#
/*
 * grep.
 *
 * Runs on the Decus compiler or on vms.
 *
 * On vms, define as:
 *
 *	grep :== "$disk:[account]grep"		(native)
 *	grep :== "$disk:[account]grep grep"	(Decus)
 *
 * See below for more information.
 *
 */

char	*documentation[] {
"grep searches a file for a given pattern.  Execute by",
"        grep [flags] regular_expression file_list",
"",
"Flags are single characters preceeded by '-':",
"   -c      Only a count of matching lines is printed",
"   -f      Print file name for matching lines switch, see below",
"   -n      Each line is preceeded by its line number",
"   -v      Only print non-matching lines",
"",
"On RSX, RT11, RSTS, input or output may be redirected:",
"        grep ... <file.in >file.out",
"The file_list is a list of files (wildcards are acceptable on RSX modes).",
"If no files are given, input comes from the terminal.  There is no prompting.",
"The file name is normally printed if there is a file given.",
"The -f flag reverses this action (print name no file, not if more).",
"",
"The regular_expression defines the pattern to search for.  Upper- and",
"lower-case are always ignored.  Blank lines never match.  The expression",
"should be quoted to prevent file-name translation.",
"x	An ordinary character (not mentioned below) matches that character.",
"'\\'	The backslash quotes any character.  \"\\$\" matches a dollar-sign.",
"'^'	A circumflex at the beginning of an expression matches the",
"	  beginning of a line.",
"'$'	A dollar-sign at the end of an expression matches the end of",
"	  a line.",
"'.'	A period matches any character except \"new-line\".",
"':a'	A colon matches a class of characters described by the following",
"':d'	  character.  \":a\" matches any alphabetic, \":d\" matches digits,",
"':n'	  \":n\" matches alphanumerics, \": \" matches spaces, tabs, and",
"': '	  other control characters, such as new-line.",
"'*'	An expression followed by an asterisk matches zero or more",
"	  occurrances of that expression: \"fo*\" matches \"f\", \"fo\"",
"	  \"foo\", etc.",
"'+'	An expression followed by a plus sign matches one or more",
"	  occurrances of that expression: \"fo+\" matches \"fo\", etc.",
"'-'	An expression followed by a minus sign optionally matches",
"	  the expression.",
"'[]'	A string enclosed in square brackets matches any character in",
"	  that string, but no others.  If the first character in the",
"	  string is a circumflex, the expression matches any character",
"	  except \"new-line\" and the characters in the string.  For",
"	  example, \"[xyz]\" matches \"xx\" and \"zyx\", while \"[^xyz]\"",
"	  matches \"abc\" but not \"axb\".  A range of characters may be",
"	  specified by two characters seperated by \"-\".  Note that,",
"	  [a-z] matches alphabetics, while [z-a] never matches.",
"",
"The concatenation of regular expressions is a regular expression.",
"",
0 };

#ifdef	vms
#define	VMS				/* VMS native compiler		*/
#define	error(s)	_error(s)
#endif

#include <stdio.h>

#define	LMAX	512
#define PMAX	256

#define CHAR	1
#define BOL	2
#define EOL	3
#define	ANY	4
#define CLASS	5
#define	NCLASS	6
#define STAR	7
#define	PLUS	8
#define	MINUS	9
#define	ALPHA	10
#define	DIGIT	11
#define	NALPHA	12
#define	PUNCT	13
#define RANGE	14
#define	ENDPAT	15

int	cflag;
int	fflag;
int	nflag;
int	vflag;
int	nfile;
int	debug	=	0;		/* Set for debug code		*/
char	*pp;

#ifndef	vms
char	file_name[81];
#endif

char	lbuf[LMAX];
char	pbuf[PMAX];

main(argc, argv)
char *argv[];
{
	register char	*p;
	register int	c, i;
	int		gotpattern;
	FILE		*f;
	int		gotcha;

	if (argc <= 1)
		usage("No arguments");
	if (argv[1][0] == '?' && argv[1][1] == 0) {
		help();
		return;
	}
	nfile = argc-1;
	gotpattern = 0;
	for (i=1; i < argc; ++i) {
		p = argv[i];
		if (*p == '-') {
			++p;
			while (c = *p++) {
				switch(lower(c)) {

				case '?':
					help();
					break;

				case 'c':
					++cflag;
					break;

				case 'd':
					++debug;
					break;

				case 'f':
					++fflag;
					break;

				case 'n':
					++nflag;
					break;

				case 'v':
					++vflag;
					break;

				default:
					usage("Unknown flag");
				}
			}
			argv[i] = 0;
			--nfile;
		} else if (!gotpattern) {
			compile(p);
			argv[i] = 0;
			++gotpattern;
			--nfile;
		}
	}
	if (!gotpattern)
		usage("No pattern");
	if (nfile == 0)
		grep(stdin, 0);
	else {
		fflag = fflag ^ (nfile > 0);
		for (i=1; i < argc; ++i) {
			if (p = argv[i]) {
#ifdef vms
				if ((f=fopen(p, "r")) == NULL)
					cant(p);
				else {
					grep(f, p);
					fclose(f);
				}
#else
				if ((f = fwild(p, "r")) == NULL)
					cant(p);
				else {
					gotcha = 0;
					while (fnext(f) != NULL) {
						iovtoa(f, file_name);
						grep(f, file_name);
						gotcha = 1;
				    	}
					if (!gotcha)
						cant(p);
				}
#endif
			}
		}
	}
}


file(s)
char *s;
{
	printf("File %s:\n", s);
}


cant(s)
char *s;
{
	fprintf(stderr, "%s: cannot open\n", s);
}


help()
/*
 * Give good help
 */
{
	register char	**dp;

	for (dp = documentation; *dp; dp++)
		printf("%s\n", *dp);
}


usage(s)
char	*s;
{
	fprintf(stderr, "?GREP-E-%s\n", s);
	fprintf(stderr,
		"Usage: grep [-cfnv] pattern [file ...].  grep ? for help\n");
	exit(1);
}



compile(source)
char		*source;	/* Pattern to compile			*/
/*
 * Compile the pattern into global pbuf[]
 */
{
	register char		*s;	/* Source string pointer	*/
	register char		*lp;	/* Last pattern pointer		*/
	register int		c;	/* Current character		*/
	int			o;	/* Temp				*/
	char			*spp;	/* Save beginning of pattern	*/
	char		*cclass();	/* Compile class routine	*/

	s = source;
	if (debug)
		printf("Pattern = \"%s\"\n", s);
	pp = pbuf;
	while (c = *s++) {
		/*
		 * STAR, PLUS and MINUS are special.
		 */
		if (c == '*' || c == '+' || c == '-') {
			if (pp == pbuf || (o=pp[-1]) == BOL ||
					o == EOL || o == STAR ||
					o == PLUS || o == MINUS)
				badpat("Illegal occurrance op.", source, s);
			store(ENDPAT);
			store(ENDPAT);
			spp = pp;		/* Save pattern end	*/
			while (--pp > lp)	/* Move pattern	down	*/
				*pp = pp[-1];	/* one byte		*/
			*pp =	(c == '*') ? STAR :
				(c == '-') ? MINUS : PLUS;
			pp = spp;		/* Restore pattern end	*/
			continue;
		}
		/*
		 * All the rest.
		 */
		lp = pp;			/* Remember start	*/
		switch(c) {

		case '^':
			store(BOL);
			break;

		case '$':
			store(EOL);
			break;

		case '.':
			store(ANY);
			break;

		case '[':
			s = cclass(source, s);
			break;

		case ':':
			if (*s) {
				c = *s++;
				switch(lower(c)) {

				case 'a':
					store(ALPHA);
					break;

				case 'd':
					store(DIGIT);
					break;

				case 'n':
					store(NALPHA);
					break;

				case ' ':
					store(PUNCT);
					break;

				default:
					badpat("Unknown : type", source, s);

				}
				break;
			}
			else	badpat("No : type", source, s);

		case '\\':
			if (*s)
				c = *s++;

		default:
			store(CHAR);
			store(lower(c));
		}
	}
	store(ENDPAT);
	store(0);				/* Terminate string	*/
	if (debug) {
		for (lp = pbuf; lp < pp;) {
			if ((c = (*lp++ & 0377)) < ' ')
				printf("\\%o ", c);
			else	printf("%c ", c);
		  }
		  printf("\n");
	}
}

char *
cclass(source, src)
char		*source;	/* Pattern start -- for error msg.	*/
char		*src;		/* Class start				*/
/*
 * Compile a class (within [])
 */
{
	register char	*s;		/* Source pointer		*/
	register char	*cp;		/* Pattern start		*/
	register int	c;		/* Current character		*/
	int		o;		/* Temp				*/

	s = src;
	o = CLASS;
	if (*s == '^') {
		++s;
		o = NCLASS;
	}
	store(o);
	cp = pp;
	store(0);				/* Byte count		*/
	while ((c = *s++) && c!=']') {
		if (c == '\\') {		/* Store quoted char	*/
			if ((c = *s++) == '\0')	/* Gotta get something	*/
				badpat("Class terminates badly", source, s);
			else	store(lower(c));
		}
		else if (c == '-' &&
				(pp - cp) > 1 && *s != ']' && *s != '\0') {
			c = pp[-1];		/* Range start		*/
			pp[-1] = RANGE;		/* Range signal		*/
			store(c);		/* Re-store start	*/
			c = *s++;		/* Get end char and	*/
			store(lower(c));	/* Store it		*/
		}
		else {
			store(lower(c));	/* Store normal char	*/
		}
	}
	if (c != ']')
		badpat("Unterminated class", source, s);
	if ((c = (pp - cp)) >= 256)
		badpat("Class too large", source, s);
	if (c == 0)
		badpat("Empty class", source, s);
	*cp = c;
	return(s);
}

store(op)
{
	if (pp >= &pbuf[PMAX])
		error("Pattern too complex\n");
	*pp++ = op;
}

lower(c)
register int c;
{
	if (c>='A' && c<='Z')
		c += 'a'-'A';
	return(c);
}

badpat(message, source, stop)
char		*message;	/* Error message			*/
char		*source;	/* Pattern start			*/
char		*stop;		/* Pattern end				*/
{
	register int	c;

	fprintf(stderr, "-GREP-E-%s, pattern is\"%s\"\n", message, source);
	fprintf(stderr, "-GREP-E-Stopped at byte %d, '%c'\n",
			stop-source, stop[-1]);
	error("?GREP-E-Bad pattern\n");
}


grep(fp, fn)
FILE		*fp;		/* File to process			*/
char		*fn;		/* File name (for -f option)		*/
/*
 * Scan the file for the pattern in pbuf[]
 */
{
	register int lno, count, m;

	lno = 0;
	count = 0;
	while (fgetss(lbuf, sizeof lbuf, fp)) {
		++lno;
		m = match();
		if ((m && !vflag) || (!m && vflag)) {
			++count;
			if (!cflag) {
				if (fflag && fn) {
					file(fn);
					fn = 0;
				}
				if (nflag)
					printf("%d\t", lno);
				printf("%s\n", lbuf);
			}
		}
	}
	if (cflag) {
		if (fflag && fn)
			file(fn);
		printf("%d\n", count);
	}
}

match()
/*
 * Match the current line (in lbuf[]), return 1 if it does.
 */
{
	register char	*l;		/* Line pointer			*/
	char *pmatch();

	for (l = lbuf; *l; l++) {
		if (pmatch(l, pbuf))
			return(1);
	}
	return(0);
}

char *
pmatch(line, pattern)
char		*line;		/* (partial) line to match		*/
char		*pattern;	/* (partial) pattern to match		*/
{
	register char	*l;		/* Current line pointer		*/
	register char	*p;		/* Current pattern pointer	*/
	register char	c;		/* Current character		*/
	char		*e;		/* End for STAR and PLUS match	*/
	int		op;		/* Pattern operation		*/
	int		n;		/* Class counter		*/
	char		*are;		/* Start of STAR match		*/

	l = line;
	if (debug > 1)
		printf("pmatch(\"%s\")\n", line);
	p = pattern;
	while ((op = *p++) != ENDPAT) {
		if (debug > 1)
			printf("byte[%d] = 0%o, '%c', op = 0%o\n",
					l-line, *l, *l, op);
		switch(op) {

		case CHAR:
			if (lower(*l++) != *p++)
				return(0);
			break;

		case BOL:
			if (l != lbuf)
				return(0);
			break;

		case EOL:
			if (*l != '\0')
				return(0);
			break;

		case ANY:
			if (*l++ == '\0')
				return(0);
			break;

		case DIGIT:
			if ((c = *l++) < '0' || (c > '9'))
				return(0);
			break;

		case ALPHA:
			c = lower(*l++);
			if (c < 'a' || c > 'z')
				return(0);
			break;

		case NALPHA:
			c = lower(*l++);
			if (c >= 'a' && c <= 'z')
				break;
			else if (c < '0' || c > '9')
				return(0);
			break;

		case PUNCT:
			c = *l++;
			if (c == 0 || c > ' ')
				return(0);
			break;

		case CLASS:
		case NCLASS:
			c = lower(*l++);
			n = *p++ & 0377;
			do {
				if (*p == RANGE) {
					p += 3;
					n -= 2;
					if (c >= p[-2] && c <= p[-1])
						break;
				}
				else if (c == *p++)
					break;
			} while (--n > 1);
			if ((op == CLASS) == (n <= 1))
				return(0);
			if (op == CLASS)
				p += n - 2;
			break;

		case MINUS:
			e = pmatch(l, p);	/* Look for a match	*/
			while (*p++ != ENDPAT);	/* Skip over pattern	*/
			if (e)			/* Got a match?		*/
				l = e;		/* Yes, update string	*/
			break;			/* Always succeeds	*/

		case PLUS:			/* One or more ...	*/
			if ((l = pmatch(l, p)) == 0)
				return(0);	/* Gotta have a match	*/
		case STAR:			/* Zero or more ...	*/
			are = l;		/* Remember line start	*/
			while (*l && (e = pmatch(l, p)))
				l = e;		/* Get longest match	*/
			while (*p++ != ENDPAT);	/* Skip over pattern	*/
			while (l >= are) {	/* Try to match rest	*/
				if (e = pmatch(l, p))
					return(e);
				--l;		/* Nope, try earlier	*/
			}
			return(0);		/* Nothing else worked	*/

		default:
			printf("Bad op code %d\n", op);
			error("Cannot happen -- match\n");
		}
	}
	return(l);
}