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%{
#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;
}
|