#pragma prototyped
static const char usage[] =
"[-?\n@(#)$Id: fold (AT&T Labs Research) 2003-08-11 $\n]"
USAGE_LICENSE
"[+NAME?fold - fold lines]"
"[+DESCRIPTION?\bfold\b is a filter that folds lines from its input, "
"breaking the lines to have a maximum of \awidth\a column "
"positions (or bytes if the \b-b\b option is specified). Lines "
"are broken by the insertion of a newline character such that "
"each output line is the maximum width possible that does not "
"exceed the specified number of column positions, (or bytes). A line "
"will not be broken in the middle of a character.] "
"[+?Unless the \b-b\b option is specified, the following will be treated "
"specially:]{"
"[+carriage-return?The current count of line width will be set "
"to zero. \bfold\b will not insert a newline immediately "
"before or after a carriage-return.]"
"[+backspace?If positive, the current count of line width will be "
"decremented by one. \bfold\b will not insert a newline "
"immediately before or after a backspace.]"
"[+tab?Each tab character encountered will advance the column "
"position to the next tab stop. Tab stops are at each "
"column position \an\a, where \an\a modulo 8 equals 1.]"
"}"
"[+?If no \afile\a is given, or if the \afile\a is \b-\b, \bfold\b "
"reads from standard input. The start of the file is defined "
"as the current offset.]"
"[b:bytes?Count bytes rather than columns so that each carriage-return, "
"backspace, and tab counts as 1.]"
"[d:delimiter?Break at \adelim\a boundaries.]:[delim]"
"[s:spaces?Break at word boundaries. If the line contains any blanks, "
"(spaces or tabs), within the first \awidth\a column positions or "
"bytes, the line is broken after the last blank meeting the "
"\awidth\a constraint.]"
"[w:width]#[width:=80?Use a maximum line length of \awidth\a columns "
"instead of the default.]"
"\n"
"\n[file ...]\n"
"\n"
"[+EXIT STATUS?]{"
"[+0?All files processed successfully.]"
"[+>0?An error occurred.]"
"}"
"[+SEE ALSO?\bpaste\b(1)]"
;
#include <cmdlib.h>
#define WIDTH 80
#define TABSIZE 8
#define T_EOF 1
#define T_NL 2
#define T_BS 3
#define T_TAB 4
#define T_SP 5
#define T_RET 6
static char cols[1<<CHAR_BIT];
static void fold(Sfio_t *in, Sfio_t *out, register int width)
{
register char *cp, *first;
register int n, col=0, x=0;
register char *last_space=0;
cols[0] = 0;
for (;;)
{
if (!(cp = sfgetr(in,'\n',0)))
{
if (!(cp = sfgetr(in,'\n',-1)) || (n = sfvalue(in)) <= 0)
break;
x = cp[--n];
cp[n] = '\n';
}
if(cols['\b']==0 && (n=sfvalue(in))<=width)
{
sfwrite(out,cp,n);
continue;
}
first = cp;
col = 0;
last_space = 0;
for(;;)
{
while((n=cols[*(unsigned char*)cp++])==0);
while((cp-first) > (width-col))
{
if(last_space)
col = last_space - first;
else
col = width-col;
sfwrite(out,first,col);
first += col;
col = 0;
last_space = 0;
if(cp>first+1 || (n!=T_NL && n!=T_BS))
sfputc(out,'\n');
}
switch(n)
{
case T_NL:
if(x)
*(cp-1) = x;
break;
case T_RET:
col = 0;
continue;
case T_BS:
if((cp+(--col)-first)>0)
col--;
continue;
case T_TAB:
n = (TABSIZE-1) - (cp+col-1-first)&(TABSIZE-1);
col +=n;
if((cp-first) > (width-col))
{
sfwrite(out,first,(--cp)-first);
sfputc(out,'\n');
first = cp;
col = TABSIZE-1;
last_space = 0;
continue;
}
if(cols[' '])
last_space = cp;
continue;
case T_SP:
last_space = cp;
continue;
default:
continue;
}
break;
}
sfwrite(out,first,cp-first);
}
}
int
b_fold(int argc, char *argv[], void* context)
{
register int n, width=WIDTH;
register Sfio_t *fp;
register char *cp;
cmdinit(argv, context, ERROR_CATALOG, 0);
cols['\t'] = T_TAB;
cols['\b'] = T_BS;
cols['\n'] = T_NL;
cols['\r'] = T_RET;
for (;;)
{
switch (optget(argv, usage))
{
case 0:
break;
case 'b':
cols['\r'] = cols['\b'] = 0;
cols['\t'] = cols[' '];
continue;
case 'd':
if (n = *opt_info.arg)
cols[n] = T_SP;
continue;
case 's':
cols[' '] = T_SP;
if(cols['\t']==0)
cols['\t'] = T_SP;
continue;
case 'w':
if ((width = opt_info.num) <= 0)
error(2, "%d: width must be positive", opt_info.num);
continue;
case ':':
error(2, "%s", opt_info.arg);
continue;
case '?':
error(ERROR_usage(2), "%s", opt_info.arg);
continue;
}
break;
}
argv += opt_info.index;
argc -= opt_info.index;
if(error_info.errors)
error(ERROR_usage(2),"%s", optusage(NiL));
if(cp = *argv)
argv++;
do
{
if(!cp || streq(cp,"-"))
fp = sfstdin;
else if(!(fp = sfopen(NiL,cp,"r")))
{
error(ERROR_system(0),"%s: cannot open",cp);
error_info.errors = 1;
continue;
}
fold(fp,sfstdout,width);
if(fp!=sfstdin)
sfclose(fp);
}
while(cp= *argv++);
return(error_info.errors);
}