V10/cmd/cut.c

static char sccsid[] = "@(#)cut.c	1.2";
#
/* cut : cut and paste columns of a table (projection of a relation)  (GWRL) */
/* Release 1.5; handles single backspaces as produced by nroff    */
# include <stdio.h>	/* make: cc cut.c */
#include <errno.h>
# define NFIELDS 512	/* max no of fields or resulting line length */
# define BACKSPACE 8
main(argc, argv)
int argc; 
char **argv;
{
	int del = '\t';
	int i, j, count, poscnt, r, s, t;
	int endflag, supflag, cflag, fflag, backflag, filenr;
	int sel[NFIELDS];
	register int c;
	register char *p1;
	char *p2, outbuf[NFIELDS];
	FILE *inptr;
	endflag = supflag = cflag = fflag = 0;


	for (i=0; i<NFIELDS; i++)
		sel[i] = 0;
	while (argc > 1 && argv[1][0] == '-'){
		for (i = 1; (c = argv[1][i]) != '\0'; i++) {
			switch(c) {
			case 'd' : 
				del = argv[1][++i];
				if (del == '\0') diag("no delimiter\n");
				break;
			case 's': 
				supflag++ ;
				break;
			case 'c': 
				cflag++ ;
				break;
			case 'f': 
				fflag++ ;
				break;
			default : 
				diag("Usage: cut [-s] [-d<char>] {-c<list> | -f<list>} file ...\n");
				break;
			}
			if (!endflag && (cflag || fflag)) {
				endflag = 1;
				r = s = t = 0;
				do {	
					c = argv[1][++i];
					switch(c) {
					case '-' : 
						if (r) diagl();
						r = 1;
						if (t == 0)  s = 1;
						else {
							s = t; 
							t = 0;
						}
						continue;
					case '\0' :
					case ','  : 
						if (t >= NFIELDS) diagl();
						if (r) { 
							if (t == 0) t = NFIELDS - 1;
							if (t<s) diagl();
							for(j = s; j <= t; j++) sel[j] = 1;
						}
						else sel[t] = (t > 0 ? 1 : 0);
						r = s = t = 0;
						if (c == '\0') {
							i--; 
							break;
						}
						continue;
					default :
						if (c< '0' || c> '9') diagl();
						t = 10*t + c - '0';
						continue;
					}
					for (j = t = 0; j < NFIELDS; j++) t += sel[j];
					if (t == 0) diag("no fields\n");
				} while (c != '\0');
			}
		}
		--argc;
		++argv;
	} /* end options */
	if (!(cflag || fflag)) diagl();

	--argc;
	filenr = 1;
	do {	/* for all input files */
		if (argc > 0) inptr = fopen(argv[filenr], "r");
		else inptr = stdin;

		if (inptr == NULL)
			diag(argv[filenr]);
		endflag = 0;
		do {	/* for all lines of a file */
			count = poscnt = backflag = 0;
			p1 = &outbuf[0] - 1 ;
			p2 = p1;
			do { 	/* for all char of the line */
				c = fgetc(inptr);
				if (c == EOF) {
					endflag = 1;
					break;
				}
				if (count == NFIELDS - 1) diag("line too long\n");
				if (c != '\n') *++p1 = c;
				if (cflag && (c == BACKSPACE)) backflag++ ; 
				else 
				{ 
					if ( !backflag ) poscnt += 1 ; 
					else backflag-- ;
				}
				if ( backflag > 1 ) diag("cannot handle multiple adjacent backspaces\n");
				if ( ((c == '\n') && count > 0)  || c == del || cflag) {
					count += 1;
					if (fflag) poscnt = count  ;
					if (sel[poscnt]) p2 = p1; 
					else p1 = p2;
				}
			}while (c != '\n');
			if ( !endflag && (count > 0 || !supflag)) {
				if (*p1 == del) *p1 = '\0';
				else *++p1 = '\0'; /*suppress trailing delimiter*/
				puts(outbuf);
			}
		} while (!endflag) ;
		fclose(inptr);
	} while(++filenr <= argc);
}

diag(s)
char *s;
{
	write(2, "cut: ", 5);
	if(errno)
		perror(s);
	else
		write(2,s,strlen(s));
	exit(2);
}
diagl()
{
	diag("bad list for c/f option\n");
}