9base

revived minimalist port of Plan 9 userland to Unix
git clone git://git.suckless.org/9base
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grep.y (2815B)

      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 }