ref: dae5a44111dfb21a714824a5cec2abee4f9f9080
dir: /sys/src/cmd/grep/comp.c/
#include "grep.h"
/*
* incremental compiler.
* add the branch c to the
* state s.
*/
void
increment(State *s, int c)
{
int i;
State *t, **tt;
Re *re1, *re2;
nfollow = 0;
gen++;
matched = 0;
for(i=0; i<s->count; i++)
fol1(s->re[i], c);
qsort(follow, nfollow, sizeof(*follow), fcmp);
for(tt=&state0; t = *tt;) {
if(t->count > nfollow) {
tt = &t->linkleft;
goto cont;
}
if(t->count < nfollow) {
tt = &t->linkright;
goto cont;
}
for(i=0; i<nfollow; i++) {
re1 = t->re[i];
re2 = follow[i];
if(re1 > re2) {
tt = &t->linkleft;
goto cont;
}
if(re1 < re2) {
tt = &t->linkright;
goto cont;
}
}
if(!!matched && !t->match) {
tt = &t->linkleft;
goto cont;
}
if(!matched && !!t->match) {
tt = &t->linkright;
goto cont;
}
s->next[c] = t;
return;
cont:;
}
t = sal(nfollow);
*tt = t;
for(i=0; i<nfollow; i++) {
re1 = follow[i];
t->re[i] = re1;
}
s->next[c] = t;
t->match = matched;
}
int
fcmp(void *va, void *vb)
{
Re **aa, **bb;
Re *a, *b;
aa = va;
bb = vb;
a = *aa;
b = *bb;
if(a > b)
return 1;
if(a < b)
return -1;
return 0;
}
void
fol1(Re *r, int c)
{
Re *r1;
loop:
if(r->gen == gen)
return;
if(nfollow >= maxfollow)
error("nfollow");
r->gen = gen;
switch(r->type) {
default:
error("fol1");
case Tcase:
if(c >= 0 && c < 256)
if(r1 = r->cases[c])
follow[nfollow++] = r1;
if(r = r->next)
goto loop;
break;
case Talt:
case Tor:
fol1(r->alt, c);
r = r->next;
goto loop;
case Tbegin:
if(c == '\n' || c == Cbegin)
follow[nfollow++] = r->next;
break;
case Tend:
if(c == '\n') {
if(r->next == 0) {
matched = 1;
break;
}
r = r->next;
goto loop;
}
break;
case Tclass:
if(c >= r->lo && c <= r->hi)
follow[nfollow++] = r->next;
break;
}
}
int tab1[] =
{
0x007f,
0x07ff,
0xffff,
};
int tab2[] =
{
0x003f,
0x0fff,
0x3ffff,
};
Re2
rclass(Rune p0, Rune p1)
{
char xc0[6], xc1[6];
int i, n, m;
Re2 x;
if(p0 > p1)
return re2char(0xff, 0xff); // no match
/*
* bust range into same length
* character sequences
*/
for(i=0; i<nelem(tab1); i++) {
m = tab1[i];
if(p0 <= m && p1 > m)
return re2or(rclass(p0, m), rclass(m+1, p1));
}
/*
* bust range into part of a single page
* or into full pages
*/
for(i=0; i<nelem(tab2); i++) {
m = tab2[i];
if((p0 & ~m) != (p1 & ~m)) {
if((p0 & m) != 0)
return re2or(rclass(p0, p0|m), rclass((p0|m)+1, p1));
if((p1 & m) != m)
return re2or(rclass(p0, (p1&~m)-1), rclass(p1&~m, p1));
}
}
n = runetochar(xc0, &p0);
i = runetochar(xc1, &p1);
if(i != n)
error("length");
x = re2char(xc0[0], xc1[0]);
for(i=1; i<n; i++)
x = re2cat(x, re2char(xc0[i], xc1[i]));
return x;
}
int
pcmp(void *va, void *vb)
{
int n;
Rune *a, *b;
a = va;
b = vb;
n = a[0] - b[0];
if(n)
return n;
return a[1] - b[1];
}
/*
* convert character chass into
* run-pair ranges of matches.
* this is 10646/utf specific and
* needs to be changed for some
* other input character set.
* this is the key to a fast
* regular search of characters
* by looking at sequential bytes.
*/
Re2
re2class(char *s)
{
Rune pairs[200+2], *p, *q, ov;
int nc;
Re2 x;
nc = 0;
if(*s == '^') {
nc = 1;
s++;
}
p = pairs;
s += chartorune(p, s);
for(;;) {
if(*p == '\\')
s += chartorune(p, s);
if(*p == 0)
break;
p[1] = *p;
p += 2;
if(p >= pairs + nelem(pairs) - 2)
error("class too big");
s += chartorune(p, s);
if(*p != '-')
continue;
s += chartorune(p, s);
if(*p == '\\')
s += chartorune(p, s);
if(*p == 0)
break;
p[-1] = *p;
s += chartorune(p, s);
}
*p = 0;
qsort(pairs, (p-pairs)/2, 2*sizeof(*pairs), pcmp);
q = pairs;
for(p=pairs+2; *p; p+=2) {
if(p[0] > p[1])
continue;
if(p[0] > q[1] || p[1] < q[0]) {
q[2] = p[0];
q[3] = p[1];
q += 2;
continue;
}
if(p[0] < q[0])
q[0] = p[0];
if(p[1] > q[1])
q[1] = p[1];
}
q[2] = 0;
p = pairs;
if(nc) {
x = rclass(0, p[0]-1);
ov = p[1]+1;
for(p+=2; *p; p+=2) {
x = re2or(x, rclass(ov, p[0]-1));
ov = p[1]+1;
}
x = re2or(x, rclass(ov, Runemax));
} else {
x = rclass(p[0], p[1]);
for(p+=2; *p; p+=2)
x = re2or(x, rclass(p[0], p[1]));
}
return x;
}