#include "e.h"#include "y.tab.h"#include <ctype.h>#include <errno.h> Infile	infile[10];Infile	*curfile = infile; #define	MAXSRC	50Src	src[MAXSRC];	/* input source stack */Src	*srcp	= src; extern int getarg(char *);extern	void eprint(void); void pushsrc(int type, char *ptr)	/* new input source */{	if (++srcp >= src + MAXSRC)		ERROR "inputs nested too deep" FATAL;	srcp->type = type;	srcp->sp = ptr;	if (dbg > 1) {		printf("\n%3d ", srcp - src);		switch (srcp->type) {		case File:			printf("push file %s\n", ((Infile *)ptr)->fname);			break;		case Macro:			printf("push macro <%s>\n", ptr);			break;		case Char:			printf("push char <%c>\n", *ptr);			break;		case String:			printf("push string <%s>\n", ptr);			break;		case Free:			printf("push free <%s>\n", ptr);			break;		default:			ERROR "pushed bad type %d\n", srcp->type FATAL;		}	}} void popsrc(void)	/* restore an old one */{	if (srcp <= src)		ERROR "too many inputs popped" FATAL;	if (dbg > 1) {		printf("%3d ", srcp - src);		switch (srcp->type) {		case File:			printf("pop file\n");			break;		case Macro:			printf("pop macro\n");			break;		case Char:			printf("pop char <%c>\n", *srcp->sp);			break;		case String:			printf("pop string\n");			break;		case Free:			printf("pop free\n");			break;		default:			ERROR "pop weird input %d\n", srcp->type FATAL;		}	}	srcp--;} Arg	args[10];	/* argument frames */Arg	*argfp = args;	/* frame pointer */int	argcnt;		/* number of arguments seen so far */ void dodef(tbl *stp)	/* collect args and switch input to defn */{	int i, len;	char *p;	Arg *ap; 	ap = argfp+1;	if (ap >= args+10)		ERROR "more than arguments\n" FATAL;	argcnt = 0;	if (input() != '(')		ERROR "disaster in dodef\n"FATAL;	if (ap->argval == 0)		ap->argval = malloc(1000);	for (p = ap->argval; (len = getarg(p)) != -1; p += len) {		ap->argstk[argcnt++] = p;		if (input() == ')')			break;	}	for (i = argcnt; i < MAXARGS; i++)		ap->argstk[i] = "";	if (dbg)		for (i = 0; i < argcnt; i++)			printf("arg %d.%d = <%s>\n", ap-args, i+1, ap->argstk[i]);	argfp = ap;	pushsrc(Macro, stp->cval);} getarg(char *p)	/* pick up single argument, store in p, return length */{	int n, c, npar; 	n = npar = 0;	for ( ;; ) {		c = input();		if (c == EOF)			ERROR "end of file in getarg!\n" FATAL;		if (npar == 0 && (c == ',' || c == ')'))			break;		if (c == '"')	/* copy quoted stuff intact */			do {				*p++ = c;				n++;			} while ((c = input()) != '"' && c != EOF);		else if (c == '(')			npar++;		else if (c == ')')			npar--;		n++;		*p++ = c;	}	*p = 0;	unput(c);	return(n + 1);} #define	PBSIZE	2000char	pbuf[PBSIZE];		/* pushback buffer */char	*pb	= pbuf-1;	/* next pushed back character */ char	ebuf[200];		/* collect input here for error reporting */char	*ep	= ebuf; input(void){	register int c = 0;   loop:	switch (srcp->type) {	case File:		c = getc(curfile->fin);		if (c == EOF) {			if (curfile == infile)				break;			if (curfile->fin != stdin) {				fclose(curfile->fin);				free(curfile->fname);	/* assumes allocated */			}			curfile--;			printf(".lf %d %s\n", curfile->lineno, curfile->fname);			popsrc();			goto loop;		}		if (c == '\n')			curfile->lineno++;		break;	case Char:		if (pb >= pbuf) {			c = *pb--;			popsrc();			break;		} else {	/* can't happen? */			popsrc();			goto loop;		}	case String:		c = *srcp->sp++;		if (c == '\0') {			popsrc();			goto loop;		} else {			if (*srcp->sp == '\0')	/* empty, so pop */				popsrc();			break;		}	case Macro:		c = *srcp->sp++;		if (c == '\0') {			if (--argfp < args)				ERROR "argfp underflow" FATAL;			popsrc();			goto loop;		} else if (c == '$' && isdigit(*srcp->sp)) {			int n = 0;			while (isdigit(*srcp->sp))				n = 10 * n + *srcp->sp++ - '0';			if (n > 0 && n <= MAXARGS)				pushsrc(String, argfp->argstk[n-1]);			goto loop;		}		break;	case Free:	/* free string */		free(srcp->sp);		popsrc();		goto loop;	}	if (ep >= ebuf + sizeof ebuf)		ep = ebuf;	*ep++ = c;	return c;}  unput(int c){	if (++pb >= pbuf + sizeof pbuf)		ERROR "pushback overflow\n"FATAL;	if (--ep < ebuf)		ep = ebuf + sizeof(ebuf) - 1;	*pb = c;	pushsrc(Char, pb);	return c;} void pbstr(char *s){	pushsrc(String, s);} void error(int die, char *s){	extern char *cmdname; 	if (synerr)		return;	fprintf(stderr, "%s: ", cmdname);	fprintf(stderr, s);	if (errno > 0)		perror("???");	if (curfile->fin)		fprintf(stderr, " near %s:%d",			curfile->fname, curfile->lineno+1);	fprintf(stderr, "\n");	eprint();	synerr = 1;	errno = 0;	if (die) {		if (dbg)			abort();		else			exit(1);	}} void yyerror(char *s){	error(0, s);	/* temporary */} char errbuf[200];#undef putc void eprint(void)	/* try to print context around error */{	char *p, *q; 	if (ep == ebuf)		return;				/* no context */	p = ep - 1;	if (p > ebuf && *p == '\n')		p--;	for ( ; p >= ebuf && *p != '\n'; p--)		;	while (*p == '\n')		p++;	fprintf(stderr, " context is\n\t");	for (q=ep-1; q>=p && *q!=' ' && *q!='\t' && *q!='\n'; q--)		;	while (p < q)		putc(*p++, stderr);	fprintf(stderr, " >>> ");	while (p < ep)		putc(*p++, stderr);	fprintf(stderr, " <<< ");	while (pb >= pbuf)		putc(*pb--, stderr);	if (curfile->fin)		fgets(ebuf, sizeof ebuf, curfile->fin);	fprintf(stderr, "%s", ebuf);	pbstr("\n.EN\n");	/* safety first */	ep = ebuf;}