grep.y - 9base - revived minimalist port of Plan 9 userland to Unix
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grep.y (2815B)
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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 }