1 %{
2 #include	"grep.h"
3 %}
4 
5 %union
6 {
7 	int	val;
8 	char*	str;
9 	Re2	re;
10 }
11 
12 %type	<re>	expr prog
13 %type	<re>	expr0 expr1 expr2 expr3 expr4
14 %token	<str>	LCLASS
15 %token	<val>	LCHAR
16 %token		LLPAREN LRPAREN LALT LSTAR LPLUS LQUES
17 %token		LBEGIN LEND LDOT LBAD LNEWLINE
18 %%
19 
20 prog:
21 	expr newlines
22 	{
23 		$$.beg = ral(Tend);
24 		$$.end = $$.beg;
25 		$$ = re2cat(re2star(re2or(re2char(0x00, '\n'-1), re2char('\n'+1, 0xff))), $$);
26 		$$ = re2cat($1, $$);
27 		$$ = re2cat(re2star(re2char(0x00, 0xff)), $$);
28 		topre = $$;
29 	}
30 
31 expr:
32 	expr0
33 |	expr newlines expr0
34 	{
35 		$$ = re2or($1, $3);
36 	}
37 
38 expr0:
39 	expr1
40 |	LSTAR { literal = 1; } expr1
41 	{
42 		$$ = $3;
43 	}
44 
45 expr1:
46 	expr2
47 |	expr1 LALT expr2
48 	{
49 		$$ = re2or($1, $3);
50 	}
51 
52 expr2:
53 	expr3
54 |	expr2 expr3
55 	{
56 		$$ = re2cat($1, $2);
57 	}
58 
59 expr3:
60 	expr4
61 |	expr3 LSTAR
62 	{
63 		$$ = re2star($1);
64 	}
65 |	expr3 LPLUS
66 	{
67 		$$.beg = ral(Talt);
68 		patchnext($1.end, $$.beg);
69 		$$.beg->u.alt = $1.beg;
70 		$$.end = $$.beg;
71 		$$.beg = $1.beg;
72 	}
73 |	expr3 LQUES
74 	{
75 		$$.beg = ral(Talt);
76 		$$.beg->u.alt = $1.beg;
77 		$$.end = $1.end;
78 		appendnext($$.end,  $$.beg);
79 	}
80 
81 expr4:
82 	LCHAR
83 	{
84 		$$.beg = ral(Tclass);
85 		$$.beg->u.x.lo = $1;
86 		$$.beg->u.x.hi = $1;
87 		$$.end = $$.beg;
88 	}
89 |	LBEGIN
90 	{
91 		$$.beg = ral(Tbegin);
92 		$$.end = $$.beg;
93 	}
94 |	LEND
95 	{
96 		$$.beg = ral(Tend);
97 		$$.end = $$.beg;
98 	}
99 |	LDOT
100 	{
101 		$$ = re2class("^\n");
102 	}
103 |	LCLASS
104 	{
105 		$$ = re2class($1);
106 	}
107 |	LLPAREN expr1 LRPAREN
108 	{
109 		$$ = $2;
110 	}
111 
112 newlines:
113 	LNEWLINE
114 |	newlines LNEWLINE
115 %%
116 
117 void
118 yyerror(char *e, ...)
119 {
120 	if(filename)
121 		fprint(2, "grep: %s:%ld: %s\n", filename, lineno, e);
122 	else
123 		fprint(2, "grep: %s\n", e);
124 	exits("syntax");
125 }
126 
127 int
128 yylex(void)
129 {
130 	char *q, *eq;
131 	int c, s;
132 
133 	if(peekc) {
134 		s = peekc;
135 		peekc = 0;
136 		return s;
137 	}
138 	c = getrec();
139 	if(literal) {
140 		if(c != 0 && c != '\n') {
141 			yylval.val = c;
142 			return LCHAR;
143 		}
144 		literal = 0;
145 	}
146 	switch(c) {
147 	default:
148 		yylval.val = c;
149 		s = LCHAR;
150 		break;
151 	case '\\':
152 		c = getrec();
153 		yylval.val = c;
154 		s = LCHAR;
155 		if(c == '\n')
156 			s = LNEWLINE;
157 		break;
158 	case '[':
159 		goto getclass;
160 	case '(':
161 		s = LLPAREN;
162 		break;
163 	case ')':
164 		s = LRPAREN;
165 		break;
166 	case '|':
167 		s = LALT;
168 		break;
169 	case '*':
170 		s = LSTAR;
171 		break;
172 	case '+':
173 		s = LPLUS;
174 		break;
175 	case '?':
176 		s = LQUES;
177 		break;
178 	case '^':
179 		s = LBEGIN;
180 		break;
181 	case '$':
182 		s = LEND;
183 		break;
184 	case '.':
185 		s = LDOT;
186 		break;
187 	case 0:
188 		peekc = -1;
189 	case '\n':
190 		s = LNEWLINE;
191 		break;
192 	}
193 	return s;
194 
195 getclass:
196 	q = u.string;
197 	eq = q + nelem(u.string) - 5;
198 	c = getrec();
199 	if(c == '^') {
200 		q[0] = '^';
201 		q[1] = '\n';
202 		q[2] = '-';
203 		q[3] = '\n';
204 		q += 4;
205 		c = getrec();
206 	}
207 	for(;;) {
208 		if(q >= eq)
209 			error("class too long");
210 		if(c == ']' || c == 0)
211 			break;
212 		if(c == '\\') {
213 			*q++ = c;
214 			c = getrec();
215 			if(c == 0)
216 				break;
217 		}
218 		*q++ = c;
219 		c = getrec();
220 	}
221 	*q = 0;
222 	if(c == 0)
223 		return LBAD;
224 	yylval.str = u.string;
225 	return LCLASS;
226 }