/* Copyright 2009
* Kaz Kylheku <kkylheku@gmail.com>
* Vancouver, Canada
* All rights reserved.
*
* BSD License:
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#include <assert.h>
#include <dirent.h>
#include <setjmp.h>
#include <dirent.h>
#include "config.h"
#include "lib.h"
#include "unwind.h"
#include "regex.h"
typedef unsigned int bitcell_t;
#define BITCELL_ALL1 UINT_MAX
#define CHAR_SET_SIZE (256 / (sizeof (bitcell_t) * CHAR_BIT))
#define CHAR_SET_INDEX(CH) ((CH) / (sizeof (bitcell_t) * CHAR_BIT))
#define CHAR_SET_BIT(CH) ((CH) % (sizeof (bitcell_t) * CHAR_BIT))
#define CHAR_SET_L0(CH) ((CH) & 0xFF)
#define CHAR_SET_L1(CH) (((CH) >> 8) & 0xF)
#define CHAR_SET_L2(CH) (((CH) >> 12) & 0xF)
#define CHAR_SET_L3(CH) (((CH) >> 16) & 0x1F)
#define CHAR_SET_L2_LO(CH) ((CH) & (~(wchar_t) 0xFFFF))
#define CHAR_SET_L2_HI(CH) ((CH) | ((wchar_t) 0xFFFF))
#define CHAR_SET_L1_LO(CH) ((CH) & (~(wchar_t) 0xFFF))
#define CHAR_SET_L1_HI(CH) ((CH) | ((wchar_t) 0xFFF))
#define CHAR_SET_L0_LO(CH) ((CH) & (~(wchar_t) 0xFF))
#define CHAR_SET_L0_HI(CH) ((CH) | ((wchar_t) 0xFF))
typedef enum {
CHSET_SMALL, CHSET_DISPLACED, CHSET_LARGE, CHSET_XLARGE
} chset_type_t;
typedef bitcell_t cset_L0_t[CHAR_SET_SIZE];
typedef cset_L0_t *cset_L1_t[16];
typedef cset_L1_t *cset_L2_t[16];
typedef cset_L2_t *cset_L3_t[17];
struct any_char_set {
unsigned type : 3;
unsigned comp : 1;
};
struct small_char_set {
unsigned type : 3;
unsigned comp : 1;
cset_L0_t bitcell;
};
struct displaced_char_set {
unsigned type : 3;
unsigned comp : 1;
cset_L0_t bitcell;
wchar_t base;
};
struct large_char_set {
unsigned type : 3;
unsigned comp : 1;
cset_L2_t dir;
};
struct xlarge_char_set {
unsigned type : 3;
unsigned comp : 1;
cset_L3_t dir;
};
typedef union char_set {
struct any_char_set any;
struct small_char_set s;
struct displaced_char_set d;
struct large_char_set l;
struct xlarge_char_set xl;
} char_set_t;
#define NFA_SET_SIZE 512
typedef enum {
nfa_accept, nfa_empty, nfa_wild, nfa_single, nfa_set
} nfa_kind_t;
struct nfa_state_accept {
nfa_kind_t kind;
unsigned visited;
};
struct nfa_state_empty {
nfa_kind_t kind;
unsigned visited;
nfa_state_t *trans0;
nfa_state_t *trans1;
};
struct nfa_state_single {
nfa_kind_t kind;
unsigned visited;
nfa_state_t *trans;
wchar_t ch;
};
struct nfa_state_set {
nfa_kind_t kind;
unsigned visited;
nfa_state_t *trans;
char_set_t *set;
};
union nfa_state {
struct nfa_state_accept a;
struct nfa_state_empty e;
struct nfa_state_single o;
struct nfa_state_set s;
};
struct nfa_machine {
cnum last_accept_pos;
unsigned visited;
nfa_state_t **move, **clos, **stack;
int nmove, nclos;
cnum count;
nfa_t nfa;
};
static int L0_full(cset_L0_t *L0)
{
int i;
for (i = 0; i < (int) CHAR_SET_SIZE; i++)
if ((*L0)[i] != ((bitcell_t) -1))
return 0;
return 1;
}
static void L0_fill_range(cset_L0_t *L0, wchar_t ch0, wchar_t ch1)
{
int i;
int bt0 = CHAR_SET_BIT(ch0);
int bc0 = CHAR_SET_INDEX(ch0);
bitcell_t mask0 = ~(((bitcell_t) 1 << bt0) - 1);
int bt1 = CHAR_SET_BIT(ch1);
int bc1 = CHAR_SET_INDEX(ch1);
bitcell_t mask1 = (((bitcell_t) 1 << (bt1 + 1) % 32) - 1);
if (bc1 == bc0) {
(*L0)[bc0] |= (mask0 & mask1);
} else {
(*L0)[bc0] |= mask0;
(*L0)[bc1] |= mask1;
for (i = bc0 + 1; i < bc1; i++)
(*L0)[i] = ((bitcell_t) -1);
}
}
static int L0_contains(cset_L0_t *L0, wchar_t ch)
{
return ((*L0)[CHAR_SET_INDEX(ch)] & (1 << CHAR_SET_BIT(ch))) != 0;
}
static int L1_full(cset_L1_t *L1)
{
int i;
for (i = 0; i < 16; i++)
if ((*L1)[i] != (cset_L0_t *) -1)
return 0;
return 1;
}
static void L1_fill_range(cset_L1_t *L1, wchar_t ch0, wchar_t ch1)
{
int i1, i10, i11;
i10 = CHAR_SET_L1(ch0);
i11 = CHAR_SET_L1(ch1);
for (i1 = i10; i1 <= i11; i1++) {
wchar_t c0 = 0, c1 = 0;
cset_L0_t *L0;
if (i1 > i10 && i1 < i11) {
free((*L1)[i1]);
(*L1)[i1] = (cset_L0_t *) -1;
continue;
} else if (i10 == i11) {
c0 = ch0;
c1 = ch1;
} else if (i1 == i10) {
c0 = ch0;
c1 = CHAR_SET_L0_HI(ch0);
} else if (i1 == i11) {
c0 = CHAR_SET_L0_LO(ch1);
c1 = ch1;
}
if ((L0 = (*L1)[i1]) == (cset_L0_t *) -1)
continue;
if (L0 == 0) {
static cset_L0_t blank;
L0 = (*L1)[i1] = (cset_L0_t *) chk_malloc(sizeof *L0);
memcpy(L0, &blank, sizeof *L0);
}
L0_fill_range(L0, CHAR_SET_L0(c0), CHAR_SET_L0(c1));
if (L0_full(L0)) {
free(L0);
(*L1)[i1] = (cset_L0_t *) -1;
}
}
}
static int L1_contains(cset_L1_t *L1, wchar_t ch)
{
int i1 = CHAR_SET_L1(ch);
cset_L0_t *L0 = (*L1)[i1];
if (L0 == 0)
return 0;
else if (L0 == (cset_L0_t *) -1)
return 1;
else
return L0_contains(L0, CHAR_SET_L0(ch));
}
static void L1_free(cset_L1_t *L1)
{
int i1;
if (L1 == (cset_L1_t *) -1)
return;
for (i1 = 0; i1 < 16; i1++)
if ((*L1)[i1] != (cset_L0_t *) -1)
free((*L1)[i1]);
}
static int L2_full(cset_L2_t *L2)
{
int i;
for (i = 0; i < 16; i++)
if ((*L2)[i] != (cset_L1_t *) -1)
return 0;
return 1;
}
static void L2_fill_range(cset_L2_t *L2, wchar_t ch0, wchar_t ch1)
{
int i2, i20, i21;
i20 = CHAR_SET_L2(ch0);
i21 = CHAR_SET_L2(ch1);
for (i2 = i20; i2 <= i21; i2++) {
wchar_t c0 = 0, c1 = 0;
cset_L1_t *L1;
if (i2 > i20 && i2 < i21) {
free((*L2)[i2]);
(*L2)[i2] = (cset_L1_t *) -1;
continue;
} else if (i20 == i21) {
c0 = ch0;
c1 = ch1;
} else if (i2 == i20) {
c0 = ch0;
c1 = CHAR_SET_L1_HI(ch0);
} else if (i2 == i21) {
c0 = CHAR_SET_L1_LO(ch1);
c1 = ch1;
}
if ((L1 = (*L2)[i2]) == (cset_L1_t *) -1)
continue;
if (L1 == 0) {
static cset_L1_t blank;
L1 = (*L2)[i2] = (cset_L1_t *) chk_malloc(sizeof *L1);
memcpy(L1, &blank, sizeof *L1);
}
L1_fill_range(L1, c0, c1);
if (L1_full(L1)) {
free(L1);
(*L2)[i2] = (cset_L1_t *) -1;
}
}
}
static int L2_contains(cset_L2_t *L2, wchar_t ch)
{
int i2 = CHAR_SET_L2(ch);
cset_L1_t *L1 = (*L2)[i2];
if (L1 == 0)
return 0;
else if (L1 == (cset_L1_t *) -1)
return 1;
else
return L1_contains(L1, ch);
}
static void L2_free(cset_L2_t *L2)
{
int i2;
for (i2 = 0; i2 < 16; i2++) {
cset_L1_t *L1 = (*L2)[i2];
if (L1 != 0 && L1 != (cset_L1_t *) -1) {
L1_free((*L2)[i2]);
free((*L2)[i2]);
}
}
}
static void L3_fill_range(cset_L3_t *L3, wchar_t ch0, wchar_t ch1)
{
int i3, i30, i31;
i30 = CHAR_SET_L3(ch0);
i31 = CHAR_SET_L3(ch1);
for (i3 = i30; i3 <= i31; i3++) {
wchar_t c0 = 0, c1 = 0;
cset_L2_t *L2;
if (i3 > i30 && i3 < i31) {
free((*L3)[i3]);
(*L3)[i3] = (cset_L2_t *) -1;
continue;
} else if (i30 == i31) {
c0 = ch0;
c1 = ch1;
} else if (i3 == i30) {
c0 = ch0;
c1 = CHAR_SET_L2_HI(ch0);
} else if (i3 == i31) {
c0 = CHAR_SET_L2_LO(ch1);
c1 = ch1;
}
if ((L2 = (*L3)[i3]) == (cset_L2_t *) -1)
continue;
if (L2 == 0) {
static cset_L2_t blank;
L2 = (*L3)[i3] = (cset_L2_t *) chk_malloc(sizeof *L2);
memcpy(L2, &blank, sizeof *L2);
}
L2_fill_range(L2, c0, c1);
if (L2_full(L2)) {
free(L2);
(*L3)[i3] = (cset_L2_t *) -1;
}
}
}
static int L3_contains(cset_L3_t *L3, wchar_t ch)
{
int i3 = CHAR_SET_L3(ch);
cset_L2_t *L2 = (*L3)[i3];
if (L2 == 0)
return 0;
else if (L2 == (cset_L2_t *) -1)
return 1;
else
return L2_contains(L2, ch);
}
static void L3_free(cset_L3_t *L3)
{
int i3;
for (i3 = 0; i3 < 17; i3++) {
cset_L2_t *L2 = (*L3)[i3];
if (L2 != 0 && L2 != (cset_L2_t *) -1) {
L2_free((*L3)[i3]);
free((*L3)[i3]);
}
}
}
static char_set_t *char_set_create(chset_type_t type, wchar_t base)
{
static char_set_t blank;
char_set_t *cs = (char_set_t *) chk_malloc(sizeof *cs);
*cs = blank;
cs->any.type = type;
if (type == CHSET_DISPLACED)
cs->d.base = base;
return cs;
}
static void char_set_destroy(char_set_t *set)
{
switch (set->any.type) {
case CHSET_DISPLACED:
case CHSET_SMALL:
free(set);
break;
case CHSET_LARGE:
L2_free(&set->l.dir);
free(set);
break;
case CHSET_XLARGE:
L3_free(&set->xl.dir);
free(set);
break;
}
}
static void char_set_compl(char_set_t *set)
{
set->any.comp = 1;
}
static void char_set_add(char_set_t *set, wchar_t ch)
{
switch (set->any.type) {
case CHSET_DISPLACED:
assert (ch >= set->d.base && ch < set->d.base + 256);
ch -= set->d.base;
/* fallthrough */
case CHSET_SMALL:
assert (ch < 256);
set->s.bitcell[CHAR_SET_INDEX(ch)] |= (1 << CHAR_SET_BIT(ch));
break;
case CHSET_LARGE:
assert (ch < 0x10000);
L2_fill_range(&set->l.dir, ch, ch);
break;
case CHSET_XLARGE:
assert (ch < 0x110000);
L3_fill_range(&set->xl.dir, ch, ch);
break;
}
}
static void char_set_add_range(char_set_t *set, wchar_t ch0, wchar_t ch1)
{
if (ch0 >= ch1)
return;
switch (set->any.type) {
case CHSET_DISPLACED:
assert (ch0 >= set->d.base && ch1 < set->d.base + 256);
ch0 -= set->d.base;
ch1 -= set->d.base;
/* fallthrough */
case CHSET_SMALL:
assert (ch1 < 256);
L0_fill_range(&set->s.bitcell, ch0, ch1);
break;
case CHSET_LARGE:
assert (ch1 < 0x10000);
L2_fill_range(&set->l.dir, ch0, ch1);
break;
case CHSET_XLARGE:
assert (ch1 < 0x110000);
L3_fill_range(&set->xl.dir, ch0, ch1);
break;
}
}
static int char_set_contains(char_set_t *set, wchar_t ch)
{
int result = 0;
switch (set->any.type) {
case CHSET_DISPLACED:
if (ch < set->d.base)
break;
ch -= set->d.base;
/* fallthrough */
case CHSET_SMALL:
if (ch >= 256)
break;
result = L0_contains(&set->s.bitcell, ch);
break;
case CHSET_LARGE:
if (ch >= 0x10000)
break;
result = L2_contains(&set->l.dir, ch);
break;
case CHSET_XLARGE:
if (ch >= 0x110000)
break;
result = L3_contains(&set->xl.dir, ch);
break;
}
return set->any.comp ? !result : result;
}
static nfa_state_t *nfa_state_accept(void)
{
nfa_state_t *st = (nfa_state_t *) chk_malloc(sizeof *st);
st->a.kind = nfa_accept;
st->a.visited = 0;
return st;
}
static nfa_state_t *nfa_state_empty(nfa_state_t *t0, nfa_state_t *t1)
{
nfa_state_t *st = (nfa_state_t *) chk_malloc(sizeof *st);
st->e.kind = nfa_empty;
st->e.visited = 0;
st->e.trans0 = t0;
st->e.trans1 = t1;
return st;
}
static nfa_state_t *nfa_state_single(nfa_state_t *t, wchar_t ch)
{
nfa_state_t *st = (nfa_state_t *) chk_malloc(sizeof *st);
st->o.kind = nfa_single;
st->o.visited = 0;
st->o.trans = t;
st->o.ch = ch;
return st;
}
static nfa_state_t *nfa_state_wild(nfa_state_t *t)
{
nfa_state_t *st = (nfa_state_t *) chk_malloc(sizeof *st);
st->o.kind = nfa_wild;
st->o.visited = 0;
st->o.trans = t;
st->o.ch = 0;
return st;
}
static void nfa_state_free(nfa_state_t *st)
{
if (st->a.kind == nfa_set)
char_set_destroy(st->s.set);
free(st);
}
static void nfa_state_shallow_free(nfa_state_t *st)
{
free(st);
}
static nfa_state_t *nfa_state_set(nfa_state_t *t, char_set_t *cs)
{
nfa_state_t *st = (nfa_state_t *) chk_malloc(sizeof *st);
st->s.kind = nfa_set;
st->s.visited = 0;
st->s.trans = t;
st->s.set = cs;
return st;
}
/*
* An acceptance state is converted to an empty transition
* state with specified transitions. It thereby loses
* its acceptance state status. This is used during
* compilation to hook new output paths into an inner NFA,
* either back to itself, or to a new state in the
* surrounding new NFA.
*/
static void nfa_state_empty_convert(nfa_state_t *acc, nfa_state_t *t0,
nfa_state_t *t1)
{
assert (acc->a.kind == nfa_accept);
acc->e.kind = nfa_empty;
acc->e.trans0 = t0;
acc->e.trans1 = t1;
}
/*
* Acceptance state takes on the kind of st, and all associated
* data. I.e. we merge the identity of accept,
* with the contents of st, such that the new state has
* all of the outgoing arrows of st, and
* all of the incoming arrows of acc.
* This is easily done with an assignment, provided
* that st doesn't have any incoming arrows.
* We ensure that start states don't have any incoming
* arrows in the compiler, by ensuring that repetition
* operators terminate their backwards arrows on an
* existing start state, and allocate a new start
* state in front of it.
*/
static void nfa_state_merge(nfa_state_t *acc, nfa_state_t *st)
{
assert (acc->a.kind == nfa_accept);
*acc = *st;
}
static nfa_t nfa_make(nfa_state_t *s, nfa_state_t *acc)
{
nfa_t ret;
ret.start = s;
ret.accept = acc;
return ret;
}
/*
* Combine two NFA's representing regexps that are catenated.
* The acceptance state of the predecessor is merged with the start state of
* the successor.
*/
static nfa_t nfa_combine(nfa_t pred, nfa_t succ)
{
nfa_t ret;
ret.start = pred.start;
ret.accept = succ.accept;
nfa_state_merge(pred.accept, succ.start);
nfa_state_shallow_free(succ.start); /* No longer needed. */
return ret;
}
static nfa_t nfa_compile_set(val args, int comp)
{
val iter;
wchar_t min = WCHAR_MAX;
wchar_t max = 0;
chset_type_t cst;
for (iter = args; iter; iter = rest(iter)) {
val item = first(iter);
if (consp(item)) {
val from = car(item);
val to = cdr(item);
assert (typeof(from) == chr_s && typeof(to) == chr_s);
if (c_chr(from) < min)
min = c_chr(from);
if (c_chr(from) > max)
max = c_chr(from);
if (c_chr(to) < min)
min = c_chr(to);
if (c_chr(to) > max)
max = c_chr(to);
} else if (typeof(item) == chr_s) {
if (c_chr(item) < min)
min = c_chr(item);
if (c_chr(item) > max)
max = c_chr(item);
} else {
assert(0 && "bad regex set");
}
}
if (max < 0x100)
cst = CHSET_SMALL;
else if (max - min < 0x100)
cst = CHSET_DISPLACED;
else if (max < 0x10000)
cst = CHSET_LARGE;
else
cst = CHSET_XLARGE;
{
char_set_t *set = char_set_create(cst, min);
nfa_state_t *acc = nfa_state_accept();
nfa_state_t *s = nfa_state_set(acc, set);
nfa_t ret = nfa_make(s, acc);
for (iter = args; iter; iter = rest(iter)) {
val item = first(iter);
if (consp(item)) {
val from = car(item);
val to = cdr(item);
assert (typeof(from) == chr_s && typeof(to) == chr_s);
char_set_add_range(set, c_chr(from), c_chr(to));
} else if (typeof(item) == chr_s) {
char_set_add(set, c_chr(item));
} else {
assert(0 && "bad regex set");
}
}
if (comp)
char_set_compl(set);
return ret;
}
}
/*
* Input is the items from a regex form,
* not including the regex symbol.
* I.e. (rest '(regex ...)) not '(regex ...).
*/
nfa_t nfa_compile_regex(val items)
{
if (nullp(items)) {
nfa_state_t *acc = nfa_state_accept();
nfa_state_t *s = nfa_state_empty(acc, 0);
nfa_t nfa = nfa_make(s, acc);
return nfa;
} else {
val item = first(items), others = rest(items);
nfa_t nfa;
if (typeof(item) == chr_s) {
nfa_state_t *acc = nfa_state_accept();
nfa_state_t *s = nfa_state_single(acc, c_chr(item));
nfa = nfa_make(s, acc);
} else if (item == wild_s) {
nfa_state_t *acc = nfa_state_accept();
nfa_state_t *s = nfa_state_wild(acc);
nfa = nfa_make(s, acc);
} else if (consp(item)) {
val sym = first(item);
val args = rest(item);
if (sym == set_s) {
nfa = nfa_compile_set(args, 0);
} else if (sym == cset_s) {
nfa = nfa_compile_set(args, 1);
} else if (sym == compound_s) {
nfa = nfa_compile_regex(args);
} else if (sym == zeroplus_s) {
nfa_t nfa_args = nfa_compile_regex(args);
nfa_state_t *acc = nfa_state_accept();
/* New start state has empty transitions going through
the inner NFA, or skipping it right to the new acceptance state. */
nfa_state_t *s = nfa_state_empty(nfa_args.start, acc);
/* Convert acceptance state of inner NFA to one which has
an empty transition back to the start state, and
an empty transition to the new acceptance state. */
nfa_state_empty_convert(nfa_args.accept, nfa_args.start, acc);
nfa = nfa_make(s, acc);
} else if (sym == oneplus_s) {
/* One-plus case differs from zero-plus in that the new start state
does not have an empty transition to the acceptance state.
So the inner NFA must be traversed once. */
nfa_t nfa_args = nfa_compile_regex(args);
nfa_state_t *acc = nfa_state_accept();
nfa_state_t *s = nfa_state_empty(nfa_args.start, 0); /* <-- diff */
nfa_state_empty_convert(nfa_args.accept, nfa_args.start, acc);
nfa = nfa_make(s, acc);
} else if (sym == optional_s) {
/* In this case, we can keep the acceptance state of the inner
NFA as the acceptance state of the new NFA. We simply add
a new start state which can short-circuit to it via an empty
transition. */
nfa_t nfa_args = nfa_compile_regex(args);
nfa_state_t *s = nfa_state_empty(nfa_args.start, nfa_args.accept);
nfa = nfa_make(s, nfa_args.accept);
} else if (sym == or_s) {
/* Simple: make a new start and acceptance state, which form
the ends of a spindle that goes through two branches. */
nfa_t nfa_first = nfa_compile_regex(first(args));
nfa_t nfa_second = nfa_compile_regex(second(args));
nfa_state_t *acc = nfa_state_accept();
/* New state s has empty transitions into each inner NFA. */
nfa_state_t *s = nfa_state_empty(nfa_first.start, nfa_second.start);
/* Acceptance state of each inner NFA converted to empty
transition to new combined acceptance state. */
nfa_state_empty_convert(nfa_first.accept, acc, 0);
nfa_state_empty_convert(nfa_second.accept, acc, 0);
nfa = nfa_make(s, acc);
} else {
assert (0 && "internal error: bad operator in regex");
}
} else {
assert (0 && "internal error: bad regex item");
}
/* We made an NFA for the first item, but others follow.
Compile the others to an NFA recursively, then
stick it with this NFA. */
if (others) {
nfa_t nfa_others = nfa_compile_regex(others);
nfa = nfa_combine(nfa, nfa_others);
}
return nfa;
}
}
static int nfa_all_states(nfa_state_t **inout, int num, unsigned visited)
{
int i;
for (i = 0; i < num; i++)
inout[i]->a.visited = visited;
for (i = 0; i < num; i++) {
nfa_state_t *s = inout[i];
if (num >= NFA_SET_SIZE)
internal_error("NFA set size exceeded");
switch (s->a.kind) {
case nfa_accept:
break;
case nfa_empty:
{
nfa_state_t *e0 = s->e.trans0;
nfa_state_t *e1 = s->e.trans1;
if (e0 && e0->a.visited != visited) {
e0->a.visited = visited;
inout[num++] = e0;
}
if (e1 && e1->a.visited != visited) {
e1->a.visited = visited;
inout[num++] = e1;
}
}
break;
case nfa_wild:
case nfa_single:
case nfa_set:
if (s->o.trans->a.visited != visited) {
s->o.trans->a.visited = visited;
inout[num++] = s->o.trans;
}
break;
}
}
if (num > NFA_SET_SIZE)
internal_error("NFA set size exceeded");
return num;
}
void nfa_free(nfa_t nfa)
{
nfa_state_t **all = (nfa_state_t **) chk_malloc(NFA_SET_SIZE * sizeof *all);
int nstates, i;
all[0] = nfa.start;
all[1] = nfa.accept;
nstates = nfa_all_states(all, 2, nfa.start->a.visited);
for (i = 0; i < nstates; i++)
nfa_state_free(all[i]);
free(all);
}
/*
* Compute the epsilon-closure of the NFA states stored in the set in, whose
* size is given by nin. The results are stored in the set out, the size of
* which is returned. The stack parameter provides storage used by the
* algorithm, so it doesn't have to be allocated and freed repeatedly.
* The visited parameter is a stamp used for marking states which are added
* to the epsilon-closure set, so that sets are not added twice.
* If any of the states added to the closure are acceptance states,
* the accept parameter is used to store the flag 1.
*
* An epsilon-closure is the set of all input states, plus all additional
* states which are reachable from that set with empty (epsilon) transitions.
* (Transitions that don't do not consume and match an input character).
*/
static int nfa_closure(nfa_state_t **stack, nfa_state_t **in, int nin,
nfa_state_t **out, unsigned visited, int *accept)
{
int i, nout = 0;
int stackp = 0;
/* First, add all states in the input state to the closure,
push them on the stack, and mark them as visited. */
for (i = 0; i < nin; i++) {
if (stackp >= NFA_SET_SIZE)
internal_error("NFA set size exceeded");
in[i]->a.visited = visited;
stack[stackp++] = in[i];
out[nout++] = in[i];
if (in[i]->a.kind == nfa_accept)
*accept = 1;
}
while (stackp) {
nfa_state_t *top = stack[--stackp];
if (nout >= NFA_SET_SIZE)
internal_error("NFA set size exceeded");
/* Only states of type nfa_empty are interesting.
Each such state at most two epsilon transitions. */
if (top->a.kind == nfa_empty) {
nfa_state_t *e0 = top->e.trans0;
nfa_state_t *e1 = top->e.trans1;
if (e0 && e0->a.visited != visited) {
e0->a.visited = visited;
stack[stackp++] = e0;
out[nout++] = e0;
if (e0->a.kind == nfa_accept)
*accept = 1;
}
if (e1 && e1->a.visited != visited) {
e1->a.visited = visited;
stack[stackp++] = e1;
out[nout++] = e1;
if (e1->a.kind == nfa_accept)
*accept = 1;
}
}
}
if (nout > NFA_SET_SIZE)
internal_error("NFA set size exceeded");
return nout;
}
/*
* Compute the move set from a given set of NFA states. The move
* set is the set of states which are reachable from the set of
* input states on the consumpion of the input character given by ch.
*/
static int nfa_move(nfa_state_t **in, int nin, nfa_state_t **out, wchar_t ch)
{
int i, nmove;
for (nmove = 0, i = 0; i < nin; i++) {
nfa_state_t *s = in[i];
switch (s->a.kind) {
case nfa_wild:
/* Unconditional match; don't have to look at ch. */
break;
case nfa_single:
if (s->o.ch == ch) /* Character match. */
break;
continue; /* no match */
case nfa_set:
if (char_set_contains(s->s.set, ch)) /* Set match. */
break;
continue; /* no match */
default:
/* Epsilon-transition and acceptance states have no character moves. */
continue;
}
/* The state matches the character, so add it to the move set.
C trick: all character-transitioning state types have the
pointer to the next state in the same position,
among a common set of leading struct members in the union. */
if (nmove >= NFA_SET_SIZE)
internal_error("NFA set size exceeded");
out[nmove++] = s->o.trans;
}
return nmove;
}
/*
* Match regex against the string in. The match is
* anchored to the front of the string; to search
* within the string, a .* must be added to the front
* of the regex.
*
* Returns the length of the prefix of the string
* which matches the regex. Or, if you will,
* the position of the first mismatching
* character.
*
* If the regex does not match at all, zero is
* returned.
*
* Matching stops when a state is reached from which
* there are no transitions on the next input character,
* or when the string runs out of characters.
* The most recently visited acceptance state then
* determines the match length (defaulting to zero
* if no acceptance states were encountered).
*/
cnum nfa_run(nfa_t nfa, const wchar_t *str)
{
const wchar_t *last_accept_pos = 0, *ptr = str;
unsigned visited = nfa.start->a.visited + 1;
nfa_state_t **move = (nfa_state_t **) chk_malloc(NFA_SET_SIZE * sizeof *move);
nfa_state_t **clos = (nfa_state_t **) chk_malloc(NFA_SET_SIZE * sizeof *clos);
nfa_state_t **stack = (nfa_state_t **) chk_malloc(NFA_SET_SIZE * sizeof *stack);
int nmove = 1, nclos;
int accept = 0;
move[0] = nfa.start;
nclos = nfa_closure(stack, move, nmove, clos, visited++, &accept);
if (accept)
last_accept_pos = ptr;
for (; *ptr != 0; ptr++) {
wchar_t ch = *ptr;
accept = 0;
nmove = nfa_move(clos, nclos, move, ch);
nclos = nfa_closure(stack, move, nmove, clos, visited++, &accept);
if (accept)
last_accept_pos = ptr + 1;
if (nclos == 0) /* dead end; no match */
break;
}
nfa.start->a.visited = visited;
free(stack);
free(clos);
free(move);
return last_accept_pos ? last_accept_pos - str : -1;
}
cnum nfa_machine_match_span(nfa_machine_t *nfam)
{
return nfam->last_accept_pos;
}
/*
* NFA machine: represents the logic of the nfa_run function as state machine
* object which can be fed one character at a time.
*/
void nfa_machine_reset(nfa_machine_t *nfam)
{
int accept = 0;
nfam->last_accept_pos = -1;
nfam->visited = nfam->nfa.start->a.visited + 1;
nfam->nmove = 1;
nfam->count = 0;
nfam->move[0] = nfam->nfa.start;
nfam->nclos = nfa_closure(nfam->stack, nfam->move, nfam->nmove,
nfam->clos, nfam->visited++, &accept);
if (accept)
nfam->last_accept_pos = nfam->count;
}
void nfa_machine_init(nfa_machine_t *nfam, nfa_t nfa)
{
nfam->nfa = nfa;
nfam->move = (nfa_state_t **) chk_malloc(NFA_SET_SIZE * sizeof *nfam->move);
nfam->clos = (nfa_state_t **) chk_malloc(NFA_SET_SIZE * sizeof *nfam->clos);
nfam->stack = (nfa_state_t **) chk_malloc(NFA_SET_SIZE * sizeof *nfam->stack);
nfa_machine_reset(nfam);
}
void nfa_machine_cleanup(nfa_machine_t *nfam)
{
free(nfam->stack);
free(nfam->clos);
free(nfam->move);
nfam->stack = 0;
nfam->clos = 0;
nfam->move = 0;
nfam->nfa.start = 0;
nfam->nfa.accept = 0;
}
nfam_result_t nfa_machine_feed(nfa_machine_t *nfam, wchar_t ch)
{
int accept = 0;
if (ch != 0) {
nfam->count++;
nfam->nmove = nfa_move(nfam->clos, nfam->nclos, nfam->move, ch);
nfam->nclos = nfa_closure(nfam->stack, nfam->move, nfam->nmove, nfam->clos,
nfam->visited++, &accept);
if (accept)
nfam->last_accept_pos = nfam->count;
}
nfam->nfa.start->a.visited = nfam->visited;
if (ch && nfam->nclos != 0) {
if (accept)
return NFAM_MATCH;
return NFAM_INCOMPLETE;
}
/* Reached if the null character is
consumed, or NFA hit a transition dead end. */
if (nfam->last_accept_pos == nfam->count)
return NFAM_MATCH;
if (nfam->last_accept_pos == -1)
return NFAM_FAIL;
return NFAM_INCOMPLETE;
}
static void regex_destroy(val regex)
{
nfa_t *pnfa = (nfa_t *) regex->co.handle;
nfa_free(*pnfa);
free(pnfa);
regex->co.handle = 0;
}
static struct cobj_ops regex_obj_ops = {
cobj_equal_op,
cobj_print_op,
regex_destroy,
cobj_mark_op,
cobj_hash_op
};
val regex_compile(val regex_sexp)
{
nfa_t *pnfa = (nfa_t *) chk_malloc(sizeof *pnfa);
*pnfa = nfa_compile_regex(regex_sexp);
return cobj((mem_t *) pnfa, regex_s, ®ex_obj_ops);
}
val regexp(val obj)
{
return (is_ptr(obj) && obj->co.type == COBJ && obj->co.cls == regex_s)
? t : nil;
}
nfa_t *regex_nfa(val reg)
{
assert (reg->co.type == COBJ && reg->co.cls == regex_s);
return (nfa_t *) reg->co.handle;
}
val search_regex(val haystack, val needle_regex, val start,
val from_end)
{
nfa_t *pnfa = regex_nfa(needle_regex);
if (length_str_lt(haystack, start)) {
return nil;
} else {
if (from_end) {
cnum i;
cnum s = c_num(start);
const wchar_t *h = c_str(haystack);
for (i = c_num(length_str(haystack)) - 1; i >= s; i--) {
cnum span = nfa_run(*pnfa, h + i);
if (span >= 0)
return cons(num(i), num(span));
}
} else {
nfa_machine_t nfam;
val i, pos = start, retval;
nfam_result_t last_res = NFAM_INCOMPLETE;
nfa_machine_init(&nfam, *pnfa);
again:
for (i = pos; length_str_gt(haystack, i); i = plus(i, one)) {
last_res = nfa_machine_feed(&nfam, c_chr(chr_str(haystack, i)));
if (last_res == NFAM_FAIL) {
nfa_machine_reset(&nfam);
pos = plus(pos, one);
goto again;
}
}
last_res = nfa_machine_feed(&nfam, 0);
switch (last_res) {
case NFAM_INCOMPLETE:
case NFAM_MATCH:
retval = cons(pos, num(nfa_machine_match_span(&nfam)));
nfa_machine_cleanup(&nfam);
return retval;
case NFAM_FAIL:
nfa_machine_cleanup(&nfam);
return nil;
}
}
return nil;
}
}
val match_regex(val str, val reg, val pos)
{
nfa_machine_t nfam;
val i, retval;
nfam_result_t last_res = NFAM_INCOMPLETE;
nfa_t *pnfa = regex_nfa(reg);
nfa_machine_init(&nfam, *pnfa);
for (i = pos; length_str_gt(str, i); i = plus(i, one)) {
last_res = nfa_machine_feed(&nfam, c_chr(chr_str(str, i)));
if (last_res == NFAM_FAIL)
break;
}
last_res = nfa_machine_feed(&nfam, 0);
switch (last_res) {
case NFAM_INCOMPLETE:
case NFAM_MATCH:
retval = plus(pos, num(nfa_machine_match_span(&nfam)));
nfa_machine_cleanup(&nfam);
return retval;
case NFAM_FAIL:
nfa_machine_cleanup(&nfam);
return nil;
}
return nil;
}