%{#include	"grep.h"%} %union{	int	val;	char*	str;	Re2	re;} %type	<re>	expr prog%type	<re>	expr0 expr1 expr2 expr3 expr4%token	<str>	LCLASS%token	<val>	LCHAR%token		LLPAREN LRPAREN LALT LSTAR LPLUS LQUES%token		LBEGIN LEND LDOT LBAD LNEWLINE%% prog:	/* empty */	{		yyerror("empty pattern");	}|	expr newlines	{		$$.beg = ral(Tend);		$$.end = $$.beg;		$$ = re2cat(re2star(re2or(re2char(0x00, '\n'-1), re2char('\n'+1, 0xff))), $$);		$$ = re2cat($1, $$);		$$ = re2cat(re2star(re2char(0x00, 0xff)), $$);		topre = $$;	} expr:	expr0|	expr newlines expr0	{		$$ = re2or($1, $3);	} expr0:	expr1|	LSTAR { literal = 1; } expr1	{		$$ = $3;	} expr1:	expr2|	expr1 LALT expr2	{		$$ = re2or($1, $3);	} expr2:	expr3|	expr2 expr3	{		$$ = re2cat($1, $2);	} expr3:	expr4|	expr3 LSTAR	{		$$ = re2star($1);	}|	expr3 LPLUS	{		$$.beg = ral(Talt);		patchnext($1.end, $$.beg);		$$.beg->alt = $1.beg;		$$.end = $$.beg;		$$.beg = $1.beg;	}|	expr3 LQUES	{		$$.beg = ral(Talt);		$$.beg->alt = $1.beg;		$$.end = $1.end;		appendnext($$.end,  $$.beg);	} expr4:	LCHAR	{		$$.beg = ral(Tclass);		$$.beg->lo = $1;		$$.beg->hi = $1;		$$.end = $$.beg;	}|	LBEGIN	{		$$.beg = ral(Tbegin);		$$.end = $$.beg;	}|	LEND	{		$$.beg = ral(Tend);		$$.end = $$.beg;	}|	LDOT	{		$$ = re2class("^\n");	}|	LCLASS	{		$$ = re2class($1);	}|	LLPAREN expr1 LRPAREN	{		$$ = $2;	} newlines:	LNEWLINE|	newlines LNEWLINE%% voidyyerror(char *e, ...){	va_list args; 	fprint(2, "grep: ");	if(filename)		fprint(2, "%s:%ld: ", filename, lineno);	else if (pattern)		fprint(2, "%s: ", pattern);	va_start(args, e);	vfprint(2, e, args);	va_end(args);	fprint(2, "\n");	exits("syntax");} longyylex(void){	char *q, *eq;	int c, s; 	if(peekc) {		s = peekc;		peekc = 0;		return s;	}	c = getrec();	if(literal) {		if(c != 0 && c != '\n') {			yylval.val = c;			return LCHAR;		}		literal = 0;	}	switch(c) {	default:		yylval.val = c;		s = LCHAR;		break;	case '\\':		c = getrec();		yylval.val = c;		s = LCHAR;		if(c == '\n')			s = LNEWLINE;		break;	case '[':		goto getclass;	case '(':		s = LLPAREN;		break;	case ')':		s = LRPAREN;		break;	case '|':		s = LALT;		break;	case '*':		s = LSTAR;		break;	case '+':		s = LPLUS;		break;	case '?':		s = LQUES;		break;	case '^':		s = LBEGIN;		break;	case '$':		s = LEND;		break;	case '.':		s = LDOT;		break;	case 0:		peekc = -1;	case '\n':		s = LNEWLINE;		break;	}	return s; getclass:	q = u.string;	eq = q + nelem(u.string) - 5;	c = getrec();	if(c == '^') {		q[0] = '^';		q[1] = '\n';		q[2] = '-';		q[3] = '\n';		q += 4;		c = getrec();	}	for(;;) {		if(q >= eq)			error("class too long");		if(c == ']' || c == 0)			break;		if(c == '\\') {			*q++ = c;			c = getrec();			if(c == 0)				break;		}		*q++ = c;		c = getrec();	}	*q = 0;	if(c == 0)		return LBAD;	yylval.str = u.string;	return LCLASS;}