */
void
regcompile(s, len, r, searchflag)
     const char *s;
     size_t len;
     struct regexp *r;
     int searchflag;
{
  if (case_fold)	/* dummy folding in service of regmust() */
    {
	static char *p;

	case_fold = 0;
	for (p = (char *)s; *p != 0; p++)
		if (isupper((int)*p))
			*p = tolower((int) *p);
...

I.e., when the -i flag is given, it folds the entire regexp to lower
case before doing anything else with it.  I failed to find any reason
for this: the search routines handle case folding on their own anyway,
and removing the above loop didn't seem to have any other effect than
removing the undesired effect of -i flag on \W (and \B).  

Does somebody know if the folding loop is necessary in some other
program using dfa.c (or do they maybe have the same bug)?

If yes, the following should work (avoids changing letters after a \):

	for (p = (char *)s; *p != 0; p++)
		if (isupper((int)*p))
			*p = tolower((int) *p);
                else if (*p == '\\' && *(p+1))
                        p++;

As far as e?grep is concerned, however, just removing the loop seems
to work just fine (the declaration of p can be removed as well).
Here's a context diff for just that (actually it #if's them
out rather than deletes them and adds a comment):

*** dfa.old	Sat Sep 16 12:04:32 1989
--- dfa.c	Sat Sep 16 12:04:34 1989
***************
*** 1668,1679 ****
--- 1668,1685 ----
  {
    if (case_fold)	/* dummy folding in service of regmust() */
      {
+ /* the following two #if 0's added by Tapani Tarvainen 16 Sep 89   */
+ /* to prevent -i flag from affecting \W and \B in e?grep           */
+ #if 0
  	static char *p;
+ #endif
  
  	case_fold = 0;
+ #if 0
  	for (p = (char *)s; *p != 0; p++)
  		if (isupper((int)*p))
  			*p = tolower((int) *p);
+ #endif
  	reginit(r);
  	r->mustn = 0;
  	r->must[0] = '\0';
-- 
Tapani Tarvainen    (tarvaine@tukki.jyu.fi, tarvainen@finjyu.bitnet)

The y-command doesn't seem to work with Gnu SED 1.02: e.g.,

echo a | sed 'y/a/A/'

complains "extra characters after command".  I tried it under
SunOS 4.0 and MS-DOS with identical results.

Is 1.02 the latest release, and if not, where could a newer one
be found?  (I just might try fixing this myself.)

-- 
Tapani Tarvainen    (tarvaine@tukki.jyu.fi, tarvainen@finjyu.bitnet)

In article <1311@tukki.jyu.fi> tarvaine@tukki.jyu.fi I wrote:
>The y-command doesn't seem to work with Gnu SED 1.02

The bug turned out to be that the program assumed that there is
always '\n' at the end of a line, but it can be EOF as well.
Here's my fix:

*** sed.old	Sun Sep 17 22:28:15 1989
--- sed.c	Sun Sep 17 22:42:38 1989
***************
*** 704,710 ****
  				cur_cmd->x.translate[*string++]=ch;
  			}
  			flush_buffer(b);
! 			if(inchar()!=slash || inchar()!='\n')
  				bad_prog(LINE_JUNK);
  			break;
  
--- 704,710 ----
  				cur_cmd->x.translate[*string++]=ch;
  			}
  			flush_buffer(b);
! 			if(inchar()!=slash || ((ch=inchar())!='\n' && ch!=EOF)
  				bad_prog(LINE_JUNK);
  			break;
  
-- 
Tapani Tarvainen    (tarvaine@tukki.jyu.fi, tarvainen@finjyu.bitnet)

I just found yet abother bug in the y-command of Gnu SED 1.02:
characters >127 won't get translated properly.  This depends on
the compiler, though; the offending line is

				cur_cmd->x.translate[*string++]=ch;

and the problem is that string is declared as char *,
and if chars are signed and *string is negative, the ANSI
promotion rules keep it negative when converted to an int.

The easiest fix (or first that I could think of) is to declare
string as unsigned char*; lint &c will complain about mixing
pointers to signed and unsigned chars, but who cares (if you do,
throw in a few casts or declare all chars as unsigned).
At least it seems to work.

Anyway, here's the diff (this includes the earlier patch):

*** sed.old	Sun Sep 17 22:28:15 1989
--- sed.c	Mon Sep 18 01:58:58 1989
***************
*** 412,418 ****
  	int	ch;
  	int	slash;
  	VOID	*b;
! 	char	*string;
  	int	num;
  
  	FILE *compile_filename();
--- 412,418 ----
  	int	ch;
  	int	slash;
  	VOID	*b;
! 	unsigned char	*string;
  	int	num;
  
  	FILE *compile_filename();
***************
*** 704,710 ****
  				cur_cmd->x.translate[*string++]=ch;
  			}
  			flush_buffer(b);
! 			if(inchar()!=slash || inchar()!='\n')
  				bad_prog(LINE_JUNK);
  			break;
  
--- 704,710 ----
  				cur_cmd->x.translate[*string++]=ch;
  			}
  			flush_buffer(b);
! 			if(inchar()!=slash || ((ch=inchar())!='\n' && ch!=EOF))
  				bad_prog(LINE_JUNK);
  			break;
  


-- 
Tapani Tarvainen    (tarvaine@tukki.jyu.fi, tarvainen@finjyu.bitnet)