1 files changed, 226 insertions, 0 deletions
diff --git a/src/cmd/grep/grep.y b/src/cmd/grep/grep.y
new file mode 100644
index 00000000..94a744cf
--- /dev/null
+++ b/src/cmd/grep/grep.y
@@ -0,0 +1,226 @@
+%{
+#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:
+	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
+	{
+		$$ = re2class($1);
+	}
+|	LLPAREN expr1 LRPAREN
+	{
+		$$ = $2;
+	}
+
+newlines:
+	LNEWLINE
+|	newlines LNEWLINE
+%%
+
+void
+yyerror(char *e, ...)
+{
+	if(filename)
+		fprint(2, "grep: %s:%ld: %s\n", filename, lineno, e);
+	else
+		fprint(2, "grep: %s\n", e);
+	exits("syntax");
+}
+
+long
+yylex(void)
+{
+	char *q, *eq;
+	int c, s;
+
+	if(peekc) {
+		s = peekc;
+		peekc = 0;
+		return s;
+	}
+	c = getrec();
+	if(literal) {
+		if(c != 0 && c != '\n') {
+			yylval.val = c;
+			return LCHAR;
+		}
+		literal = 0;
+	}
+	switch(c) {
+	default:
+		yylval.val = c;
+		s = LCHAR;
+		break;
+	case '\\':
+		c = getrec();
+		yylval.val = c;
+		s = LCHAR;
+		if(c == '\n')
+			s = LNEWLINE;
+		break;
+	case '[':
+		goto getclass;
+	case '(':
+		s = LLPAREN;
+		break;
+	case ')':
+		s = LRPAREN;
+		break;
+	case '|':
+		s = LALT;
+		break;
+	case '*':
+		s = LSTAR;
+		break;
+	case '+':
+		s = LPLUS;
+		break;
+	case '?':
+		s = LQUES;
+		break;
+	case '^':
+		s = LBEGIN;
+		break;
+	case '$':
+		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;
+}